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Sample records for silver fluoride activated

  1. Synthesis and characterization of activated lithium fluoride with silver

    International Nuclear Information System (INIS)

    Encarnacion E, E. K.; Guerrero S, Z.; Reyes A, J.

    2017-10-01

    The present work shows part of the results obtained in the development of the research that has been carried out since 2015 entitled -Synthesis and characterization of new thermoluminescent materials for the radiation dosimetry and its applications in health-. In the development of this research, the synthesis of crystals of pure lithium fluoride (LiF) and activated with different concentrations of silver (LiF:Ag); synthesized samples are also presented using different temperatures, as well as varying the concentration of the solvent (water-ethanol). The synthesized materials were characterized through different techniques: scanning electron microscopy and X-ray diffraction. Specifically, the results of the calculation of the size of the LiF crystals are presented using the Scherrer equation. Within the results, a dependence on the size of the crystals is highlighted by means of the following factors: the amount of activator in the sample, the temperature at which the sample was synthesized, as well as the amount of solvent in the synthesis. The samples have a simple cubic crystalline phase. (Author)

  2. Antibacterial Effect of Silver Diamine Fluoride on Cariogenic Organisms.

    Science.gov (United States)

    Lou, Yali; Darvell, Brain W; Botelho, Michael G

    2018-05-01

    To screen the possible antimicrobial activity of a range of clinically used, silver-based compounds on cariogenic organisms: silver diamine fluoride (SDF), silver fluoride, and silver nitrate. Preliminary screening disk-diffusion susceptibility tests were conducted on Mueller-Hinton agar plates inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces naeslundii, organisms known to be cariogenic. In order to identify which component of the silver compounds was responsible for any antibacterial (AB) effect, and to provide controls, the following were also investigated at high and low concentrations: sodium fluoride, ammonium fluoride, ammonium chloride, sodium fluoride, sodium chloride, and sodium nitrate, as well as deionized water as control. A volume of 10 pL of a test solution was dispensed onto a paper disk resting on the inoculated agar surface, and the plate incubated anaerobically at 37°C for 48 hours. The zones of inhibition were then measured. Silver diamine fluoride, silver fluoride, silver nitrate, and ammonium fluoride had significant AB effect (p effect at low concentration; the remaining other compounds had no effect. Silver ions appear to be the principal AB agent at both high and low concentration; fluoride ions only have an AB effect at high concentration, while ammonium, nitrate, chloride and sodium ions have none. The anticaries effect of topical silver solutions appears restricted to that of the silver ions. Silver compounds, such as SDF, silver fluoride, and silver nitrate have AB effect against cariogenic organisms and these may have clinical impact in arresting or preventing dental decay. Sodium fluoride did not have AB effect under the conditions tested.

  3. Silver diamine fluoride: a caries "silver-fluoride bullet".

    Science.gov (United States)

    Rosenblatt, A; Stamford, T C M; Niederman, R

    2009-02-01

    The antimicrobial use of silver compounds pivots on the 100-year-old application of silver nitrate, silver foil, and silver sutures for the prevention and treatment of ocular, surgical, and dental infections. Ag(+) kills pathogenic organisms at concentrations of linings, water purification systems, hospital gowns, and caries prevention. To distill the current best evidence relative to caries, this systematic review asked: Will silver diamine fluoride (SDF) more effectively prevent caries than fluoride varnish? A five-database search, reference review, and hand search identified 99 human clinical trials in three languages published between 1966 and 2006. Dual review for controlled clinical trials with the patient as the unit of observation, and excluding cross-sectional, animal, in vitro studies, and opinions, identified 2 studies meeting the inclusion criteria. The trials indicated that SDF's lowest prevented fractions for caries arrest and caries prevention were 96.1% and 70.3%, respectively. In contrast, fluoride varnish's highest prevented fractions for caries arrest and caries prevention were 21.3% and 55.7%, respectively. Similarly, SDF's highest numbers needed to treat for caries arrest and caries prevention were 0.8 (95% CI=0.5-1.0) and 0.9 (95% CI=0.4-1.1), respectively. For fluoride varnish, the lowest numbers needed to treat for caries arrest and prevention were 3.7 (95% CI=3.4-3.9) and 1.1 (95% CI=0.7-1.4), respectively. Adverse events were monitored, with no significant differences between control and experimental groups. These promising results suggest that SDF is more effective than fluoride varnish, and may be a valuable caries-preventive intervention. As well, the availability of a safe, effective, efficient, and equitable caries-preventive agent appears to meet the criteria of both the WHO Millennium Goals and the US Institute of Medicine's criteria for 21st century medical care.

  4. Coprecipitation of iron and silver with barium fluoride

    International Nuclear Information System (INIS)

    Kopilova, N.V.; Khamidov, B.O.; Kashina, Z.A.; Ikrami, D.D.

    1986-01-01

    Distribution of trace contaminants of iron and silver at coprecipitation of barium fluoride is studied in present work. It is defined that iron almost completely coprecipitated with barium fluoride in wide range of ph 5.5-12. Silver coprecipitated with barium fluoride in ph range 4-7. The value of coprecipitation varies from 94% to 100%.

  5. Formation of Fluorohydroxyapatite with Silver Diamine Fluoride.

    Science.gov (United States)

    Mei, M L; Nudelman, F; Marzec, B; Walker, J M; Lo, E C M; Walls, A W; Chu, C H

    2017-09-01

    Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared-calcium phosphate (CaCl 2 ·2H 2 O + K 2 HPO 4 in buffer solution) and SDF (Ag[NH 3 ] 2 F in buffer solution). After incubation at 37 o C for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with

  6. Silver copper fluoride: A novel perovskite cathode for lithium batteries

    Science.gov (United States)

    Tong, Wei; Amatucci, Glenn G.

    2017-09-01

    An electrochemically active nanostructured silver copper fluoride (SCF) perovskite, AgCuF3, was synthesized via a mechanochemical reaction between AgF and CuF2 precursors. Phase composition and electrochemical properties of the SCF perovskites produced under various synthetic parameters were studied. The optimum SCF perovskite sample exhibited an appreciable electrochemical performance through the use of conductive carbon matrix in a primary lithium half cell. A high specific capacity of 270 mAh g-1 was achieved at a cutoff voltage of 2 V with 190 mAh g-1 above 3 V, leading to a total volumetric energy density of 3666 Wh L-1 at >3 V and 4848 Wh L-1 at >2 V.

  7. Efficacy of silver diamine fluoride for Arresting Caries Treatment.

    NARCIS (Netherlands)

    Yee, R.T.F.; Holmgren, C.J.; Mulder, J.; Lama, D.; Walker, D.; Palenstein Helderman, W.H. van

    2009-01-01

    Arresting Caries Treatment (ACT) has been proposed to manage untreated dental caries in children. This prospective randomized clinical trial investigated the caries-arresting effectiveness of a single spot application of: (1) 38% silver diamine fluoride (SDF) with tannic acid as a reducing agent;

  8. Fluoride concentration in urine after silver diamine fluoride application on tooth enamel

    Science.gov (United States)

    Sari, D. L.; Bahar, A.; Gunawan, H. A.; Adiatman, M.; Rahardjo, A.; Maharani, D. A.; Toptanci, I. R.; Yavuz, I.

    2017-08-01

    Silver Diammine Fluoride (SDF), which contains fluoride, is known to inhibit tooth enamel demineralization and increase fluoride concentrations in saliva and urine. The aim of this study is to analyze the fluoride concentration in urine after application of SDF on tooth enamel. Urine from four subjects was collected prior to, 30 minutes after, and two and three hours after the application of SDF, and an ion-selective electrode was used to measure the fluoride concentrations. There was no significant difference between time 1 and time 2, time 1 and time 3, time 1 and time 4, time 2 and 3 (p > 0.05), and there was a significant difference between time 2 and time 4 as well as time 3 and time 4 (p < 0.05). There was a decrease in the concentration of fluoride ions in urine from the baseline to 30 minutes after application, and an increase from baseline to two and three hours after the application of SDF.

  9. Short term serum pharmacokinetics of diammine silver fluoride after oral application.

    Science.gov (United States)

    Vasquez, Elsa; Zegarra, Graciela; Chirinos, Edgar; Castillo, Jorge L; Taves, Donald R; Watson, Gene E; Dills, Russell; Mancl, Lloyd L; Milgrom, Peter

    2012-12-31

    There is growing interest in the use of diammine silver fluoride (DSF) as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized. This preliminary study determined the applied doses (3 teeth treated), maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL). Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively. Fluoride exposure was below the U.S. Environmental Protection Agency (EPA) oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults. NCT01664871.

  10. Root caries prevention via sodium fluoride, chlorhexidine and silver diamine fluoride in vitro.

    Science.gov (United States)

    Göstemeyer, Gerd; Kohls, Anna; Paris, Sebastian; Schwendicke, Falk

    2018-01-31

    Uncertainty exists as to how to best prevent root caries development. The aim of the present study was to compare sodium fluoride (NaF), chlorhexidine (CHX) and silver diamine fluoride (SDF) varnishes (V) and rinses (R) regarding their caries preventive effect in an artificial caries biofilm model. 140 bovine root dentin samples were cut, polished and embedded. Samples were allocated to seven treatment groups (n = 20/group): Four varnishes (applied once prior biofilm challenge): 38% SDF (SDFV), 35% CHX-varnish (CHXV), 22,600 ppm NaF-varnish (NaFV), placebo-varnish (PV); two rinses (applied once daily during biofilm challenge): 500 ppm NaF solution (NaFR), 0.1% CHX solution (CHXR); one untreated group. Caries was induced in a multi-station, continuous-culture Lactobacillus rhamnosus GG (LGG) biofilm model. Bacteria were inoculated 1 × daily, while 2% sucrose was supplied 8 ×/day followed by artificial saliva for 10 min. After 12 days, mineral loss (ΔZ) was measured in the effect area and adjacent to the varnished areas. Bacterial counts were assessed on de-Man-Rogosa-Sharpe agar. ΔZ was significantly lower in the NaFR group compared with all other groups. Varnishes did not significantly prevent mineral loss in adjacent areas. None of the agents had a significant antimicrobial effect on LGG. Regular fluoride rinses showed highest root caries-preventive effect.

  11. Preconcentration of silver as silver xanthate on activated carbon

    International Nuclear Information System (INIS)

    Ramadevi, P.; Naidu, U.V.; Naidu, G.R.K.

    1988-01-01

    Silver from aqueous solution was preconcentrated by adsorption on activated carbon as silver xanthate. Factors influencing the adsorption of silver were studied. Optimum conditions for the preconcentration of silver were established. (author) 9 refs.; 3 tabs

  12. Short term serum pharmacokinetics of diammine silver fluoride after oral application

    Directory of Open Access Journals (Sweden)

    Vasquez Elsa

    2012-12-01

    Full Text Available Abstract Background There is growing interest in the use of diammine silver fluoride (DSF as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized. Methods This preliminary study determined the applied doses (3 teeth treated, maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL. Results Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively. Conclusions Fluoride exposure was below the U.S. Environmental Protection Agency (EPA oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults. Clinical trials registration NCT01664871.

  13. Arrest of Root Carious Lesions via Sodium Fluoride, Chlorhexidine and Silver Diamine Fluoride In Vitro

    Directory of Open Access Journals (Sweden)

    Gerd Göstemeyer

    2017-12-01

    Full Text Available Objective: To compare the root carious lesion arrest of chlorhexidine (CHX and silver diamine fluoride (SDF varnishes and/or sodium fluoride rinses (NaF in vitro. Background: Effective and easily applicable interventions for treating root carious lesions are needed, as these lesions are highly prevalent amongst elderly individuals. Methods: In 100 bovine dentin samples, artificial root carious lesions were induced using acetic acid and a continuous-culture Lactobacillus rhamnosus biofilm model. One quarter of each induced lesion was excavated and baseline dentinal bacterial counts assessed as Colony-Forming-Units (CFU per mg. Samples were allocated to one of four treatments (n = 25/group: (1 untreated control; (2 38% SDF or (3 35% CHX varnish, each applied once, plus 500 ppm daily NaF rinse in the subsequent lesion progression phase; and (4 daily NaF rinses only. Samples were re-transferred to the biofilm model and submitted to a cariogenic challenge. After six days, another quarter of each lesion was used to assess bacterial counts and the remaining sample was used to assess integrated mineral loss (ΔZ using microradiography. Results: ΔZ did not differ significantly between control (median (25th/75th percentiles: 9082 (7859/9782 vol % × µm, NaF (6704 (4507/9574 and SDF 7206 (5389/8082 (p < 0.05/Kruskal–Wallis test. CHX significantly reduced ΔZ (3385 (2447/4496 compared with all other groups (p < 0.05. Bacterial numbers did not differ significantly between control (1451 (875/2644 CFU/µg and NaF (750 (260/1401 (p > 0.05. SDF reduced bacterial counts (360 (136/1166 significantly compared with control (p < 0.05. CHX reduced bacterial counts (190 (73/517 significantly compared with NaF and control (p < 0.05. Conclusion: CHX varnish plus regular NaF rinses arrested root carious lesions most successfully.

  14. Evaluation of silver diamine fluoride application in children and factors associated with arrested caries survival

    Science.gov (United States)

    Chandra, L.; Rahardjo, A.; Adiatman, M.; Darwita, R.; Maharani, D. A.; Callea, M.

    2017-08-01

    Dental caries is one of the most prevalent infectious diseases in children in Indonesia. Therefore, a solution to overcome caries is needed. Evaluate Silver diamine fluoride (SDF) application for overcoming caries in children and determine factors related to the percentage of arrested caries after SDF application. Cohort study for evaluation and a cross-sectional study; 115 children aged 3-5 years who had active dentin caries were the subjects. Caries risk factors were measured by questionnaires filled out by subjects’ parents. Active caries treated with SDF had odds ratios of 9.9 and 6.8 of being arrested after 3 and 10 months, respectively, when compared with those not treated. Conclusion: SDF is effective in arresting caries and decreasing toothaches suffered by children, thus potentially increasing children’s quality of life.

  15. Effectiveness of silver diamine fluoride in caries prevention and arrest: a systematic literature review

    OpenAIRE

    Contreras, Violeta; Toro, Milagros J.; Elías-Boneta, Augusto R.; Encarnación-Burgos, Angeliz

    2017-01-01

    This study aimed to evaluate the scientific evidence regarding the effectiveness of silver diamine fluoride (SDF) in preventing and arresting caries in the primary dentition and permanent first molars. A systematic review (SR) was performed by 2 independent reviewers using 3 electronic databases (PubMed, ScienceDirect, and Scopus). The database search employed the following key words: “topical fluorides” AND “children” AND “clinical trials”; “topical fluorides” OR “silver diamine fluoride” AN...

  16. Gramicidin D enhances the antibacterial activity of fluoride

    OpenAIRE

    Nelson, James W.; Zhou, Zhiyuan; Breaker, Ronald R.

    2014-01-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in B. subtilis and that the antibacterial activity of this compound...

  17. An ex vivo study of arrested primary teeth caries with silver diamine fluoride therapy.

    Science.gov (United States)

    Mei, May L; Ito, L; Cao, Y; Lo, Edward C M; Li, Q L; Chu, C H

    2014-04-01

    This ex vivo study compared the physico-chemical structural differences between primary carious teeth biannually treated with silver diamine fluoride (SDF) and carious teeth without such treatment. Twelve carious primary upper-central incisors were collected from 6-year-old children. Six teeth had arrested caries after 24-month biannual SDF applications and 6 had active caries when there was no topical fluoride treatment. The mineral density, elemental contents, surface morphology, and crystal characteristics were assessed by micro-computed tomography (micro-CT), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Micro-CT examination revealed a superficial opaque band approximately 150μm on the arrested cavitated dentinal lesion. This band was limited in the active carious lesion. EDX examination detected a higher intensity of calcium and phosphate of 150μm in the surface zone than in the inner zone, but this zone was restricted in the active cavitated dentinal lesion. SEM examination indicated that the collagens were protected from being exposed in the arrested cavitated dentinal lesion, but were exposed in the active cavitated dentinal lesion. TEM examination suggested that remineralised hydroxyapatites were well aligned in the arrested cavitated dentinal lesion, while those in the active cavitated dentinal lesion indicated a random apatite arrangement. A highly remineralised zone rich in calcium and phosphate was found on the arrested cavitated dentinal lesion of primary teeth with an SDF application. The collagens were protected from being exposed in the arrested cavitated dentinal lesion. Clinical SDF application positively influences dentine remineralisation. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Synthesis and characterization of lithium fluoride nano crystals doped with silver

    International Nuclear Information System (INIS)

    Rosario M, B. R.; Ramirez C, G.; Encarnacion E, E. K.; Sosa A, M. A.

    2017-10-01

    Thermoluminescence (Tl) is the emission of light by certain materials to be heated below its incandescence temperature, having previously been exposed to an exciting agent such as ionizing radiation. Lithium fluoride (LiF) is the thermoluminescent material used in the manufacture of Tl-100 dosimeters. What morphological characteristics (size, crystallinity) do the nano crystals of pure lithium fluoride (LiF) have when doped with silver (Ag) by the precipitation method? The objective of this study was to synthesize and characterize the LiF nano crystals doped with silver (Ag) in concentrations of 0.02, 0.04, 0.06, 0.08, 0.1 and 0.2%. The samples were synthesized using as reagents; distilled water, ammonium fluoride (NH 4 F), lithium chloride (LiCl), silver nitrate (AgNO 3 ); and materials such as: 0.1 mg precision balance, spatulas, test piece, magnetic stirrer, beaker, volumetric flask, burette, burette clamp, key and magnetic stirring wand. In the characterization process we used and X-ray diffractometer (XRD) with which we obtained the X-ray diffraction spectrum with well-defined peaks that are characteristic of LiF. Using the Scherrer equation we calculate the sizes of nano crystals. This study demonstrates that is possible to synthesize LiF using new dopant materials. (Author)

  19. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    International Nuclear Information System (INIS)

    Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R; Kolar, M

    2011-01-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  20. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    Energy Technology Data Exchange (ETDEWEB)

    Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17. Listopadu 12, 77146 Olomouc (Czech Republic); Kolar, M, E-mail: ales.panacek@upol.cz [Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 77520 Olomouc (Czech Republic)

    2011-07-06

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  1. The effectiveness of silver diamine fluoride in arresting caries.

    Science.gov (United States)

    Richards, Derek

    2017-10-27

    Data sourcesPubMed, Embase, Scopus, China National Knowledge Infrastructure (CNKI), Ichushi-web, Biblioteca Virtual en Salud Espana (BVSE) and Biblioteca Virtual em Saude (BVS) databases. There were no limits on language or publication dates.Study selectionTwo reviewers selected prospective clinical studies investigating SDF treatment for caries prevention in children.Data extraction and synthesisData was abstracted independently by two reviewers and risk of bias assessed. Meta-analysis was performed on studies in which the caries-arresting rate using 38% SDF solution on primary teeth could be obtained or calculated.ResultsNineteen studies were included; 16 were conducted in the primary dentition and three in permanent dentition. Fourteen studies used 38% SDF, three 30% SDF, and two 10% SDF. Eight studies using 38% SDF contributed to a meta-analysis and the overall proportion of arrested caries was 81% (95% CI; 68-89%). Percentage reductions were also calculated for 6,12,18,24 and >30 months. Arrested carious lesions stained black but no other adverse effects were reported.ConclusionsSDF commonly used at a high concentration (38%, 44,800ppm fluoride) is effective in arresting caries among children. There is no consensus on its number and frequency of application to arrest caries. Further studies are necessary to develop evidence-based guidelines on its use in children.

  2. Potential of nano-silver fluoride for tooth enamel caries prevention

    Science.gov (United States)

    Silva, Amitis V. C.; Mota, Cláudia C. B. O.; Teixeira, Joás. A.; Lins, Emery C.; Gomes, Anderson S. L.; Rosenblatt, Aronita

    2018-02-01

    This ex vivo study evaluated the efficiency of nano-silver fluoride (NSF) to enamel remineralization of deciduous teeth submitted to a high cariogenic challenge. 33 specimens of sound enamel were distributed into three groups: treated with sodium fluoride, with NSF, and deionized water. All specimens were submitted to microhardness test before chemical caries induction; post-induction of caries; and post-cariogenic challenge. The high cariogenic challenge was carried out in 14 daily cycles. There was no significant statistical difference (p=0.958) of enamel microhardness between NSFtreated and NaF-treated specimens. However, it presented significant difference between water-treated specimens and both NSF-treated and NaF-treated specimens (p=0.003).Furthermore, optical coherence tomography was employed for caries diagnosis, as it can be used in clinical environment.

  3. Gramicidin D enhances the antibacterial activity of fluoride.

    Science.gov (United States)

    Nelson, James W; Zhou, Zhiyuan; Breaker, Ronald R

    2014-07-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in Bacillus subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Fluoride

    Science.gov (United States)

    Opalescence® ... Fluoride is used to prevent tooth decay. It is taken up by teeth and helps to strengthen ... and block the cavity-forming action of bacteria. Fluoride usually is prescribed for children and adults whose ...

  5. Novel electrospun polyvinylidene fluoride-graphene oxide-silver nanocomposite membranes with protein and bacterial antifouling characteristics

    Directory of Open Access Journals (Sweden)

    C. Liu

    2018-04-01

    Full Text Available We developed and fabricated novel polyvinylidene fluoride (PVDF-(0.5–2%Ag and PVDF-(0.5–2%Ag-1% graphene oxide (GO nanocomposite membranes with antifouling properties through electrospinning. Silver nanoparticles (AgNPs were in situ synthesized from silver nitrate precursor directly. The tensile properties, wetting, antifouling characteristics of pristine PVDF and its nanocomposite membranes were studied. Tensile tests showed that the addition of 0.5–2% AgNPs to PVDF improves its elastic modulus and tensile strength markedly. A further increase in both tensile modulus and strength of PVDF were obtained by hybridizing AgNPs with 1% GO. Water contact angle measurements revealed that the incorporation of AgNPs or AgNPs/GO nanofillers into PVDF decreases its degree of hydrophobicity. This led to the nanocomposite membranes having higher water flux permeation. In addition, AgNPs and AgNPs/GO fillers played a crucial role against protein and bacterial fouling of the resulting composite membranes. The antibacterial activities of electrospun nanocomposite membranes were assessed against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. On the basis of water contact angle, water permeation flux and antifouling results, electrospun PVDF-2% Ag-GO composite membrane was found to exhibit excellent filtration performance, protein antifouling and bactericidal activities. Thus such a fibrous nanocomposite is considered as a high-potential membrane for water purification and disinfection applications.

  6. Mechanisms of silver diamine fluoride on arresting caries: a literature review.

    Science.gov (United States)

    Zhao, Irene Shuping; Gao, Sherry Shiqian; Hiraishi, Noriko; Burrow, Michael Francis; Duangthip, Duangporn; Mei, May Lei; Lo, Edward Chin-Man; Chu, Chun-Hung

    2018-04-01

    To review the evidence regarding the mechanisms of silver diamine fluoride (SDF) for arresting caries. A literature search was conducted using the keywords silver diamine fluoride, and its alternative names, in seven databases: PubMed, Embase and Scopus (English); China National Knowledge Infrastructure (Chinese); Bilioteca Virtual em Saude (Portuguese); Biblioteca Virtual en Salud Espana (Spanish); and Ichushi-Web (Japanese). The titles and abstracts were screened. Full texts were retrieved for publications that studied mechanisms of actions of SDF, including its effects on remineralisation of carious lesions and on cariogenic bacteria. A total of 1,123 publications were identified. Twenty-nine articles were included and they investigated the effect of SDF on cariogenic bacteria and dental hard tissues. Eleven studies investigated the antibacterial properties of SDF. They found that SDF was bactericidal to cariogenic bacteria, mainly Streptococcus mutans. It inhibited the growth of cariogenic biofilms on teeth. Twenty studies reported the remineralisation of demineralised enamel or dentine by SDF. They found that mineral loss of demineralised enamel and dentine was reduced after SDF treatment. A highly mineralised surface rich in calcium and phosphate was formed on arrested carious lesions. Four studies examined the effect of SDF on dentine collagen. They found that SDF inhibited collagenases (matrix metalloproteinases and cysteine cathepsins) and protected dentine collagen from destruction. SDF is a bactericidal agent and reduces the growth of cariogenic bacteria. It inhibits demineralisation and promotes the remineralisation of demineralised enamel and dentine. It also hampers degradation of the dentine collagen. © 2017 FDI World Dental Federation.

  7. Fabrication and characterization of functionally graded poly(vinylidine fluoride)-silver nanocomposite hollow fibers for sustainable water recovery

    KAUST Repository

    Francis, Lijo

    2014-12-01

    Poly(vinylidine fluoride) (PVDF) asymmetric hydrophobic hollow fibers were fabricated successfully using dryjet wet spinning. Hydrophobic silver nanoparticles were synthesized and impregnated into the PVDF polymer matrix and functionally graded PVDF-silver nanocomposite hollow fibers are fabricated and tested in the direct contact membrane distillation (DCMD) process. The as-synthesized silver nanoparticles were characterized for Transmission Electron Microscopy (TEM), particle size distribution (PSD) and Ultra Violet (UV) visible spectroscopy. Both the PVDF and PVDF-silver nanocomposite asymmetric hollow fibers were characterized for their morphology, water contact angle and mechanical strength. Addition of hydrophobic silver nanoparticles was found to enhance the hydrophobicity and ~ 2.5 fold increase the mechanical strength of the hollow fibers. A water vapor flux of 31.9kg m-2 h-1 was observed at a feed inlet temperature of 80 °C and at a permeate temperature of 20 °C in the case of hollow fiber membrane modules fabricated using PVDF hollow fibers; the water vapor flux was found to be increased by about 8% and to reach 34.6kg m-2 h-1 for the hollow fiber membrane modules fabricated from the PVDF-silver nanocomposite hollow fibers at the same operating conditions with 99.99% salt rejection.

  8. FLUORIDE SORPTION USING MORRINGA INDICA-BASED ACTIVATED CARBON

    Directory of Open Access Journals (Sweden)

    G. Karthikeyan, S. Siva Ilango

    2007-01-01

    Full Text Available Batch adsorption experiments using activated carbon prepared from Morringa Indica bark were conducted to remove fluoride from aqueous solution. A minimum contact time of 25 min was required for optimum fluoride removal. The influence of adsorbent, dose, pH, co-ions (cations and anions on fluoride removal by the activated carbon has been experimentally verified. The adsorption of fluoride was studied at 30 C, 40 C and 50 C. The kinetics of adsorption and adsorption isotherms at different temperatures were studied. The fluoride adsorption obeyed both Langmuir and Freundlich isotherms and followed a pseudo first order kinetic model. The thermodynamic studies revealed that the fluoride adsorption by Morringa Indica is an endothermic process indicating an increase in sorption rate at higher temperatures. The negative values of G indicate the spontaneity of adsorption. SEM and XRD studies confirmed the surface morphological characteristics of the adsorbent and the deposition of fluoride on the surface of the material.

  9. Oral fluoride retention after professional topical application in children with caries activity: comparison between 1.23% fluoride foam and fluoride gel

    Directory of Open Access Journals (Sweden)

    Cecília Claudia Costa Ribeiro

    2008-01-01

    Full Text Available Objective: This study evaluated fluoride retention in the saliva of children with caries activity after topical fluoride application in the form of gel and foam. Methods: A cross-sectional, blind and randomized study, conducted with ten caries-active children aged between 8 and 10 years, in two stage, with a washout interval of two weeks between them. The treatments consisted of: a application of 2mL acidulated phosphate fluoride of the gel type in a mold and b application of 2mL acidulated phosphate fluoride of the foam type in a mold. After the washout, the treatments were inverted. Non-stimulated saliva was collected from the children at the times of 5, 15, 30 and 60 minutes after topical fluoride application. For statistical analysis the Student’s-t test was used, with a level of significance of 5%. Results: Saliva analysis was performed using a fluoride-specific electrode (ISE25F/ Radiometer, Copenhagen, Denmark at the Aquatic Science Center of the Federal University of Marana, which revealed differences after 5 minutes (p=0.0055 and 15 minutes (p=0.0208. The topical application of fluoride in the gel form revealed a higher concentration of fluoride in the saliva. Conclusion: There were differences in the retention of fluoride in the saliva of children with caries activity after the topical application of fluoride gel and the topical application of fluoride foam after 5 and 15 minutes of their application. The topical application of fluoride foam is recommended, on the basis of the lower probability of toxicity during its use.

  10. PREPARATION AND CHARACTERIZATION OF STRONTIUM FLUORIDE POWDERS ACTIVATED BY NEODYMIUM FLUORIDE

    Directory of Open Access Journals (Sweden)

    S. V. Kuznetsov

    2015-07-01

    Full Text Available Subject of Study. The paper deals with preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry. Method. Nitrate of strontium, neodymium nitrate hexahydrate, with the content equal to 99. 99 % of the basic substance and ammonium fluoride were used as the source of substances. Activated powders of strontium fluoride were obtained by the method of deposition from aqueous solutions by washing the precipitate with a solution of ammonium fluoride, taken over 114 - 120% from stoichiometry. The washed precipitate was centrifuged for 5-7 min, dried in the air at 30-350 C. Heat treatment of the dried precipitate was carried out in two stages: the first stage at the temperature of 200- 2500 C for 0.5-1 hour, the second one at 550- 6000 C for 2-3 hours. X-ray analysis of the synthesized samples was carried out on a Bruker D8 Advance diffractometer, radiation Cu K. The size and shape measuring of the particles of activated strontium fluoride was carried out by means of electron microscope Carl Zeiss NVision 40. The content of neodymium in activated powders of strontium fluoride was determined by the method of spectral emission analysis on the device LEA - S500. Chemical analysis for determination of ammonium ion (NH4+ content in the obtained samples was performed by the method of Kjeldahl. Calculations of lattice parameters, size of coherent scattering regions and the values of micro-deformations were carried out by TOPAS program. Main Results. Preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry, provides obtaining the firm solution Sr1-x-yNdx(NH4yF2+x-y of the cubic fluorite structure. It has been found out that the morphology and size of the resulting product depend on the quantity of

  11. Electrocatalytic activity of bismuth doped silver electrodes

    CERN Document Server

    Amjad, M

    2002-01-01

    Investigation of redox reactions on silver, and bismuth doped silver electrodes in aqueous KOH solutions, by using potentiostatic steady-state polarization technique, has been carried out. The redox wave potential and current displacements along with multiplicity of the latter have been examined. These electrodes were employed for the oxidation of organic molecules such as ethylamine in alkaline media. Subsequently, these electrodes were ranked with respect to their activity for the redox reactions. (author)

  12. Use of Silver Diamine Fluoride for Dental Caries Management in Children and Adolescents, Including Those with Special Health Care Needs.

    Science.gov (United States)

    Crystal, Yasmi O; Marghalani, Abdullah A; Ureles, Steven D; Wright, John Timothy; Sulyanto, Rosalyn; Divaris, Kimon; Fontana, Margherita; Graham, Laurel

    2017-09-15

    This manuscript presents evidence-based guidance on the use of 38 percent silver diamine fluoride (SDF) for dental caries management in children and adolescents, including those with special health care needs. A guideline workgroup formed by the American Academy of Pediatric Dentistry developed guidance and an evidence-based recommendation regarding the application of 38 percent SDF to arrest cavitated caries lesions in primary teeth. The basis of the guideline's recommendation is evidence from an existing systematic review "Clinical trials of silver diamine fluoride in arresting caries among children: A systematic review." (JDR Clin Transl Res 2016;1[3]:201-10). A systematic search was conducted in PubMed®/MEDLINE, Embase®, Cochrane Central Register of Controlled Trials, and gray literature databases to identify randomized controlled trials and systematic reviews reporting on the effect of silver diamine fluoride and address peripheral issues such as adverse effects and cost. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess the quality of the evidence and the evidence-to-decision framework was employed to formulate a recommendation. The panel made a conditional recommendation regarding the use of 38 percent SDF for the arrest of cavitated caries lesions in primary teeth as part of a comprehensive caries management program. After taking into consideration the low cost of the treatment and the disease burden of caries, panel members were confident that the benefits of SDF application in the target populations outweigh its possible undesirable effects. Per GRADE, this is a conditional recommendation based on low-quality evidence. Conclusions and practical implications: The guideline intends to inform the clinical practices involving the application of 38 percent SDF to enhance dental caries management outcomes in children and adolescents, including those with special health care needs. These recommended

  13. Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes

    Energy Technology Data Exchange (ETDEWEB)

    Gusseme, B.D.; Fitts, J.; Hennebel, T.; Christiaens, E.; Saveyn, H.; Verbeken, K.; Boon, N.; Verstraete, W.

    2011-03-01

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sub powder}{sup 0} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {micro}g L{sup -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {micro}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale. In biogenic silver, silver nanoparticles are attached to a bacterial carrier matrix. Bio-Ag{sup 0} was successfully immobilized in PVDF membranes using immersion-precipitation. The antiviral activity of this material was demonstrated in a plate membrane reactor. The antimicrobial mechanism was most probably related to the slow release of Ag{sup +} ions. The membranes can be applied for treatment of limited volumes of contaminated water.

  14. Activity of Antimicrobial Silver Polystyrene Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Palomba

    2012-01-01

    Full Text Available A simple technique based on doping polymers with in situ generated silver nanoparticles (Ag/PS films has been developed. In particular, an antiseptic material has been prepared by dissolving silver 1,5-cyclooctadiene-hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution has been heated for ca. 10 s at a convenient temperature (180°C. Under such conditions the metal precursor decomposes producing silver atoms that diffuse into the polymer and clusterize. The antimicrobial characteristics of the resulting polystyrene-based material have been accurately evaluated toward Escherichia coli (E. coli comparing the cytotoxicity effect of 10 wt.% and 30 wt.% (drastic and mild annealing silver-doped polystyrene to the corresponding pure micrometric silver powder. Two different bacterial viability assays were performed in order to demonstrate the cytotoxic effect of Ag/PS films on cultured E. coli: (1 turbidimetric determination of optical density; (2 BacLight fluorescence-based test. Both methods have shown that silver-doped polystyrene (30 wt.% provides higher antibacterial activity than pure Ag powder, under similar concentration and incubation conditions.

  15. Pharmacological and toxicological effects of co-exposure of human gingival fibroblasts to silver nanoparticles and sodium fluoride

    Directory of Open Access Journals (Sweden)

    Inkielewicz-Stepniak I

    2014-04-01

    Full Text Available Iwona Inkielewicz-Stepniak,1,* Maria Jose Santos-Martinez,2–4,* Carlos Medina,2,4 Marek W Radomski2,41Department of Medicinal Chemistry, Medical University Gdansk, Debinki, Poland; 2The School of Pharmacy and Pharmaceutical Sciences, Panoz Institute, Trinity College Dublin, Dublin, Ireland; 3School of Medicine, Trinity College Dublin, Dublin, Ireland; 4Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland*These authors contributed equally to this workBackground: Silver nanoparticles (AgNPs and fluoride (F are pharmacological agents widely used in oral medicine and dental practice due to their anti-microbial/anti-cavity properties. However, risks associated with the co-exposure of local cells and tissues to these xenobiotics are not clear. Therefore, we have evaluated the effects of AgNPs and F co-exposure on human gingival fibroblast cells.Methods: Human gingival fibroblast cells (CRL-2014 were exposed to AgNPs and/or F at different concentrations for up to 24 hours. Cellular uptake of AgNPs was examined by transmission electron microscopy. Downstream inflammatory effects and oxidative stress were measured by real-time quantitative polymerase chain reaction (PCR and reactive oxygen species (ROS generation. Cytotoxicity and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and real-time quantitative PCR and flow cytometry, respectively. Finally, the involvement of mitogen-activated protein kinases (MAPK was studied using Western blot.Results: We found that AgNPs penetrated the cell membrane and localized inside the mitochondria. Co-incubation experiments resulted in increased oxidative stress, inflammation, and apoptosis. In addition, we found that co-exposure to both xenobiotics phosphorylated MAPK, particularly p42/44 MAPK.Conclusion: A combined exposure of human fibroblasts to AgNPs and F results in increased cellular damage. Further studies are needed in order to evaluate

  16. Antimicrobial activity of fluoride and its in vivo importance: identification of research questions.

    Science.gov (United States)

    Van Loveren, C

    2001-01-01

    This manuscript discusses the antimicrobial activity of fluoride and its in vivo importance in order to identify research questions. There is a lot of information on mechanisms by which fluoride may interfere with bacterial metabolism and dental plaque acidogenicity. The antimicrobial activity of fluoride products is enhanced when fluoride is associated with antimicrobial cations like Sn(2+) and amine. It is not clear whether the antimicrobial mechanisms of fluoride are operating in vivo or even to what extent antimicrobial activity can contribute to caries prevention. This latter question may be the most important one in research. Copyright 2001 S. Karger AG, Basel.

  17. In vitro assessment of activity of graphene silver composite sheets ...

    African Journals Online (AJOL)

    Purpose: To synthesize graphene-based silver nanocomposites and evaluate their antimicrobial and anti-Tomato Bushy Stunt Virus (TBSV) activities. Methods: A graphene-based silver composite was prepared by adsorbing silver nanoparticles AgNPs to the surfaces of graphene oxide (GO) sheets. Scanning electron ...

  18. Polyvinylidene Fluoride Micropore Membranes as Solid-Phase Extraction Disk for Preconcentration of Nanoparticulate Silver in Environmental Waters.

    Science.gov (United States)

    Zhou, Xiao-Xia; Lai, Yu-Jian; Liu, Rui; Li, Sha-Sha; Xu, Jing-Wen; Liu, Jing-Fu

    2017-12-05

    Efficient separation and preconcentration of trace nanoparticulate silver (NAg) from large-volume environmental waters is a prerequisite for reliable analysis and therefore understanding the environmental processes of silver nanoparticles (AgNPs). Herein, we report the novel use of polyvinylidene fluoride (PVDF) filter membrane for disk-based solid phase extraction (SPE) of NAg in 1 L of water samples with the disk-based SPE system, which consists of a syringe pump and a syringe filter holder to embed the filter membrane. While the PVDF membrane can selectively adsorb NAg in the presence of Ag + , aqueous solution of 2% (m/v) FL-70 is found to efficiently elute NAg. Analysis of NAg is performed following optimization of filter membrane and elution conditions with an enrichment factor of 1000. Additionally, transmission electron microscopy (TEM), UV-vis spectroscopy, and size-exclusion chromatography coupled with ICP-MS (SEC-ICP-MS) analysis showed that the extraction gives rise to no change in NAg size or shape, making this method attractive for practical applications. Furthermore, feasibility of the protocol is verified by applying it to extract NAg in four real waters with recoveries of 62.2-80.2% at 0.056-0.58 μg/L spiked levels. This work will facilitate robust studies of trace NAg transformation and their hazard assessments in the environment.

  19. Preparation of Nanofibrous Silver/Poly(vinylidene fluoride) Composite Membrane with Enhanced Infrared Extinction and Controllable Wetting Property.

    Science.gov (United States)

    Ren, Da-Ming; Huang, Hua-Kun; Yu, Yun; Li, Zeng-Tian; Jiang, Li-Wang; Chen, Shui-Mei; Lam, Kwok-Ho; Lin, Bo; Shi, Bo; He, Fu-An; Wu, Hui-Jun

    2018-05-01

    Nanofibrous silver (Ag)/poly(vinylidene fluoride) (PVDF) composite membranes were obtained from a two-step preparation method. In the first step, the electrospun silver nitrate (AgNO3)/PVDF membranes were prepared and the influence of the AgNO3 content on the electrospinning process was studied. According to scanning electron microscopy (SEM) results, when the electrospinning solution contained AgNO3 in the range between 3 to 7 wt.%, the nanofiber morphologies can be obtained. In the second step, the electrospun AgNO3/PVDF membranes were reduced by sodium borohydride to form the nanofibrous Ag/PVDF composite membranes. The resultant composite membranes were characterized by SEM, X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), differential scanning calorimetry, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared. The XRD, XPS, and EDS characterizations proved the existence of Ag in the nanofibrous Ag/PVDF composite membranes. The crystallinity degree of PVDF for composite membranes declined with the increase in Ag content. More importantly, the nanofibrous Ag/PVDF composite membranes had obviously higher Rosseland extinction coefficients and lower thermal radiative conductivities in comparison with electrospun PVDF membrane, which demonstrates that such composite membranes with high porosity, low density, and good water vapor permeability are promising thermal insulating materials to block the heat transfer resulting from thermal radiation. In addition, three different methods for surface modification have been used to successfully improve the hydrophobicity of nanofibrous Ag/PVDF composite membranes.

  20. Fluoride sorption using Cynodon dactylon based activated carbon

    Directory of Open Access Journals (Sweden)

    Alagumuthu G.

    2011-01-01

    Full Text Available This study deals the application of Cynodon dactylon based thermally activated carbon for fluoride toxicity. The batch adsorption techniques was followed at neutral pH as the functions of contact time, adsorbent dose, adsorbate concentration, temperature and the effect of co-anions. The data indicate that the prepared adsorbent surface sites are heterogeneous in nature and that fits into a heterogeneous site-binding model. The present system followed the Redlich-Peterson isotherm as well as Langmuir adsorption isotherm model. Lagergren pseudo-first-order, pseudo-second-order, intra particle diffusion and Elovich kinetics were modeled to describe the adsorption rate of fluoride and determined as this scheme followed pseudo-second-order kinetics. The calculated enthalpy change, ΔH°, and entropy change, ΔS°, for the adsorption process are +8.725 kJ/mol and +0.033 J/mol K respectively and shows endothermic experience. Instrumental analysis of XRD, FTIR and SEM gives the idea about the fluoride binding ability of adsorbent.

  1. Topical silver diamine fluoride for dental caries arrest in preschool children: A randomized controlled trial and microbiological analysis of caries associated microbes and resistance gene expression.

    Science.gov (United States)

    Milgrom, Peter; Horst, Jeremy A; Ludwig, Sharity; Rothen, Marilynn; Chaffee, Benjamin W; Lyalina, Svetlana; Pollard, Katherine S; DeRisi, Joseph L; Mancl, Lloyd

    2018-01-01

    The Stopping Cavities Trial investigated effectiveness and safety of 38% silver diamine fluoride in arresting caries lesions. The study was a double-blind randomized placebo-controlled superiority trial with 2 parallel groups. The sites were Oregon preschools. Sixty-six preschool children with ≥1 lesion were enrolled. Silver diamine fluoride (38%) or placebo (blue-tinted water), applied topically to the lesion. The primary endpoint was caries arrest (lesion inactivity, Nyvad criteria) 14-21days post intervention. Dental plaque was collected from all children, and microbial composition was assessed by RNA sequencing from 2 lesions and 1 unaffected surface before treatment and at follow-up for 3 children from each group. Average proportion of arrested caries lesions in the silver diamine fluoride group was higher (0.72; 95% CI; 0.55, 0.84) than in the placebo group (0.05; 95% CI; 0.00, 0.16). Confirmatory analysis using generalized estimating equation log-linear regression, based on the number of arrested lesions and accounting for the number of treated surfaces and length of follow-up, indicates the risk of arrested caries was significantly higher in the treatment group (relative risk, 17.3; 95% CI: 4.3 to 69.4). No harms were observed. RNA sequencing analysis identified no consistent changes in relative abundance of caries-associated microbes, nor emergence of antibiotic or metal resistance gene expression. Topical 38% silver diamine fluoride is effective and safe in arresting cavities in preschool children. The treatment is applicable to primary care practice and may reduce the burden of untreated tooth decay in the population. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  2. Nd:YAG laser irradiation on temporary teeth carious tissue using 12% diamine silver fluoride as a photo-absorber - a morphological study

    International Nuclear Information System (INIS)

    Calmon, Andrea de Avillez

    2001-01-01

    Since Nd:YAG laser radiation was first introduced in Dentistry various photo-absorbers were employed with the intent of improving its efficacy when used on dental carious tissue. The purpose of the present study was to analyze the influence of this radiation using Scanning and Optical microscopy over carious tissue of primary teeth using two photo-absorbers. 15 primary human teeth were used and, in each one, 3 cavity preparations were performed. Specimens were then submitted to an in vitro demineralizing environment during 18 days. Two of the cavities of each specimen were laser irradiated using the Nd:YAG laser with 60 mJ of energy per pulse, 10 Hz and average power of 0,6 W. The 12% diamine silver fluoride or the mineral coal were used as photo-absorbers. The third cavity of the specimens was used as a control and received no laser irradiation. Samples were transversally cut and the section analyzed by SEM and OM. Results showed that the 12% diamine silver fluoride is an efficient photo-absorber and, when used it the Nd:YAG laser, leading to melting and resolidification of the carious tissue. It can be concluded that the 12% diammine silver fluoride presents advantages over the mineral coal as a photo absorber when used in primary teeth as it promotes and improves the efficacy of laser irradiation. This substance also works as a barrier on the carie progression in deeper areas such as the infected and necrotic zones. (author)

  3. Spectrum of antimicrobial activity associated with ionic colloidal silver.

    Science.gov (United States)

    Morrill, Kira; May, Kathleen; Leek, Daniel; Langland, Nicole; Jeane, La Deana; Ventura, Jose; Skubisz, Corey; Scherer, Sean; Lopez, Eric; Crocker, Ephraim; Peters, Rachel; Oertle, John; Nguyen, Krystine; Just, Scott; Orian, Michael; Humphrey, Meaghan; Payne, David; Jacobs, Bertram; Waters, Robert; Langland, Jeffrey

    2013-03-01

    Silver has historically and extensively been used as a broad-spectrum antimicrobial agent. However, the Food and Drug Administration currently does not recognize colloidal silver as a safe and effective antimicrobial agent. The goal of this study was to further evaluate the antimicrobial efficacy of colloidal silver. Several strains of bacteria, fungi, and viruses were grown under multicycle growth conditions in the presence or absence of ionic colloidal silver in order to assess the antimicrobial activity. For bacteria grown under aerobic or anaerobic conditions, significant growth inhibition was observed, although multiple treatments were typically required. For fungal cultures, the effects of ionic colloidal silver varied significantly between different genera. No viral growth inhibition was observed with any strains tested. The study data support ionic colloidal silver as a broad-spectrum antimicrobial agent against aerobic and anaerobic bacteria, while having a more limited and specific spectrum of activity against fungi.

  4. [Bactericidal activity of colloidal silver against grampositive and gramnegative bacteria].

    Science.gov (United States)

    Afonina, I A; Kraeva, L A; Tseneva, G Ia

    2010-01-01

    It was shown that colloidal silver solution prepared in cooperation with the A. F. Ioffe Physical Technical Institute of the Russian Academy of Sciences, had significant bactericidal activity. Stable bactericidal effect on gramnegative microorganisms was observed after their 2-hour exposition in the solution of colloidal silver at a concentration of 10 ppm. Grampositive capsule-forming microorganisms were less susceptible to the colloidal silver solution: their death was observed after the 4-hour exposition in the solution.

  5. Virus Disinfection in Water by Biogenic Silver Immobilized in Polyvinylidene Fluoride Membranes

    Energy Technology Data Exchange (ETDEWEB)

    B De Gusseme; T Hennebel; E Christiaens; H Saveyn; K Verbeken; J Fitts; N Boon; W Vertraete

    2011-12-31

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sup 0}{sub powder} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {mu}g L{sub -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {mu}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale.

  6. Comparative evaluation of 2% sodium fluoride iontophoresis and other cavity liners beneath silver amalgam restorations

    Directory of Open Access Journals (Sweden)

    Gupta M

    2010-06-01

    Full Text Available Background: This study was designed to compare 2% sodium fluoride (NaF iontophoresis with other cavity liners. Materials and Methods: This study was carried out in 30 patients in the age group 10-14 years with bilateral carious permanent first molars. The study evaluated the use of 2% NaF iontophoresis as a cavity liner and also compared its desensitizing effect with varnish and an adhesive bonded liner. Sensitivity gradings were done on a subjective verbal rating scale. Results: All the liner treatments decreased the sensitivity following liner application. However, decrease of sensitivity in the case of 2% NaF iontophoresis was more compared with that of varnish and adhesive bonded liner. The results were statistically significant. Conclusions: It was found that 2% NaF iontophoresis was more effective in reducing the postoperative sensitivity compared with that of varnish and scotchbond multipurpose.

  7. Biosynthesis of silver nanoparticles and its antibacterial activity ...

    African Journals Online (AJOL)

    In the present research work, biosynthesis of silver nanoparticles and its activity on bacterial pathogens were investigated. Silver nanoparticles were rapidly synthesized using Urospora sp. and the formation of nanoparticles was observed within 30 min. The results recorded from UV–vis spectrum, Fourier Transform Infrared ...

  8. Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

    Science.gov (United States)

    Campillo Gloria, E.; Ederley, Vélez; Gladis, Morales; César, Hincapié; Jaime, Osorio; Oscar, Arnache; Uribe José, Ignacio; Franklin, Jaramillo

    2017-06-01

    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ~ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated.

  9. Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

    International Nuclear Information System (INIS)

    Gloria, E. Campillo; Ederley, Vélez; César, Hincapié; Gladis, Morales; Jaime, Osorio; Oscar, Arnache; José, Ignacio Uribe; Franklin, Jaramillo

    2017-01-01

    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO 3 ) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) – Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV–visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λ max ∼ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated. (paper)

  10. Release and antimicrobial activity of silver sulphadiazine from different creams

    NARCIS (Netherlands)

    Saene, J.J.M.; Trooster, J.F.G.; Meulenhoff, A.M.C.; Lerk, C.F.; Bult, A.

    The release and antimicrobial activity of silver sulphadiazine from five different creams were studied: unguentum emulsilicans aquosum, unguentum hydrophy. licum non ionogenicum, paraffin cream (15 per cent), a homemade preparation and a commercially available preparation (Flamazine). A diffusion

  11. Removal of Fluoride from Drinking Water Using Modified Immobilized Activated Alumina

    Directory of Open Access Journals (Sweden)

    Aneeza Rafique

    2013-01-01

    Full Text Available The study describes the removal of fluoride from drinking water using modified immobilized activated alumina (MIAA prepared by sol-gel method. The modification was done by adding a specific amount of alum during the sol formation step. The fluoride removal efficiency of MIAA was 1.35 times higher as compared to normal immobilized activated alumina. A batch adsorption study was performed as a function of adsorbent dose, contact time, stirring rate, and initial fluoride concentration. More than 90% removal of fluoride was achieved within 60 minutes of contact time. The adsorption potential of MIAA was compared with activated charcoal which showed that the removal efficiency was about 10% more than the activated charcoal. Both the Langmuir and Freundlich adsorption isotherms fitted well for the fluoride adsorption on MIAA with the regression coefficient R2 of 0.99 and 0.98, respectively. MIAA can both be regenerated thermally and chemically. Adsorption experiments using MIAA were employed on real drinking water samples from a fluoride affected area. The study showed that modified immobilized activated alumina is an effective adsorbent for fluoride removal.

  12. Silver enhances antibiotic activity against gram-negative bacteria.

    Science.gov (United States)

    Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

    2013-06-19

    A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

  13. The antimicrobial efficiency of silver activated sorbents

    International Nuclear Information System (INIS)

    Đolić, Maja B.; Rajaković-Ognjanović, Vladana N.; Štrbac, Svetlana B.; Rakočević, Zlatko Lj.; Veljović, Đorđe N.; Dimitrijević, Suzana I.; Rajaković, Ljubinka V.

    2015-01-01

    Highlights: • Different sorbents were activated by Ag + -ions and modified sorbents were determined by sorption capacities, in range of values: 42.06–3.28 mg/g. • Granulated activated carbon (GAC), natural zeolit (Z) and titanium dioxide (T) activated by Ag + -ions were tested against E. coli, S. aureus and C. albicans. • The most successful bacteria removal was obtained using Ag/Z against S. aureus and E. coli, while the yeast cell reduction reached unsatisfactory effect for all three activated sorbents. • XRD, XPS and FE-SEM analysis showed that the chemical state of the silver activating agent affects the antimicrobial activity, as well as the structural properties of the material. • An overall microbial cell reduction, which is performed by separated antimicrobial tests on the Ag + -activated surface and Ag + -ions in aquatic solutions, is a consequence of both mechanisms. - Abstract: This study is focused on the surface modifications of the materials that are used for antimicrobial water treatment. Sorbents of different origin were activated by Ag + -ions. The selection of the most appropriate materials and the most effective activation agents was done according to the results of the sorption and desorption kinetic studies. Sorption capacities of selected sorbents: granulated activated carbon (GAC), zeolite (Z), and titanium dioxide (T), activated by Ag + -ions were following: 42.06, 13.51 and 17.53 mg/g, respectively. The antimicrobial activity of Ag/Z, Ag/GAC and Ag/T sorbents were tested against Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus and yeast C. albicans. After 15 min of exposure period, the highest cell removal was obtained using Ag/Z against S. aureus and E. coli, 98.8 and 93.5%, respectively. Yeast cell inactivation was unsatisfactory for all three activated sorbents. The antimicrobial pathway of the activated sorbents has been examined by two separate tests – Ag + -ions desorbed from the activated surface to the

  14. Effect of sodium fluoride on phytase activity during germination of Pisum sativum L. seeds

    Energy Technology Data Exchange (ETDEWEB)

    Hauskrecht, I

    1972-01-01

    The effects of fluoride ion, in concentrations varying from 0 to 4 mM F/sup -/, on phytase activity in the course of germination of Pisum sativum L. seeds and in the course of incubation in vitro are reported. The fluoride ion in 1 mM concentration cause a significant 80% decrease of the phytase activity in the incubation medium and a 24% decrease in the course of germination. The inhibition of phytase, as well as its synthesis, by fluoride ion during germination may influence the metabolism of phosphorus at the initial stage of ontogenesis.

  15. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima

    2014-11-12

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  16. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima; Hong, Pei-Ying; Sougrat, Rachid; Nunes, Suzana Pereira

    2014-01-01

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  17. The effectiveness of the biannual application of silver nitrate solution followed by sodium fluoride varnish in arresting early childhood caries in preschool children: study protocol for a randomised controlled trial.

    Science.gov (United States)

    Chu, Chun-Hung; Gao, Sherry Shiqian; Li, Samantha Ky; Wong, May Cm; Lo, Edward Cm

    2015-09-25

    The application of 38 % silver diamine fluoride (SDF) has been shown to be effective in arresting early childhood caries (ECC). Since SDF is not available in certain countries, some dentists use adjunctive application of 25 % silver nitrate (AgNO3) and 5 % sodium fluoride (NaF) to arrest ECC. This randomised controlled trial will systematically compare the efficacy of a 25 % AgNO3 solution followed by 5 % NaF varnish with that of a 38 % SDF solution in arresting ECC when applied at half-yearly intervals over a 30-month period. This study is a randomised, double-blinded, non-inferiority clinical trial. The hypothesis tested is that adjunctive application of 25 % AgNO3 followed by 5 % NaF is at least not appreciably worse than a 38 % SDF in arresting ECC. Approximately 3100 kindergarten children aged 3-4 years will be screened and at least 1070 children with caries will be recruited. This sample size is sufficient for an appropriate statistical analysis (power at 90 % (β = 0.10) with a 2-sided type-I error of α = 0.05), allowing for an overall 20 % drop-out rate. The children will be randomly allocated into 2 groups to treat their caries over a 30-month period: Group A - biannual adjunctive application of a 25 % AgNO3 solution and a 5 % NaF varnish, and Group B - biannual adjunctive application of a 38 % SDF solution followed by a placebo varnish. Clinical examinations will be conducted at 6-month intervals. Primary outcome measured is the number of active caries surfaces which are arrested. Information on confounding factors such as oral hygiene habits will be collected through a parental questionnaire. We expect that adjunctive application of 25 % AgNO3 solution and 5 % NaF varnish and of 38 % SDF solution can both effectively arrest ECC. Lower concentrations of silver and fluoride are contained in 25 % AgNO3 and 5 % NaF, respectively, than in 38 % SDF; therefore, AgNO3/NaF are more favourable for use in young children. Because its use for caries management is

  18. Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles

    Science.gov (United States)

    Bindhu, M. R.; Sathe, V.; Umadevi, M.

    2013-11-01

    Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

  19. La3+-modified activated alumina for fluoride removal from water

    International Nuclear Information System (INIS)

    Cheng, Jiemin; Meng, Xiaoguang; Jing, Chuanyong; Hao, Jumin

    2014-01-01

    Graphical abstract: - Highlights: • A La 3+ -modified activated alumina adsorbent was prepared for effective removal F − . • SEM/EDS and EXAFS analyses determined the formation of La(OH) 3 coating on the AA. • The La-AA had much high adsorption rate and capacity than the AA. • The La-AA was promising adsorbent for effective removal of F − from water. - Abstract: A La 3+ -modified activated alumina (La-AA) adsorbent was prepared for effective removal of fluoride from water. The surface properties of adsorbent were characterized with zeta potential analysis, SEM-EDS and EXAFS. Batch and column experiments were conducted to evaluate improvement of F − removal by the La-AA. SEM/EDS and EXAFS analyses determined the formation of La(OH) 3 coating on the AA and strong bonding interactions between La 3+ and the Al atoms. The points of zero charge (pH PZC ) of AA and La-AA were at pH 8.94 and 9.57, respectively. Batch experimental results indicated that the La-AA had much higher adsorption rate and capacity than the AA. The F − adsorption processes on La-AA and AA followed the pseudo-second-order kinetics and the Langmuir isotherm. Column filtration results shows that the La-AA and AA treated 270 and 170 bed volumes of the F − -spiked tap water, respectively, before F − breakthrough occurred. The results demonstrated that the La-AA was a promising adsorbent for effective removal of F − from water

  20. Review on fluoride-releasing restorative materials--fluoride release and uptake characteristics, antibacterial activity and influence on caries formation.

    Science.gov (United States)

    Wiegand, Annette; Buchalla, Wolfgang; Attin, Thomas

    2007-03-01

    The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression. Information from original scientific full papers or reviews listed in PubMed (search term: fluoride release AND (restorative OR glass-ionomer OR compomer OR polyacid-modified composite resin OR composite OR amalgam)), published from 1980 to 2004, was included in the review. Papers dealing with endodontic or orthodontic topics were not taken into consideration. Clinical studies concerning secondary caries development were only included when performed in split-mouth design with an observation period of at least three years. Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Short- and long-term fluoride releases from restoratives are related to their matrices, setting mechanisms and fluoride content and depend on several environmental conditions. Fluoride-releasing materials may act as a fluoride reservoir and may increase the fluoride level in saliva, plaque and dental hard tissues. However, clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries and affect the growth of caries-associated bacteria compared to non-fluoridated restoratives. Fluoride release and uptake characteristics depend on the matrices, fillers and fluoride content as well as on the setting mechanisms and environmental conditions of the restoratives. Fluoride-releasing materials, predominantly glass-ionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of

  1. [Antimicrobial activity of stable silver nanoparticles of a certain size].

    Science.gov (United States)

    Mukha, Iu P; Eremenko, A M; Smirnova, N P; Mikhienkova, A I; Korchak, G I; Gorchev, V F; Chunikhin, A Iu

    2013-01-01

    Conditions for obtaining stable silver nanoparticles smaller than 10 nm were developed using a binary stabilizer polyvinylpyrrolidone/sodium dodecylsulphate in optimal ratio. Optical spectra, morphology and dependence of size of the nanoparticles on the amount of reducing agent were studied. Colloidal solutions of nanosilver showed a high bactericidal activity against strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, and fungicidal activity against Candida albicans. The mechanism of action of nanosized silver on microbial cell was examined by laser scanning confocal microscope using fluorescent label. First step of antimicrobial effect on microorganisms was membrane damage and penetration of silver nanoparticles into the cell. Prolonged stability of nanoparticles and their antimicrobial activity over the past two years were showed.

  2. Groundwater fluoride enrichment in an active rift setting: Central Kenya Rift case study

    Energy Technology Data Exchange (ETDEWEB)

    Olaka, Lydia A., E-mail: lydiaolaka@gmail.com [Department of Geology, University of Nairobi, P.O Box 30197, Nairobi (Kenya); Wilke, Franziska D.H. [Geoforschungs Zentrum, Telegrafenberg, 14473 Potsdam (Germany); Olago, Daniel O.; Odada, Eric O. [Department of Geology, University of Nairobi, P.O Box 30197, Nairobi (Kenya); Mulch, Andreas [Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325 Frankfurt (Germany); Institut für Geowissenschaften, Goethe Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt (Germany); Musolff, Andreas [UFZ-Helmholtz-Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig (Germany)

    2016-03-01

    Groundwater is used extensively in the Central Kenya Rift for domestic and agricultural demands. In these active rift settings groundwater can exhibit high fluoride levels. In order to address water security and reduce human exposure to high fluoride in drinking water, knowledge of the source and geochemical processes of enrichment are required. A study was therefore carried out within the Naivasha catchment (Kenya) to understand the genesis, enrichment and seasonal variations of fluoride in the groundwater. Rocks, rain, surface and groundwater sources were sampled for hydrogeochemical and isotopic investigations, the data was statistically and geospatially analyzed. Water sources have variable fluoride concentrations between 0.02–75 mg/L. 73% exceed the health limit (1.5 mg/L) in both dry and wet seasons. F{sup −} concentrations in rivers are lower (0.2–9.2 mg/L) than groundwater (0.09 to 43.6 mg/L) while saline lake waters have the highest concentrations (0.27–75 mg/L). The higher values are confined to elevations below 2000 masl. Oxygen (δ{sup 18}O) and hydrogen (δD) isotopic values range from − 6.2 to + 5.8‰ and − 31.3 to + 33.3‰, respectively, they are also highly variable in the rift floor where they attain maximum values. Fluoride base levels in the precursor vitreous volcanic rocks are higher (between 3750–6000 ppm) in minerals such as cordierite and muscovite while secondary minerals like illite and kaolinite have lower remnant fluoride (< 1000 ppm). Thus, geochemical F{sup −} enrichment in regional groundwater is mainly due to a) rock alteration, i.e. through long residence times and natural discharge and/or enhanced leakages of deep seated geothermal water reservoirs, b) secondary concentration fortification of natural reservoirs through evaporation, through reduced recharge and/or enhanced abstraction and c) through additional enrichment of fluoride after volcanic emissions. The findings are useful to help improve water management

  3. Synthesis and antibacterial activity of of silver nanoparticles

    International Nuclear Information System (INIS)

    Maliszewska, I; Sadowski, Z

    2009-01-01

    Silver nanoparticles have been known to have inhibitory and bactericidal effects but the antimicrobial mechanism have not been clearly revealed. Here, we report on the synthesis of metallic nanoparticles of silver using wild strains of Penicillium isolated from environment. Kinetics of the formation of nanosilver was monitored using the UV-Vis. TEM micrographs showed the formation of silver nanoparticles in the range 10-100 nm. Obtained Ag nanoparticles were evaluated for their antimicrobial activity against the gram-positive and gram-negative bacteria. As results, Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were effectively inhibited. Nanosilver is a promising candidate for development of future antibacterial therapies because of its wide spectrum of activity.

  4. Estimation of silver in Ag-meta kaolinite by neutron activation

    International Nuclear Information System (INIS)

    Daniels, E.A.; Rao, S.M.

    1981-01-01

    The present work is based on the neutron activation of Ag-meta kaolinite for the determination of its silver content from the β-activity of the compound using standard tables which showed the percentage of silver in mixtures of silver nitrate and meta kaolinite of known composition against β-activity of the mixture activated under identical conditions. (author)

  5. Antidotal activity of Averrhoa carambola (Star fruit on fluoride induced toxicity in rats

    Directory of Open Access Journals (Sweden)

    Vasant Rupal A.

    2014-06-01

    Full Text Available Consumption of fluoride leads to several physiological disturbances in carbohydrate, lipid and antioxidant metabolisms. Averrhoa carambola L. fruit (Star fruit is a commonly consumed fruit in tropical countries and is an ingredient in folklore medicines. As the fruits have high polyphenolic and antioxidant contents, the present study was undertaken to investigate the potential of star fruit as a dietary supplement in attenuating the fluoride induced hyperglycemia, hypercholesterolemia and oxidative stress in laboratory rats. A four-week exposure to fluoride caused sustained hyperglycemia, hyperlipidemia and oxidative stress and, when the diet was supplemented with star fruit powder, carbohydrate, lipid and antioxidant profiles were restored significantly. It is surmised that the antihyperglycemic, antihypercholesterolemic and antioxidant activities of star fruit in fluoride exposed rats could be due to the presence of polyphenols, flavonoids, saponins, phytosterols, ascorbic acid and fibers in the fruit, which are all well known regulators of carbohydrate, lipid and antioxidant metabolisms. These findings suggest that star fruit can be used as a dietary supplement in fluoride endemic regions to contain fluoride induced hyperglycemia, hyperlipidemia and oxidative stress

  6. Antidotal activity of Averrhoa carambola (Star fruit) on fluoride induced toxicity in rats.

    Science.gov (United States)

    Vasant, Rupal A; Narasimhacharya, A V R L

    2014-06-01

    Consumption of fluoride leads to several physiological disturbances in carbohydrate, lipid and antioxidant metabolisms. Averrhoa carambola L. fruit (Star fruit) is a commonly consumed fruit in tropical countries and is an ingredient in folklore medicines. As the fruits have high polyphenolic and antioxidant contents, the present study was undertaken to investigate the potential of star fruit as a dietary supplement in attenuating the fluoride induced hyperglycemia, hypercholesterolemia and oxidative stress in laboratory rats. A four-week exposure to fluoride caused sustained hyperglycemia, hyperlipidemia and oxidative stress and, when the diet was supplemented with star fruit powder, carbohydrate, lipid and antioxidant profiles were restored significantly. It is surmised that the antihyperglycemic, antihypercholesterolemic and antioxidant activities of star fruit in fluoride exposed rats could be due to the presence of polyphenols, flavonoids, saponins, phytosterols, ascorbic acid and fibers in the fruit, which are all well known regulators of carbohydrate, lipid and antioxidant metabolisms. These findings suggest that star fruit can be used as a dietary supplement in fluoride endemic regions to contain fluoride induced hyperglycemia, hyperlipidemia and oxidative stress.

  7. Characterization of silver nanoparticles synthesized using an endophytic fungus, Penicillium oxalicum having potential antimicrobial activity

    Science.gov (United States)

    Bhattacharjee, Sukla; Debnath, Gopal; Das, Aparajita Roy; Krishna Saha, Ajay; Das, Panna

    2017-12-01

    The aim of the present study was to test the efficacy of the extracellular mycelium extract of Penicillium oxalicum isolated from Phlogacanthus thyrsiflorus to biosynthesize silver nanoparticles. It was characterized using ultraviolet-visible absorption spectroscopy, atomic force microscopy, transmission electron microscopy and Fourier transforms infrared spectroscopy. The silver nanoparticles were evaluated for antimicrobial activity. The characterization confirms the synthesis of silver nanoparticles. Both silver nanoparticles and combination of silver nanoparticles with streptomycin showed activity against the four bacteria. The results suggested that P. oxalicum offers eco-friendly production of silver nanoparticles and the antibacterial activity may find application in biomedicine.

  8. Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

    International Nuclear Information System (INIS)

    Chudasama, Bhupendra; Vala, Anjana K.; Andhariya, Nidhi; Mehta, R. V.; Upadhyay, R. V.

    2010-01-01

    In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO 3 using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ = 18.3%) and 31.1 ± 4.5 nm (σ = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive (Bacillus megaterium and Staphylococcus aureus), and three Gram negative (Escherichiacoli, Proteusvulgaris and Shigellasonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.

  9. Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

    Energy Technology Data Exchange (ETDEWEB)

    Chudasama, Bhupendra, E-mail: bnchudasama@gmail.co [Thapar University, School of Physics and Materials Science (India); Vala, Anjana K.; Andhariya, Nidhi; Mehta, R. V. [Bhavnagar University, Department of Physics (India); Upadhyay, R. V. [Charotar University of Science and Technology, P.D. Patel Institute of Applied Sciences (India)

    2010-06-15

    In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO{sub 3} using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 {+-} 1.5 nm ({sigma} = 18.3%) and 31.1 {+-} 4.5 nm ({sigma} = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive (Bacillus megaterium and Staphylococcus aureus), and three Gram negative (Escherichiacoli, Proteusvulgaris and Shigellasonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.

  10. The effect of propolis fluoride on caries dentine activity

    Science.gov (United States)

    Darwita, Risqa Rina; Soekanto, Sri Angky; Finisha, Andanali Rhukul; Wahyuni, Hardiati Nur; Andiani, Salsabila Ghina

    2018-02-01

    This research was conducted to analyze the effect of propolis fluoride on the occurrence of arrested caries dentine surface. The design of the study was a clinical trial experimental. The respondent were primary school students aged 6-8 years, from primary school in Kukusan, Depok, West Java, Indonesia. They were screened of dental examination and the total number of 296 children with an age range of 6-8 year old were included in the study. All students who had dentin caries were get dental treatment with propolis fluoride topical application in dentin caries surface. After one month, two months and four months all students who were got propolis fluoride topical application in dentin caries surface were controlled. All data were analyzed by Wilcoxon test. The total number of dentinal decay of 296 student was 1740 surfaces indicated to Flolis topical application. After one, two and three months of Flolis application, all arrested of dentinal decay was evaluated, the result of evaluation from the second month to the third month evaluation was found that the arrested dentinal caries surfaces were decreased significantly at 29.36% (pcaries surface from the first month to the third month was decreased significantly at 38.62% (pcaries, and their ability to arrest dental caries was significantly different. Flolis was found to be effective in arresting dentinal caries surface until three months application, and should be repeated after 3 months of Flolis application.

  11. Effect of gamma irradiation on fluoride release and antibacterial activity of resin dental materials

    International Nuclear Information System (INIS)

    Carvalho, Fabiola Galbiatti de; Fucio, Suzana Beatriz Portugal de; Correr-Sobrinho, Lourenco; Pascon, Fernanda Miori; Kantovitz, Kamila Rosamilia; Puppin-Rontani, Regina Maria

    2009-01-01

    This study evaluated the effect of gamma irradiation on fluoride release and antibacterial activity of FluroShield (FS) and Clearfil Protect Bond (CPB). Four groups were formed: G1-FS + gamma; G2-FS without gamma; G3-CPB + gamma; G4-CPB without gamma. For fluoride release analysis, 12 disks of each material were prepared and covered with nail polish, except for one side (50.4 mm 2 area). G1 and G3 were sterilized with a 14.5 KGy dose at 27 deg C for 24 h, while G2 and G4 (controls) were not sterilized and were maintained under the same time and temperature conditions. Fluoride release measurements were made in duplicate (n=6) by an ion specific electrode. The antibacterial activity of the CPB and FS against Streptococcus mutans after gamma sterilization was evaluated by the agar-disc diffusion method. The diameter of the zones of microbial growth inhibition was recorded after 48 h. Data were analyzed statistically by ANOVA and Tukey's test (alpha=5%). Gamma sterilization decreased the fluoride release of FS by approximately 50%, while CPB was not affected. There was no statistically significant difference (p>0.05) in the antibacterial effect of CPB between gamma and non-gamma sterilization groups. FS presented no antibacterial activity. Gamma irradiation decreased the fluoride release of FS, but did not affect the antibacterial activity of the studied materials. (author)

  12. Effect of gamma irradiation on fluoride release and antibacterial activity of resin dental materials

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Fabiola Galbiatti de; Fucio, Suzana Beatriz Portugal de; Correr-Sobrinho, Lourenco [Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP (Brazil). Piracicaba Dental School. Dept. of Dental Materials; Pascon, Fernanda Miori; Kantovitz, Kamila Rosamilia; Puppin-Rontani, Regina Maria [Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP (Brazil). Piracicaba Dental School. Dept. of Pedriatric Dentistry], e-mail: rmpuppin@fop.unicamp.br

    2009-07-01

    This study evaluated the effect of gamma irradiation on fluoride release and antibacterial activity of FluroShield (FS) and Clearfil Protect Bond (CPB). Four groups were formed: G1-FS + gamma; G2-FS without gamma; G3-CPB + gamma; G4-CPB without gamma. For fluoride release analysis, 12 disks of each material were prepared and covered with nail polish, except for one side (50.4 mm{sup 2} area). G1 and G3 were sterilized with a 14.5 KGy dose at 27 deg C for 24 h, while G2 and G4 (controls) were not sterilized and were maintained under the same time and temperature conditions. Fluoride release measurements were made in duplicate (n=6) by an ion specific electrode. The antibacterial activity of the CPB and FS against Streptococcus mutans after gamma sterilization was evaluated by the agar-disc diffusion method. The diameter of the zones of microbial growth inhibition was recorded after 48 h. Data were analyzed statistically by ANOVA and Tukey's test (alpha=5%). Gamma sterilization decreased the fluoride release of FS by approximately 50%, while CPB was not affected. There was no statistically significant difference (p>0.05) in the antibacterial effect of CPB between gamma and non-gamma sterilization groups. FS presented no antibacterial activity. Gamma irradiation decreased the fluoride release of FS, but did not affect the antibacterial activity of the studied materials. (author)

  13. Antibacterial activity of silver-killed bacteria: the "zombies" effect

    Science.gov (United States)

    Wakshlak, Racheli Ben-Knaz; Pedahzur, Rami; Avnir, David

    2015-04-01

    We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria. Langmuirian behavior, as well as deviations from it, support the proposed mechanism.

  14. Revitalising Silver Nitrate for Caries Management

    Directory of Open Access Journals (Sweden)

    Sherry Shiqian Gao

    2018-01-01

    Full Text Available Silver nitrate has been adopted for medical use as a disinfectant for eye disease and burned wounds. In dentistry, it is an active ingredient of Howe’s solution used to prevent and arrest dental caries. While medical use of silver nitrate as a disinfectant became subsidiary with the discovery of antibiotics, its use in caries treatment also diminished with the use of fluoride in caries prevention. Since then, fluoride agents, particularly sodium fluoride, have gained popularity in caries prevention. However, caries is an infection caused by cariogenic bacteria, which demineralise enamel and dentine. Caries can progress and cause pulpal infection, but its progression can be halted through remineralisation. Sodium fluoride promotes remineralisation and silver nitrate has a profound antimicrobial effect. Hence, silver nitrate solution has been reintroduced for use with sodium fluoride varnish to arrest caries as a medical model strategy of caries management. Although the treatment permanently stains caries lesions black, this treatment protocol is simple, painless, non-invasive, and low-cost. It is well accepted by many clinicians and patients and therefore appears to be a promising strategy for caries control, particularly for young children, the elderly, and patients with severe caries risk or special needs.

  15. Fabrication, Characterization, and Antimicrobial Activity, Evaluation of Low Silver Concentrations in Silver-Doped Hydroxyapatite Nanoparticles

    Directory of Open Access Journals (Sweden)

    A. Costescu

    2013-01-01

    Full Text Available The aim of this study was the evaluation of (Ca10-xAgx(PO46(OH2 nanoparticles (Ag:HAp-NPs for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years as a major public health problem worldwide. In this paper, we report a comparison of the antimicrobial activity of low concentrations silver-doped hydroxyapatite nanoparticles. The silver-doped nanocrystalline hydroxyapatite powder was synthesized at 100°C in deionised water. The as-prepared Ag:Hap nanoparticles were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, FT-IR, and FT-Raman spectroscopy. X-ray diffraction (XRD studies demonstrate that powders obtained by coprecipitation at 100°C exhibit the apatite characteristics with good crystal structure, without any new phase or impurities found. FT-IR and FT-Raman spectroscopy revealed the presence of the various vibrational modes corresponding to phosphates and hydroxyl groups and the absence of any band characteristic to silver. The specific microbiological assays demonstrated that Ag:HAp-NPs exhibited antimicrobial features, but interacted differently with the Gram-positive, Gram-negative bacterial and fungal tested strains.

  16. Effect of preconditioning on silver leaching and bromide removal properties of silver-impregnated activated carbon (SIAC).

    Science.gov (United States)

    Rajaeian, Babak; Allard, Sébastien; Joll, Cynthia; Heitz, Anna

    2018-07-01

    Silver impregnated activated carbon (SIAC) has been found to be effective in mitigating the formation of brominated-disinfection by products during drinking water treatment. However, there are still uncertainties regarding its silver leaching properties, and strategies for the prevention of silver leaching have remained elusive. This study focused on the evaluation of one type of commercially available SIAC for its ability to remove bromide while minimising silver leaching from the material. Both synthetic and real water matrices were tested. Depending on solution pH, it was found that changing the surface charge properties of SIAC, as measured by the point of zero charge pH, can result in additional bromide removal while minimising the extent of silver leaching. To better understand the mechanism of silver leaching from the SIAC, eight preconditioning environments, i.e. variable pH and ionic strength were tested for a fixed amount of SIAC and two preconditioning environments were selected for a more detailed investigation. Experiments carried out in synthetic water showed that preconditioning at pH 10.4 did not deteriorate the capacity of SIAC to remove bromide, but significantly decreased the release of silver in the form of ionic silver (Ag + ), silver bromide (AgBr) and silver chloride (AgCl) from 40% for the pristine to 3% for the treated SIAC. This was confirmed using a groundwater sample. These results suggest that preconditioned SIAC has the potential to be an effective method for bromide removal with minimised silver leaching in a long-term field application for drinking water production. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Activation of PERK signaling through fluoride-mediated endoplasmic reticulum stress in OS732 cells

    International Nuclear Information System (INIS)

    Xu, Hui; Zhou, Yu-lai; Zhang, Xiu-yun; Lu, Peng; Li, Guang-sheng

    2010-01-01

    Our proteomical analysis of osteoblasts exposed to fluoride revealed a distinctive upregulation of proteins in osteoblast. These upregulated proteins play key roles in the protein folding. The PRK-like ER kinase (PERK) signaling, one branch of unfolded protein response (UPR) to combat ER stress, is a transcription factor needed for osteoblast proliferation and differentiation. The mechanism of skeletal fluorosis by which fluoride regulates osteoblast is not fully defined. Here we studied the effect of fluoride on PERK signaling genes and x-box binding protein 1 (xbp-1) in OS7232 cells (human osteoblast-like cell line). Meantime, genes associated with bone turnover were examined in this study. We found that early and continuous fluoride exposure increased the binding immunoglobulin protein (BiP) expression and activated the PERK signaling pathway, resulting in activation of transcription factor 4 (ATF4) and nuclear factor erythroid 2-related factor 2 (Nrf2). The altered expression of cbfa1, osteoprotegerin (OPG)/nuclear factor kappa B ligand (RANKL) were viewed in this study. These results showed fluoride impelled a distinctive ER stress response in OS732 cells, primarily by activating PERK and PERK-dependent signaling. Little effects were viewed for activating xbp-1, a common target of the other two canonical sensors of ER stress, ATF6 and IRE1. In this study the altered expression of bone turnover genes were consistent with activation of ER stress and PERK signaling. This study proved that PERK signaling play major roles in action of fluoride on osteoblast, and suggested that bone response in skeletal fluorosis may be due in part to PERK signaling pathway.

  18. Antibacterial activity of silver nanoparticles synthesized from serine

    Energy Technology Data Exchange (ETDEWEB)

    Jayaprakash, N. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); SRM Valliammai Engineering College, Department of Chemistry, Chennai 603 203 (India); Judith Vijaya, J., E-mail: jjvijayaloyola@yahoo.co.in [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); John Kennedy, L. [Materials Division, School of Advanced Sciences, VIT University, Chennai Campus, Chennai 600 048 (India); Priadharsini, K.; Palani, P. [Department of Center for Advanced Study in Botany, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2015-04-01

    Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV–Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443 nm. The emission spectrum of Ag NPs showed an emission band at 484 nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO{sub 3} against Gram-positive and Gram-negative bacteria. - Highlights: • Microwave irradiation method is used to synthesize silver nanoparticles. • Highly stable silver nanoparticles are produced from serine. • A detailed study of antibacterial activities is discussed. • Formation mechanism of silver microspheres has been proposed.

  19. Effects of fluoridation of porcine hydroxyapatite on osteoblastic activity of human MG63 cells

    International Nuclear Information System (INIS)

    Li, Zhipeng; Huang, Baoxin; Mai, Sui; Wu, Xiayi; Zhang, Hanqing; Qiao, Wei; Luo, Xin; Chen, Zhuofan

    2015-01-01

    Biological hydroxyapatite, derived from animal bones, is the most widely used bone substitute in orthopedic and dental treatments. Fluorine is the trace element involved in bone remodeling and has been confirmed to promote osteogenesis when administered at the appropriate dose. To take advantage of this knowledge, fluorinated porcine hydroxyapatite (FPHA) incorporating increasing levels of fluoride was derived from cancellous porcine bone through straightforward chemical and thermal treatments. Physiochemical characteristics, including crystalline phases, functional groups and dissolution behavior, were investigated on this novel FPHA. Human osteoblast-like MG63 cells were cultured on the FPHA to examine cell attachment, cytoskeleton, proliferation and osteoblastic differentiation for in vitro cellular evaluation. Results suggest that fluoride ions released from the FPHA play a significant role in stimulating osteoblastic activity in vitro, and appropriate level of fluoridation (1.5 to 3.1 atomic percents of fluorine) for the FPHA could be selected with high potential for use as a bone substitute. (paper)

  20. Activation of glycolysis and inhibition of glucose transport into leaves by fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Lustinec, J; Pokorna, V; Ruzicka, J

    1962-01-01

    During stimulation of wheat leaf respiration by fluoride at 100 to 200 ppM fluorine in dry tissue the ratio of radioactivities of /sup 14/CO/sub 2/ released from glucose-6-/sup 14/C and that released from glucose-1-/sup 14/C (C/sub 6//C/sub 1/) increases due especially to an increased output of 6-/sup 14/CO/sub 2/ which suggests an activation of glycolysis. The absolute values of radioactivity of /sup 14/CO/sub 2/, however, are decreased by the action of fluoride due to its inhibition of the transport of glucose into leaves. 15 references, 2 figures, 2 tables.

  1. Bone metabolic activity in hyperostosis cranialis interna measured with {sup 18}F-fluoride PET

    Energy Technology Data Exchange (ETDEWEB)

    Waterval, Jerome J.; Dongen, Thijs M.A. van; Stokroos, Robert J.; Manni, Johannes J. [Maastricht University Medical Center, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht (Netherlands); Teule, Jaap G.J.; Kemerink, Gerrit J.; Brans, Boudewijn [Maastricht University Medical Center, Department of Nuclear Medicine, Maastricht (Netherlands); Nieman, Fred H.M. [Maastricht University Medical Center, Department of Clinical Epidemiology and Medical Technology Assessment, Maastricht (Netherlands)

    2011-05-15

    {sup 18}F-Fluoride PET/CT is a relatively undervalued diagnostic test to measure bone metabolism in bone diseases. Hyperostosis cranialis interna (HCI) is a (hereditary) bone disease characterised by endosteal hyperostosis and osteosclerosis of the skull and the skull base. Bone overgrowth causes entrapment and dysfunction of several cranial nerves. The aim of this study is to compare standardised uptake values (SUVs) at different sites in order to quantify bone metabolism in the affected anatomical regions in HCI patients. Nine affected family members, seven non-affected family members and nine non-HCI non-family members underwent {sup 18}F-fluoride PET/CT scans. SUVs were systematically measured in the different regions of interest: frontal bone, sphenoid bone, petrous bone and clivus. Moreover, the average {sup 18}F-fluoride uptake in the entire skull was measured by assessing the uptake in axial slides. Visual assessment of the PET scans of affected individuals was performed to discover the process of disturbed bone metabolism in HCI. {sup 18}F-Fluoride uptake is statistically significantly higher in the sphenoid bone and clivus regions of affected family members. Visual assessment of the scans of HCI patients is relevant in detecting disease severity and the pattern of disturbed bone metabolism throughout life. {sup 18}F-Fluoride PET/CT is useful in quantifying the metabolic activity in HCI and provides information about the process of disturbed bone metabolism in this specific disorder. Limitations are a narrow window between normal and pathological activity and the influence of age. This study emphasises that {sup 18}F-fluoride PET/CT may also be a promising diagnostic tool for other metabolic bone disorders, even those with an indolent course. (orig.)

  2. Bone metabolic activity in hyperostosis cranialis interna measured with 18F-fluoride PET

    International Nuclear Information System (INIS)

    Waterval, Jerome J.; Dongen, Thijs M.A. van; Stokroos, Robert J.; Manni, Johannes J.; Teule, Jaap G.J.; Kemerink, Gerrit J.; Brans, Boudewijn; Nieman, Fred H.M.

    2011-01-01

    18 F-Fluoride PET/CT is a relatively undervalued diagnostic test to measure bone metabolism in bone diseases. Hyperostosis cranialis interna (HCI) is a (hereditary) bone disease characterised by endosteal hyperostosis and osteosclerosis of the skull and the skull base. Bone overgrowth causes entrapment and dysfunction of several cranial nerves. The aim of this study is to compare standardised uptake values (SUVs) at different sites in order to quantify bone metabolism in the affected anatomical regions in HCI patients. Nine affected family members, seven non-affected family members and nine non-HCI non-family members underwent 18 F-fluoride PET/CT scans. SUVs were systematically measured in the different regions of interest: frontal bone, sphenoid bone, petrous bone and clivus. Moreover, the average 18 F-fluoride uptake in the entire skull was measured by assessing the uptake in axial slides. Visual assessment of the PET scans of affected individuals was performed to discover the process of disturbed bone metabolism in HCI. 18 F-Fluoride uptake is statistically significantly higher in the sphenoid bone and clivus regions of affected family members. Visual assessment of the scans of HCI patients is relevant in detecting disease severity and the pattern of disturbed bone metabolism throughout life. 18 F-Fluoride PET/CT is useful in quantifying the metabolic activity in HCI and provides information about the process of disturbed bone metabolism in this specific disorder. Limitations are a narrow window between normal and pathological activity and the influence of age. This study emphasises that 18 F-fluoride PET/CT may also be a promising diagnostic tool for other metabolic bone disorders, even those with an indolent course. (orig.)

  3. Enabling nucleophilic substitution reactions of activated alkyl fluorides through hydrogen bonding.

    Science.gov (United States)

    Champagne, Pier Alexandre; Pomarole, Julien; Thérien, Marie-Ève; Benhassine, Yasmine; Beaulieu, Samuel; Legault, Claude Y; Paquin, Jean-François

    2013-05-03

    It was discovered that the presence of water as a cosolvent enables the reaction of activated alkyl fluorides for bimolecular nucleophilic substitution reactions. DFT calculations show that activation proceeds through stabilization of the transition structure by a stronger F···H2O interaction and diminishing C-F bond elongation, and not simple transition state electrostatic stabilization. Overall, the findings put forward a distinct strategy for C-F bond activation through H-bonding.

  4. Fluoridated Water

    Science.gov (United States)

    ... Genetics Services Directory Cancer Prevention Overview Research Fluoridated Water On This Page What is fluoride, and where is it found? What is water fluoridation? When did water fluoridation begin in the ...

  5. Synthesis and Antimicrobial Activity of a Silver-Hydroxyapatite Nanocomposite

    Directory of Open Access Journals (Sweden)

    Marcos Díaz

    2009-01-01

    Full Text Available A silver-hydroxyapatite nanocomposite has been obtained by a colloidal chemical route and subsequent reduction process in H2/Ar atmosphere at 350∘C. This material has been characterized by TEM, XRD, and UV-Visible spectroscopy, showing the silver nanoparticles (∼65 nm supported onto the HA particles (∼130 nm surface without a high degree of agglomeration. The bactericidal effect against common Gram-positive and Gram-negative bacteria has been also investigated. The results indicated a high antimicrobial activity for Staphylococcus aureus, Pneumococcus and Escherichia coli, so this material can be a promising antimicrobial biomaterial for implant and reconstructive surgery applications.

  6. Fluoride therapy for osteoporosis: characterization of the skeletal response by serial measurements of serum alkaline phosphatase activity.

    Science.gov (United States)

    Farley, S M; Wergedal, J E; Smith, L C; Lundy, M W; Farley, J R; Baylink, D J

    1987-03-01

    Optimum use of fluoride therapy for osteoporosis requires a sensitive and convenient index of the skeletal response to fluoride. Since previous studies had shown that serum alkaline phosphatase activity (SALP) was increased in response to fluoride therapy, we examined serial measurements of SALP in 53 osteoporotics treated with 66 to 110 mg of sodium fluoride (NaF) for 12 to 91 months. SALP was increased in 87% of the subjects during therapy with fluoride. The increase in SALP was thought to reflect the osteogenic action of fluoride based on the findings that SALP correlated with both trabecular bone area (r = .81, P less than .001) and osteoid length (r = .67, P less than .01) in iliac crest biopsies, predicted increased bone density on spinal radiographs in response to fluoride therapy with an 87% accuracy, and predicted decreased back pain in response to fluoride with a 91% accuracy. In addition, the SALP response to fluoride was seen earlier than other therapeutic responses as indicated by the findings that the tau 1/2 for the SALP response (ie, time for 1/2 of the patients to show a significant response) was significantly less (1.2 +/- 0.3 yr) than that for the pain response (1.6 +/- 0.3 yr, P less than .05) or that for the radiographic response (3.7 +/- 0.5 yr, P less than .001). Although most patients responded to fluoride with an increase in SALP, evaluation of the kinetics of the SALP response to fluoride revealed marked interpatient variation.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Antibacterial and Antimycotic Activity of Cotton Fabrics, Impregnated with Silver and Binary Silver/Copper Nanoparticles

    Science.gov (United States)

    Eremenko, A. M.; Petrik, I. S.; Smirnova, N. P.; Rudenko, A. V.; Marikvas, Y. S.

    2016-01-01

    Effective method of obtaining of the bactericidal bandage materials by impregnation of cotton fabric by aqueous solutions of silver and copper salts followed by a certain regime of heat treatment is developed. The study of obtained materials by methods of optical spectroscopy, electron microscopy, and X-ray phase analysis showed the formation of crystalline silver nanoparticles (NPs) and bimetallic Ag/Cu composites with the corresponding surface plasmon resonance (SPR) bands in the absorption spectra. High antimicrobial and antimycotic properties of tissues with low concentrations of Ag and Ag/Cu nanoparticles (Ag/Cu NPs) (in the range 0.06-0.25 weight percent (wt%) for Ag and 0.015-0.13 wt% for Ag/Cu) is confirmed in experiments with a wide range of multidrug-resistant bacteria and fungi: Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, Candida albicans yeasts, and micromycetes . Textile materials with Ag NPs demonstrate high antibacterial activity, while fabrics doped with bimetallic composite Ag/Cu have pronounced antimycotic properties. Bactericidal and antifungal properties of the obtained materials do not change after a washing. Production of such materials is extremely fast, convenient, and cost-effective.

  8. Arresting rampant dental caries with silver diamine fluoride in a young teenager suffering from chronic oral graft versus host disease post-bone marrow transplantation: a case report.

    Science.gov (United States)

    Chu, Chun-Hung; Lee, Angeline Hui-Cheng; Zheng, Liwu; Mei, May Lei; Chan, Godfrey Chi-Fung

    2014-01-03

    Rampant caries is an advanced and severe dental disease that affects multiple teeth. This case describes the management of rampant caries in a young teenager suffering from chronic oral graft versus host disease after allogeneic bone marrow transplantation. A 14-year-old Chinese boy suffering from β-thalassemia major was referred to the dental clinic for the management of rampant dental caries. An oral examination revealed pale conjunctiva, bruising of lips, and depapillation of tongue indicating an underlying condition of anemia. The poor oral condition due to topical and systemic immunosuppressants was seriously aggravated, and rampant caries developed rapidly, affecting all newly erupted, permanent teeth. The teeth were hypersensitive and halitosis was apparent. Strategies for oral health education and diet modification were given to the patient. Xylitol chewing gum was used to stimulate saliva flow to promote remineralization of teeth. Silver diamine fluoride was topically applied to arrest rampant caries and to relieve pain from hypersensitivity. Carious teeth with pulpal involvement were endodontically treated. Stainless steel crowns were provided on molars to restore chewing function, and polycarbonate crowns were placed on premolars, upper canines and incisors. This case report demonstrates success in treating a young teenager with severe rampant dental decay by contemporary caries control and preventive strategy.

  9. The antimicrobial activity of as-prepared silver-loaded phosphate glasses and zirconium phosphate

    International Nuclear Information System (INIS)

    Jing, Wang; Jiang, Ji Zhi; Yang, Yang; Yan, Zhao Chun; Yan, Wang Xiao; He, Shui Zhong

    2016-01-01

    The antimicrobial activities of silver-loaded zirconium phosphate (JDG) and silver-loaded phosphate glasses (ZZB) against Escherichia coli were studied. Although the silver content in JDG was higher than that in ZZB, ZZB suspensions showed better antimicrobial property than JDG suspensions, especially at low concentrations. The antimicrobial activity was analyzed using minimum inhibitory concentrations, bacterial inhibition ring tests, and detection of silver ions in the suspensions. Furthermore, the amounts of silver ions in suspensions with/without bacterial cells were analyzed. Results revealed that only a portion of released silver ions could be adsorbed by E. coli cells, which are critical to cell death. The damaged microstructures of E. coli cells observed by transmission electron microscopy may further prove that the adsorbed silver ions play an important role in the antimicrobial process.

  10. Determination of silver using cyclic epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Pun, T.H.; Landsberger, S.

    2012-01-01

    A fast pneumatic transfer facility was installed in Nuclear Engineering Teaching Laboratory (NETL) of the University of Texas at Austin for the purpose of cyclic thermal and epithermal neutron activation analysis. In this study efforts were focused on the evaluation of cyclic epithermal neutron activation analysis (CENAA). Various NIST and CANMET certified materials were analyzed by the system. Experiment results showed 110 Ag with its 25 s half-life as one of the isotopes favored by the system. Thus, the system was put into practical application in identifying silver in metallic ores. Comparison of sliver concentrations as determined by CENAA in CANMET certified reference materials gave very good results. (author)

  11. Green synthesis of silver nanoparticles from seed extract of Brassica nigra and its antibacterial activity

    Directory of Open Access Journals (Sweden)

    RAKSHA PANDIT

    2015-05-01

    Full Text Available Pandit R. 2015. Green synthesis of silver nanoparticles from seed extract of Brassica nigra and its antibacterial activity. Nusantara Bioscience 7: 15-19. We report the green synthesis of silver nanoparticles using seed extract of Brassica nigra. UV-visible spectroscopic analysis showed the absorbance peak at 432 nm which indicated the synthesis of silver nanoparticles. Nanoparticles Tracking and Analysis (NTA was used to determine the size of synthesized silver nanoparticles. Zeta potential analysis was carried out to study the stability of nanoparticles while FTIR analysis confirmed the presence of proteins as capping agents that provided stability to nanoparticles in colloid. Antibacterial activity of silver nanoparticles was evaluated against Propionibacterium acnes, Pseudomonas aeruginosa and Klebsiella pneumoniae. The activity of Vancomycin was significantly increased in combination with silver nanoparticles showing synergistic activity against all bacteria while the maximum activity was noted against P. acnes.

  12. Formulation of microemulsion propolis fluoride (PF) as varnish topical agent to stop activity of teeth caries

    Science.gov (United States)

    Sahlan, Muhamad; Prakoso, Chandra Dwi; Darwita, Risqa Rina; Hermansyah, Heri

    2017-02-01

    Topical fluoride is proven to have higher efficacy in preventing dental caries with low production cost and easy to apply. The objective of this research is to formulate alternative agent topical fluoride NH4F 5% mixed with extract ethanol propolis (EEP) in the micro-emulsion system that has high stability, antimicrobial activity, and remineralization capability to arrest teeth caries activity. By using total plate count (TPC) analysis, formulation 2.7% EEP; 6,3% surfactant; and 90,9% NH4F shows good perform to inhibit cariogenic bacteria development around 78-80%. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) result also showed that sample successfully remineralized enamel surface. In addition, sample showed good pH, flavonoid, and polyphenol stability for 40 days.

  13. Green Synthesis of Silver Nanoparticles Using Pimpinella anisum L. Seed Aqueous Extract and Its Antioxidant Activity

    Directory of Open Access Journals (Sweden)

    Hashem Akhlaghi

    2015-09-01

    Full Text Available An aqueous extract of Pimpinella anisum was used for green synthesis of silver nanoparticles by bio reduction of an aqueous solution of silver nitrate. Silver nanoparticles were characterized by UV–Vis spectrometry, Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD analysis, scanning electron microscopy (SEM and energy-dispersive X-ray analysis (EDAX. The increase in absorption at 420 nm was used for recording the formation of a colloidal suspension of silver nanoparticles. The binding properties of the capped Ag nanoparticles synthesized from aqueous extract of P. anisum were analyzed by FTIR. XRD studies revealed that most of the nanoparticles were cubic and face centered cubic in shape. SEM analysis showed the size and shape of silver nanoparticles and EDAX confirmed the presence of silver. The synthesized silver nanoparticles showed DPPH free radical scavenging activity.

  14. Determination of fluoride in human nails via cyclic instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Spate, V.L.; Morris, J.S.; Baskett, C.K.; Mason, M.M.; Reams, C.L.

    1994-01-01

    The role of fluorine in human health has become somewhat controversial. It is widely accepted as protective against dental caries, may be protective against osteoporosis, and has been very conservatively implicated with osteosarcoma in male rats. The develepment of a neutron activation analysis method and its application to the analysis of human nails is reported. It has been found that toenails collected in population-based epidemiology studies apparently reflect fluoride intake. (author) 11 refs.; 2 tabs

  15. Studies on the method for determination of fluoride concentration in rat hard tissues by neutron activation analysis using 20F

    International Nuclear Information System (INIS)

    Nakakura, Tadao

    1991-01-01

    Neutron activation analysis method (non disruptive analysis, short time period measurement) has been recognized as a high precision analysis of fluoride concentration in hard tissue. Heat neutron irradiation analysis using instrumental neutron activation analysis (INAA) method was used to investigate 20 F concentration. Results were as follows. F concentration in a dried material of hard tissue using INAA method can be fixed by measuring the 20 F's energy peak for 10 seconds after neutron irradiation under 1 x 10 n/cm 2 ·s for 10 seconds. Non responding time that is caused by short half reduction time of 20 F can be recovered enough by a revise calculation. Reproducibility of measured fluoride concentration using INAA method was well stabilized. Rat hard tissue which takes no fluoride can be determined fluoride concentration without sodium restriction. Femur fluoride concentrations using INAA method had significant correlation with conventional microdiffusion analysis method (r=0.997, regression line: Y=1.13X + 2.98). Increase of fluoride density in dentine of rat molars under growing period according to fluoride intake was 1/3 of femurs and mandibles. (author)

  16. Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens

    Science.gov (United States)

    Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Vanaja, Mahendran; Annadurai, Gurusamy

    2016-07-01

    The present investigation shows the biosynthesis of eco-friendly silver nanoparticles using culture supernatant of Enterococcus sp. and study the effect of enhanced antimicrobial activity, anticancer activity against pathogenic bacteria, fungi and cancer cell lines. Silver nanoparticles was synthesized by adding 1 mM silver nitrate into the 100 ml of 24 h freshly prepared culture supernatant of Enterococcus sp. and were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Selected Area Diffraction X-Ray (SAED), Energy Dispersive X Ray (EDX) and Fourier Transform Infra red Spectroscopy (FT-IR). The synthesized silver nanoparticles were impregnated with commercial antibiotics for evaluation of enhanced antimicrobial activity. Further these synthesized silver nanoparticles were assessed for its anticancer activity against cancer cell lines. In this study crystalline structured nanoparticles with spherical in the size ranges from 10 to 80 nm and it shows excellent enhanced antimicrobial activity than the commercial antibiotics. The in vitro assay of silver nanoparticles on anticancer have great potential to inhibit the cell viability. Amide linkages and carboxylate groups of proteins from Enterococcus sp. may bind with silver ions and convert into nanoparticles. The activities of commercial antibiotics were enhanced by coating silver nanoparticles shows significant improved antimicrobial activity. Silver nanoparticles have the great potential to inhibit the cell viability of liver cancer cells lines (HepG2) and lung cancer cell lines (A549).

  17. In vitro caries-inhibitory properties of a silver cermet.

    Science.gov (United States)

    Swift, E J

    1989-06-01

    Recurrent caries is one of the primary causes of failure of dental restorations. One method for reducing the frequency and severity of this problem is the use of fluoride-releasing restorative materials. The glass-ionomer cements are a type of fluoride-releasing material. They have been used extensively in recent years for a variety of clinical applications. However, in comparison with other restorative materials such as amalgam and composite resins, glass ionomers have relatively poor physical properties. Sintering of silver particles to glass-ionomer powder is a means of improving these physical properties. The sintered material is called a silver-glass ionomer or silver cermet. This study examined the in vitro caries-inhibitory potential of a silver cement by means of two methods. First, long-term fluoride release was measured. Second, an artificial caries system was used for evaluation of caries inhibition by cerment restorations in extracted teeth. In comparison with a standard glass-ionomer restorative material, fluoride release from the cermet material was significantly less throughout a 12-month period. The results from the artificial caries system indicated that this decreased fluoride release corresponded with a lesser degree of caries inhibition. Lesions around cermet restorations in both enamel and root surfaces were significantly more severe than those around conventional glass-ionomer restorations. However, in comparison with amalgam and composite resin restorations, the cermet did have some cariostatic activity.

  18. Antimicrobial active silver nanoparticles and silver/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid

    International Nuclear Information System (INIS)

    An Jing; Wang Desong; Luo Qingzhi; Yuan Xiaoyan

    2009-01-01

    Uniform silver nanoparticles and silver/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM].BF 4 ). [BMIM].BF 4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5-15 nm and 15-25 nm, respectively. The X-ray diffraction analysis reveals the face-centered cubic geometry of silver nanoparticles. The as-prepared nanoparticles were also characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. In addition, antimicrobial activities against E. coli and S. aureus were studied and the results show that both silver nanoparticles and core-shell nanoparticles possess excellent antimicrobial activities. The antimicrobial mechanism of the as-prepared nanoparticles was discussed.

  19. 'Chocolate' silver nanoparticles: Synthesis, antibacterial activity and cytotoxicity.

    Science.gov (United States)

    Chowdhury, Neelika Roy; MacGregor-Ramiasa, Melanie; Zilm, Peter; Majewski, Peter; Vasilev, Krasimir

    2016-11-15

    Silver nanoparticles (AgNPs) have emerged as a powerful weapon against antibiotic resistant microorganisms. However, most conventional AgNPs syntheses require the use of hazardous chemicals and generate toxic organic waste. Hence, in recent year's, plant derived and biomolecule based synthetics have has gained much attention. Cacao has been used for years for its medicinal benefits and contains a powerful reducing agent - oxalic acid. We hypothesized that, due to the presence of oxalic acid, cacao extract is capable of reducing silver nitrate (AgNO3) to produce AgNPs. In this study, AgNPs were synthesized by using natural cacao extract as a reducing and stabilizing agent. The reaction temperature, time and reactant molarity were varied to optimize the synthesis yield. UV-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization demonstrated that the synthesized AgNPs were spherical particles ranging in size from 35 to 42.5nm. The synthesized AgNPs showed significant antibacterial activity against clinically relevant pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. Importantly, these green AgNPs are not cytotoxic to human dermal fibroblasts (HDFs) at concentrations below 32μg/ml. We conclude that cacao-based synthesis is a reproducible and sustainable method for the generation of stable antimicrobial silver nanoparticles with low cytotoxicity to human cells. The AgNPs synthesized in this work have promising properties for applications in the biomedical field. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

    Science.gov (United States)

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Chifiriuc, Mariana Carmen; Costescu, Adrian; Le Coustumer, Philippe; Predoi, Daniela

    2013-01-01

    The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO4)6(OH)2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures. PMID:23509801

  1. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Carmen Steluta Ciobanu

    2013-01-01

    Full Text Available The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO46(OH2 nanoparticles (Ag:HAp-NPs for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures.

  2. Synthesis and antimicrobial activity of silver-doped hydroxyapatite nanoparticles.

    Science.gov (United States)

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Chifiriuc, Mariana Carmen; Costescu, Adrian; Le Coustumer, Philippe; Predoi, Daniela

    2013-01-01

    The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca(10-x)Ag(x)(PO4)6(OH)2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against gram-positive and gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures.

  3. ANTIFUNGAL ACTIVITY OF SILVER NANOPARTICLES OBTAINED BY GREEN SYNTHESIS

    Directory of Open Access Journals (Sweden)

    Eduardo José J. MALLMANN

    2015-04-01

    Full Text Available Silver nanoparticles (AgNPs are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment.

  4. Effects of fluoride on mitochondrial activity in higher plants. [Glycine max, Zea mays

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J E; Miller, G W

    1974-01-01

    The effects of fluoride on respiration of plant tissue and mitochondria were investigated. Fumigation of young soybean plants (Glycine max Merr. cm. Hawkeye) with 9-12 ..mu..g x m/sup -3/ HF caused a stimulation of respiration at about 2 days of treatment followed by inhibition 2 days later. Mitochondria isolated from the stimulated tissue had higher respiration rates, greater ATPase activity, and lower P/O ratios, while in mitochondria from inhibited tissue, all three were reduced. Treatment of etiolated soybean hypocotyl sections in Hoagland's solution containing KF for 3 to 10 h only resulted in inhibition of respiration. Mitochondria isolated from this tissue elicited increased respiration rates with malate as substrate and inhibited respiration with succinate. With both substrates respiratory control and ADP/O ratios were decreased. Direct treatment of mitochondria from etiolated soybean hypocotyl tissue with fluoride resulted in inhibition of state 3 respiration and lower ADP/O ratios with the substrates succinate, malate, and NADH. Fluoride was also found to increase the amount of osmotically induced swelling and cause a more rapid leakage of protein with mitochondria isolated from etiolated corn shoots (Zea mays L. cv. Golden Cross Bantam). 40 references, 1 figure, 5 tables.

  5. An investigation of in vivo wound healing activity of biologically synthesized silver nanoparticles

    Science.gov (United States)

    Kaler, Abhishek; Mittal, Amit Kumar; Katariya, Mahesh; Harde, Harshad; Agrawal, Ashish Kumar; Jain, Sanyog; Banerjee, Uttam Chand

    2014-09-01

    Therapeutic use of nano-silver is claimed to have reduced side effects and enhanced curative activity as compared to its ionic counterpart (silver ions). The present work aims to screen microbes for the synthesis of silver nanoparticles (AgNPs), to formulate the nano-silver-based Carbopol gel and evaluating its wound healing efficacy on rat model. The goal was to develop the topical formulation based on bio-nano-silver to control the infection and healing the wounds with higher efficacy. Procedure involved the use of Saccharomyces boulardii for the synthesis of silver nanoparticles in the size range of 3-10 nm and these nanoparticles were used for the preparation of Carbopol-based nano-silver gel. Highly stable Carbopol nanogel was developed with good rheological properties. The burn wound healing potential of this nano-silver gel was evaluated on SD rats via visual observation, transepidermal water loss and histology of skin. Excellent wound healing was observed with AgNPs. Biologically synthesized AgNPs-based nano-silver gel showed superior wound healing efficacy as compared to marketed formulations and silver ions.

  6. Studying the morphological features of plasma treated silver and PEGylated silver nanoparticles: antibacterial activity

    Science.gov (United States)

    Waseem, M.; Awan, T.; Yasin, H. M.; Rehman, N. U.

    2018-03-01

    A strategy to treat the silver and PEGylated silver nanoparticles with plasma was being purposed. Oil in water (o/w) microemulsion method was used for the synthesis of Ag nanoparticles (AgNPs). Polyethylene glycol (PEG) having molecular weight 600 was used to coat the surface of AgNPs. Optical emission spectroscopy (OES) was used to characterize the plasma and it is noted that plasma treatment is useful to modify the structural characteristic of silver nanoparticles. The nanoparticles were treated with helium-oxygen mixture plasma, generated in plasma needle at atmospheric pressure. Both AgNPs and PEGylated AgNPs before and after plasma treatment were characterized by x-rays diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The crystallite size of silver nanoparticles after the treatment of plasma decreases from 71 nm to 27 nm. The SEM micrographs show that the size of Ag nanoparticles was nearly 118 nm whereas the thickness of the silver needle was around 135 nm. All the characteristics IR bands associated to the silver nanoparticles were detected. The FTIR spectrum also support the accumulation of OH radicals in the plasma treated samples. The samples before and after plasma treatment were screened against Gram positive (Bacillus Subtilis and Staphylococcus Aureus) and Gram negative (Escherichia Coli and Pseudomonas Aeruginosa) bacteria. The promising response was detected when plasma treated PEGylated AgNPs was tested against bacterial strains.

  7. Analysis of gold and silver concentration on gold mining tailings by neutron activation analysis

    International Nuclear Information System (INIS)

    Sadikov, I.I.; Salimov, M.I.; Sadykova, Z.O.

    2014-01-01

    Full text: Instrumental neutron-activation analysis without radiochemical separation is one of most applicable and often used methods to analyze the concentration of gold, silver and other rare and noble metals in gold ores. This method is not suitable for analyzing low concentration of gold and silver in gold mining tailings due to rather high concentration of some elements. Samples are dissolved by boiling in a mixture of concentrated hydrochloric and nitric acids to extract gold and silver into the solution. Chemical yield of gold and silver after dissolution of the sample and further chromatographic separation is between 92 and 95 percent respectively

  8. Investigation of antibacterial activity of cotton fabric incorporating nano silver colloid

    International Nuclear Information System (INIS)

    Ngo Vo Ke Thanh; Nguyen Thi Phuong Phong

    2009-01-01

    In this work, silver nanoparticles were prepared by polyol process with microwave heating and incorporated on cotton fabric surfaces. The antibacterial performance of the antibacterial cotton fabric was tested for different concentration of nano-sized silver colloid, contact time germs, and washing times. It was found that antibacterial activity increased with the increasing concentration of nano-sized silver colloid. The antibacterial fabric with 758 mg/kg of silver nanoparticles on surface cotton was highly effective in killing test bacteria and had excellent water resisting property.

  9. Antimicrobial Activities of Silver Nanoparticles Synthesized by Using Water Extract of Arnicae anthodium.

    Science.gov (United States)

    Dobrucka, Renata; Długaszewska, Jolanta

    2015-06-01

    Green synthesis of nanoparticles has gained significant importance in recent years and has become the one of the most preferred methods. Also, green synthesis of nanoparticles is valuable branch of nanotechnology. Plant extracts are eco-friendly and can be an economic option for synthesis of nanoparticles. This study presents method the synthesis of silver nanoparticles using water extract of Arnicae anthodium. Formation of silver nanoparticles was confirmed by UV-visble spectroscopy, Fourier transform infrared spectroscopy and total reflection X-ray fluorescence analysis. The morphology of the synthesized silver nanoparticles was verified by SEM-EDS. The obtained silver nanoparticles were used to study their antimicrobial activity.

  10. Towards understanding of poly-guanine activated fluorescent silver nanoclusters

    International Nuclear Information System (INIS)

    Walczak, Sylwia; Morishita, Kiyoshi; Ahmed, Moin; Liu, Juewen

    2014-01-01

    It has been recently reported that the fluorescence of some DNA-templated silver nanoclusters (AgNCs) can be significantly enhanced upon by hybridizing with a partially complementary DNA containing a G-rich overhang near the AgNCs. This discovery has found a number of analytical applications but many fundamental questions remain to be answered. In this work, the photostability of these activated AgNCs is reported. After adding the G-rich DNA activator, the fluorescence intensity peaks in ∼1 h and then starts to decay, where the decaying rate is much faster with light exposure. The lost fluorescence is recovered by adding NaBH 4 , suggesting that the bleaching is an oxidative process. Once activated, the G-rich activator can be removed while the AgNCs still maintain most of their fluorescence intensity. UV–vis spectroscopy suggests that new AgNC species are generated upon hybridization with the activator. The base sequence and length of the template DNA have also been varied, leading to different emission colors and color change after hybridization. G-rich aptamers can also serve as activators. Our results indicate that activation of the fluorescence by G-rich DNA could be a convenient method for biosensor development since the unstable NaBH 4 is not required for the activation step. (paper)

  11. Antimicrobial activity of silver nanoparticles synthesized using honey and gamma radiation against silver-resistant bacteria from wounds and burns

    Science.gov (United States)

    Hosny, A. M. S.; Kashef, M. T.; Rasmy, S. A.; Aboul-Magd, D. S.; El-Bazza, Z. E.

    2017-12-01

    Silver nanoparticles (AgNPs) are promising antimicrobial agents for treatment of wounds and burns. We synthesized AgNPs using honey at different pH values or with different gamma irradiation doses. The resulting nanoparticles were characterized by UV-vis spectroscopy, TEM, DLS and FTIR. Their antimicrobial activity, against standard bacterial strains and silver-resistant clinical isolates from infected wounds and burns, was evaluated in vitro through determination of their minimum inhibitory concentration (MIC). AgNPs prepared using 30 g of honey exposed to 5 kGy gamma radiation had the best physical characters regarding stability and uniformity of particle size and shape. They recorded the lowest MIC values against both the standard and silver-resistant isolates. In conclusion, honey and gamma radiation can be used in synthesis of highly stable pure AgNPs, without affecting the physico-chemical and antimicrobial activity of honey. This offered an advantage in terms of inhibition of silver-resistant bacteria isolates.

  12. Adsorption performance of silver-loaded activated carbon fibers

    Directory of Open Access Journals (Sweden)

    Yan Xue-Feng

    2018-01-01

    Full Text Available Silver-loaded activated carbon fiber is prepared, and its adsorption performance is studied experimentally using five methylene blue solutions with different concentrations under three different temperature conditions. The adsorption tests show that fibers adsorption increase as the increase of temperature, and there is an optimal value for solution concentration, beyond which its adsorption will de-crease. Fibers isothermal adsorption to methylene blue is different from those by the monolayer adsorption by Langmuir model and the multilayer adsorption by Freundlich model. Through the analysis of thermodynamic parameters, Gibbs free energy, standard entropy, and standard enthalpy, it is found that the fibers adsorption to methylene blue is an exothermic process of physical adsorption.

  13. Laser ablation studies of Deposited Silver Colloids Active in SERS

    International Nuclear Information System (INIS)

    La Porte, R.T.; Moreno, D.S.; Striano, M.C.; Munnoz, M.M.; Garcia-Ramos, J.V.; Cortes, S.S.; Koudoumas, E.

    2002-01-01

    Laser ablation of deposited silver colloids, active in SERS, is carried out at three different laser wavelengths (KrF, XeCl and Nd:YAG at λ = 248, 308 and 532 nm respectively). Emission form excited neutral Ag and Na atoms, present in the ablation plume, is detected with spectral and temporal resolution. The expansion velocity of Ag in the plume is estimated in ∼1x104m s-1, Low-fluence laser ablation of the colloids yields ionized species that are analyzed by time-of-flight mass spectroscopy. Na+ and Agn+(n≤3) are observed. Composition of the mass spectra and widths of the mass peaks are found to be dependent on laser wavelength, suggesting that the dominant ablation mechanisms are different at the different wavelenghts.

  14. Intracellular Biosynthesis and Antibacterial Activity of Silver Nanoparticles Using Edible Mushrooms

    Directory of Open Access Journals (Sweden)

    Sankaran MIRUNALINI

    2012-11-01

    Full Text Available The process of biosynthesis of silver nanoparticles is a simple, cost effective and eco-friendly approach. Biosynthesis of silver nanoparticles using some commonly available edible mushroom extracts and their antimicrobial activity was demonstrated in the current study. The formation of silver nanoparticles was confirmed by UV, FTIR and SEM and antibacterial activity was tested using disc diffusion method. From the results it is confirmed the successful formation of silver nanoparticles using mushroom extracts; they performed their role as a reducing and capping agent and also exhibited a potent antibacterial activity against S. aureus (gram positive bacteria. Thus the biosynthesis of silver nanoparticles using edible mushroom extract will deserve to be a good candidate as an antibacterial agent.

  15. Biosynthesis of silver nanoparticles from Tribulus terrestris and its antimicrobial activity: a novel biological approach.

    Science.gov (United States)

    Gopinath, V; MubarakAli, D; Priyadarshini, S; Priyadharsshini, N Meera; Thajuddin, N; Velusamy, P

    2012-08-01

    In the recent decades, increased development of green synthesis of nanoparticles is inevitable because of its incredible applications in all fields of science. There were numerous work have been produced based on the plant and its extract mediated synthesis of nanoparticles, in this present study to explore that the novel approaches for the biosynthesis of silver nanoparticles using plant fruit bodies. The plant, Tribulus terrestris L. fruit bodies are used in this study, where the dried fruit body extract was mixed with silver nitrate in order to synthesis of silver nanoparticles. The active phytochemicals present in the plant were responsible for the quick reduction of silver ion (Ag(+)) to metallic silver nanoparticles (Ag(0)). The reduced silver nanoparticles were characterized by Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), XRD, FTIR, UV-vis spectroscopy. The spherical shaped silver nanoparticles were observed and it was found to be 16-28 nm range of sizes. The diffraction pattern also confirmed that the higher percentage of silver with fine particles size. The antibacterial property of synthesized nanoparticles was observed by Kirby-Bauer method with clinically isolated multi-drug resistant bacteria such as Streptococcus pyogens, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The plant materials mediated synthesis of silver nanoparticles have comparatively rapid and less expensive and wide application to antibacterial therapy in modern medicine. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

    International Nuclear Information System (INIS)

    Chiamenti, Ismael; Costa, Larissa N. da; Kalinowski, Hypolito J.; Bonfigli, Francesca; Montereali, Rosa Maria; Gomes Anderson, S. L.

    2014-01-01

    Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F 2 and F 3 + color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10 −3 −10 −4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF

  17. Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

    Science.gov (United States)

    Ismael, Chiamenti; Francesca, Bonfigli; Anderson, S. L. Gomes; Rosa, Maria Montereali; Larissa, N. da Costa; Hypolito, J. Kalinowski

    2014-01-01

    Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F2 and F3+ color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10-3-10-4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF.

  18. Interpretation of neutron activation analysis data of ancient silver

    International Nuclear Information System (INIS)

    Meyers, P.; van Zelst, L.; Sayre, E.V.

    1976-01-01

    Results from work on Sasanian silver and objects from related periods and geographic provenances are used to demonstrate that analytical data in combination with other properties can be used with reasonable success in establishing groups of objects of common geographic provenances, in providing information on the production, use, and distribution of silver metal, and on ancient metal working techniques

  19. Biosynthesis of silver nanoparticles using Ocimum sanctum (Tulsi) leaf extract and screening its antimicrobial activity

    Science.gov (United States)

    Singhal, Garima; Bhavesh, Riju; Kasariya, Kunal; Sharma, Ashish Ranjan; Singh, Rajendra Pal

    2011-07-01

    Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles. In this study, biosynthesis of stable silver nanoparticles was done using Tulsi ( Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV-vis spectrophotometer, Atomic Absorption Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV-vis absorption spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4-30 nm possessing antimicrobial activity suggesting their possible application in medical industry.

  20. Biosynthesis of silver nanoparticles using Ocimum sanctum (Tulsi) leaf extract and screening its antimicrobial activity

    International Nuclear Information System (INIS)

    Singhal, Garima; Bhavesh, Riju; Kasariya, Kunal; Sharma, Ashish Ranjan; Singh, Rajendra Pal

    2011-01-01

    Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles. In this study, biosynthesis of stable silver nanoparticles was done using Tulsi (Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV–vis spectrophotometer, Atomic Absorption Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV–vis absorption spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4–30 nm possessing antimicrobial activity suggesting their possible application in medical industry.

  1. Negative optical absorption and up-energy conversion in dendrites of nanostructured silver grafted with α/β-poly(vinylidene fluoride) in small hierarchical structures

    Science.gov (United States)

    Phule, A. D.; Ram, S.; Shinde, S. K.; Choi, J. H.; Tyagi, A. K.

    2018-04-01

    We report that a negative optical absorption arises in a sharp band at 325 nm (energy hν2) in a nanostructured silver (n-Ag) doped poly(vinylidene fluoride) (PVF2) in a hybrid nanocomposite of films (∼100 μm thickness). Two polymorphs α- and β-PVF2 are co-stretched through the n-Ag crystallites in dendrites of hierarchical structures. A critical 0.5 wt% n-Ag dosage promotes this band of extinction coefficient to be enhanced by as much as 2.009 × 103, i.e. a 30% value in the Ag-surface plasmon band 350-650 nm (hν1). An electron donor Ag (4d105s1) bonds to an electron accepter moiety CF2 of PVF2, it tunes a dielectric field and sets up an up-energy conversion of the plasmon band. The FESEM and HRTEM images reveal fcc-Ag dendrites entangled with in-built PVF2 surface layers (2-3 nm thickness). The IR phonon bands show how a α → β-PVF2 transformation propagates onto a nascent n-Ag surface and how it is raised-up in small steps of 0.1 wt% and up to 5.0 wt%. In a model scheme, we illustrate how a rigid core-shell of a capsule conducts a new transfer mechanism of the energy to a cold surface plasmon (core) in a coherent collision, so as to balance a net value hν2 = h(ν3 - ν1). It absorbs light in a weak band at 210 nm (hν3) in a π → π* electron transition in the Cdbnd C bonds of the PVF2 (shell), and results in a negative absorption in a coherent excitation of the energy-carriers. A light-emitter on absorption over a wide range of wavelengths (200-650 nm) offers a unique type of energy-converter.

  2. Cytotoxicity and antimicrobial activities of green synthesized silver nanoparticles.

    Science.gov (United States)

    Lokina, S; Stephen, A; Kaviyarasan, V; Arulvasu, C; Narayanan, V

    2014-04-09

    Bio-inspired silver nanoparticles are synthesized using Malus domestica (apple) extract. Polyphenols present in the apple extract act as a reducing and capping agent to produce the silver nanoparticles. UV-Visible analysis shows the surface plasmon resonance (SPR) absorption at 420 nm. The FTIR analysis was used to identify the functional groups responsible for the bio-reduction of silver ion. The XRD and HRTEM images confirm the formation of silver nanoparticles. The minimal inhibitory concentration (MIC) of silver nanoparticles was recorded against most of the bacteria and fungus. Further, MCF-7 human breast adenocarcinoma cancer cell line was employed to observe the efficacy of cancer cell killing. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  3. Alteration of paraoxonase, arylesterase and lactonase activities in people around fluoride endemic area of Tamil Nadu, India.

    Science.gov (United States)

    Arulkumar, Mani; Vijayan, Raji; Penislusshiyan, Sakayanathan; Sathishkumar, Palanivel; Angayarkanni, Jayaraman; Palvannan, Thayumanavan

    2017-08-01

    Toxicity due to excess fluoride concentration in drinking water is of great concern in people who rely only on the ground water as their water source in many region of the world. We collected samples and examined the toxicity of fluoride in a population residing at Salem, Dharmapuri and Krishnagiri districts of Tamil Nadu, India and measured HDL bound enzyme (PON1), erythrocyte membrane bound enzymes (acetylcholinesterase, AChE) and adenosine 5' triphosphatase (ATPases), plasma enzyme (butyrylcholinesterase, BChE) and rate limiting enzyme in heme biosynthesis (delta aminolevulinic acid dehydratase, δ-ALAD) activities. In fluorosis patients, formation of lipid peroxidation product was more in erythrocytes than in plasma. The observation further revealed that there was 50% reduction in the activity of HDL bound anti atherogenic enzyme-paraoxonase (PON1). The activities of membrane bound and signaling enzymes (acetylcholinesterase - AChE and adenosine 5' triphosphatase - ATPase) of erythrocyte were also diminished. These results suggested that there was defectiveness in the signaling and energy metabolism in fluorosis patients. Altered isoenzyme pattern of lactate dehydrogenase (LDH) in fluorosis samples was observed. Furthermore, the result suggested that both the heart (LDH 1) and liver (LDH 5) were most affected by fluoride toxicity. The study also provided reference values for tests which are used to predict the severity of fluoride toxicity. The toxic effect of fluoride was due to the collective effects on vital protective system rather than single factor. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Antibacterial activity of nitric oxide releasing silver nanoparticles

    Science.gov (United States)

    Seabra, Amedea B.; Manosalva, Nixson; de Araujo Lima, Bruna; Pelegrino, Milena T.; Brocchi, Marcelo; Rubilar, Olga; Duran, Nelson

    2017-06-01

    Silver nanoparticles (AgNPs) are well known potent antimicrobial agents. Similarly, the free radical nitric oxide (NO) has important antibacterial activity, and due to its instability, the combination of NO and nanomaterials has been applied in several biomedical applications. The aim of this work was to synthesize, characterize and evaluate the antibacterial activity of a new NO-releasing AgNPs. Herein, AgNPs were synthesized by the reduction of silver ions (Ag+) by catechin, a natural polyphenol and potent antioxidant agent, derived from green tea extract. Catechin acts as a reducing agent and as a capping molecule on the surface of AgNPs, minimizing particle agglomeration. The as-synthesized nanoparticles were characterized by different techniques. The results showed the formation of AgNPs with average hydrodynamic size of 44 nm, polydispersity index of 0.21, and zeta potential of -35.9 mV. X-ray diffraction and Fourier transform infrared spectroscopy revealed the presence of the AgNP core and cathecin as capping agent. The low molecular weight mercaptosuccinic acid (MSA), which contain free thiol group, was added on the surface of catechin-AgNPs, leading to the formation of MSA-catechin-AgNPs (the NO precursor nanoparticle). Free thiol groups of MSA-catechin-AgNPs were nitrosated leading to the formation of S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), the NO donor. The amount of 342 ± 16 µmol of NO was released per gram of S-nitroso-MSA-catechin-AgNPs. The antibacterial activities of catechin-AgNPs, MSA-catechin-AgNPs, and S-nitroso-MSA-catechin-AgNPs were evaluated towards different resistant bacterial strains. The results demonstrated an enhanced antibacterial activity of the NO-releasing AgNP. For instance, the minimal inhibitory concentration values for Pseudomonas aeruginosa (ATCC 27853) incubated with AgNPs-catechin, AgNPs-catechin-MSA, and AgNPs-catechin-S-nitroso-MSA were found to be 62, 125 and 3 µg/mL, respectively. While in the case of

  5. Evaluation of Biological Activities of Chemically Synthesized Silver Nanoparticles

    International Nuclear Information System (INIS)

    Mostafa, A. A.; Solkamy, E.N.; Sayed, Sh. R. M.; Khan, M.; Shaik, M.R.; Al-Warthan, A.; Adil, S.F.

    2015-01-01

    Silver nanoparticles were synthesized by the earlier reported methods. The synthesized nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV/Vis), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray powder diffraction (XRD). The synthesized materials were also evaluated for their antibacterial activity against Gram positive and Gram negative bacterial strains. TEM micrograph showed the spherical morphology of AgNPs with size range of 40-60 nm. The synthesized nanoparticles showed a strong antimicrobial activity and their effect depends upon bacterial strain as AgNPs exhibited greater inhibition zone for Pseudomonas aeruginosa (19.1 mm) followed by Staphylococcus aureus (14.8?mm) and S. pyogenes (13.6 mm) while the least activity was observed for Salmonella typhi (12.5 mm) at concentration of 5 μg/disc. The minimum inhibitory concentration (MIC) of AgNPs against S. aureus was 2.5 μg/disc and less than 2.5 μg/disc for P. aeruginosa. These results suggested that AgNPs can be used as an effective antiseptic agent for infectious control in medical field.

  6. Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage.

    Science.gov (United States)

    Raja, K; Saravanakumar, A; Vijayakumar, R

    2012-11-01

    In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Biosynthesis of silver nanoparticles using aqueous leaf extract of Thevetia peruviana Juss and its antimicrobial activities

    Science.gov (United States)

    Oluwaniyi, Omolara O.; Adegoke, Haleemat I.; Adesuji, Elijah T.; Alabi, Aderemi B.; Bodede, Sunday O.; Labulo, Ayomide H.; Oseghale, Charles O.

    2016-08-01

    Biosynthesizing of silver nanoparticles using microorganisms or various plant parts have proven more environmental friendly, cost-effective, energy saving and reproducible when compared to chemical and physical methods. This investigation demonstrated the plant-mediated synthesis of silver nanoparticles using the aqueous leaf extract of Thevetia peruviana. UV-Visible spectrophotometer was used to measure the surface plasmon resonance of the nanoparticles at 460 nm. Fourier Transform Infrared showed that the glycosidic -OH and carbonyl functional group present in extract were responsible for the reduction and stabilization of the silver nanoparticles. X ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and Selected Area Electron Diffraction analyses were used to confirm the nature, morphology and shape of the nanoparticles. The silver nanoparticles are spherical in shape with average size of 18.1 nm. The synthesized silver nanoparticles showed activity against fungal pathogens and bacteria. The zone of inhibition observed in the antimicrobial study ranged between 10 and 20 mm.

  8. Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage

    Science.gov (United States)

    Raja, K.; Saravanakumar, A.; Vijayakumar, R.

    2012-11-01

    In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.

  9. Antibacterial Activity of Silver Nanoparticles Synthesized by Using Extracts of Hedera helix

    Directory of Open Access Journals (Sweden)

    Ahmadreza Abbasifar

    2017-01-01

    Full Text Available Background Silver nanoparticles (AgNPs are one of the most widely applicable particles whose application is increasing in Nano world daily. Silver nanoparticles have expressed significant advances owing to wide range of applications in the field of bio-medical, sensors, antimicrobials, catalysts, electronics, optical fibers, agricultural, bio-labeling and the other areas. Green synthesis is the safe and easiest method of producing silver nanoparticles. Because of the production of the silver ions, silver nanoparticles are found to have the antibacterial activity. Objectives The aim of this study was to investigate antibacterial activity of silver nanoparticles synthesized by using extracts of Hedera helix against Bacillus subtilis and Klebsiella pneumoniae. Methods In this experimental study AgNPs were prepared by the reaction of 1mM silver nitrate and extracts of Hedera helix. Antibacterial activity of AgNPs was assessed by using disc diffusion method against Bacillus subtilis and Klebsiella pneumoniae. The AgNPs were characterized by UV-visible (vis spectrophotometer, particle size analyzer by dynamic light scattering (DLS method, transmission electron microscopy (TEM. Results AgNPs obtained showed significantly higher antimicrobial activities against B. subtilis and K. pneumonia in comparison to both AgNO3 and raw plant extracts. Conclusions Biological methods are a good competent for the chemical procedures, which are environment friendly and convenient.

  10. Bone metabolic activity measured with positron emission tomography and [18F] fluoride ion in renal osteodystrophy: Correlation with bone histomorphometry

    International Nuclear Information System (INIS)

    Messa, C.; Goodman, W.G.; Hoh, C.K.; Choi, Y.; Nissenson, A.R.; Salusky, I.B.; Phelps, M.E.; Hawkins, R.A.

    1993-01-01

    The authors evaluated the bone metabolic activity in patients with renal osteodystrophy using positron emission tomography and [ 18 F] fluoride ion. Eight patients had secondary hyperparathyroidism (HPT), and three had low-turnover bone disease. Eleven normal subjects were also studied, and three of the eight HPT patients were reevaluated after therapy. A rate constant (K) describing the net transport of [ 18 F] fluoride ion into a bound compartment in bone was calculated using both a three-compartment model and Patlak graphical analysis. Values of K were compared with biochemical data and with histomorphometric indices. The results indicate that K is significantly higher (P 18 F] fluoride ion can differentiate low turnover from high turnover lesions of renal osteodystropy and provide quantitative estimates of bone cell activity that correlate with histomorphometric data

  11. Development and Antibacterial Activity of Cashew Gum-Based Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Maria José dos S. Soares

    2013-03-01

    Full Text Available The present study describes the development of a green synthesis of silver nanoparticles reduced and stabilized by exuded gum from Anacardium occidentale L. and evaluates in vitro their antibacterial and cytotoxic activities. Characterization of cashew gum-based silver nanoparticles (AgNPs was carried out based on UV–Vis spectroscopy, transmission electron microscopy and dynamic light scattering analysis which revealed that the synthesized silver nanoparticles were spherical in shape, measuring about 4 nm in size with a uniform dispersal. AgNPs presented antibacterial activity, especially against Gram-negative bacteria, in concentrations where no significant cytotoxicity was observed.

  12. Surface characteristics and antibacterial activity of a silver-doped carbon monolith

    Directory of Open Access Journals (Sweden)

    Marija Vukčević et al

    2008-01-01

    Full Text Available A carbon monolith with a silver coating was prepared and its antimicrobial behaviour in a flow system was examined. The functional groups on the surface of the carbon monolith were determined by temperature-programmed desorption and Boehm's method, and the point of zero charge was determined by mass titration. The specific surface area was examined by N2 adsorption using the Brunauer, Emmett and Teller (BET method. As a test for the surface activity, the deposition of silver from an aqueous solution of a silver salt was used. The morphology and structure of the silver coatings were characterized by scanning electron microscopy and x-ray diffraction. The resistance to the attrition of the silver deposited on the carbon monolith was tested. The antimicrobial activity of the carbon monolith with a silver coating was determined using standard microbiological methods. Carbon monolith samples with a silver coating showed good antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans, and are therefore suitable for water purification, particularly as personal disposable water filters with a limited capacity.

  13. Bio-synthesis and antimicrobial activity of silver nanoparticles using anaerobically digested parthenium slurry.

    Science.gov (United States)

    Adur, Alaknanda J; Nandini, N; Shilpashree Mayachar, K; Ramya, R; Srinatha, N

    2018-06-01

    Silver nanoparticles were prepared through eco-friendly, cost effective, bio-mediated technique using anaerobically digested Parthenium hysterophorous digested slurry (PDS) for the first time. The synthesized nanoparticles were characterized through different techniques such as UV-Vis spectrophotometer for optical properties; X-ray diffractometer (XRD), high resolution transmission electron spectroscopy (HR-TEM) and Fourier Transform Infra Red (FTIR) Spectroscopy for structural property investigations. It was observed that the prepared silver nanoparticles were crystallized in face centered cubic crystal structure with an average particle size of 19 nm as confirmed from XRD. Also HR-TEM studies reveal the formation of nano-sized silver particles with face centered cubic nano structure. In addition, absorption spectra exhibit Surface Plasmon Resonance (SPR) which suggests the formation of silver nanoparticles. FTIR results show the presence of different characteristic functional groups and their stretching / bending vibrations in turn responsible for the bioreduction of silver ions in Parthenium digested slurry. Further investigations on antimicrobial activity were done by subjecting the synthesized silver nanoparticles on E-coli and Pseudomonas as marker organisms for the group of gram negative bacteria by well plate method on enrichment media. The result obtained shows a clear zone of inhibition confirming the antibacterial activity. Overall, the investigated results confirm the biosynthesized silver nanoparticles are potential candidates for antimicrobial activity applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. An in vitro antifungal efficacy of silver nanoparticles activated by diode laser to Candida albicans

    Science.gov (United States)

    Astuti, S. D.; Kharisma, D. H.; Kholimatussa'diah, S.; Zaidan, A. H.

    2017-09-01

    Microbial infectious diseases and increased resistance to antibiotics become urgent problems requiring immediate solutions. One promising alternative is the using of silver nanoparticles. The combination of the microbial inhibition characteristic of silver nanotechnology enhances the activity of antimicrobial effect. This study aims to determine effectiveness of antifungal silver nanoparticles with the activation of the diode laser on Candida albicans. The samples were culture of Candida albicans. Candida albicans cultures were incubated with silver nanoparticles (concentration 10-4 M) and treated with various exposure time of diode laser (15, 30, 45, 60, 75, 90)s. The suspension was planted on Sabouraud Dextrone Agar sterile media and incubated for 24 hours at temperature of 37oC. The number of colony-forming units per milliliter (CFU/ml) was determined after incubation. The results were log-transformed and analyzed by analysis of variance (ANOVA). In this analysis, P value ≤0.05 was considered to indicate a statistically significant difference. The result of this study showed the quantum yield of silver nanoparticles with diode laser 450 nm was 63,61%. Irradiating with diode laser 450 nm for 75 s resulted in the highest decreasing percentage of Candida albicans viability 65,03%. Irradiating with diode laser 450 nm 75 s with silver nanoparticles resulted in the higest decreasing percentage of Candida albicans viability 84,63%. Therefore, silver nanoparticles activated with diode laser irradiation of 450 nm resulted antifungal effect to Candida albicans viability.

  15. Reactivity and Catalytic Activity of Hydrogen Atom Chemisorbed Silver Clusters.

    Science.gov (United States)

    Manzoor, Dar; Pal, Sourav

    2015-06-18

    Metal clusters of silver have attracted recent interest of researchers as a result of their potential in different catalytic applications and low cost. However, due to the completely filled d orbital and very high first ionization potential of the silver atom, the silver-based catalysts interact very weakly with the reacting molecules. In the current work, density functional theory calculations were carried out to investigate the effect of hydrogen atom chemisorption on the reactivity and catalytic properties of inert silver clusters. Our results affirm that the hydrogen atom chemisorption leads to enhancement in the binding energy of the adsorbed O2 molecule on the inert silver clusters. The increase in the binding energy is also characterized by the decrease in the Ag-O and increase in the O-O bond lengths in the case of the AgnH silver clusters. Pertinent to the increase in the O-O bond length, a significant red shift in the O-O stretching frequency is also noted in the case of the AgnH silver clusters. Moreover, the hydrogen atom chemisorbed silver clusters show low reaction barriers and high heat of formation of the final products for the environmentally important CO oxidation reaction as compared to the parent catalytically inactive clusters. The obtained results were compared with those of the corresponding gold and hydrogen atom chemisorbed gold clusters obtained at the same level of theory. It is expected the current computational study will provide key insights for future advances in the design of efficient nanosilver-based catalysts through the adsorption of a small atom or a ligand.

  16. Biosynthesis, structural characterization and antimicrobial activity of gold and silver nanoparticles.

    Science.gov (United States)

    Ahmad, Tokeer; Wani, Irshad A; Manzoor, Nikhat; Ahmed, Jahangeer; Asiri, Abdullah M

    2013-07-01

    An eco friendly simple biosynthetic route was used for the preparation of monodisperse and highly crystalline gold and silver nanoparticles using cell free extract of fungus, Candida albicans. Transmission electron microscopic studies show the formation of gold and silver nanocrystals of average size of 5 nm and 30 nm with the specific surface areas of 18.9 m(2)/g and 184.4 m(2)/g respectively. The interaction of gold and silver nanoparticles with proteins has been formulated by FT-IR spectroscopy and thermal gravimetric analysis. The formation of gold and silver nanoparticles was also confirmed by the appearance of a surface plasmon band at 540 nm and 450 nm respectively. The antimicrobial activity of the synthesized gold and silver nanoparticles was investigated against both Staphylococcus aureus and Escherichia coli. The results suggest that these nanoparticles can be used as effective growth inhibitors against the test microorganisms. Greater bactericidal activity was observed for silver nanoparticles. The E. coli, a gram negative bacterium was found to be more susceptible to gold and silver nanoparticles than the S. aureus, a gram positive bacterium. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Trichoderma koningii assisted biogenic synthesis of silver nanoparticles and evaluation of their antibacterial activity

    Science.gov (United States)

    Tripathi, R. M.; Gupta, Rohit Kumar; Shrivastav, Archana; Singh, M. P.; Shrivastav, B. R.; Singh, Priti

    2013-09-01

    The present study demonstrates the biosynthesis of silver nanoparticles using Trichoderma koningii and evaluation of their antibacterial activity. Trichoderma koningii secretes proteins and enzymes that act as reducing and capping agent. The biosynthesized silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD). UV-Vis spectra showed absorbance peak at 413 nm corresponding to the surface plasmon resonance of silver nanoparticles. DLS was used to find out the size distribution profile. The size and morphology of the AgNPs was determined by TEM, which shows the formation of spherical nanoparticles in the size range of 8-24 nm. X-ray diffraction showed intense peaks corresponding to the crystalline silver. The antibacterial activity of biosynthesized AgNPs was evaluated by growth curve and inhibition zone and it was found that the AgNPs show potential effective antibacterial activity.

  18. Trichoderma koningii assisted biogenic synthesis of silver nanoparticles and evaluation of their antibacterial activity

    International Nuclear Information System (INIS)

    Tripathi, R M; Shrivastav, Archana; Gupta, Rohit Kumar; Singh, M P; Shrivastav, B R; Singh, Priti

    2013-01-01

    The present study demonstrates the biosynthesis of silver nanoparticles using Trichoderma koningii and evaluation of their antibacterial activity. Trichoderma koningii secretes proteins and enzymes that act as reducing and capping agent. The biosynthesized silver nanoparticles (AgNPs) were characterized by UV–Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD). UV–Vis spectra showed absorbance peak at 413 nm corresponding to the surface plasmon resonance of silver nanoparticles. DLS was used to find out the size distribution profile. The size and morphology of the AgNPs was determined by TEM, which shows the formation of spherical nanoparticles in the size range of 8–24 nm. X-ray diffraction showed intense peaks corresponding to the crystalline silver. The antibacterial activity of biosynthesized AgNPs was evaluated by growth curve and inhibition zone and it was found that the AgNPs show potential effective antibacterial activity. (paper)

  19. Mechanism of adsorption of gold and silver species on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Y.F.; Steele, C.J.; Hayward, I.P.; Thomas, K.M. [University of Newcastle-upon-Tyne, Newcastle-upon-Tyne (United Kingdom). Northern Carbon Research Labs., Dept. of Chemistry

    1998-12-31

    The adsorption characteristics of gold and silver cyanide anionic species on a suite of active carbons derived from coal, coconut shell and polyacrylonitrile was investigated. The gold and silver cyanide adsorption capacities for both coconut shell and coal derived carbons correlated with total pore volume. Nitric acid treatment of the carbon was detrimental to gold adsorption in spite of the incorporation of oxygen into the carbon through oxidation. The influence of nitrogen functional groups in the carbon structure on gold and silver adsorption was investigated using carbons with very high nitrogen contents derived from polyacrylonitrile.

  20. Experimental study of mutagenous and mitosis modifying activity of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    B. S. Kirbik

    2015-01-01

    Full Text Available Mutagenous and mitosis modifying impact of silver nanoparticles has been studied on outbred mice. Nanoparticles were of round shape with dimensions of 5-50 nm, size of generated organic shell of 2-5 nm, the quantity in 1 mcm3 makes 120-270. Metaphasic analysis of mice bone marrow cells was used as a testing technique. The frequency of chromosome aberrations and mitotic index of preparations were accounted. During single intraperitoneal administration of the agent in the dose of 250 mcg/kg the silver nanoparticles demonstrated mitosis stimulating activity. No mutagenous effect of silver nanoparticles by daily administration for 4 days of 25 mcg/kg and single administration in the dose of 250 mcg/kg has been registered, but there is statistically insignificant tendency of aberrant metaphases increase. Consequently silver nanoparticles in the investigated doses demonstrated no mutagenous activity and can be considered safe for mammalian cells.

  1. Synthesis, characterization and antimicrobial activity of dextran stabilized silver nanoparticles in aqueous medium.

    Science.gov (United States)

    Bankura, K P; Maity, D; Mollick, M M R; Mondal, D; Bhowmick, B; Bain, M K; Chakraborty, A; Sarkar, J; Acharya, K; Chattopadhyay, D

    2012-08-01

    A simple one-step rapid synthetic route is described for the preparation of silver nanoparticles by reduction of silver nitrate (AgNO3) using aqueous dextran solution which acts as both reducing and capping agent. The formation of silver nanoparticles is assured by characterization with UV-vis spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The absorbance of the silver nanoparticles is observed at 423 nm. The AFM image clearly shows the surface morphology of the well-dispersed silver nanoparticles with size range of 10-60 nm. TEM images show that the nanoparticles are spherical in shape with ∼5-10 nm dimensions. The crystallinity of Ag nanoparticles is assured by XRD analysis. The antimicrobial activity of as synthesized silver nanoparticles is tested against the bacteria, Bacillus subtilis, Bacillus cereus, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The bacterial growth is inhibited by gradual reduction of the concentration of the silver nanoparticles. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Diclofenac and 2‐anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver

    Science.gov (United States)

    Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

    2012-01-01

    Summary The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio‐MnOx), biogenic silver nanoparticles (Bio‐Ag0) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2‐anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by Pseudomonas putida MnB6. Furthermore, whereas preoxidized Bio‐MnOx, Bio‐Ag0 and Ag+ separately did not show any removal capacity for diclofenac, an enhanced removal occurred when Bio‐MnOx and silver species were combined. Similar results were obtained for APA. Finally, a slow removal of diclofenac but more rapid APA degradation was observed when silver was added to manganese‐free P. putida biomass. Combining these results, three mechanisms of diclofenac and APA removal could be distinguished: (i) a co‐metabolic removal during active Mn2+ oxidation by P. putida; (ii) a synergistic interaction between preoxidized Bio‐MnOx and silver species; and (iii) a (bio)chemical process by biomass enriched with silver catalysts. This paper demonstrates the use of P. putida for water treatment purposes and is the first report of the application of silver combined with biogenic manganese for the removal of organic water contaminants. PMID:22221449

  3. Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities

    International Nuclear Information System (INIS)

    Rao, N.Hanumanta; Lakshmidevi, N.; Pammi, S.V.N.; Kollu, Pratap; Ganapaty, S.; Lakshmi, P.

    2016-01-01

    Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV–Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (−) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. - Highlights: • Biosynthesis of silver nanoparticles (Ag NPs) using root extracts of Diospyros paniculata. • Average diameter of Ag NPs is about 17 nm from TEM analysis which is in good agreement with XRD analysis. • Antimicrobial activities of root extract mediated synthesis of silver Ag NPs were discussed in detail.

  4. Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.Hanumanta [Advanced Analytical Laboratory, DST-PURSE Programme, Andhra University, Visakhapatnam 530003 (India); Lakshmidevi, N. [Department of Microbiology, College of Science and Technology, Andhra University, Visakhapatnam 530003 (India); Pammi, S.V.N. [Advanced Analytical Laboratory, DST-PURSE Programme, Andhra University, Visakhapatnam 530003 (India); Department of Materials Science and Engineering, Chungnam National University, Daeduk Science Town, 305-764, Daejeon (Korea, Republic of); Kollu, Pratap [DST-INSPIRE Faculty, Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Ganapaty, S. [GITAM Institute of Pharmacy, GITAM University, Visakhapatnam (India); Lakshmi, P., E-mail: lmkandregula@gmail.com [Department of Microbiology, College of Science and Technology, Andhra University, Visakhapatnam 530003 (India)

    2016-05-01

    Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV–Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (−) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. - Highlights: • Biosynthesis of silver nanoparticles (Ag NPs) using root extracts of Diospyros paniculata. • Average diameter of Ag NPs is about 17 nm from TEM analysis which is in good agreement with XRD analysis. • Antimicrobial activities of root extract mediated synthesis of silver Ag NPs were discussed in detail.

  5. Antimicrobial activity and properties of irreversible hydrocolloid impression materials incorporated with silver nanoparticles.

    Science.gov (United States)

    Ginjupalli, Kishore; Alla, Rama Krishna; Tellapragada, Chaitanya; Gupta, Lokendra; Upadhya Perampalli, Nagaraja

    2016-06-01

    Conventional spray and the immersion disinfection of irreversible hydrocolloid impression materials may lead to dimensional changes. The purpose of this in vitro study was to investigate the antimicrobial activity and properties of irreversible hydrocolloid impression materials incorporated with silver nanoparticles. The antimicrobial activity and properties of 2 commercially available irreversible hydrocolloid impression materials were evaluated after incorporating varying concentrations of silver nanoparticles. Antimicrobial activity was determined using the disk diffusion method. The gel strength, permanent deformation, flow, and gelation time were measured according to American Dental Association specification #18. Analysis of variance was used to identify the significant differences within and across the groups (α=.05). Adding silver nanoparticles to irreversible hydrocolloid impression materials resulted in superior antimicrobial activity without adversely affecting their properties. Adding silver nanoparticles to Zelgan significantly increased the gel strength compared with the control group, except at 5 wt%. However, the gel strength of Tropicalgin was unaffected except at 5 wt%. An increase in the permanent deformation was found with the incorporation of silver nanoparticles in both Zelgan and Tropicalgin. The flow of Zelgan increased with the incorporation of silver nanoparticles, whereas a decrease in the flow of Tropicalgin was observed at 1 wt% and 2 wt%. An increase in the gelation time of both Zelgan and Tropicalgin was observed with the incorporation of silver nanoparticles. Based on this in vitro study, silver nanoparticles can be incorporated into irreversible hydrocolloid impression materials as antimicrobial agents without adversely affecting their properties. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  6. Biosynthesis of silver nanoparticles using lingonberry and cranberry juices and their antimicrobial activity.

    Science.gov (United States)

    Puišo, Judita; Jonkuvienė, Dovilė; Mačionienė, Irena; Šalomskienė, Joana; Jasutienė, Ina; Kondrotas, Rokas

    2014-09-01

    In this study lingonberry and cranberry juices were used for silver nanoparticle synthesis. The berry juices were characterized by total phenolics, total anthocyanins and benzoic acid content, respectively 1.9-2.7mg/ml, 55.2-83.4mg/l and 590.8-889.2mg/l. The synthesis of silver nanoparticles was performed at room temperature assisting in solutions irradiated by ultraviolet for 30min. Ultraviolet-visible (UV-vis) spectroscopy and microscopy confirmed the formation of nanoparticles as well as the dark red color of colloid of silver samples showed the formation of stable nanoparticles. Broad localized surface plasmon resonance (LSPR) peaks in UV-vis spectra indicated the formation of polydispersive silver nanoparticles and LSPR was observed at 485nm and 520nm for the silver nanoparticles synthesis using lingonberry and cranberry juices, respectively. The antimicrobial activity of silver nanoparticles was determined against the reference strains of microorganisms that could be found in food products: Staphylococcus aureus ATCC 25923, Salmonella typhimurium ATCC 13076, Listeria monocytogenes ATCC 19111, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Candida albicans ATCC 10231 and foodborne B. cereus producing and non-producing enterotoxins. Silver nanoparticles showed a broad spectrum of antimicrobial activity and were most active against S. aureus ATCC 25923, B. subtilis ATCC 6633 and B. cereus ATCC 11778 reference cultures, and less active against C. albicans ATCC 10231 and foodborne B. cereus. It can be concluded that lingonberry and cranberry juices could be used as bioreductants for silver ions. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Biosynthesis of silver nanoparticles using Alternanthera sessilis (Linn.) extract and their antimicrobial, antioxidant activities.

    Science.gov (United States)

    Niraimathi, K L; Sudha, V; Lavanya, R; Brindha, P

    2013-02-01

    The present work focuses the use of the aqueous extract of Alternanthera sessilis Linn. (Amaranthaceae) in producing silver nanoparticles (AgNPs) from silver nitrate aqueous. Phytochemical analysis of the extract revealed the presence of alkaloid, tannins, ascorbic acid, carbohydrates and proteins and they serve as effective reducing and capping agents for converting silver nitrate into nanoparticles. The synthesized silver nanoparticles (AgNPs) were also tested for proteins and ascorbic acid. Its pH was also determined (5.63). The AgNPs obtained was characterized by UV-vis spectroscopy, FT-IR spectroscopy, SEM, Zeta sizer and TG-DSC. SEM images which revealed the presence of various shapes and sizes. FT-IR spectrum showed the AgNPs having a coating of proteins indicating a dual role of bio-molecules responsible for capping and efficient stabilization of the silver nanoparticles. Presence of impurities and melting point profile were screened by TG-DSC analyzer. AgNPs were synthesized from the silver nitrate through the reducing power of ascorbic acid present in A. sessilis leaves. In this study, we also investigated antimicrobial and antioxidant activity of green synthesized AgNPs. The antimicrobial activity is investigated by Bauer et al.'s method. Antioxidant activity was done by DPPH method. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Antimicrobial activity and the mechanism of silver nanoparticle thermosensitive gel

    Directory of Open Access Journals (Sweden)

    Chen M

    2011-11-01

    Full Text Available Meiwan Chen1,2,‡, Zhiwen Yang1,‡, Hongmei Wu1, Xin Pan1, Xiaobao Xie3, Chuanbin Wu11Research and Development Center of Pharmaceutical Engineering, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China; 2State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China; 3Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangzhou, China ‡These authors contributed equally to this workPurpose: The purpose of the present study was to elucidate the antimicrobial activity and mechanism of silver nanoparticles incorporated into thermosensitive gel (S-T-Gel on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.Patients and methods: This study investigated the growth, permeability, and morphology of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa cells in order to observe the action of S-T-Gel on the membrane structure of these three bacteria. The cell morphology of normal and treated bacteria cells was assessed by transmission electron microscopy (TEM, and the effects of S-T-Gel on genome DNA of bacterial cells were evaluated by agarose gel electrophoresis.Results: S-T-Gel showed promising activity against Staphylococcus aureus and moderate activity against Escherichia coli and Pseudomonas aeruginosa. The observation with TEM suggested that S-T-Gel may destroy the structure of bacterial cell membranes in order to enter the bacterial cell. S-T-Gel then condensed DNA and combined and coagulated with the cytoplasm of the damaged bacteria, resulting in the leakage of the cytoplasmic component and the eventual death of these three bacteria. In addition, the analysis of agarose gel electrophoresis demonstrated that S-T-Gel could increase the decomposability of genome DNA.Conclusion: These results about promising antimicrobial activity and mechanism of S-T-Gel may be useful for further research

  9. Biosynthesis of Silver Nanoparticles Using Oscillatoria Extract and Evaluation the Anticancer and Antibacterial Activities

    Directory of Open Access Journals (Sweden)

    T Ghasemipour

    2017-07-01

    Full Text Available Abstract Background and aim: The emergence of nanotechnology is one of the most promising areas for medical research. Today, biological methods of synthesizing nanoparticles have been considered in the fight against many diseases. The purpose of this study was to evaluate the anti-cancer and anti-bacterial activity of silver nanoparticles, biosynthesized with cyanobacteria acetate extract. Methods: In the present experimental study, the silver nanoparticles biosynthesis was performed using silver ions regeneration with cyanobacteria acetate extracts. Techniques such as X-ray diffraction, scanning electron microscopy and transient evaluation of silver nanoparticles were evaluated. In order to investigate the antibacterial activity of synthesized nanosilver, serial dilution method was used for broth microdilution test to determine minimum inhibitory concentration (MIC. The effects of silver nanoparticle toxicity on T47D breast cancer cell line were evaluated using MTT colorimetric method. Also, the proximal anxine 0.5 propidoid yodide kit and flow cytometry system were evaluated to evaluate the percentage of apoptosis and necrosis in cancer cells treated with silver nanoparticles. Results: Characterization of biosynthetic silver nanoparticles indicated that these nanoparticles had a mean size of 30 nm with dominant spherical morphology. The evaluation of the antibacterial properties of biosynthetic nanoparticles showed that the minimum inhibitory concentration for Escherichia coli, Acinetobacter Bumanni and Staphylococcus aureus was 25, 50 and 12.5 μg / ml, respectively. The results of cell proliferation of nanoparticles showed that its effect depends on the concentration and time of treatment of silver nanoparticles on cancerous cells. In addition, flow cytometric results showed an apoptotic cell death rate of 35% in the T47D cell line. Conclusion: Biosynthesis nanoparticles have anticancer and antibacterial activity and can be studied further

  10. Nickel-plating for active metal dissolution resistance in molten fluoride salts

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Luke [Department of Engineering Physics, 1500 Engineering Drive, University of Wisconsin, Madison, WI 53706 (United States); Sridharan, Kumar, E-mail: kumar@engr.wisc.edu [Department of Engineering Physics, 1500 Engineering Drive, University of Wisconsin, Madison, WI 53706 (United States); Anderson, Mark; Allen, Todd [Department of Engineering Physics, 1500 Engineering Drive, University of Wisconsin, Madison, WI 53706 (United States)

    2011-04-15

    Ni electroplating of Incoloy-800H was investigated with the goal of mitigating Cr dissolution from this alloy into molten 46.5%LiF-11.5%NaF-42%KF eutectic salt, commonly referred to as FLiNaK. Tests were conducted in graphite crucibles at a molten salt temperature of 850 deg. C. The crucible material graphite accelerates the corrosion process due to the large activity difference between the graphite and the alloy. For the purposes of providing a baseline for this study, un-plated Incoloy-800H and a nearly pure Ni-alloy, Ni-201 were also tested. Results indicate that Ni-plating has the potential to significantly improve the corrosion resistance of Incoloy-800H in molten fluoride salts. Diffusion of Cr from the alloy through the Ni-plating does occur and if the Ni-plating is thin enough this Cr eventually dissolves into the molten salt. The post-corrosion test microstructure of the Ni-plating, particularly void formation was also observed to depend on the plating thickness. Diffusion anneals in a helium environment of Ni-plated Incoloy-800H and an Fe-Ni-Cr model alloy were also investigated to understand Cr diffusion through the Ni-plating. Further enhancements in the efficacy of the Ni-plating as a protective barrier against Cr dissolution from the alloy into molten fluoride salts can be achieved by thermally forming a Cr{sub 2}O{sub 3} barrier film on the surface of the alloy prior to Ni electroplating.

  11. Catalytic activity of supported silver and potassium salts of tungstophosphoric acid in dehydration of ethanol

    International Nuclear Information System (INIS)

    Haber, J.; Matachowski, L.; Pamin, K.; Napruszewska, B.

    2002-01-01

    Potassium and silver salts of tungstophosphoric acid (HPW) have been supported on silica. Two series of potassium and silver salts of tungstophosphoric acid K x H 3-x PW 12 O 40 and Ag x H 3-x PW 12 O 40 where x = 1;2;3 supported on silica were prepared using incipient wetness method. In a typical synthesis, the heteropolyacid which after deposition on silica was washed with water to remove the part of heteropolyacid not bound to the support was reacted with silver or potassium salt. The vapor-phase dehydration of ethanol was employed as a test reaction. All the catalytic tests were carried out in a conventional flow type reactor, under atmospheric pressure, in the temperature range 125-500 o C. The results of these studies were used to explain the differences between the catalytic activities of heteropolysalts of potassium and silver supported on silica. (author)

  12. Communication: CO oxidation by silver and gold cluster cations: Identification of different active oxygen species

    International Nuclear Information System (INIS)

    Popolan, Denisia M.; Bernhardt, Thorsten M.

    2011-01-01

    The oxidation of carbon monoxide with nitrous oxide on mass-selected Au 3 + and Ag 3 + clusters has been investigated under multicollision conditions in an octopole ion trap experiment. The comparative study reveals that for both gold and silver cations carbon dioxide is formed on the clusters. However, whereas in the case of Au 3 + the cluster itself acts as reactive species that facilitates the formation of CO 2 from N 2 O and CO, for silver the oxidized clusters Ag 3 O x + (n= 1-3) are identified as active in the CO oxidation reaction. Thus, in the case of the silver cluster cations N 2 O is dissociated and one oxygen atom is suggested to directly react with CO, whereas a second kind of oxygen strongly bound to silver is acting as a substrate for the reaction.

  13. Communication: CO oxidation by silver and gold cluster cations: Identification of different active oxygen species

    Science.gov (United States)

    Popolan, Denisia M.; Bernhardt, Thorsten M.

    2011-03-01

    The oxidation of carbon monoxide with nitrous oxide on mass-selected Au3+ and Ag3+ clusters has been investigated under multicollision conditions in an octopole ion trap experiment. The comparative study reveals that for both gold and silver cations carbon dioxide is formed on the clusters. However, whereas in the case of Au3+ the cluster itself acts as reactive species that facilitates the formation of CO2 from N2O and CO, for silver the oxidized clusters Ag3Ox+ (n = 1-3) are identified as active in the CO oxidation reaction. Thus, in the case of the silver cluster cations N2O is dissociated and one oxygen atom is suggested to directly react with CO, whereas a second kind of oxygen strongly bound to silver is acting as a substrate for the reaction.

  14. Silver Colloid Nanoparticles: Synthesis, Characterization, and Their Antibacterial Activity

    Czech Academy of Sciences Publication Activity Database

    Panáček, A.; Kvítek, L.; Prucek, R.; Kolář, M.; Večeřová, R.; Pizúrová, Naděžda; Sharma, V. K.; Nevěčná, T.; Zbořil, R.

    2006-01-01

    Roč. 110, č. 33 (2006), s. 16248-16253 ISSN 1520-6106 R&D Projects: GA MŠk(CZ) 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : silver colloid nanoparticles * antimicrobial and bactericidal assays * particle size Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.115, year: 2006

  15. Antimicrobial activity of latex silver nanoparticles using Calotropis procera

    Directory of Open Access Journals (Sweden)

    Nadia Hussein Mohamed

    2014-11-01

    Conclusions: It can be concluded that serum latex of Calotropis procera was found to display strong potential for the synthesis of AgNPs as antimicrobial agents through rapid reduction of silver ions (Ag+ to Ag0. The green synthesized AgNPs were found to show higher antimicrobial efficacy than crude latex.

  16. Biosynthesis of silver nanoparticles and its antibacterial activity ...

    African Journals Online (AJOL)

    Dr.Rajasekar

    2012-07-19

    Jul 19, 2012 ... Available online at http://www.academicjournals.org/AJB ... Transmission Electron Microscopy (HRTEM) support the biosynthesis and characterization of silver nanoparticles. ... nanoparticle from seaweed is a green chemical method ... operating at a voltage of 80 kV and a current of 30 mA (Chandran.

  17. Phosphatase activity of Poa pratensis seeds. III. Effect of fluoride, citrate, urea and other substances on the activity of acid phosphatase Ia2 and Ia3

    Directory of Open Access Journals (Sweden)

    Irena Lorenc-Kubis

    2015-01-01

    Full Text Available Effects of fluoride, citrate, urea and other substances on the activity of acid phosphatase a2 and a3 toward p-nitrophenylphosphate and phenylphosphate were investigated. Both enzymes were inhibited by fluoride, p-chloromercuribenzoate and oxalate. Fluoride inhibited acid phosphatase a2 noncorapetitively with p-mitrophenylphosphate, whereas acid phosphatase a3 showed inhibition of mixed type. Hydrolysis of phenylphosphate by both acid phosphatases was activated by citrate. Cytosine and uridine inhibited the activity of phosphatase a2 toward p-nitrophenylphosphate and phenylphosphate, but no effect was observed in case of acid phosphatase a3. After 30 min. incubation with 4 M urea both enzymes lost about 30% of activity.

  18. Small molecule fluoride toxicity agonists.

    Science.gov (United States)

    Nelson, James W; Plummer, Mark S; Blount, Kenneth F; Ames, Tyler D; Breaker, Ronald R

    2015-04-23

    Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here, we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Evaluation of antimicrobial activity of silver nanoparticles for carboxymethylcellulose film applications in food packaging.

    Science.gov (United States)

    Siqueira, Maria C; Coelho, Gustavo F; de Moura, Márcia R; Bresolin, Joana D; Hubinger, Silviane Z; Marconcini, José M; Mattoso, Luiz H C

    2014-07-01

    In this study, silver nanoparticles were prepared and incorporated into carboxymethylcellulose films to evaluate the antimicrobial activity for food packaging applications. The techniques carried out for material characterization were: infrared spectroscopy and thermal analysis for the silver nanoparticles and films, as well as particle size distribution for the nanoparticles and water vapor permeability for the films. The antimicrobial activity of silver nanoparticles prepared by casting method was investigated. The minimum inhibitory concentration (MIC) value of the silver nanoparticles to test Gram-positive (Enterococcus faecalis) and Gram-negative (Escherichia coli) microorganisms was carried out by the serial dilution technique, tested in triplicate to confirm the concentration used. The results were developed using the Mcfarland scale which indicates that the presence or absence of turbidity tube demonstrates the inhibition of bacteria in relation to the substance inoculated. It was found that the silver nanoparticles inhibited the growth of the tested microorganisms. The carboxymethylcellulose film embedded with silver nanoparticles showed the best antimicrobial effect against Gram-positive (E. faecalis) and Gram-negative (E. coli) bacteria (0.1 microg cm(-3)).

  20. Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F- detection

    Science.gov (United States)

    Liu, Biwu; Huang, Zhicheng; Liu, Juewen

    2016-07-01

    Nanomaterial-based enzyme mimics (nanozymes) are currently a new forefront of chemical research. However, the application of nanozymes is limited by their low catalytic activity and low turnover numbers. Cerium dioxide nanoparticles (nanoceria) are among the few with oxidase activity. Herein, we report an interesting finding addressing their limitations. The oxidase activity of nanoceria is improved by over 100-fold by fluoride capping, making it more close to real oxidases. The turnover number reached 700 in 15 min, drastically improved from ~15 turnovers for the naked particles. The mechanism is attributed to surface charge modulation and facilitated electron transfer by F- capping based on ζ-potential and free radical measurements. Ultrasensitive sensing of fluoride was achieved with a detection limit of 0.64 μM F- in water and in toothpastes, while no other tested anions can achieve the activity enhancement.Nanomaterial-based enzyme mimics (nanozymes) are currently a new forefront of chemical research. However, the application of nanozymes is limited by their low catalytic activity and low turnover numbers. Cerium dioxide nanoparticles (nanoceria) are among the few with oxidase activity. Herein, we report an interesting finding addressing their limitations. The oxidase activity of nanoceria is improved by over 100-fold by fluoride capping, making it more close to real oxidases. The turnover number reached 700 in 15 min, drastically improved from ~15 turnovers for the naked particles. The mechanism is attributed to surface charge modulation and facilitated electron transfer by F- capping based on ζ-potential and free radical measurements. Ultrasensitive sensing of fluoride was achieved with a detection limit of 0.64 μM F- in water and in toothpastes, while no other tested anions can achieve the activity enhancement. Electronic supplementary information (ESI) available: Methods, TMB oxidation kinetics and control experiments. See DOI: 10.1039/c6nr02730j

  1. Antimicrobial activity of silver and gold in toothpastes: A comparative analysis.

    Science.gov (United States)

    Junevičius, Jonas; Žilinskas, Juozas; Česaitis, Kęstutis; Česaitienė, Gabrielė; Gleiznys, Darius; Maželienė, Žaneta

    2015-01-01

    In this study, we compared the antimicrobial activity of identical toothpastes differing only in silver or gold nanoparticles against the activity of one of the common toothpastes containing a chemical active ingredient. We also compared the active concentrations of the toothpastes. For this study, we selected "Royal Denta" toothpastes containing silver and gold particles, and the "Blend-A-Med Complete" toothpaste containing zinc citrate as the active ingredient. We used 8 standard microorganism cultures on the basis of their individual mechanisms of protection. The antimicrobial activity of each studied preparation was evaluated at 9 concentrations. Most effective against gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) was the "Silver Technology" – MIC was 0.004-0.0015 g/mL. Neither "Silver Technology" nor "Orange and Gold Technology" had any effect on Escherichia coli or Proteus mirabilis. Antimicrobial activity against the motile bacterium Proteus mirabilis was observed in "Silver Technology", "Orange and Gold Technology", and "Blend-A-Med Complete" – the MIC was 0.015 g/mL or lower. No antimicrobial activity against Candida albicans fungus at the studied concentrations was observed in the "Orange and Gold Technology". The toothpaste "Blend-A-Med" demonstrated the most effective antimicrobial activity - the MIC of 0.0015 g/mL and 0.015 g/mL inhibited Staphylococcus aureus and Enterococcus faecalis, respectively, and the MIC of 0.15 g/mL inhibited the growth of the bacteria Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and fungus Candida albicans. Silver in toothpaste has a greater antimicrobial effect than gold, but its effect is still inferior to that of a chemical antimicrobial agent.

  2. Antitumor activity of colloidal silver on MCF-7 human breast cancer cells.

    Science.gov (United States)

    Franco-Molina, Moisés A; Mendoza-Gamboa, Edgar; Sierra-Rivera, Crystel A; Gómez-Flores, Ricardo A; Zapata-Benavides, Pablo; Castillo-Tello, Paloma; Alcocer-González, Juan Manuel; Miranda-Hernández, Diana F; Tamez-Guerra, Reyes S; Rodríguez-Padilla, Cristina

    2010-11-16

    Colloidal silver has been used as an antimicrobial and disinfectant agent. However, there is scarce information on its antitumor potential. The aim of this study was to determine if colloidal silver had cytotoxic effects on MCF-7 breast cancer cells and its mechanism of cell death. MCF-7 breast cancer cells were treated with colloidal silver (ranged from 1.75 to 17.5 ng/mL) for 5 h at 37°C and 5% CO2 atmosphere. Cell Viability was evaluated by trypan blue exclusion method and the mechanism of cell death through detection of mono-oligonucleosomes using an ELISA kit and TUNEL assay. The production of NO, LDH, and Gpx, SOD, CAT, and Total antioxidant activities were evaluated by colorimetric assays. Colloidal silver had dose-dependent cytotoxic effect in MCF-7 breast cancer cells through induction of apoptosis, shown an LD50 (3.5 ng/mL) and LD100 (14 ng/mL) (*P colloidal silver. The present results showed that colloidal silver might be a potential alternative agent for human breast cancer therapy.

  3. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...... capacity was found to be 18.3 meq/100 g at pH 6 and 8.6 meq/100 g at pH 7. A competitive Langmuir sorption isotherm where sorption is dependant on both pH and fluoride concentration is employed to characterise the experimental sorption and desorption data. The sorption and desorption isotherms revealed...

  4. In vitro assessment of the antimicrobial activity of silver and zinc oxide nanoparticles against fish pathogens.

    Science.gov (United States)

    Shaalan, Mohamed Ibrahim; El-Mahdy, Magdy Mohamed; Theiner, Sarah; El-Matbouli, Mansour; Saleh, Mona

    2017-07-21

    Antibiotic resistance is a global issue that threatens public health. The excessive use of antibiotics contributes to this problem as the genes of antibiotic resistance can be transferred between the bacteria in humans, animals and aquatic organisms. Metallic nanoparticles could serve as future substitutes for some conventional antibiotics because of their antimicrobial activity. The aim of this study was to evaluate the antimicrobial effects of silver and zinc oxide nanoparticles against major fish pathogens and assess their safety in vitro. Silver nanoparticles were synthesized by chemical reduction and characterized with UV-Vis spectroscopy, transmission electron microscopy and zeta sizer. The concentrations of silver and zinc oxide nanoparticles were measured using inductively coupled plasma-mass spectrometry. Subsequently, silver and zinc oxide nanoparticles were tested for their antimicrobial activity against Aeromonas hydrophila, Aeromonas salmonicida subsp. salmonicida, Edwardsiella ictaluri, Edwardsiella tarda, Francisella noatunensis subsp. orientalis, Yersinia ruckeri and Aphanomyces invadans and the minimum inhibitory concentrations were determined. MTT assay was performed on eel kidney cell line (EK-1) to determine the cell viability after incubation with nanoparticles. The interaction between silver nanoparticles and A. salmonicida was investigated by transmission electron microscopy. The tested nanoparticles exhibited marked antimicrobial activity. Silver nanoparticles inhibited the growth of both A. salmonicida and A. invadans at a concentration of 17 µg/mL. Zinc oxide nanoparticles inhibited the growth of A. salmonicida, Y. ruckeri and A. invadans at concentrations of 15.75, 31.5 and 3.15 µg/mL respectively. Silver nanoparticles showed higher cell viability when compared to zinc oxide nanoparticles in the MTT assay. Transmission electron microscopy showed the attachment of silver nanoparticles to the bacterial membrane and disruption of its

  5. Effect of Sodium Fluoride Ingestion on Malondialdehyde Concentration and the Activity of Antioxidant Enzymes in Rat Erythrocytes

    Directory of Open Access Journals (Sweden)

    José A. Morales-González

    2010-06-01

    Full Text Available Fluoride intoxication has been shown to produce diverse deleterious metabolic alterations within the cell. To determine the effects of sodium fluoride (NaF treatment on malondialdehyde (MDA levels and on the activity of antioxidant enzymes in rat erythrocytes, Male Wistar rats were treated with 50 ppm of NaF or were untreated as controls. Erythrocytes were obtained from rats sacrificed weekly for up to eight weeks and the concentration of MDA in erythrocyte membrane was determined. In addition, the activity of the enzymes superoxide, dismutase, catalase, and glutathione peroxidase were determined. Treatment with NaF produces an increase in the concentration of malondialdehyde in the erythrocyte membrane only after the eight weeks of treatment. On the other hand, antioxidant enzyme activity was observed to increase after the fourth week of NaF treatment. In conclusion, intake of NaF produces alterations in the erythrocyte of the male rat, which indicates induction of oxidative stress.

  6. The study of antibacterial activity and stability of dyed cotton fabrics modified with different forms of silver

    Directory of Open Access Journals (Sweden)

    Lazić Vesna

    2012-01-01

    Full Text Available This study compares the effect of colloidal silver nanoparticles and commercial RUCO-BAC AGP agent with silver chloride as an active component on antibacterial activity of dyed cotton fabrics. Cotton fabrics were dyed with vat dyes Bezanthren olive T and Bezanthren grey FFB. Antibacterial activity of silver loaded dyed cotton fabrics was tested against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli. Unlike RUCO-BAC AGP synthesized silver nanoparticles deposited onto dyed cotton fabrics provided maximum bacteria reduction independently of applied dye. The stability of modified cotton fabrics was analyzed in artificial sweat at pH 5.5 and 8.0. Approximately the same amount of silver was released from differently modified cotton fabrics in artificial sweat. Larger amount of silver was released in the sweat at pH 8.0.

  7. Mechanisms of antibacterial activity and stability of silver ...

    Indian Academy of Sciences (India)

    using scanning electron microscopy revealed that the size and surface density of AgNPs grown by the photoreduc- tion of silver ... doped TiO2 nanosheet films against S. aureus and E. coli in the dark .... Zeiss) with an attached Axiovert 200M (Zeiss) inverted flu- ... SEM imaging of TiO2 and AgNPs/TiO2 coatings as well as.

  8. [Degradation of Acid Orange 7 with Persulfate Activated by Silver Loaded Granular Activated Carbon].

    Science.gov (United States)

    Wang, Zhong-ming; Huang, Tian-yin; Chen, Jia-bin; Li, Wen-wei; Zhang, Li-ming

    2015-11-01

    Granular activated carbon with silver loaded as activator (Ag/GAC) was prepared using impregnation method. N2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were adopted to characterize the Ag/GAC, showing that silver was successfully loaded on granular activated carbon. The oxidation degradation of acid orange 7 (AO7) by the Ag/GAC activated by persulfate (PS) was investigated at ambient temperature. The influences of factors such as Ag loading, PS or Ag/GAC dosages and initial pH on the degradation of AO7 were evaluated. The results demonstrated that the degradation rate of AO7 could reach more than 95.0% after 180 min when the Ag loading content, PS/AO7 molar ratio, the Ag/GAC dosage were 12.7 mg x g(-1), 120: 1, 1.0 g x L(-1), respectively. The initial pH had significant effect on the AO7 degradation, with pH 5.0 as the optimal pH for the degradation of AO7. The possible degradation pathway was proposed for the AO7 degradation by using UV-visible spectroscopy and gas chromatography-mass spectrometry (GG/MS). The azo bond and naphthalene ring in the AO7 were destroyed during the degradation, with phthalic acid and acetophenone as the main degradation products.

  9. Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

    International Nuclear Information System (INIS)

    Venil, Chidambaram Kulandaisamy; Sathishkumar, Palanivel; Malathi, Mahalingam; Usha, Rajamanickam; Jayakumar, Rajarajeswaran; Yusoff, Abdull Rahim Mohd; Ahmad, Wan Azlina

    2016-01-01

    In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ("1H NMR and "1"3C NMR), UV–Vis, and LC–MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36 μg mL"−"1. This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent. - Highlights: • First report on flexirubin mediated silver nanoparticles • Silver nanoparticles synthesised using flexirubin • Flexirubin mediated silver nanoparticles found to possess in vitro anti-cancer activity

  10. Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

    Energy Technology Data Exchange (ETDEWEB)

    Venil, Chidambaram Kulandaisamy, E-mail: ckvenil@gmail.com [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Sathishkumar, Palanivel [Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Malathi, Mahalingam [Department of Chemistry, Bannari Amman Institute of Technology, Sathyamangalam 638 401, Tamil Nadu (India); Usha, Rajamanickam [Department of Microbiology, Karpagam University, Coimbatore 641 023, Tamil Nadu (India); Jayakumar, Rajarajeswaran [Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia); Yusoff, Abdull Rahim Mohd [Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Ahmad, Wan Azlina, E-mail: azlina@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia)

    2016-02-01

    In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ({sup 1}H NMR and {sup 13}C NMR), UV–Vis, and LC–MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36 μg mL{sup −1}. This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent. - Highlights: • First report on flexirubin mediated silver nanoparticles • Silver nanoparticles synthesised using flexirubin • Flexirubin mediated silver nanoparticles found to possess in vitro anti-cancer activity.

  11. Activated carbon from pyrolysed sugarcane bagasse: Silver nanoparticle modification and ecotoxicity assessment

    Energy Technology Data Exchange (ETDEWEB)

    Gonçalves, Suely Patrícia C., E-mail: suely.goncalves@lnnano.cnpem.br [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); Strauss, Mathias; Delite, Fabrício S. [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); Clemente, Zaira [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); Laboratory of Ecotoxicology and Biosafety, Embrapa, CEP 13820-000 Jaguariúna, SP (Brazil); Castro, Vera L. [Laboratory of Ecotoxicology and Biosafety, Embrapa, CEP 13820-000 Jaguariúna, SP (Brazil); Martinez, Diego Stéfani T., E-mail: diego.martinez@lnnano.cnpem.br [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); School of Technology, University of Campinas (UNICAMP), CEP 13484-332 Limeira, SP (Brazil)

    2016-09-15

    Activated carbon from pyrolysed sugarcane bagasse (ACPB) presented pore size ranges from 1.0 to 3.5 nm, and surface area between 1200 and 1400 m{sup 2} g{sup −1} that is higher than commonly observed to commercial activated carbon. The ACPB material was successfully loaded with of silver nanoparticles with diameter around 35 nm (0.81 wt.%). X-ray photoelectron spectroscopy (XPS) analyses showed that the material surface contains metallic/Ag{sup 0} (93.60 wt.%) and ionic/Ag{sup +} states (6.40 wt.%). The adsorption capacity of organic model molecules (i.e. methylene blue and phenol) was very efficient to ACPB and ACPB loaded with silver nanoparticles (ACPB-AgNP), indicating that the material modification with silver nanoparticles has not altered its adsorption capacity. ACPB-AgNP inhibited bacteria growth (Escherichia coli), it is a promising advantage for the use of these materials in wastewater treatment and water purification processes. However, ACPB-AgNP showed environmental risks, with toxic effect to the aquatic organism Hydra attenuata (i.e. LC50 value of 1.94 mg L{sup −1}), and it suppressed root development of Lycopersicum esculentum plant (tomato). Finally, this work draw attention for the environmental implications of activated carbon materials modified with silver nanoparticles. - Highlights: • Production of very efficient activated carbon by pyrolysis process of sugarcane bagasse. • Modification of activated carbon with silver nanoparticles to environmental remediation and water purification. • Activated carbon modified with silver nanoparticles showed acute ecotoxic effects.

  12. Activated carbon from pyrolysed sugarcane bagasse: Silver nanoparticle modification and ecotoxicity assessment

    International Nuclear Information System (INIS)

    Gonçalves, Suely Patrícia C.; Strauss, Mathias; Delite, Fabrício S.; Clemente, Zaira; Castro, Vera L.; Martinez, Diego Stéfani T.

    2016-01-01

    Activated carbon from pyrolysed sugarcane bagasse (ACPB) presented pore size ranges from 1.0 to 3.5 nm, and surface area between 1200 and 1400 m"2 g"−"1 that is higher than commonly observed to commercial activated carbon. The ACPB material was successfully loaded with of silver nanoparticles with diameter around 35 nm (0.81 wt.%). X-ray photoelectron spectroscopy (XPS) analyses showed that the material surface contains metallic/Ag"0 (93.60 wt.%) and ionic/Ag"+ states (6.40 wt.%). The adsorption capacity of organic model molecules (i.e. methylene blue and phenol) was very efficient to ACPB and ACPB loaded with silver nanoparticles (ACPB-AgNP), indicating that the material modification with silver nanoparticles has not altered its adsorption capacity. ACPB-AgNP inhibited bacteria growth (Escherichia coli), it is a promising advantage for the use of these materials in wastewater treatment and water purification processes. However, ACPB-AgNP showed environmental risks, with toxic effect to the aquatic organism Hydra attenuata (i.e. LC50 value of 1.94 mg L"−"1), and it suppressed root development of Lycopersicum esculentum plant (tomato). Finally, this work draw attention for the environmental implications of activated carbon materials modified with silver nanoparticles. - Highlights: • Production of very efficient activated carbon by pyrolysis process of sugarcane bagasse. • Modification of activated carbon with silver nanoparticles to environmental remediation and water purification. • Activated carbon modified with silver nanoparticles showed acute ecotoxic effects.

  13. Silver-Stained Fibrin Zymography: Separation of Proteases and Activity Detection Using a Single Substrate-Containing Gel.

    Science.gov (United States)

    Park, Chang-Su; Kang, Dae-Ook; Choi, Nack-Shick

    2017-01-01

    Silver-stained fibrin zymography for separation of protease bands and activity detection using a single substrate gel was designed. The method takes advantage of the nano-scale sensitivity of both zymography and silver staining. After sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) in a gel containing fibrin (protease substrate), the gel was incubated in enzyme reaction buffer and the zymogram gel was silver-stained. Bands with protease activity were stained with silver in clear areas where the protein substrate had been degraded. The molecular sizes of proteases were accurately determined.

  14. Antifungal activity of fabrics knitted by metalized Silver/Polyester composite yarn

    Science.gov (United States)

    Özkan, İ.; Duru Baykal, P.

    2017-10-01

    In this study, antifungal properties of fabric knitted from metalized silver/polyester composite yarn were investigated. Intermingling is an alternative technique for yarn blending process. Yarns having different features can be combined by feeding the same intermingling jet. This process is defined as commingling. In the study, intermingling process was used to produce metalized silver/polyester composite yarn. Commingled yarns were knitted to single jersey fabrics by IPM brand sample type circular knitting machine. Antifungal activity test was applied to samples against Aspergillus Niger according to AATCC 30 test procedure. It has been identified that the application provides antifungal activity to fabric.

  15. Determination of gold and silver in geological standard samples MGI by instrument neutron activation analysis

    International Nuclear Information System (INIS)

    Lu Huijiuan; Zhou; Yunlu

    1987-01-01

    Gold and silver in geological standard samples MGI were determined by instrument neutron activation analysis. The various interferences of nuclides were considered. Corrected factors of the geometry in different positions have been determined. Using the geological standard sample MGM and radiochemical separation neutron activation method as reference, the reliability of this method is proved. Gold content in samples is 0.4-0.009 g/t, silver content is 9-0.3 g/t. Standard deviation is less than 3.5%, the precision of the measurement is 4.8-11.6%

  16. Removal of fluoride by thermally activated carbon prepared from neem (Azadirachta indica) and kikar (Acacia arabica) leaves.

    Science.gov (United States)

    Kumar, Sunil; Gupta, Asha; Yadav, J P

    2008-03-01

    The present investigation deals with fluoride removal from aqueous solution by thermally activated neem (Azadirachta indica) leaves carbon (ANC) and thermally activated kikar (Acacia arabica) leaves carbon (AKC) adsorbents. In this study neem leaves carbon and kikar leaves carbon prepared by heating the leaves at 400 degrees C in electric furnace was found to be useful for the removal of fluoride. The adsorbents of 0.3 mm and 1.0 mm sizes of neem and kikar leaves carbon was prepared by standard sieve. Batch experiments done to see the fluoride removal properties from synthetic solution of 5 ppm to study the influence of pH, adsorbent dose and contact time on adsorption efficiency The optimum pH was found to be 6 for both adsorbents. The optimum dose was found to be 0.5g/100 ml forANC (activated neem leaves carbon) and 0.7g/100 ml forAKC (activated kikar leaves carbon). The optimum time was found to be one hour for both the adsorbent. It was also found that adsorbent size of 0.3 mm was more efficient than the 1.0 mm size. The adsorption process obeyed Freundlich adsorption isotherm. The straight line of log (qe-q) vs time at ambient temperature indicated the validity of langergren equation consequently first order nature of the process involved in the present study. Results indicate that besides intraparticle diffusion there maybe other processes controlling the rate which may be operating simultaneously. All optimized conditions were applied for removal of fluoride from four natural water samples.

  17. Active film of poly(vinyl chloride)/silver: synthesis, characterization and evaluation as antimicrobial active packaging

    International Nuclear Information System (INIS)

    Braga, Lilian R.; Rangel, Ellen T.; Machado, Fabricio

    2015-01-01

    The antimicrobial films based on poly(vinyl chloride) (PVC) mediated silver (1, 2, 4 and 8 wt%) were evaluated as antimicrobial active packaging using the casting method. The structure of the active films was characterized by SEM, EDX-XRF, XRD, FTIR and TG. FTIR spectra confirmed the PVC-Ag interaction due to the presence of new bands at 1745 cm"-"1 and 1165 cm"-"1 bands, which are absent in the PVC control. The FRX-EDX spectrum confirmed the presence of silver ions in all the films. TG and SEM results showed that the increased concentration of silver provided an improved thermal stability and presence of pores in the active films, respectively. Antimicrobial activity was evaluated by disk diffusion method for Bacillus subtilis, Fusarium solani and Apergillus niger, which proved the efficiency of the films active. (author)

  18. TTC- Based Test as an Efficient Method to Determine Antibiofilm Activity of Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Chojniak Joanna

    2017-01-01

    Full Text Available Among metal nanoparticles, silver nanoparticles are a widely used in various life sectors such as in biomedical applications, air and water purification, food production, cosmetics, garments and in various household products. There are several methods for production of silver nanoparticles. Generally, silver nanoparticles can be prepared by chemical methods such as chemical reduction and electrochemical techniques, physical methods, and biological methods such as the use of microorganisms. The biological route of synthesis provides a great diversity in choice for its raw materials such as bacteria, algae, fungi and plants. The aim of the study was to evaluate the tetrazolium/formazan test as a method to determine antibiofilm activity of biological synthetized silver nanoparticles. In this study Bacillus subtilis grown on brewery effluent and produced biosurfactant was used for silver nanoparticles (Ag-NPs synthesis. The culture supernatants were used in synthesis of Ag-NPs. The formation of nanoparticles accompanied by colour changes of the used reaction system was confirmed by UV-vis spectroscopy. The bacteria isolated from the biofilm of water supply system were used in the evaluation of the antibiofilm activity of biologically synthetized Ag-NPs. To compare the results the commonly used crystal violet assay (CV for biofilm analysis was applied.

  19. Green Synthesis, Characterization, and Antibacterial Activity of Silver/Polystyrene Nanocomposite

    Directory of Open Access Journals (Sweden)

    Manal A. Awad

    2015-01-01

    Full Text Available A novel, nontoxic, simple, cost-effective and ecofriendly technique was used to synthesize green silver nanoparticles (AgNPs. The AgNPs were synthesized using orange peel extract as a reducing agent for silver nitrate salt (AgNO3. The particle size distribution of AgNPs was determined by Dynamic Light Scattering (DLS. The average size of silver nanoparticles was 98.43 nm. The stable dispersion of silver nanoparticles was added slowly to polystyrene solution in toluene maintaining the temperature at 70°C. The AgNPs/polystyrene (PS nanocomposite solution was cast in a petri dish. The silver nanoparticles encapsulated within polymer chains were characterized by X-ray diffraction (XRD and Scanning Electron Microscopy (SEM equipped with Energy Dispersive Spectroscopy (EDS in addition to Transmission Electron Microscopy (TEM. The green AgNPs/PS nanocomposite film exhibited antimicrobial activity against Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae and Salmonella, and Gram-positive bacteria Staphylococcus aureus. Thus, the key findings of the work include the use of a safe and simple AgNPs/PS nanocomposite which had a marked antibacterial activity which has a potential application in food packaging.

  20. Tannic acid modified silver nanoparticles show antiviral activity in herpes simplex virus type 2 infection.

    Directory of Open Access Journals (Sweden)

    Piotr Orlowski

    Full Text Available The interaction between silver nanoparticles and herpesviruses is attracting great interest due to their antiviral activity and possibility to use as microbicides for oral and anogenital herpes. In this work, we demonstrate that tannic acid modified silver nanoparticles sized 13 nm, 33 nm and 46 nm are capable of reducing HSV-2 infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified silver nanoparticles reduced both infection and inflammatory reaction in the mouse model of HSV-2 infection when used at infection or for a post-infection treatment. Smaller-sized nanoparticles induced production of cytokines and chemokines important for anti-viral response. The corresponding control buffers with tannic acid showed inferior antiviral effects in vitro and were ineffective in blocking in vivo infection. Our results show that tannic acid modified silver nanoparticles are good candidates for microbicides used in treatment of herpesvirus infections.

  1. Influence of silver nanoparticles on spectroscopic properties of biologically active iodinated 4-aryloxymethyl coumarin dyes

    Energy Technology Data Exchange (ETDEWEB)

    Raghavendra, U.P. [Department of Physics, Bangalore Institute of Technology, Bangalore 560 004 (India); Thipperudrappa, J., E-mail: jtrphy2007@gmail.com [Department of Physics, B.N.M. Institute of Technology, Bangalore 560 070 (India); Basanagouda, Mahantesha [P.G. Department of Studies in Chemistry, K.L.E. Society' s P.C. Jabin Science College, Hubli 580 031 (India); Melavanki, R.M. [Department of Physics, M.S. Ramaiah Institute of Technology, Bangalore 560 054 (India)

    2016-04-15

    The interaction between silver nanoparticles and biologically active iodinated 4-aryloxymethyl coumarins4-(4-iodo-phenoxymethyl)-benzo[h]coumarin (4IPMBC) and 4-(4-iodo-phenoxymethyl)-6-methoxy coumarin (4IPMMC) has been studied using absorption and fluorescence spectroscopy. The absorption spectral changes of dyes with the addition of silver nanoparticles suggest their possible interaction with silver nanoparticles. Fluorescence quenching has been observed for both dyes with the addition of silver nanoparticles. The Stern–Volmer plots of fluorescence quenching are found to be nonlinear showing positive deviation. The magnitudes of quenching rate parameter and fluorescence lifetime measurements indicate the presence of static quenching mechanism. The binding constants and the number of binding sites have been estimated from fluorescence data. The role of diffusion, energy transfer and electron transfer processes in fluorescence quenching mechanism has been discussed. - Highlights: • The role of silver nanoparticles on biologically active coumarins is studied. • Fluorescence quenching is due to static mechanism. • Binding constant and the binding sites are estimated. • The role of Forster type energy transfer has been suggested. • Electron transfer is also playing a role in overall quenching mechanism.

  2. Characterization and antimicrobial activity of silver nanoparticles, biosynthesized using Bacillus species

    Science.gov (United States)

    Ghiuță, I.; Cristea, D.; Croitoru, C.; Kost, J.; Wenkert, R.; Vyrides, I.; Anayiotos, A.; Munteanu, D.

    2018-04-01

    In this work, the biosynthesis of silver nanoparticles, using AgNO3 as a precursor, by two Bacillus species, namely Bacillus amyloliquefaciens and Bacillus subtillis, is reported. After the synthesis stages, the absorbance of the brown nanoparticle colloidal solutions was assessed by UV-vis spectrophotometry, which showed the peak absorbance values at 418 nm and 414 nm, corresponding to surface plasmon resonance of silver nanoparticles. The EDX, SEM and DLS analyses confirmed the formation of spherical silver nanoparticles with an average diameter smaller than 140 nm. XRD confirmed the presence of face-centered cubic silver crystals, with the highest intensity peak at 2θ = 38.12°, which corresponds to the (111) diffraction planes. The antibacterial activity after 24 h of incubation was observed against gram negative bacteria: Escherichia coli, Pseudomonas aeruginosa, Salmonella, as well as gram positive: Staphylococcus aureus, Streptococcus pyogenes. Furthermore, the antifungal activity was assessed against Candida albicans. The inhibition zone was clearly observed on the plates containing silver nanoparticles, either standalone or in combination with antibiotics, thus showing their potentiating antibacterial effect.

  3. Highly water-dispersible silver sulfadiazine decorated with polyvinyl pyrrolidone and its antibacterial activities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ping; Wu, Longlong [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Li, Binjie, E-mail: lbj821@163.com [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Medical School of Henan University, Kaifeng 475004 (China); Zhao, Yanbao [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Qu, Peng [Department of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China)

    2016-03-01

    Highly water-dispersible silver sulfadiazine (SSD) was prepared by liquid phase method with polyvinyl pyrrolidone (PVP) as a surface modification agent. The structure and morphology of the PVP-modified silver sulfadiazine (P-SSD) were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared (FT-IR) spectrometry. The produced particles are ginkgo leaf-like architecture with the sizes of micron-nanometer. Due to hydrophilic PVP decorated on the surface, the P-SSD has excellent dispersion in water over a period of 24 h, which is obviously stable by comparison to that of the commercial silver sulfadiazine (C-SSD). In addition, the P-SSD exhibits good antibacterial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). - Highlights: • Polyvinyl pyrrolidone decorated silver sulfadiazine was synthesized via a one-pot protocol. • The produced particles present ginkgo leaf-like architectures with sizes of micro-nanometer. • The resulted silver sulfadiazine has highly dispersible in water over a period of 24 h. • The obtained sliver sulfadiazine exhibits excellent antibacterial activities against E. coli, P. aeruginosa and S. aureus.

  4. Influence of gamma irradiation on electro active properties of copolymers of vinylidene fluoride with tetrafluoroethylene

    International Nuclear Information System (INIS)

    Magerramov, A.M; Rustamova, D.F.

    2010-01-01

    Full text : Fluoropolymers are known, as one of the most promising polymers of electro active materials and they are very sensitive to radiation, with the prone to decomposition processes. One way to stabilize the piezoelectric properties of Fluor polymers may be their radiation modification of gamma-irradiation. The aim of the present work is to study the effect of gamma-irradiation on the piezoelectric properties of the copolymer of vinylidene fluoride with tetrafluoroethylene-P (VDF-TeFE). The polarization produced in the optimal range for the electric field. Irradiation of the films performed at the facility Rahm-gamma-30 both before and after polarization. For gamma irradiation, apparently as a result of conformational transitions alpha and beta is a change of relations of ferroelectric and par electric phases in upward of crystallinity, i e an increase in the ferroelectric polymer. It was discussed possible mechanisms of changes in the dielectric, piezoelectric and ferroelectric properties (hysteresis loops, the values of the coercive field) with a residual polarization of Fluor polymers when exposed to gamma-irradiation.

  5. Circular dichroism and Raman optical activity in antiferromagnetic transition metal fluorides

    International Nuclear Information System (INIS)

    Hoffman, K.R.; Lockwood, D.J.; Yen, W.M.

    2005-01-01

    The Raman optical activity (ROA) of magnons in rutile-structure antiferromagnetic FeF 2 (T N = 78 K) has been studied as a function of temperature and applied magnetic field. For exciting light incident along the c axis, ROA is observed for magnons but not for phonons. In zero field, a small splitting (0.09 cm -1 ) of the two acoustic-magnon branches is observed for the first time by inelastic light scattering. The splitting in applied magnetic field is found to reduce with increasing temperature in accordance with theory. No ROA was detected for two-magnon excitations. In optical absorption measurements performed over thirty years ago, a very small circular dichroism (CD) was observed in the magnon sidebands of other simple rutile antiferromagnetic fluorides (MnF 2 and CoF 2 ). The origin of this CD was not understood at the time. The Raman studies of the one-magnon Raman scattering in FeF 2 have demonstrated that in zero field the degeneracy of the antiferromagnetic magnon branches is lifted by a weak magnetic dipole-dipole interaction, as predicted by Pincus and Loudon and by White four decades ago. The source of the observed CD in the magnon sidebands can now be traced to this same magnetic-dipole induced splitting

  6. Fluoride enhances transfection activity of carbonate apatite by increasing cytoplasmic stability of plasmid DNA

    International Nuclear Information System (INIS)

    Chowdhury, E.H.

    2011-01-01

    Highlights: → Cytoplasmic stability of plasmid DNA is enhanced by fluoride incorporation into carbonate apatite carrier. → Fluoridated carbonate apatite promotes a robust increase in transgene expression. → Controlled dissolution of fluoridated carbonate apatite in endosomal acidic environment might buffer the endosomes and prevent degradation of the released DNA. -- Abstract: Intracellular delivery of a functional gene or a nucleic acid sequence to specifically knockdown a harmful gene is a potential approach to precisely treat a critical human disease. The intensive efforts in the last few decades led to the development of a number of viral and non-viral synthetic vectors. However, an ideal delivery tool in terms of the safety and efficacy has yet to be established. Recently, we have developed pH-sensing inorganic nanocrystals of carbonate apatite for efficient and cell-targeted delivery of gene and gene-silencing RNA. Here we show that addition of very low level of fluoride to the particle-forming medium facilitates a robust increase in transgene expression following post-incubation of the particles with HeLa cells. Confocal microscopic observation and Southern blotting prove the cytoplasmic existence of plasmid DNA delivered by likely formed fluoridated carbonate apatite particles while degradation of plasmid DNA presumably by cytoplasmic nucleases was noticed following delivery with apatite particles alone. The beneficial role of fluoride in enhancing carbonate apatite-mediated gene expression might be due to the buffering potential of generated fluoridated apatite in endosomal acidic environment, thereby increasing the half-life of delivered plasmid DNA.

  7. Fluoride enhances transfection activity of carbonate apatite by increasing cytoplasmic stability of plasmid DNA

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, E.H., E-mail: md.ezharul.hoque@med.monash.edu.my [Jeffrey Cheah School of Medicine and Health Sciences, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan (Malaysia)

    2011-06-17

    Highlights: {yields} Cytoplasmic stability of plasmid DNA is enhanced by fluoride incorporation into carbonate apatite carrier. {yields} Fluoridated carbonate apatite promotes a robust increase in transgene expression. {yields} Controlled dissolution of fluoridated carbonate apatite in endosomal acidic environment might buffer the endosomes and prevent degradation of the released DNA. -- Abstract: Intracellular delivery of a functional gene or a nucleic acid sequence to specifically knockdown a harmful gene is a potential approach to precisely treat a critical human disease. The intensive efforts in the last few decades led to the development of a number of viral and non-viral synthetic vectors. However, an ideal delivery tool in terms of the safety and efficacy has yet to be established. Recently, we have developed pH-sensing inorganic nanocrystals of carbonate apatite for efficient and cell-targeted delivery of gene and gene-silencing RNA. Here we show that addition of very low level of fluoride to the particle-forming medium facilitates a robust increase in transgene expression following post-incubation of the particles with HeLa cells. Confocal microscopic observation and Southern blotting prove the cytoplasmic existence of plasmid DNA delivered by likely formed fluoridated carbonate apatite particles while degradation of plasmid DNA presumably by cytoplasmic nucleases was noticed following delivery with apatite particles alone. The beneficial role of fluoride in enhancing carbonate apatite-mediated gene expression might be due to the buffering potential of generated fluoridated apatite in endosomal acidic environment, thereby increasing the half-life of delivered plasmid DNA.

  8. Fluoride analysis

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, C S

    1963-01-01

    The methods and procedures for the detection and estimation of fluoride are varied and numerous. The problems of sampling, contamination, and loss in sampling waters, plant and animal tissues and atmospheres are discussed, along with brief descriptors of methods most commonly used. Techniques for separating fluorides from matrixes are discussed, as well as gravimetric, calorimetric, and spectrophotometric analytical techniques.

  9. ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES: SENSITIVITY OF DIFFERENT SALMONELLA SEROVARS

    Directory of Open Access Journals (Sweden)

    Carmen eLosasso

    2014-05-01

    Full Text Available Salmonella spp. is one of the main causes of foodborne illnesses in humans worldwide. Consequently, great interest exists in reducing its impact on human health by lowering its prevalence in the food chain. Antimicrobial formulations in the form of nanoparticles exert bactericidal action due to their enhanced reactivity resultant from their high surface/volume ratio. Silver nanoparticles (AgNPs are known to be highly toxic to Gram-negative and Gram-positive microorganisms, including multidrug resistant bacteria. However, few data concerning their success against different Salmonella serovars are available. Aims of the present study were to test the antimicrobial effectiveness of AgNPs, against Salmonella Enteritidis, Hadar and Senftenberg, and to investigate the causes of their different survival abilities from a molecular point of view.Results showed an immediate, time-limited and serovar-dependent reduction of bacterial viability. In the case of S. Senftenberg, the reduction in numbers was observed for up to 4 h of incubation in the presence of 200 mg/L of AgNPs; on the contrary, S. Enteritidis and S. Hadar resulted to be inhibited for up to 48 h. RT-PCR experiments demonstrated the constitutive expression of the plasmidic silver resistance determinant (SilB by S. Senftenberg, thus suggesting the importance of a cautious use of AgNPs.

  10. Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity.

    Science.gov (United States)

    Kumar, Deenadayalan Ashok; Palanichamy, V; Roopan, Selvaraj Mohana

    2014-06-05

    A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Silver(I) complexes of N-methylbenzothiazole-2-thione: Synthesis, structures and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Aslanidis, P., E-mail: aslanidi@chem.auth.gr [Laboratory of Inorganic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Hatzidimitriou, A.G.; Andreadou, E.G. [Laboratory of Inorganic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Pantazaki, A.A., E-mail: natasa@chem.auth.gr [Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Voulgarakis, N. [Department of Logistics, Alexander Technological Educational Institute, GR-60100 Katerini (Greece)

    2015-05-01

    Three silver(I) complexes containing N-methylbenzothiazole-2-thione (mbtt) have been prepared and structurally characterized by X-ray single-crystal analysis. Silver(I) nitrate, and silver(I) triflate react with mbtt to give homoleptic complexes of formula [(mbtt){sub 2}Ag(μ-mbtt){sub 2}Ag(mbtt){sub 2}](NO{sub 3}){sub 2} (1) and [Ag(mbtt){sub 3}](CF{sub 3}SO{sub 3}) (2) respectively, while silver(I) chloride gives the binuclear halide-bridged [(mbtt){sub 2}Ag(μ{sub 2}-Cl){sub 2}Ag(mbtt){sub 2}] (3). In the binuclear complex 1 the two metal ions, separated by 3.73 Å from each other, are doubly bridged by the exocyclic S-atoms of two mbtt ligands, with the tetrahedral environment around each silver ion being completed by the S-atoms of two terminally bonded mbtt units. Compound 2 is mononuclear with the metal ion surrounded by the exocyclic S-atoms of three mbtt ligands in a nearly ideal trigonal planar arrangement. The new complexes showed significant in vitro antibacterial activity against certain Gram-positive and Gram-negative bacterial strains.

  12. Silver nanoparticles with gelatin nanoshells: photochemical facile green synthesis and their antimicrobial activity

    International Nuclear Information System (INIS)

    Pourjavadi, Ali; Soleyman, Rouhollah

    2011-01-01

    In the current study, a facile green synthesis of silver-gelatin core–shell nanostructures (spherical, spherical/cubic hybrid, and cubic, DLS diameter: 4.1–6.9 nm) is reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent cause mild reduction of silver ions into the silver nanoparticles (Ag-NPs). Gelatin protein, as an effective capping/shaping agent, was used in the reaction to self-assemble silver nanostructures. The formation of silver nanostructures and their self-assembly pattern was confirmed by SEM, AFM, and TEM techniques. Further investigations were carried out using zeta-potential, UV–Vis, FTIR, GPC, and TGA/DTG/DTA data. The prepared Ag-NPs showed proper and acceptable antimicrobial activity against three classes of microorganisms (Escherichia coli Gram-negative bacteria, Staphylococcus aureus Gram-positive bacteria, and Candida albicans fungus). The antibacterial and antifungal Ag-NPs exhibit good stability in solution and can be considered as promising candidates for a wide range of biomedical applications.

  13. Silver nanoparticles with gelatin nanoshells: photochemical facile green synthesis and their antimicrobial activity

    Science.gov (United States)

    Pourjavadi, Ali; Soleyman, Rouhollah

    2011-10-01

    In the current study, a facile green synthesis of silver-gelatin core-shell nanostructures (spherical, spherical/cubic hybrid, and cubic, DLS diameter: 4.1-6.9 nm) is reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent cause mild reduction of silver ions into the silver nanoparticles (Ag-NPs). Gelatin protein, as an effective capping/shaping agent, was used in the reaction to self-assemble silver nanostructures. The formation of silver nanostructures and their self-assembly pattern was confirmed by SEM, AFM, and TEM techniques. Further investigations were carried out using zeta-potential, UV-Vis, FTIR, GPC, and TGA/DTG/DTA data. The prepared Ag-NPs showed proper and acceptable antimicrobial activity against three classes of microorganisms ( Escherichia coli Gram-negative bacteria, Staphylococcus aureus Gram-positive bacteria, and Candida albicans fungus). The antibacterial and antifungal Ag-NPs exhibit good stability in solution and can be considered as promising candidates for a wide range of biomedical applications.

  14. Photocatalytic activity of biogenic silver nanoparticles synthesized using potato (Solanum tuberosum) infusion.

    Science.gov (United States)

    Roy, Kaushik; Sarkar, C K; Ghosh, C K

    2015-07-05

    In this study, we have reported a fast and eco-benign procedure to synthesis silver nanoparticle at room temperature using potato (Solanum tuberosum) infusion along with the study of its photocatalytic activity on methyl orange dye. After addition of potato infusion to silver nitrate solution, the color of the mixture changed indicating formation of silver nanoparticles. Time dependent UV-Vis spectra were obtained to study the rate of nanoparticle formation with time. Purity and crystallinity of the biogenic silver nanoparticles were examined by X-ray diffraction (XRD). Average size and morphology of the nanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Fourier transform infra-red spectroscopy (FTIR) was employed to detect functional bio-molecules responsible that contribute to the reduction and capping of biosynthesized Ag nanoparticles. Further, these synthesized nanoparticles were used to investigate their ability to degrade methyl orange dye under sunlight irradiation and the results showed effective photocatalytic property of these biogenic silver nanoparticles. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Antitumor activity of colloidal silver on MCF-7 human breast cancer cells

    Directory of Open Access Journals (Sweden)

    Franco-Molina Moisés A

    2010-11-01

    Full Text Available Abstract Background Colloidal silver has been used as an antimicrobial and disinfectant agent. However, there is scarce information on its antitumor potential. The aim of this study was to determine if colloidal silver had cytotoxic effects on MCF-7 breast cancer cells and its mechanism of cell death. Methods MCF-7 breast cancer cells were treated with colloidal silver (ranged from 1.75 to 17.5 ng/mL for 5 h at 37°C and 5% CO2 atmosphere. Cell Viability was evaluated by trypan blue exclusion method and the mechanism of cell death through detection of mono-oligonucleosomes using an ELISA kit and TUNEL assay. The production of NO, LDH, and Gpx, SOD, CAT, and Total antioxidant activities were evaluated by colorimetric assays. Results Colloidal silver had dose-dependent cytotoxic effect in MCF-7 breast cancer cells through induction of apoptosis, shown an LD50 (3.5 ng/mL and LD100 (14 ng/mL (*P Conclusions The present results showed that colloidal silver might be a potential alternative agent for human breast cancer therapy.

  16. Surface ligand controls silver ion release of nanosilver and its antibacterial activity against Escherichia coli

    Directory of Open Access Journals (Sweden)

    Long Y

    2017-04-01

    Full Text Available Yan-Min Long,1,2 Li-Gang Hu,1,3 Xue-Ting Yan,1,3 Xing-Chen Zhao,1,3 Qun-Fang Zhou,1,3 Yong Cai,2,4 Gui-Bin Jiang1,3 1State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Beijing, China; 2Institute of Environment and Health, Jianghan University, Wuhan, Hubei, China; 3College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China; 4Department of Chemistry and Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, USA Abstract: Understanding the mechanism of nanosilver-dependent antibacterial activity against microorganisms helps optimize the design and usage of the related nanomaterials. In this study, we prepared four kinds of 10 nm-sized silver nanoparticles (AgNPs with dictated surface chemistry by capping different ligands, including citrate, mercaptopropionic acid, mercaptohexanoic acid, and mercaptopropionic sulfonic acid. Their surface-dependent chemistry and antibacterial activities were investigated. Owing to the weak bond to surface Ag, short carbon chain, and low silver ion attraction, citrate-coated AgNPs caused the highest silver ion release and the strongest antibacterial activity against Escherichia coli, when compared to the other tested AgNPs. The study on the underlying antibacterial mechanisms indicated that cellular membrane uptake of Ag, NAD+/NADH ratio increase, and intracellular reactive oxygen species (ROS generation were significantly induced in both AgNP and silver ion exposure groups. The released silver ions from AgNPs inside cells through a Trojan-horse-type mechanism were suggested to interact with respiratory chain proteins on the membrane, interrupt intracellular O2 reduction, and induce ROS production. The further oxidative damages of lipid peroxidation and membrane breakdown caused the lethal effect on E. coli. Altogether, this study demonstrated that AgNPs exerted

  17. Silver-activated radiophotoluminescence dosemeter glass with high sensitivity and good corrosion resistance, method of production and applications

    International Nuclear Information System (INIS)

    Kaes, H.H.; Staaden, H.

    1976-01-01

    Hitherto known radiophotoluminescent dosimeter glasses have an interfering maximum of energy dependence in the γ-energy region of 40-60 KeV. The glas according to the invention does not have this disadvantage as the metaphophate group has been replaced by fluorine. The glass is melted from a mixture which besides a silver compound (AgPO 3 , AgNO 3 , Ag 2 CO 3 or LiAg[PO 3 ] 2 ) consists of at least one fluoride. Detailed examples clarify the method and give the limits of possible deviations in the composition. (UWI) [de

  18. Quorum quenching and antibacterial activity of silver nanoparticles synthesized from Sargassum polyphyllum

    Directory of Open Access Journals (Sweden)

    Mani Arunkumar

    2014-03-01

    Full Text Available Development of efficient methodology for the green synthesis of silver nanoparticles using marine algae is a modern area of research in the field of phyconanotechnology. In this regard, the present study deals with green synthesis of silver nanoparticles (AgNPs by using aqueous extracts of marine brown seaweed Sargassum polyphyllum. UV-visible spectral analysis reveals the formation of AgNPs by showing absorption maximum at 420 nm wavelength and SEM analysis clearly elucidate the polydispersed structure of AgNPs without aggregation and ranged in size from 37-43 nm. X-ray Diffraction pattern confirmed the AgNPs crystalline personality. The synthesized AgNPs showed more enduring antibacterial activity against test bacterial pathogens. Furthermore, the synthesized AgNPs exhibited varying level of inhibition of violacein production and swarming motility. In the near future, silver nanoparticles can be extremely useful in clinical medicine as an alternative method for the treatment of wound infection.

  19. Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity.

    Science.gov (United States)

    Saugo, M; Flamini, D O; Brugnoni, L I; Saidman, S B

    2015-11-01

    The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree. The highest amount of silver was deposited when the coated electrode was prepolarised at -1.00V (SCE) before silver deposition, suggesting an increase in the amount of non-oxidised segments in the polymer. Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. aureus. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

    Science.gov (United States)

    Bindhu, M. R.; Umadevi, M.

    2013-01-01

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  1. Enhanced antimicrobial activities of silver-nanoparticle-decorated reduced graphene nanocomposites against oral pathogens.

    Science.gov (United States)

    Peng, Jian-Min; Lin, Jia-Cheng; Chen, Zhuo-Yu; Wei, Meng-Chao; Fu, Yuan-Xiang; Lu, Shu-Shen; Yu, Dong-Sheng; Zhao, Wei

    2017-02-01

    As a means of capitalizing on the synergistic properties between reduced graphene nanosheets (R-GNs) and silver nanoparticles (AgNPs), an efficient and convenient chemical reduction method was used to prepare silver-nanoparticle-decorated reduced graphene nanocomposites (R-GNs/Ag). The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, which confirmed the loading of well-dispersed silver nanoparticles on reduced graphene sheets. Their antimicrobial activities against oral pathogens such as Candida albicans, Lactobacillus acidophilus, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were investigated by MIC determination, the counting of colony-forming units (CFU), agar diffusion tests, and growth curve observation. Compared with pure R-GNs and AgNPs, R-GNs/Ag composites exhibited enhanced antimicrobial properties owing to highly dispersed AgNPs on R-GNs. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.

    Science.gov (United States)

    Bindhu, M R; Umadevi, M

    2013-01-15

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Green synthesis of silver nanoparticles by using carambola fruit extract and their antibacterial activity

    International Nuclear Information System (INIS)

    Mane Gavade, S J; Nikam, G H; Dhabbe, R S; Sabale, S R; Tamhankar, B V; Mulik, G N

    2015-01-01

    In this study well defined silver nanoparticles were synthesized by using carambola fruit extract. After exposing the silver ions to the fruit extract, the rapid reduction of silver ions led to the formation of stable AgNPs in solution due to the reducing and stabilizing properties of carambola fruit juice. The synthesized NPs were analyzed by ultraviolet-visible spectroscopy and x-ray diffraction pattern. The as-synthesized AgNPs were phase pure and well crystalline with a face-centered cubic structure. The AgNPs were characterized by TEM to determine their size and morphology. The antimicrobial activity of the synthesized AgNPs was investigated against Escherichia coli and Pseudomonas aeruginosa by agar well diffusion method. This newly developed method is eco-friendly and could prove a better substitute for the current physical and chemical methods for the synthesis of AgNPs. (paper)

  4. An optical tweezer-based study of antimicrobial activity of silver ...

    Indian Academy of Sciences (India)

    This is achieved by monitoring the fluctuations of an optically trapped polystyrene bead immersed in it. Examining the changes in the fluctuation pattern of the bead with time provides an accurate characterization of the reduction in the microbial activity. Here, we report on the effect of addition of silver nanoparticles on ...

  5. Bactericidal efficacy of silver impregnated activated carbon for disinfection of water

    International Nuclear Information System (INIS)

    Sultana, L.; Khan, F.A.; Usmani, T.H.

    2009-01-01

    When highly contaminated water was passed through two types of silver coated activated carbon and their mixtures with sand, the former was found to be far better medium for disinfection of water, with bactericidal efficacy of about 2.5 times that of the latter. (author)

  6. Processing, characterization, and bactericidal activity of undoped and silver-doped vanadium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tousley, M.E.; Wren, A.W.; Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States); Mellott, N.P., E-mail: mellott@alfred.edu [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States)

    2012-12-14

    Vanadium oxide (V) and silver-doped vanadium oxide (Ag-V) powders were prepared via sol-gel processing. Structural evolution and bactericidal activity was examined as a function of temperature ranging from 250, 350, 450 and 550 Degree-Sign C. Powders were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. Results from all techniques showed vanadium pentoxide (V{sub 2}O{sub 5}) is the predominant phase regardless of heat treatment temperature or the addition of silver (Ag). XRD analysis suggests Ag is present as AgCl in samples heat treated to 250, 350, and 450 Degree-Sign C and as AgV{sub 6}O{sub 15} at 550 Degree-Sign C. Bactericidal activity was evaluated against Escherichia coli using the agar disk diffusion method considering both Ag-V and undoped, V powders. While the addition of Ag significantly increased bactericidal properties, the specific Ag valency, or crystal structure and morphology formed at higher temperatures, had little effect on functionality. -- Highlights: Black-Right-Pointing-Pointer Vanadium and silver-doped vanadium oxide powders were prepared via sol-gel. Black-Right-Pointing-Pointer Powders were characterized using advanced, complementary structural techniques. Black-Right-Pointing-Pointer Bactericidal activity was evaluated against E. coli. Black-Right-Pointing-Pointer Both vanadium and silver doped vanadium oxide show bactericidal activity.

  7. Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities.

    Science.gov (United States)

    Rao, N Hanumanta; N, Lakshmidevi; Pammi, S V N; Kollu, Pratap; S, Ganapaty; P, Lakshmi

    2016-05-01

    Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV-Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (-) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Comparison of results of assaying and neutron activation analysis when determining gold and silver content

    International Nuclear Information System (INIS)

    Vaganov, P.A.; Bulnaev, A.I.; Kulikov, V.D.; Mejer, V.A.; Zakharevich, K.V.

    1977-01-01

    Compared are results of simultaneous determination of gold and silver content in rock samples by the methods of neutron activation analysis and assaying. Rock samples were irradiated by thermal neutron flux of 5x10 13 nxcm -2 xs -1 during 12 hours. The gold content was determined in 8-12 days after irradiation, and silver content in 40-50 days. T he gold content determination was performed by 411.8 keV γ quanta of 198 Au. To establish the silver content two analytical lines of sup(110m)Ag isomer with the energy of 657.7 and 937.4 keV were used. The sensitivity threshold of Au content determination amounts to 3x10 -6 % (or 1x10 -9 g) and that for Ag is 2x10 -40 % (using γ line with the energy of 657.7 keV). The comparison of the results of assaying and neutron-activation analysis has shown for silver a good agreement between the both methods, the coefficient of pair correlation being equal to 0.997. For gold the divergence between the methods is observed. The activation analysis provides on the average lower values of gold content

  9. Antimicrobial activity of thin metallic silver flakes, waste products of a manufacturing process.

    Science.gov (United States)

    Anzano, Manuela; Tosti, Alessandra; Lasagni, Marina; Campiglio, Alfredo; Pitea, Demetrio; Collina, Elena

    2011-01-01

    The aim of the research was to develop new products and processes from a manufacturing waste from an Italian metallurgic company. The company produced thin silver metallic films and the production scraps were silver flakes. The possibility to use the silver flakes in water disinfection processes was studied. The antimicrobial activity of the flakes was investigated in batch using Escherichia coli as Gram-negative microorganism model. The flakes did not show any antimicrobial activity, so they were activated with two different processes: thermal activation in reducing atmosphere and chemical activation, obtaining, respectively, reduced flakes (RF) and chemical flakes (CF). The flakes, activated with either treatment, showed antimicrobial activity against E. coli. The kill rate was dependent on the type of activated flakes. The chemical flakes were more efficient than reduced flakes. The kill rate determined for 1 g of CF, 1.0 +/- 0.2 min(-1), was greater than the kill rate determined for 1 g of RF, 0.069 +/- 0.004 min(-1). This was confirmed also by the minimum inhibitory concentration values. It was demonstrated that the antimicrobial capability was dependent on flakes amount and on the type of aqueous medium. Furthermore, the flakes maintained their properties also when used a second time. Finally, the antimicrobial activities of flakes were tested in an effluent of a wastewater treatment plant where a variety of heterotrophic bacteria were present.

  10. Determination of fluoride ions by measuring ionic activities and using selective electrode

    International Nuclear Information System (INIS)

    Angelini, J.M.G.; Castro Miquelino, F.L. de

    1984-01-01

    Fluorides interfere adversely in electroplating baths of printed circuits and in other environments where it promotes corrosion. A calibration curve for its determination was drawn with standards of known concentrations. As the concentration of the fluorite ions in the sample did not follow the linearity of the curve, it was measured by means of the standard addition method. (C.L.B.) [pt

  11. Friedel-Crafts reaction of benzyl fluorides: selective activation of C-F bonds as enabled by hydrogen bonding.

    Science.gov (United States)

    Champagne, Pier Alexandre; Benhassine, Yasmine; Desroches, Justine; Paquin, Jean-François

    2014-12-08

    A Friedel-Crafts benzylation of arenes with benzyl fluorides has been developed. The reaction produces 1,1-diaryl alkanes in good yield under mild conditions without the need for a transition metal or a strong Lewis acid. A mechanism involving activation of the C-F bond through hydrogen bonding is proposed. This mode of activation enables the selective reaction of benzylic C-F bonds in the presence of other benzylic leaving groups. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Fluoride-induced IL-8 release in human epithelial lung cells: Relationship to EGF-receptor-, SRC- and MAP-kinase activation

    International Nuclear Information System (INIS)

    Refsnes, Magne; Skuland, Tonje; Schwarze, Per E.; Ovrevik, Johan; Lag, Marit

    2008-01-01

    Exposure of human epithelial lung cells to fluorides is known to induce a marked increase in the release of interleukin (IL)-8, a chemokine involved in neutrophil recruitment. In the present study, the involvement of mitogen-activating protein kinases (MAPKs), the role of upstream activation of Src family kinases (SFKs), epidermal growth factor receptor (EGFR) activation and the interrelationships between these pathways in fluoride-induced IL-8 were examined in a human epithelial lung cell line (A549). Sodium fluoride strongly activated MAPK, in particular JNK1/2 and p38. The ERK1/2-inhibitor PD98059, the p38-inhibitor SB202190 and the JNK1/2-inhibitor SP600125 partially inhibited the fluoride-induced IL-8 response. Combinations of these inhibitors reduced the responses nearly to basal levels. Treatment with siRNA against JNK2 also reduced the IL-8 response to fluoride. Furthermore, fluoride activated SFKs, which was abolished by the SFK-inhibitor PP2. PP2 substantially inhibited the increased levels of IL-8, and partially reduced the fluoride-induced activation of ERK1/2, p38 and JNK1/2. Fluoride exposure also led to a phosphorylation of the EGFR, that was partially inhibited by PP2. AG1478, an EGFR-inhibitor, partially reduced the fluoride-induced IL-8 response and the phosphorylation of JNK1/2 and ERK1/2, but less the phosphorylation of p38. The effects of AG1478 were less than that of PP2. In conclusion, our findings suggest that the fluoride-induced IL-8 release involves the combined activation of ERK1/2, JNK1/2 and p38, and that the phosphorylation of these kinases, and in particular JNK1/2 and ERK1/2, partly, is mediated via a SFK-dependent EGFR-linked pathway. SFK-dependent, but EGFR-independent mechanisms seem important, and especially for phosphorylation of p38

  13. Green Synthesis of Silver Nanoparticles and Their Bactericidal and Antimycotic Activities against Oral Microbes

    Directory of Open Access Journals (Sweden)

    Osvelia E. Rodríguez-Luis

    2016-01-01

    Full Text Available Nanotechnology is a new discipline with huge applications including medicine and pharmacology industries. Although several methods and reducing agents have been employed to synthesize silver nanoparticles, reactive chemicals promote toxicity and nondesired effects on the human and biological systems. The objective of this work was to synthesize silver nanoparticles from Glycyrrhiza glabra and Amphipterygium adstringens extracts and determine their bactericidal and antimycotic activities against Enterococcus faecalis and Candida albicans growth, respectively. 1 and 10 mM silver nitrate were mixed with an extract of Glycyrrhiza glabra and Amphipterygium adstringens. Green silver nanoparticles (AgNPs were characterized by TEM, Vis-NIR, FTIR, fluorescence, DLS, TGA, and X-ray diffraction (XRD analysis. Bactericidal and antimycotic activities of AgNPs were determined by Kirby and Bauer method and cell viability MTT assays. AgNPs showed a spherical shape and average size of 9 nm if prepared with Glycyrrhiza glabra extract and 3 nm if prepared with Amphipterygium adstringens extract. AgNPs inhibited the bacterial and fungal growth as was expected, without a significant cytotoxic effect on human epithelial cells. Altogether, these results strongly suggest that AgNPs could be an interesting option to control oral biofilms.

  14. Antibacterial activity of Nano-Silver capped by β-Cyclodextrin

    Directory of Open Access Journals (Sweden)

    R. Sathiya Priya

    2013-03-01

    Full Text Available Silver nanoparticles were prepared by chemical reduction method using sodium citrate as reducing agent, followed by capping with various concentrations of β-Cyclodextrin (β-CD and characterized by various physicchemical characterization techniques. Antibacterial activity of Pseudomonas aeruginosa (Gram-negative and Staphylococcus aureus (Gram-positive was determined by Well-Diffusion method. The nano-silver were spherical under Scanning electron microscopy (SEM and the XRD result shows average diameters of capped particles are smaller than their equivalent uncapped particles. Capped nano silver particles of four different concentrations were demonstrated as superior for photo stability, when exposed to intense ultraviolet (UV-Vis radiation for 4 hours, as well as significantly higher antibacterial activity. The influence of β-CD concentration (5 mM, 10 mM and 15 mM was seems to be delay in bacterial growth, showing that a Trojan horse mechanism may be owing to occur bacterial affinity, thereby improving silver ion absorption.

  15. Green synthesis of silver nanoparticles by Bacillus methylotrophicus, and their antimicrobial activity.

    Science.gov (United States)

    Wang, Chao; Kim, Yeon Ju; Singh, Priyanka; Mathiyalagan, Ramya; Jin, Yan; Yang, Deok Chun

    2016-06-01

    The synthesis of silver nanoparticles (AgNPs) by microorganisms is an area attracting growing interest in nanobiotechnology, due to the applications of these nanoparticles in various products including cosmetics and biosensors, and in the biomedical, clinical, and bioimaging fields as well. Various microorganisms have been found to be able to synthesize AgNPs when silver salts are supplied in the reaction system. The main objectives of this study were to evaluate the efficiency of synthesis of AgNPs by the strain Bacillus methylotrophicus DC3, isolated from the soil of Korean ginseng, a traditionally known oriental medicinal plant in Korea. The AgNPs showed maximum absorbance at 416 nm, when assayed by ultraviolet-visible spectroscopy (UV-vis). The field emission transmission electron micrograph (FE-TEM) results showed that the particles were spherical and 10-30 nm in size. In addition, the product was also characterized by energy dispersive X-ray spectroscopy (EDX), which displayed a 3 keV peak corresponding to the silver nanocrystal. Elemental mapping results also confirmed the presence of silver elements in the electron micrograph region. Furthermore, the AgNPs demonstrated antimicrobial activity against various pathogenic microorganisms such as Candida albicans, Salmonella enterica, Escherichia coli, and Vibrio parahaemolyticus, with enhanced antimicrobial activity being exhibited against C. albicans. Therefore, the current study describes the simple, efficient, and green method of synthesis of AgNPs by B. methylotrophicus DC3.

  16. Antimicrobial, Antioxidant and Cytotoxic Activity of Silver Nanoparticles Synthesized by Leaf Extract of Erythrina suberosa (Roxb.).

    Science.gov (United States)

    Mohanta, Yugal K; Panda, Sujogya K; Jayabalan, Rasu; Sharma, Nanaocha; Bastia, Akshaya K; Mohanta, Tapan K

    2017-01-01

    In this experiment, biosynthesized silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Erythrina suberosa (Roxb.). The biosynthesis of silver nanoparticle was continuously followed by UV-vis spectrophotometric analysis. The response of the phytoconstituents resides in E. suberusa during synthesis of stable AgNPs were analyzed by ATR- fourier-transform infrared spectroscopy. Further, the size, charge, and polydispersity nature of AgNPs were studied using dynamic light scattering spectroscopy. The morphology of the nanoparticles was determined by scanning electron microscopy. Current result shows core involvement of plant extracts containing glycosides, flavonoids, and phenolic compounds played a crucial role in the biosynthesis of AgNPs. The antimicrobial activities of silver nanoparticles were evaluated against different pathogenic bacterium and fungi. The antioxidant property was studied by radical scavenging (DPPH) assay and cytotoxic activity was evaluated against A-431 osteosarcoma cell line by MTT assay. The characteristics of the synthesized silver nanoparticles suggest their application as a potential antimicrobial and anticancer agent.

  17. Levels of Antioxidant Activity and Fluoride Content in Coffee Infusions of Arabica, Robusta and Green Coffee Beans in According to their Brewing Methods.

    Science.gov (United States)

    Wolska, J; Janda, Katarzyna; Jakubczyk, K; Szymkowiak, M; Chlubek, D; Gutowska, I

    2017-10-01

    Coffee is a rich source of dietary antioxidants, and this property links with the fact that coffee is one of the world's most popular beverages. Moreover, it is a source of macro- and microelements, including fluoride. The aim of this work was to determine antioxidant activity of coffee beverages and fluoride content depending on different coffee species and conditions of brewing. Three species of coffee, arabica, robusta and green coffee beans obtained from retail stores in Szczecin (Poland) were analyzed. Five different techniques of preparing drink were used: simple infusion, french press, espresso maker, overflow espresso and Turkish coffee. Antioxidant potential of coffee beverages was investigated spectrophotometrically by DPPH method. Fluoride concentrations were measured by potentiometric method with a fluoride ion-selective electrode. Statistical analysis was performed using Stat Soft Statistica 12.5. Antioxidant activity of infusions was high (71.97-83.21% inhibition of DPPH) depending on coffee species and beverage preparing method. It has been shown that the method of brewing arabica coffee and green coffee significantly affects the antioxidant potential of infusions. The fluoride concentration in the coffee infusions changed depending, both, on the species and conditions of brewing, too (0.013-0.502 mg/L). Methods of brewing didn't make a difference to the antioxidant potential of robusta coffee, which had also the lowest level of fluoride among studied species. Except overflow espresso, the fluoride content was the highest in beverages from green coffee. The highest fluoride content was found in Turkish coffee from green coffee beans.

  18. Studying the silver nanoparticles influence on thermodynamic behavior and antimicrobial activities of novel amide Gemini cationic surfactants.

    Science.gov (United States)

    Shaban, Samy M; Abd-Elaal, Ali A

    2017-07-01

    Three novels amide Gemini cationic surfactants with various alkyl chains and their silver nanohybrid with silver nanoparticles were synthesized and a confirmation study for surfactant and their nanoparticles formation has been established using IR, 1 HNMR, TEM and UV-Vis spectroscopy. The surface-active properties of these surfactants and their nanoform were investigated through surface tension and electrical conductivity measurements and a comparative study has been established. The thermodynamic parameters of micellization and adsorption were assessed at temperatures range from 25 to 65°C. The effect of silver particles on the surface behavior of the synthesized surfactant has been discussed. The aggregation behavior of silver nanoparticles with these synthesized Gemini surfactants in water were investigated using dynamic light scattering and transmission electron microscopy. Furthermore, the antimicrobial activities of these synthesized amide Gemini surfactants and their nanostructure with silver against both Gram positive and Gram negative bacteria were also investigated. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Fluoridation Basics

    Science.gov (United States)

    ... return on investment for community water fluoridation (including productivity losses) ranged from $4 in small communities of ... National Center for Chronic Disease Prevention and Health Promotion Email Recommend Tweet YouTube Instagram Listen Watch RSS ...

  20. Effect of fluoridated varnish and silver diamine fluoride solution on enamel demineralization: pH-cycling study Efeito do verniz fluoretado e da solução de diamino fluoreto de prata na desmineralização do esmalte: estudo utilizando modelo de ciclagem de pH

    Directory of Open Access Journals (Sweden)

    Alberto Carlos Botazzo Delbem

    2006-04-01

    Full Text Available OBJECTIVE: In the present investigation, the anticariogenic effect of fluoride released by two products commonly applied in infants was evaluated. METHODS: Bovine sound enamel blocks were randomly allocated to each one of the treatment groups: control (C, varnish (V and diamine silver fluoride solution (D. The blocks were submitted to pH cycles in an oven at 37ºC. Next, surface and cross-sectional microhardness were assessed to calculate the percentage loss of surface microhardness (%SML and the mineral loss (deltaZ. The fluoride present in enamel was also determined. RESULTS: F/Px10-3 (ANOVA, pOBJETIVOS: Este trabalho avaliou o efeito anticariogênico do flúor liberado por dois produtos comumente aplicados em crianças. MÉTODOS: Para isto, utilizaram-se blocos de esmalte de dentes bovinos distribuídos aleatoriamente em três grupos de tratamento: controle (C, verniz fluoretado (V e solução de diamino fluoreto de prata (D. Os blocos foram submetidos à ciclagem de pH a 37ºC. Após, realizou-se o teste de microdureza de superfície (para o cálculo da % da perda de microdureza de superfície - %SML e em secção longitudinal do esmalte (% de alteração da área mineral - %deltaZ e a determinação do flúor presente no esmalte (F/P x 10-3. RESULTADOS: As concentrações de flúor (ANOVA, p<0,05 na 1ª camada do esmalte, antes da ciclagem de pH, foram (C, V e D: 1,6ª; 21,6b e 4,0c. Os resultados de %SML (Kruskal-Wallis, p<0.05 foram: -64,0ª, -45,2b e -53,1c. Os valores de %deltaZ (ANOVA, p<0.05 foram: -18,7ª, -7,7b e -17,3ª. CONCLUSÃO: Os dados sugerem que o flúor liberado pelo verniz apresentou maior interação com o esmalte promovendo menor perda mineral quando comparado à solução de diamino de prata.

  1. Phase Change Activation and Characterization of Spray-Deposited Poly(vinylidene) Fluoride Piezoelectric Thin Films

    Science.gov (United States)

    Riosbaas, Miranda Tiffany

    Structural safety and integrity continues to be an issue of utmost concern in our world today. Existing infrastructures in civil, commercial, and military applications are beginning to see issues associated with age and environmental conditions. In addition, new materials are being put to service that are not yet fully characterized and understood when it comes to long term behavior. In order to assess the structural health of both old and new materials, it is necessary to implement a technique for monitoring wear and tear. Current methods that are being used today typically depend on visual inspection techniques or handheld instruments. These methods are not always ideal for large structures as they become very tedious leading to a substantial amount of both time and money spent. More recently, composite materials have been introduced into applications that can benefit from high strength-to-weight ratio materials. However, the use of more complex materials (such as composites) leads to a high demand of structural health monitoring techniques, since the damage is often internal and not visible to the naked eye. The work performed in this thesis examines the methods that can be used for phase change activation and characterization of sprayable poly(vinylidene) fluoride (PVDF) thin films in order to exploit their piezoelectric characteristics for sensing applications. PVDF is widely accepted to exist in four phases: alpha, beta, gamma, and delta. Alpha phase PVDF is produced directly from the melt and exhibits no piezoelectric properties. The activation or transition from α phase to some combination of beta and/or gamma phase PVDF leads to a polarizable piezoelectric thin film to be used in sensing applications. The work herein presents the methods used to activate phase change in PVDF, such as mechanical stretching, annealing, and chemical composition, to be able to implement PVDF as an impact detection sensor. The results and analysis provided in this thesis will

  2. Mutagenicity of silver nanoparticles in CHO cells dependent on particle surface functionalization and metabolic activation

    Science.gov (United States)

    Guigas, Claudia; Walz, Elke; Gräf, Volker; Heller, Knut J.; Greiner, Ralf

    2017-06-01

    The potential of engineered nanomaterials to induce genotoxic effects is an important aspect of hazard identification. In this study, cytotoxicity and mutagenicity as a function of metabolic activation of three silver nanoparticle (AgNP) preparations differing in surface coating were determined in Chinese hamster ovary (CHO) subclone K1 cells. Three silver nanoparticle preparations ( x 90,0 culture medium containing 10% fetal calf serum (FCS) than in medium without FCS. The HPRT test without metabolic activation system S9 revealed that compared to the other AgNP formulations, citrate-coated Ag showed a lower genotoxic effect. However, addition of S9 increased the mutation frequency of all AgNPs and especially influenced the genotoxicity of Citrate-Ag. The results showed that exogenous metabolic activation of nanosilver is crucial even if interactions of the metabolic activation system, nanosilver, and cells are not really understood up to now.

  3. The study of the antimicrobial activity of colloidal solutions of silver nanoparticles prepared using food stabilizers.

    Science.gov (United States)

    Balandin, G V; Suvorov, O A; Shaburova, L N; Podkopaev, D O; Frolova, Yu V; Ermolaeva, G A

    2015-06-01

    The bactericidal effect of colloidal solutions of silver nanoparticles based on food stabilizers, gum arabic and chitosan, against bacterial cultures of microorganisms in food production is described. The antibacterial activity of nanotechnology products containing different amounts of stabilizing additives when applied to solid pH-neutral substrates is studied. For its evaluation a method making it possible to take into account the capability of nanoparticles to diffuse in solid media was applied. Minimal inhibitory concentrations of nanoparticles used against Erwinia herbicola, Pseudomonas fluorescens, Bacillus subtilis, Sarcina flava were found. A suggestion was made concerning the influence of the spatial structure of bacteria on the antibacterial activity of colloidal solutions of silver nanoparticles. The data concerning the antibacterial activity and minimal inhibiting concentrations of nanoparticles may be used for development of products suppressing activity of microorganisms hazardous for food production.

  4. Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Hanim, Siti Aishah Mohd; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my; Ibrahim, Zaharah

    2016-01-01

    Graphical abstract: - Highlights: • Functionalization of Ag-exchanged zeolite NaY with 3-aminopropyltriethoxysilane APTES (ZSA) as antibacterial agent. • Antibacterial assay of ZSA was performed against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538. • Functionalization of Ag-exchanged zeolite NaY with APTES significantly increased the antibacterial agent. • Different mechanisms of bacterial death were suggested for each bacteria type by the functionalized Ag-exchanged zeolite NaY. - Abstract: Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver

  5. Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract.

    Science.gov (United States)

    Mamun Or Rashida, Md; Shafiul Islam, Md; Azizul Haque, Md; Arifur Rahman, Md; Tanvir Hossain, Md; Abdul Hamid, Md

    2016-01-01

    Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV-Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can't be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program.

  6. Evaluation of the Antimicrobial Activity of Different Antibiotics Enhanced with Silver-Doped Hydroxyapatite Thin Films

    Directory of Open Access Journals (Sweden)

    Daniela Predoi

    2016-09-01

    Full Text Available The inhibitory and antimicrobial effects of silver particles have been known since ancient times. In the last few years, a major health problem has arisen due to pathogenic bacteria resistance to antimicrobial agents. The antibacterial activities of new materials including hydroxyapatite (HAp, silver-doped hydroxyapatite (Ag:HAp and various types of antibiotics such as tetracycline (T-HAp and T-Ag:HAp or ciprofloxacin (C-HAp and C-Ag:HAp have not been studied so far. In this study we reported, for the first time, the preparation and characterization of various thin films based on hydroxyapatite and silver-doped hydroxyapatite combined with tetracycline or ciprofloxacin. The structural and chemical characterization of hydroxyapatite and silver-doped hydroxyapatite thin films has been evaluated by X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR. The morphological studies of the HAp, Ag:HAp, T-HAp, T-Ag:HAp, C-HAp and C-Ag:HAp thin solid films were performed using scanning electron microscopy (SEM. In order to study the chemical composition of the coatings, energy dispersive X-ray analysis (EDX and glow discharge optical emission spectroscopy (GDOES measurements have been used, obtaining information on the distribution of the elements throughout the film. These studies have confirmed the purity of the prepared hydroxyapatite and silver-doped hydroxyapatite thin films obtained from composite targets containing Ca10−xAgx(PO46(OH2 with xAg = 0 (HAp and xAg = 0.2 (Ag:HAp. On the other hand, the major aim of this study was the evaluation of the antibacterial activities of ciprofloxacin and tetracycline in the presence of HAp and Ag:HAp thin layers against Staphylococcus aureus and Escherichia coli strains. The antibacterial activities of ciprofloxacin and tetracycline against Staphylococcus aureus and Escherichia coli test strains increased in the presence of HAp and Ag:HAp thin layers.

  7. Photocatalytic, antioxidant, antibacterial and anti-inflammatory activity of silver nanoparticles synthesised using forest and edible mushroom

    Science.gov (United States)

    Sriramulu, Mohana; Sumathi, Shanmugam

    2017-12-01

    Mushroom has been part of the human diet for thousands of years, and in recent times, the amounts consumed have risen greatly, involving a large number of species. Mushrooms used for nutritional and therapeutic purposes. In this study silver nanoparticles were synthesised using an edible mushroom (Agaricus bisporus) and forest mushroom (Ganoderma lucidum) extract. The synthesised nanoparticles were characterised by UV-vis spectroscopy, FTIR, powder XRD and SEM. Silver nanoparticles were synthesised at room temperature and at 60 °C. FTIR results recognised the presence of bioactive functional groups responsible for the reduction of silver nitrate to silver nanoparticles. From the XRD, it was observed that the nanoparticles are silver with an average size of 10-80 nm. The silver nanoparticles are explored for photocatalytic activity and biological activities such as in vitro antioxidant activity, anti-inflammatory activity and antimicrobial activity against Escherichia coli and Staphylococcus aureus organisms. 98% of textile dye (direct blue 71) degradation was noticed under UV light within 150 min for forest mushroom synthesised silver nanoparticles at room temperature.

  8. Mechanisms of inhibition by fluoride of urease activities of cell suspensions and biofilms of Staphylococcus epidermidis, Streptococcus salivarius, Actinomyces naeslundii and of dental plaque.

    Science.gov (United States)

    Barboza-Silva, E; Castro, A C D; Marquis, R E

    2005-12-01

    Fluoride is known to be a potent inhibitor of bacterial ureases and can also act in the form of hydrofluoric acid as a transmembrane proton conductor to acidify the cytoplasm of intact cells with possible indirect, acid inhibition of urease. Our research objectives were to assess the inhibitory potencies of fluoride for three urease-positive bacteria commonly found in the mouth and to determine the relative importance of direct and indirect inhibition of ureases for overall inhibition of intact cells or biofilms. The experimental design involved intact bacteria in suspensions, mono-organism biofilms, cell extracts, and dental plaque. Standard enzymatic assays for ammonia production from urea were used. We found that ureolysis by cells in suspensions or mono-organism biofilms of Staphylococcus epidermidis, Streptococcus salivarius or Actinomyces naeslundii was inhibited by fluoride at plaque levels of 0.1-0.5 mm in a pH-dependent manner. The results of experiments with the organic weak acids indomethacin and capric acid, which do not directly inhibit urease enzyme, indicated that weak-acid effects leading to cytoplasmic acidification are also involved in fluoride inhibition. However, direct fluoride inhibition of urease appeared to be the major mechanism for reduction in ureolytic activity in acid environments. Results of experiments with freshly harvested supragingival dental plaque indicated responses to fluoride similar to those of S. salivarius with pH-dependent fluoride inhibition and both direct and indirect inhibition of urease. Fluoride can act to diminish alkali production from urea by oral bacteria through direct and indirect mechanisms.

  9. The cellular responses and antibacterial activities of silver nanoparticles stabilized by different polymers

    Science.gov (United States)

    Lin, Jiang-Jen; Lin, Wen-Chun; Dong, Rui-Xuan; Hsu, Shan-hui

    2012-02-01

    Silver nanoparticles (AgNPs) are known for their excellent antibacterial activities. The possible toxicity, however, is a major concern for their applications. Three types of AgNPs were prepared in this study by chemical processes. Each was stabilized by a polymer surfactant, which was expected to reduce the exposure of cells to AgNPs and therefore their cytotoxicity. The polymer stabilizers included poly(oxyethylene)-segmented imide (POEM), poly(styrene-co-maleic anhydride)-grafting poly(oxyalkylene) (SMA) and poly(vinyl alcohol) (PVA). The cytotoxicity of these chemically produced AgNPs to mouse skin fibroblasts (L929), human hepatocarcinoma cells (HepG2), and mouse monocyte macrophages (J774A1) was compared to that of physically produced AgNPs and gold nanoparticles (AuNPs) as well as the standard reference material RM8011 AuNPs. Results showed that SMA-AgNPs were the least cytotoxic among all materials, but cytotoxicity was still observed at higher silver concentrations (>30 ppm). Macrophages demonstrated the inflammatory response with cell size increase and viability decrease upon exposure to 10 ppm of the chemically produced AgNPs. SMA-AgNPs did not induce hemolysis at a silver concentration below 1.5 ppm. Regarding the antibacterial activity, POEM-AgNPs and SMA-AgNPs at 1 ppm silver content showed 99.9% and 99.3% growth inhibition against E. coli, while PVA-AgNPs at the same silver concentration displayed 79.1% inhibition. Overall, SMA-AgNPs demonstrated better safety in vitro and greater antibacterial effects than POEM-AgNPs and PVA-AgNPs. This study suggested that polymer stabilizers may play an important role in determining the toxicity of AgNPs.

  10. Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

    Science.gov (United States)

    Iconaru, Simona Liliana; Chapon, Patrick; Le Coustumer, Philippe; Predoi, Daniela

    2014-01-01

    In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FT-IR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x Ag = 0.5 are effective against E. coli and S. aureus after 24 h. PMID:24523630

  11. Efficient silver modification of TiO2 nanotubes with enhanced photocatalytic activity

    Science.gov (United States)

    Huang, Jing; Ding, Lei; Xi, Yaoning; Shi, Liang; Su, Ge; Gao, Rongjie; Wang, Wei; Dong, Bohua; Cao, Lixin

    2018-06-01

    In this paper, Ag(CH3NH2)2+, Ag(NH3)2+ and Ag+ with different radii have been used as silver sources to find out the distribution of Ag ions on the H-TNT surface, which is critical to the final performance. The influence of this distribution on visible photocatalytic activity is further studied. The results indicate that, when Ag+ used as silver source with low concentration, these small sized silver ions mainly distribute on interlayer spacing of H-TNT. After heat-treatment and photo-reduction, the generated silver nanoparticles uniformly embed in the anatase TiO2 nanotube walls, and bring large interfacial area between Ag particles and TiO2 nanotubes. The separation effect of photogenerated electron-hole pair in TiO2 is enhanced by Ag particles, and achieves the best at 0.15 g/L, much higher than P25, TiO2/0, Ag-N@TiO2 and Ag-C-N@TiO2. This paper provides new ideas for the modification of TiO2 nanotubes.

  12. Green synthesis of silver nanoparticles by Escherichia coli : Analysis of antibacterial activity

    Directory of Open Access Journals (Sweden)

    Koilparambil Divya

    2016-07-01

    Full Text Available The emerging infectious diseases and the development of drug resistance in the pathogenic microorganism is a matter of serious concern. Despite the increased knowledge of microbial pathogenesis and application of modern therapeutics, the morbidity and mortality associated with the microbial infections still remains high. Therefore, there is a pressing demand to discover novel strategies and identify new antimicrobial agents to develop the next generation of drugs or agents to control microbial infections. The use of nanoparticles is gaining impetus in the present century as they possess defined chemical, optical and mechanical properties. In the present study green synthesis of silver nanoparticles by Escherichia coli has been done. Various parameters such as mixing ratio of culture supernatant and silver nitrate, media, temperature and pH for production of silver nanoparticles were optimised. The nanoparticles synthesised was characterized using SEM, FTIR and XRD. The antibacterial activity of silver nanoparticles synthesised using both pellet and supernatant against human pathogens Salmonella typhi, Vibrio cholerae, Bacillus subtilis and Klebsiella pneumoniae was analysed and MIC was calculated as 20µg and 50µg respectively.

  13. Antimicrobial activity of thin solid films of silver doped hydroxyapatite prepared by sol-gel method.

    Science.gov (United States)

    Iconaru, Simona Liliana; Chapon, Patrick; Le Coustumer, Philippe; Predoi, Daniela

    2014-01-01

    In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FT-IR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x(Ag) = 0.5 are effective against E. coli and S. aureus after 24 h.

  14. Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Simona Liliana Iconaru

    2014-01-01

    Full Text Available In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM with energy Dispersive X-ray attachment (X-EDS, Fourier transform infrared spectroscopy (FT-IR, and glow discharge optical emission spectroscopy (GDOES. These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with xAg=0.5 are effective against E. coli and S. aureus after 24 h.

  15. Enhancement of antidandruff activity of shampoo by biosynthesized silver nanoparticles from Solanum trilobatum plant leaf

    Science.gov (United States)

    Pant, Gaurav; Nayak, Nitesh; Gyana Prasuna, R.

    2013-10-01

    The present investigation describes simple and effective method for synthesis of silver nanoparticles via green route. Solanum trilobatum Linn extract were prepared by both conventional and homogenization method. We optimized the production of silver nanoparticles under sunlight, microwave and room temperature. The best results were obtained with sunlight irradiation, exhibiting 15-20 nm silver nanoparticles having cubic and hexagonal shape. Biosynthesized nanoparticles were highly toxic to various bacterial strains tested. In this study we report antibacterial activity against various Gram negative ( Klebsiella pneumoniae, Vibrio cholerae and Salmonella typhi) and Gram positive ( Staphylococcus aureus, Bacillus cereus and Micrococcus luteus) bacterial strains. Screening was also performed for any antifungal properties of the nanoparticles against human pathogenic fungal strains ( Candida albicans and Candida parapsilosis). We also demonstrated that these nanoparticles when mixed with shampoo enhance the anti-dandruff effect against dandruff causing fungal pathogens ( Pityrosporum ovale and Pityrosporum folliculitis). The present study showed a simple, rapid and economical route to synthesize silver nanoparticles and their applications hence has a great potential in biomedical field.

  16. Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Salvioni L

    2017-03-01

    Full Text Available Lucia Salvioni,1 Elisabetta Galbiati,1 Veronica Collico,1 Giulia Alessio,1 Svetlana Avvakumova,1 Fabio Corsi,2,3 Paolo Tortora,1 Davide Prosperi,1 Miriam Colombo1 1Nanobiolab, Department of Biotechnology and Bioscience, University of Milano-Bicocca, 2Biological and Clinical Science Department, University of Milan, Milano, 3Surgery Department, Breast Unit, IRCCS S Maugeri Foundation, Pavia, Italy Background: The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases.Methods: Water-soluble, negatively charged silver nanoparticles (AgNPs were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet–visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs.Results: In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells.Conclusion: We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared

  17. Antimicrobial activity and cytotoxicity of cotton fabric coated with conducting polymers, polyaniline or polypyrrole, and with deposited silver nanoparticles

    Science.gov (United States)

    Maráková, Nela; Humpolíček, Petr; Kašpárková, Věra; Capáková, Zdenka; Martinková, Lenka; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav

    2017-02-01

    Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers. Raman and FTIR spectra proved the complete coating of substrates. Polypyrrole content was 19.3 wt.% and that of polyaniline 6.0 wt.%. Silver nanoparticles were deposited from silver nitrate solutions of various concentrations by exploiting the reduction ability of conducting polymers. The content of silver was up to 11 wt.% on polypyrrole and 4 wt.% on polyaniline. The sheet resistivity of fabrics was determined. The conductivity was reduced after deposition of silver. The chemical cleaning reduced the conductivity by less than one order of magnitude for polypyrrole coating, while for polyaniline the decrease was more pronounced. The good antibacterial activity against S. aureus and E. coli and low cytotoxicity of polypyrrole-coated cotton, both with and without deposited silver nanoparticles

  18. Colouring of PK cells nucleoli with silver in case of hyperactivation and activation of RNA nucleoli synthesis under ultraviolet radiation

    International Nuclear Information System (INIS)

    Sacharov, V.N.; Voronkova, L.N.; Valova, T.M.

    1988-01-01

    Localization and redistribution of silver-coloured nucleolus proteins in pig embryo kidney cell nuclei under postmitotic formation and evolution of nucleoli in order and under UV-microirradiation stimulated degradation and neature nucleolus compensator hyperactivation in the interphase are studied. In the anaphase chromosome set only 4 silver granules colouring the nucleolus organizer proteins were usually detected. At the initial stages of nucleolus postmitotic formation the number of silver granules in nucleolus organizer increased rapidly up to 25-30 per a nucleus, and at subsequent cellular cycle stages it doubled gradually. Under the natural growth and stimulated modifications of nucleoli the change of silver granule number in nucleoli correlated with the changes of nucleolus sizes and with the change of nucleolus RNA synthesis level. A possible connection between the nucleolus functional activity and the presence of proteins coloured with silver is discussed

  19. Photochemically synthesized heparin-based silver nanoparticles: an antimicrobial activity study

    Science.gov (United States)

    Rodriguez-Torres, Maria del Pilar; Acosta-Torres, Laura Susana; Díaz-Torres, Luis Armando

    2017-08-01

    The antimicrobial activity of silver nanoparticles has been extensively studied in the last years. Such nanoparticles constitute a potential and promising approach for the development of new antimicrobial systems especially due to the fact that several microorganisms are developing resistance to some already existing antimicrobial agents, therefore making antibacterial and antimicrobial studies on alternative materials necessary to overcome this issue. Silver nanoparticle concentration and size are determining factors on the antimicrobial activity of these nano systems. Heparin is a polysaccharide that belongs to the glycosaminoglycans (GAGs) family, molecules formed by a base disaccharide whose components are joined by a glycosidic linkage that is a repeating unit along their structure. It is highly sulfated making it a negatively charged material that is also widely used as an anticoagulant in Medicine because its biocompatibility besides it is also produced within the human body, specifically in the mast cells. Heparin alone possesses antimicrobial activity although it has not been studied very much in detail, it only has been demonstrated that it inhibits E. coli, P. aeruginosa, S. aureus and S. epidermidis, so taking this into account, this study is dedicated to assess UV photochemically-synthesized (λ=254 nm) heparin-based silver nanoparticles antimicrobial activity using the agar disk diffusion method complemented by the broth microdilution method to estimate de minimum inhibitory concentration (MIC), that is the lowest concentration at which an antimicrobial will inhibit visible growth of a microorganism. The strains used were the ones aforementioned to assess the antimicrobial activity degree these heparinbased nanoparticles exhibit.

  20. Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

    2008-01-09

    A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

  1. Biogenic synthesis of silver nanoparticles using guava ( Psidium guajava) leaf extract and its antibacterial activity against Pseudomonas aeruginosa

    Science.gov (United States)

    Bose, Debadin; Chatterjee, Someswar

    2016-08-01

    Among the various inorganic nanoparticles, silver nanoparticles have received substantial attention in the field of antimicrobial research. For safe and biocompatible use of silver nanoparticles in antimicrobial research, the different biogenic routes are developed to synthesize silver nanoparticles that do not use toxic chemicals. Among those, to synthesize silver nanoparticles, the use of plant part extract becomes an emerging field because plant part acts as reducing as well as capping agent. For large-scale production of antibacterial silver nanoparticles using plant part, the synthesis route should be very simple, rapid, cost-effective and environment friendly based on easy availability and non-toxic nature of plant, stability and antibacterial potential of biosynthesized nanoparticles. In the present study, we report a very simple, rapid, cost-effective and environment friendly route for green synthesis of silver nanoparticles using guava ( Psidium guajava) leaf extract as reducing as well as capping agent. This plant has been opted for the present study for its known medicinal properties, and it is easily available in all seasons and everywhere. The biosynthesized silver nanoparticles are characterized by UV-Vis and TEM analysis. The average particle size is 40 nm in the range of 10-90 nm. The antibacterial activity of these nanoparticles against Pseudomonas aeruginosa MTCC 741 has been measured by disc diffusion method, agar cup assay and serial dilution turbidity measurement assay. The results show that green synthesized silver nanoparticles, using guava ( Psidium guajava) leaf extract, have a potential to inhibit the growth of bacteria.

  2. Laser cladding of stainless steel with a copper-silver alloy to generate surfaces of high antimicrobial activity

    Science.gov (United States)

    Hans, Michael; Támara, Juan Carlos; Mathews, Salima; Bax, Benjamin; Hegetschweiler, Andreas; Kautenburger, Ralf; Solioz, Marc; Mücklich, Frank

    2014-11-01

    Copper and silver are used as antimicrobial agents in the healthcare sector in an effort to curb infections caused by bacteria resistant to multiple antibiotics. While the bactericidal potential of copper and silver alone are well documented, not much is known about the antimicrobial properties of copper-silver alloys. This study focuses on the antibacterial activity and material aspects of a copper-silver model alloy with 10 wt% Ag. The alloy was generated as a coating with controlled intermixing of copper and silver on stainless steel by a laser cladding process. The microstructure of the clad was found to be two-phased and in thermal equilibrium with minor Cu2O inclusions. Ion release and killing of Escherichia coli under wet conditions were assessed with the alloy, pure silver, pure copper and stainless steel. It was found that the copper-silver alloy, compared to the pure elements, exhibited enhanced killing of E. coli, which correlated with an up to 28-fold increased release of copper ions. The results show that laser cladding with copper and silver allows the generation of surfaces with enhanced antimicrobial properties. The process is particularly attractive since it can be applied to existing surfaces.

  3. The characterization of the antibacterial efficacy of an electrically activated silver ion-based surface system

    Science.gov (United States)

    Shirwaiker, Rohan A.

    There have been growing concerns in the global healthcare system about the eradication of pathogens in hospitals and other health-critical environments. The problem has been aggravated by the overuse of antibiotics and antimicrobial agents leading to the emergence of antibiotic-resistant superbugs such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) which are difficult to kill. Lower immunity of sick patients coupled with the escalating concurrent problem of antibiotic-resistant pathogens has resulted in increasing incidences of hospital acquired (nosocomial) infections. There is an immediate need to control the transmission of such infections, primarily in healthcare environments, by creating touch-contact and work surfaces (e.g., door knobs, push plates, countertops) that utilize alternative antibacterial materials like the heavy metal, silver. Recent research has shown that it is silver in its ionic (Ag+ ) and not elemental form that is antibacterial. Thus, silver-based antibacterial surfaces have to release silver ions directly into the pathogenic environment (generally, an aqueous media) in order to be effective. This dissertation presents the study and analysis of a new silver-based surface system that utilizes low intensity direct electric current (LIDC) for generation of silver ions to primarily inhibit indirect contact transmission of infections. The broader objective of this research is to understand the design, and characterization of the electrically activated silver ion-based antibacterial surface system. The specific objectives of this dissertation include: (1) Developing a comprehensive system design, and identifying and studying its critical design parameters and functional mechanisms. (2) Evaluating effects of the critical design parameters on the antibacterial efficacy of the proposed surface system. (3) Developing a response surface model for the surface system performance. These objectives are

  4. Antimicrobial activity and physical characterization of silver nanoparticles green synthesized using nitrate reductase from Fusarium oxysporum.

    Science.gov (United States)

    Gholami-Shabani, Mohammadhassan; Akbarzadeh, Azim; Norouzian, Dariush; Amini, Abdolhossein; Gholami-Shabani, Zeynab; Imani, Afshin; Chiani, Mohsen; Riazi, Gholamhossein; Shams-Ghahfarokhi, Masoomeh; Razzaghi-Abyaneh, Mehdi

    2014-04-01

    Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of -34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine.

  5. Antibacterial Properties and Mechanism of Activity of a Novel Silver-Stabilized Hydrogen Peroxide.

    Directory of Open Access Journals (Sweden)

    Nancy L Martin

    Full Text Available Huwa-San peroxide (hydrogen peroxide; HSP is a NSF Standard 60 (maximum 8 mg/L(-1 new generation peroxide stabilized with ionic silver suitable for continuous disinfection of potable water. Experiments were undertaken to examine the mechanism of HSP against planktonic and biofilm cultures of indicator bacterial strains. Contact/kill time (CT relationships that achieve effective control were explored to determine the potential utility in primary disinfection. Inhibitory assays were conducted using both nutrient rich media and a medium based on synthetic wastewater. Assays were compared for exposures to three disinfectants (HSP, laboratory grade hydrogen peroxide (HP and sodium hypochlorite at concentrations of 20 ppm (therefore at 2.5 and 5 times the NSF limit for HP and sodium hypochlorite, respectively and at pH 7.0 and 8.5 in dechlorinated tap water. HSP was found to be more or equally effective as hypochlorite or HP. Results from CT assays comparing HSP and HP at different bacterial concentrations with neutralization of residual peroxide with catalase suggested that at a high bacterial concentration HSP, but not HP, was protected from catalase degradation possibly through sequestration by bacterial cells. Consistent with this hypothesis, at a low bacterial cell density residual HSP was more effectively neutralized as less HSP was associated with bacteria and therefore accessible to catalase. Silver in HSP may facilitate this association through electrostatic interactions at the cell surface. This was supported by experiments where the addition of mono (K(+ and divalent (Ca(+2 cations (0.005-0.05M reduced the killing efficacy of HSP but not HP. Experiments designed to distinguish any inhibitory effect of silver from that of peroxide in HSP were carried out by monitoring the metabolic activity of established P. aeruginosa PAO1 biofilms. Concentrations of 70-500 ppm HSP had a pronounced effect on metabolic activity while the equivalent

  6. The Antibacterial Activity Evaluation of the Nanoparticles of Silver on Acinetobacter Baumannii

    Directory of Open Access Journals (Sweden)

    Seyedeh Nasim Karimipour

    2016-09-01

    Full Text Available Background & Objective: Due to the high drug resistance in Acinetobacter baumannii, in this research, antibacterial properties of nano silver was evaluated for Acinetobacter baumannii. Materials & Methods: The nano silver with approximate diameter of 20 nanometer from Pishtazan Inc. Mashad, Iran and 5 nanometer from the Department of Chemistry in Maragheh University were prepared. Its concentration was determined by spectroscopy method in Tabriz Chemistry University.  Antimicrobial effects were determined by Mean Inhibitory Concentration (MIC and Minimal Bacterial Concentration (MBC by micro-broth-dilution method, disc diffusion and well diffusion methods. Anti-bacterial activity of nano-silver was tested for Acinetobacter baumannii NCTC12516 on 20 clinical strains (collected from Imam Reza Hospital in Tabriz. Results: The results showed the MIC and MBC of 20nm nanoparticles were 1250 ppm and 2500 ppm, respectively. On the other hand, the MIC and MBC of 5 nm nanoparticles were 156 ppm and 312 ppm, respectively. According to these findings, the MIC and MBC identified for clinical Acinetobacter baumannii strains under study along with the NCTC12516 strain did not show a significant difference. Yet the amount of inhibition for the 20nm nanoparticles in the density of 20000 ppm of clinical Acinetobacter baumannii and NCTC12516 strains was 11 millimeter with the disc diffusion method and 9.5 millimeter for the well diffusion method with the same concentration. The amount of inhibition of 5nm nanoparticles in the 250-ppm concentration with both disc diffusion and well diffusion methods was 9.5 millimeter. Conclusions: Acinetobacter baumannii is susceptible to nano-silver. Also the same MIC and MBC in multiple clinical strains suggests that there is not resistance to silver nanoparticles in Acinetobacter baumannii

  7. Silver-Coated Nylon Dressing Plus Active DC Microcurrent for Healing of Autogenous Skin Donor Sites

    Science.gov (United States)

    2013-08-01

    harvested; (c) bloodstream infection, burn-wound infection, hemodynamic instability requiring the use of pressors, or critical illness such as one...or nursing ; (h) sensitivity to silver or nylon; and (i) patient unable to provide written informed consent. Study Device The active microstimulator...the microcurrent stimulator. A research nurse monitored patient compli- ance by recording the amount of time the microcurrent stimulator was

  8. Synthesis, characterization and antimicrobial activity of dextran sulphate stabilized silver nanoparticles

    Science.gov (United States)

    Cakić, Milorad; Glišić, Slobodan; Nikolić, Goran; Nikolić, Goran M.; Cakić, Katarina; Cvetinov, Miroslav

    2016-04-01

    Dextran sulphate stabilized silver nanoparticles (AgNPs - DS) were synthesized from aqueous solution of silver nitrate (AgNO3) and dextran sulphate sodium salt (DS). The characterization of AgNPs - DS was performed by ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and antimicrobial activity. The formation of AgNPs - DS was monitored by colour changes of the reaction mixture from yellowish to brown and by measuring the surface plasmon resonance absorption peak in UV-VIS spectra at 420 nm. The SEM analysis was used for size and shape determination of AgNPs - DS. The presence of elemental silver and its crystalline structure in AgNPs - DS were confirmed by EDX and XRD analyses. The possible functional groups of DS responsible for the reduction and stabilization of AgNPs were determinated by FTIR spectroscopy. The AgNPs - DS showed strong antibacterial activity against Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 11778, Bacillus luteus in haus strain, Bacillus subtilis ATTC 6633, Listeria monocytogenes ATCC 15313, Escherichia coli ATTC 25922, Pseudomonas aeruginosa ATTC 27853, Klebsiella pneumoniae ATTC 700603, Proteus vulgaris ATTC 8427, and antifungal activity against Candida albicans ATTC 2091.

  9. Anti-biofilm and cytotoxicity activity of impregnated dressings with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Velázquez-Velázquez, Jorge Luis [Laboratorio de Microbiología, Facultad de Ciencias Químicas, UASLP (Mexico); Santos-Flores, Andrés; Araujo-Meléndez, Javier [Servicio de Epidemiología del Hospital Central “Dr. Ignacio Morones Prieto”, San Luis Potosí (Mexico); Sánchez-Sánchez, Roberto; Velasquillo, Cristina [Laboratorio de Biotecnología, Instituto Nacional de Rehabilitación (Mexico); González, Carmen [Laboratorio de Fisiología Celular, Facultad de Ciencias Químicas, UASLP (Mexico); Martínez-Castañon, Gabriel [Maestría en Ciencias Odontológicas Facultad de Estomatología, UASLP (Mexico); Martinez-Gutierrez, Fidel, E-mail: fidel@uaslp.mx [Laboratorio de Microbiología, Facultad de Ciencias Químicas, UASLP (Mexico)

    2015-04-01

    Infections arising from bacterial adhesion and colonization on chronic wounds are a significant healthcare problem. Silver nanoparticles (AgNPs) impregnated in dressing have attracted a great deal of attention as a potential solution. The goal of the present study was to evaluate the anti-biofilm activities of AgNPs impregnated in commercial dressings against Pseudomonas aeruginosa, bacteria isolated of chronic wounds from a hospital patient. The antimicrobial activity of AgNPs was tested within biofilms generated under slow fluid shear conditions using a standard bioreactor. A 2-log reduction in the number of colony-forming units of P. aeruginosa was recorded in the reactor on exposure to dressing impregnated with 250 ppm of AgNPs, diameter 9.3 ± 1.1 nm, and also showed compatibility to mammalian cells (human fibroblasts). Our study suggests that the use of dressings with AgNPs may either prevent or reduce microbial growth in the wound environment, and reducing wound bioburden may improve wound-healing outcomes. - Highlights: • Biological activities of silver nanoparticles for wound-healing purposes • Characterization of the silver nanoparticles impregnated in dressings • Reduction in the P. aeruginosa biofilm formation was statistically significant. • Compatibility to human dermal fibroblasts as the main cell type involved in the reparation • AgNPs covering the surfaces would provide great potential for prevention and treatment.

  10. Anti-biofilm and cytotoxicity activity of impregnated dressings with silver nanoparticles

    International Nuclear Information System (INIS)

    Velázquez-Velázquez, Jorge Luis; Santos-Flores, Andrés; Araujo-Meléndez, Javier; Sánchez-Sánchez, Roberto; Velasquillo, Cristina; González, Carmen; Martínez-Castañon, Gabriel; Martinez-Gutierrez, Fidel

    2015-01-01

    Infections arising from bacterial adhesion and colonization on chronic wounds are a significant healthcare problem. Silver nanoparticles (AgNPs) impregnated in dressing have attracted a great deal of attention as a potential solution. The goal of the present study was to evaluate the anti-biofilm activities of AgNPs impregnated in commercial dressings against Pseudomonas aeruginosa, bacteria isolated of chronic wounds from a hospital patient. The antimicrobial activity of AgNPs was tested within biofilms generated under slow fluid shear conditions using a standard bioreactor. A 2-log reduction in the number of colony-forming units of P. aeruginosa was recorded in the reactor on exposure to dressing impregnated with 250 ppm of AgNPs, diameter 9.3 ± 1.1 nm, and also showed compatibility to mammalian cells (human fibroblasts). Our study suggests that the use of dressings with AgNPs may either prevent or reduce microbial growth in the wound environment, and reducing wound bioburden may improve wound-healing outcomes. - Highlights: • Biological activities of silver nanoparticles for wound-healing purposes • Characterization of the silver nanoparticles impregnated in dressings • Reduction in the P. aeruginosa biofilm formation was statistically significant. • Compatibility to human dermal fibroblasts as the main cell type involved in the reparation • AgNPs covering the surfaces would provide great potential for prevention and treatment

  11. Scandium fluorides

    International Nuclear Information System (INIS)

    Melnikov, P.; Nalin, M.; Messaddeq, Y.

    1997-01-01

    A new modification of scandium fluoride has been synthesised. The compound is deficient in fluorine, with the composition ScF 2.76 . It belongs to the tetragonal system, lattice parameters being a=3.792 and c=6.740 A and may be obtained at low temperatures by the decomposition of the precursor NH 4 ScF 4 . The reaction is topotactic, tetragonal parameters of the precursor are a=4.021 and c=6.744 A. Structural relationships with various fluorides and ammonium aminofluorides are discussed. This synthesis route with IR-assisted decomposition should be considered as a soft-chemistry approach. (orig.)

  12. Studies on low-carrier radiofluorination of non-active aromatics with no-carrier-added [18F]fluoride

    International Nuclear Information System (INIS)

    Cardinale, Jens

    2013-01-01

    In vivo imaging with positron emission tomography generally demands radiotracers with a high specific activity. In case of fluorine-18 the required no-carrier-added (n.c.a.) starting material is only available in form of fluoride. This and the short half-life of 109.7 minutes of the radionuclide lead to the demand of special methods for radiosyntheses. The only practical procedure for manufacturing n.c.a. [ 18 F]fluoro-compounds is therefore nucleophilic substitution. There is, however, still a lack of effective procedures for the labelling of electron rich aromatic molecules starting from n.c.a. [ 18 F]fluoride. A process for n.c.a. radiofluorination of these compounds is offered by the reaction of iodonium compounds as starting materials. In this study modern procedures for the synthesis of iodoniumsalts and -ylides were investigated. Several precursor molecules for the versatile synthetic building block 4-[ 18 F]fluoroiodobenzene were synthesised. In this course, a new one-pot procedure for the synthesis of iodoniumylides was developed. Further on, the syntheses of suitable iodonium precursors for two fluorophenoxy-derivatives, which are possible antidepressants, were investigated. Due to their binding profile these compounds can be considered as ligands for the serotonin reuptake transporter (SERT) and the norepinephrin reuptake transporter (NET), respectively. The preparation of appropriate iodonium salts proved to be too problematic, while the synthesis of suitable iodoniumylides could be accomplished with satisfactory yields of about 30% and 40 %, respectively. Both compounds were labelled with n.c.a. [ 18 F]fluoride and deprotected to the desired target compounds 4-((3-[ 18 F]fluorophenoxy)(phenyl)methyl)piperidine and 4-((4-[ 18 F]fluorophenoxy)(phenyl)methyl)piperidine in radiochemical yields of about 40 % and 25 %, respectively. Those are now available for preclinical evaluation studies. Furthermore, a process for the palladium catalysed synthesis of 18

  13. The preparation of highly active antimicrobial silver nanoparticles by an organometallic approach

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Eduardo J; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M; Monge, Miguel [Departamento de Quimica Grupo de SIntesis Quimica de La Rioja, UA-CSIC, Universidad de La Rioja, Complejo CientIfico-Tecnologico, E-26004 Logrono (Spain); Laguna, Antonio [Departamento de Quimica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, E-50009 Zaragoza (Spain); Torres, Carmen [Departamento de Agricultura y Alimentacion, Universidad de La Rioja, Complejo Cientifico-Tecnologico, E-26004 Logrono (Spain)], E-mail: eduardo.fernandez@unirioja.es

    2008-05-07

    Silver nanoparticles of small size with a high surface to volume ratio have been prepared using an organometallic approach. For this, the complex NBu{sub 4}[Ag(C{sub 6}F{sub 5}){sub 2}] has been treated with AgClO{sub 4} in a 1:1 molar ratio, giving rise to the nanoparticle precursor [Ag(C{sub 6}F{sub 5})] in solution. Addition of one equivalent of hexadecylamine (HDA) and 5 h of reflux in toluene leads to a deep yellow solution containing monodisperse silver nanoparticles (Ag NPs) of ca. 10 nm. This approach leads to nanoparticles with almost uncontaminated surfaces which make them very reactive. Antimicrobial studies show that these nanoparticles are very active as antimicrobial agents. Very low concentrations between 12 and 25 {mu}g ml{sup -1} of Ag NPs are enough to produce bacteriostatic and bactericidal effectiveness.

  14. The preparation of highly active antimicrobial silver nanoparticles by an organometallic approach

    International Nuclear Information System (INIS)

    Fernandez, Eduardo J; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M; Monge, Miguel; Laguna, Antonio; Torres, Carmen

    2008-01-01

    Silver nanoparticles of small size with a high surface to volume ratio have been prepared using an organometallic approach. For this, the complex NBu 4 [Ag(C 6 F 5 ) 2 ] has been treated with AgClO 4 in a 1:1 molar ratio, giving rise to the nanoparticle precursor [Ag(C 6 F 5 )] in solution. Addition of one equivalent of hexadecylamine (HDA) and 5 h of reflux in toluene leads to a deep yellow solution containing monodisperse silver nanoparticles (Ag NPs) of ca. 10 nm. This approach leads to nanoparticles with almost uncontaminated surfaces which make them very reactive. Antimicrobial studies show that these nanoparticles are very active as antimicrobial agents. Very low concentrations between 12 and 25 μg ml -1 of Ag NPs are enough to produce bacteriostatic and bactericidal effectiveness

  15. Biosynthesis, characterisation and antimicrobial activity of silver nanoparticles using Hibiscus rosa-sinensis petals extracts.

    Science.gov (United States)

    Nayak, Debasis; Ashe, Sarbani; Rauta, Pradipta Ranjan; Nayak, Bismita

    2015-10-01

    Green synthesis of metallic nanoparticles has lured the world from the chemical and physical approaches owing to its rapid, non-hazardous and economic aspect of production mechanism. In this study, silver nanoparticles (AgNPs) were synthesised using petal extracts of Hibiscus rosa-sinensis. The AgNPs displayed characteristic surface plasmon resonance peak at around 421 nm having a mean particle size of 76.25±0.17 nm and carried a charge of -41±0.2 mV. The X-ray diffraction patterns displayed typical peaks of face centred cubic crystalline silver. The surface morphology was characterised by scanning electron microscopy and atomic force microscopy. Fourier transform infrared spectroscopy studies confirmed the surface modifications of the functional groups for the synthesis of AgNPs. Furthermore, the synthesised AgNPs displayed proficient antimicrobial activity against pathogenic strains of Vibrio cholerae, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus.

  16. Photocatalytic activity of silver oxide capped Ag nanoparticles constructed by air plasma irradiation

    Science.gov (United States)

    Fang, Yingcui; Wu, Qingmeng; Li, Huanhuan; Zhang, Bing; Yan, Rong; Chen, Junling; Sun, Mengtao

    2018-04-01

    We construct a kind of structure of silver oxide capped silver nanoparticles (AgNPs) by cost-efficient air plasma irradiation, and study its visible-light driven photocatalytic activity (PA). By controlling the oxidization time, the relationship between the intensity of the localized surface plasmon resonance (LSPR) and the PA is well established. The PA reaches the maximum when the LSPR of AgNPs is nearly completely damped (according to absorption spectra); however, under this condition, the LSPR still works, confirmed with the high efficient selective transformation of p-Aminothiophenol (PATP) to p, p'-dimercaptoazobenzene (DMAB) under visible light. The mechanism of the LSPR damping induced PA improvement is discussed. We not only provide a cost-efficient approach to construct a LSPR strong damping structure but also promote the understanding of LSPR strong damping and its relationship with photocatalysis.

  17. Silver nanoparticles containing hybrid polymer microgels with tunable surface plasmon resonance and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ajmal, Muhammad; Siddiq, Mohammad [Quaid-I-Azam University, Islamabad (Pakistan); Farooqi, Zahoor Hussain [University of the Punjab, Lahore (Pakistan)

    2013-11-15

    Multi-responsive poly(N-isopropylacrylamide-methacrylic acid-acrylamide) [P(NIPAM-MAA-AAm)] copolymer microgel was prepared by free radical emulsion polymerization. Silver nanoparticles were fabricated inside the microgel network by in-situ reduction of silver nitrate. Swelling and deswelling behavior of the pure microgels was studied under various conditions of pH and temperature using dynamic light scattering. A red shift was observed in surface plasmon resonance wavelength of Ag nanoparticles with pH induced swelling of hybrid microgel. The catalytic activity of the hybrid system was investigated by monitoring the reduction of p-nitrophenol under different conditions of temperature and amount of catalysts. For this catalytic reaction a time delay of 8 to 10min was observed at room temperature, which was reduced to 2 min at high temperature due to swelling of microgels, which facilitated diffusion of reactants to catalyst surface and increased rate of reaction.

  18. Influence of Thermal Treatment on the Antimicrobial Activity of Silver-Doped Biological Apatite

    Science.gov (United States)

    Popa, Cristina Liana; Ciobanu, Carmen Steluta; Voicu, Georgeta; Vasile, Eugenia; Chifiriuc, Mariana Carmen; Iconaru, Simona Liliana; Predoi, Daniela

    2015-12-01

    In this paper, we report the structural and morphological properties of silver-doped hydroxyapatite (AgHAp) with a silver concentration x Ag = 0.5 before and after being thermal treated at 600 and 1000 °C. The results obtained by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy suggest that the structure of the samples changes gradually, from hydroxyapatite (AgHAp_40) to a predominant β-TCP structure (AgHAp_1000), achieved when the thermal treatment temperature is 1000 °C. In the AgHAp_600 sample, the presence of two phases, HAp and β-TCP, was highlighted. Also, scanning electron microscopy studies suggest that the shape and dimension of the nanoparticles begin to change when the temperature increases. The antimicrobial activity of the obtained compounds was evaluated against Klebsiella pneumoniae, Staphylococcus aureus, and Candida albicans strains.

  19. PVP-coated silver nanoparticles showing antifungal improved activity against dermatophytes

    Science.gov (United States)

    Silva, Edgar; Saraiva, Sofia M.; Miguel, Sónia P.; Correia, Ilídio J.

    2014-11-01

    Fungal infections affecting human beings have increased during the last years and the currently available treatments, when administered for long periods, trigger microbial resistance. Such demands the development of new viable therapeutic alternatives. Silver is known since the antiquity by its antimicrobial properties and, herein, it was used to produce two types of nanoparticles (NPs), uncoated and coated with polyvinylpyrrolidone (PVP), which were aimed to be used in fungal infection treatment. NPs properties were characterized by Transmission electron microscopy, X-ray diffraction, UV-Vis, Dynamic light scattering, Fourier transform infrared, and Energy-dispersive X-ray spectroscopy. Furthermore, in vitro studies were also performed to evaluate NPs cytotoxic profile and antifungal activity. The results obtained revealed that the produced nanoparticles are biocompatible and have a good potential for being used in the treatment of common skin infections caused by Trichophyton rubrum and Trichophyton mentagrophytes, being PVP-coated silver NPs the most suitable ones.

  20. Enhanced antimicrobial activities of silver-nanoparticle-decorated reduced graphene nanocomposites against oral pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Jian-min; Lin, Jia-cheng; Chen, Zhuo-yu; Wei, Meng-chao [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Fu, Yuan-xiang; Lu, Shu-shen [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Yu, Dong-sheng, E-mail: yudsh@mail.sysu.edu.cn [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Zhao, Wei, E-mail: zhaowei3@mail.sysu.edu.cn [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China)

    2017-02-01

    As a means of capitalizing on the synergistic properties between reduced graphene nanosheets (R-GNs) and silver nanoparticles (AgNPs), an efficient and convenient chemical reduction method was used to prepare silver-nanoparticle-decorated reduced graphene nanocomposites (R-GNs/Ag). The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, which confirmed the loading of well-dispersed silver nanoparticles on reduced graphene sheets. Their antimicrobial activities against oral pathogens such as Candida albicans, Lactobacillus acidophilus, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were investigated by MIC determination, the counting of colony-forming units (CFU), agar diffusion tests, and growth curve observation. Compared with pure R-GNs and AgNPs, R-GNs/Ag composites exhibited enhanced antimicrobial properties owing to highly dispersed AgNPs on R-GNs. - Highlights: • This study synthesized R-GNs/Ag composites by a chemical reduction method. • AgNPs were successfully dispersed on reduced graphene nanosheets. • R-GNs/Ag composites showed enhanced antimicrobial activities against oral pathogens compared with plain AgNPs or R-GNs.

  1. Enhanced antimicrobial activities of silver-nanoparticle-decorated reduced graphene nanocomposites against oral pathogens

    International Nuclear Information System (INIS)

    Peng, Jian-min; Lin, Jia-cheng; Chen, Zhuo-yu; Wei, Meng-chao; Fu, Yuan-xiang; Lu, Shu-shen; Yu, Dong-sheng; Zhao, Wei

    2017-01-01

    As a means of capitalizing on the synergistic properties between reduced graphene nanosheets (R-GNs) and silver nanoparticles (AgNPs), an efficient and convenient chemical reduction method was used to prepare silver-nanoparticle-decorated reduced graphene nanocomposites (R-GNs/Ag). The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, which confirmed the loading of well-dispersed silver nanoparticles on reduced graphene sheets. Their antimicrobial activities against oral pathogens such as Candida albicans, Lactobacillus acidophilus, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were investigated by MIC determination, the counting of colony-forming units (CFU), agar diffusion tests, and growth curve observation. Compared with pure R-GNs and AgNPs, R-GNs/Ag composites exhibited enhanced antimicrobial properties owing to highly dispersed AgNPs on R-GNs. - Highlights: • This study synthesized R-GNs/Ag composites by a chemical reduction method. • AgNPs were successfully dispersed on reduced graphene nanosheets. • R-GNs/Ag composites showed enhanced antimicrobial activities against oral pathogens compared with plain AgNPs or R-GNs.

  2. Enhanced Carbon Dioxide Electroreduction to Carbon Monoxide over Defect-Rich Plasma-Activated Silver Catalysts.

    Science.gov (United States)

    Mistry, Hemma; Choi, Yong-Wook; Bagger, Alexander; Scholten, Fabian; Bonifacio, Cecile S; Sinev, Ilya; Divins, Nuria J; Zegkinoglou, Ioannis; Jeon, Hyo Sang; Kisslinger, Kim; Stach, Eric A; Yang, Judith C; Rossmeisl, Jan; Roldan Cuenya, Beatriz

    2017-09-11

    Efficient, stable catalysts with high selectivity for a single product are essential if electroreduction of CO 2 is to become a viable route to the synthesis of industrial feedstocks and fuels. A plasma oxidation pre-treatment of silver foil enhances the number of low-coordinated catalytically active sites, which dramatically lowers the overpotential and increases the activity of CO 2 electroreduction to CO. At -0.6 V versus RHE more than 90 % Faradaic efficiency towards CO was achieved on a pre-oxidized silver foil. While transmission electron microscopy (TEM) and operando X-ray absorption spectroscopy showed that oxygen species can survive in the bulk of the catalyst during the reaction, quasi in situ X-ray photoelectron spectroscopy showed that the surface is metallic under reaction conditions. DFT calculations reveal that the defect-rich surface of the plasma-oxidized silver foils in the presence of local electric fields drastically decrease the overpotential of CO 2 electroreduction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Neutron activation analysis of high purity silver using high resolution gamma-spectrometry

    International Nuclear Information System (INIS)

    Gilbert, E.N.; Veriovkin, G.V.; Botchkaryov, B.N.; Godovikov, A.A.; Zhavoronkov, V.Ya.; Mikhailov, V.A.

    1975-01-01

    A method of neutron activation determination of microimpurities in high purity silver has been developed. For matrix activity separation the extraction of silver by dibuthylsulfide /DBS/ was employed. The purification coefficient was 10 8 after triple extraction. To study the behaviour of microimpurities in the extraction procedure and to determine their chemical yields some tracer experiments were undertaken with radionuclides of Na, Se, Fe, Co, Cu, As, Sc, Te, Zr, Hf, Mo, W, Cd, In, Sb, La, Ce, Eu, Ta, Re, Ir, Ru. All the elements studied were found to remain in the aqueous phase up to 96-99% after triple extraction with DBS. To estimate the accuracy of the method and to study the mutual influence of the elements in the sample in various relative amounts on the accuracy of the analysis, a number of experiments of ''added-found'' type was performed and the results were treated statistically. In these experiments model mixtures of 30 nuclides were analysed after triple DBS extraction. The t-criterion values for the confidence interval at P=0.95 show the absence of systematic errors. Variation coefficient values do not exceed 15%. Using Ge/Li/ detector it was possible to determine 30 elements simultaneously in silver samples. (T.G.)

  4. New bioactive silver(I) complexes: Synthesis, characterization, anticancer, antibacterial and anticarbonic anhydrase II activities

    Science.gov (United States)

    Ozdemir, Ummuhan O.; Ozbek, Neslihan; Genc, Zuhal Karagoz; İlbiz, Firdevs; Gündüzalp, Ayla Balaban

    2017-06-01

    Silver(I) complexes of alkyl sulfonic acide hydrazides were newly synthesized as homologous series. Methanesulfonic acide hydrazide (L1), ethanesulfonic acide hydrazide (L2), propanesulfonic acide hydrazide (L3) and butanesulfonic acide hydrazide (L4) were used for complexation with Ag(I) ions. The silver complexes obtained in the mol ratio of 1:2 have the structural formula as Ag(L1)2NO3 (I), Ag(L2)2NO3 (II), Ag(L3)2NO3(III), (Ag(L4)2NO3 (IV). The Ag(I) complexes exhibit distorted linear two-fold coordination in [AgL2]+ cations with uncoordinated nitrates. Ligands are chelated with silver(I) ions through unsubstituted primary nitrogen in hydrazide group. Ag(I) complexes were characterized by using elemental analysis, spectroscopic methods (FT-IR, LC-MS), magnetic susceptibility and conductivity measurements. Silver(I) complexes were optimized using PBEPBE/LanL2DZ/DEF2SV basic set performed by DFT method with the Gaussian 09 program package. The geometrical parameters, frontier molecular orbitals (HOMOs and LUMOs) and molecular electrostatic potential (MEP) mapped surfaces of the optimized geometries were also determined by this quantum set. The anticancer activities of silver(I) complexes on MCF-7 human breast cancer cell line were investigated by comparing IC50 values. The antibacterial activities of complexes were studied against Gram positive bacteria; S. aureus ATCC 6538, B. subtilis ATCC 6633, B. cereus NRRL-B-3711, E. faecalis ATCC 29212 and Gram negative bacteria; E. coli ATCC 11230, P. aeruginosa ATCC 15442, K. pneumonia ATCC 70063 by using disc diffusion method. The inhibition activities of Ag(I) complexes on carbonic anhydrase II enzyme (hCA II) were also investigated by comparing IC50 and Ki values. The biological activity screening shows that Ag(I) complex of butanesulfonicacidehydrazide (IV) has the highest activity against tested breast cancer cell lines MCF-7, Gram positive/Gram negative bacteria and carbonic anhydrase II (hCA II) isoenzyme.

  5. Antibacterial activity of single crystalline silver-doped anatase TiO{sub 2} nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangyu, E-mail: zhangxiangyu@tyut.edu.cn; Li, Meng; He, Xiaojing; Hang, Ruiqiang; Huang, Xiaobo; Wang, Yueyue; Yao, Xiaohong; Tang, Bin, E-mail: tangbin@tyut.edu.cn

    2016-05-30

    Graphical abstract: The silver-doped TiO{sub 2} nanowire arrays on titanium foil substrate were synthesized via a two-step process. It includes: deposition of AgTi films on titanium foil by magnetron sputtering; preparation of AgNW arrays on AgTi films via alkali (NaOH) hydrothermal treatment and ion-exchange with HCl, followed by calcinations. - Highlights: • Ag-doped TiO{sub 2} nanowire arrays have been prepared by a duplex-treatment. • The duplex-treatment consisted of magnetron sputtering and hydrothermal growth. • Ag-doped nanowire arrays show excellent antibacterial activity against E. coli. - Abstract: Well-ordered, one-dimensional silver-doped anatase TiO{sub 2} nanowire (AgNW) arrays have been prepared through a hydrothermal growth process on the sputtering-deposited AgTi layers. Electron microscope analyses reveal that the as-synthesized AgNW arrays exhibit a single crystalline phase with highly uniform morphologies, diameters ranging from 85 to 95 nm, and lengths of about 11 μm. Silver is found to be doped into TiO{sub 2} nanowire evenly and mainly exists in the zerovalent state. The AgNW arrays show excellent efficient antibacterial activity against Escherichia coli (E. coli), and all of the bacteria can be killed within 1 h. Additionally, the AgNW arrays can still kill E. coli after immersion for 60 days, suggesting the long-term antibacterial property. The technique reported here is environmental friendly for formation of silver-containing nanostructure without using any toxic organic solvents.

  6. Activities in Retirement: Individual Experience of Silver Work

    Directory of Open Access Journals (Sweden)

    Leena Maxin

    2011-12-01

    Full Text Available One consequence of demographic change is a longer average remaining lifetime after retirement. Many people, however, remain able and willing to continue work after reaching the statutory retirement age. Given the predicted shortage of skilled workers in the future, post-retirement activities have the potential to contribute to both organisations and society. This article elaborates the prerequisites for productivity in retirement age and the changed nature of retirement at present.It also quantifies the extent to which activities are continued at retirement age. Paid employment still occurs beyond the applicable retirement age, whereby with increasing age, self-employed persons and assistant family members make up the lion’s share of the statistics. An empirical study shows the concrete situation of active retirees and the prerequisites for post-retirement activities. At the explorative level, individual experiences of the transition into retirement, the reasons for and the framework of post-retirement activities, motivational factors in job design, and physical and intellectual demands before and after retirement are characterised. The qualitative data indicate that retirement entails changes towards more flexible structures in everyday life. Decisive reasons for taking up post-retirement activities are the desire to help, pass on knowledge or remain active; personal development and contact with others; and gaining appreciation and recognition. Flexible job design and freedom to make decisions constitute major elements in shaping post-retirement working activities. Offering autonomy, skill variety, and task significance is important for the design of post-retirement activities. The paper closes with identifying relevant research fields and the concrete need to take action at individual,  organisational, and societal levels. All in all, the transition from working life to retirement should be made flexible enough to do greater justice to the

  7. Geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples, and its possible relationship with the prevalence of enamel fluorosis in children in four municipalities of the department of Huila (Colombia).

    Science.gov (United States)

    Martignon, Stefania; Opazo-Gutiérrez, Mario Omar; Velásquez-Riaño, Möritz; Orjuela-Osorio, Iván Rodrigo; Avila, Viviana; Martinez-Mier, Esperanza Angeles; González-Carrera, María Clara; Ruiz-Carrizosa, Jaime Alberto; Silva-Hermida, Blanca Cecilia

    2017-06-01

    Fluoride is an element that affects teeth and bone formation in animals and humans. Though the use of systemic fluoride is an evidence-based caries preventive measure, excessive ingestion can impair tooth development, mainly the mineralization of tooth enamel, leading to a condition known as enamel fluorosis. In this study, we investigated the geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples in four endemic enamel fluorosis sentinel municipalities of the department of Huila, Colombia (Pitalito, Altamira, El Agrado and Rivera), and its possible relationship with the prevalence of enamel fluorosis in children. The concentration of fluoride in drinking water, table salt, active sediment, rock, and soil was evaluated by means of an ion selective electrode and the geochemical analyses were performed using X-ray fluorescence. Geochemical analysis revealed fluoride concentrations under 15 mg/kg in active sediment, rock and soil samples, not indicative of a significant delivery to the watersheds studied. The concentration of fluoride in table salt was found to be under the inferior limit (less than 180 μg/g) established by the Colombian regulations. Likewise, exposure doses for fluoride water intake did not exceed the recommended total dose for all ages from 6 months. Although the evidence does not point out at rocks, soils, fluoride-bearing minerals, fluoridated salt and water, the hypothesis of these elements as responsible of the current prevalence of enamel fluorosis cannot be discarded since, aqueducts might have undergone significant changes overtime.

  8. Effects of fluoride on germination, early growth and antioxidant enzyme activities of legume plant species Prosopis juliflora.

    Science.gov (United States)

    Saini, Poonam; Khan, Suphiya; Baunthiyal, Mamta; Sharma, Vinay

    2013-03-01

    Prosopis juliflora (Mimosoideae) is a fast growing and drought resistant tree of semi-arid region of India where fluoride (F) toxicity is a common problem. In the present investigations this species was fluoride tested to check their capacity as bioindicator plant and its efficiency to accumulate. To achieve this aim, P. juliflora seedlings grown in hydroponic culture containing different concentrations of F were analyzed for germination percentage together with some biochemical parameters viz, antioxidant enzyme activities, total chlorophyll and accumulation of F in different plant parts. After 15 days of treatment, root growth (r = -0.928, p juliflora did not show any morphological changes (marginal and tip chlorosis of leaf portions, necrosis and together these features are referred to as leaf "tip-burn") therefore, this species may be used as suitable bioindicator species for potentially F affected areas. Further, higher accumulation of F in roots indicates that P. juliflora is a suitable species for the removal of F in phytoremediation purposes.

  9. Synthesis of silver/silver chloride/graphene oxide composite and its surface-enhanced Raman scattering activity and self-cleaning property

    Science.gov (United States)

    Zhao, Nan; Fei, Xiao; Cheng, Xiaonong; Yang, Juan

    2017-09-01

    Recently, silver nanoparticles decorated with graphene and graphene oxide (GO) sheets can be employed as surface-enhanced Raman scattering (SERS) substrates. However, their SERS activity on macromolecular compound detection is all one-time process. In order to solve this issue and decrease the cost of routine SERS detection, silver/silver chloride (Ag/AgCl) with photocatalytic activity under visible light was introduced. In this study, a novel, simple and clean approach is carried out for synthesis of the Ag/AgCl/GO composite. The Ag/AgCl colloidal solution is obtained by hydrothermal method and then mixed with GO solution to obtain the Ag/AgCl/GO composite using a facile electrostatic self-assembly method. Results showed that the Ag/AgCl/GO composite has the optimized SERS activity to Rhodamine 6G molecules with the maximum enhancement factor value of 3.8×107. Furthermore, the Ag/AgCl particles with high efficient and stable photocatalytic activity under visible light lead to an outstanding self-cleaning property of the Ag/AgCl/GO composite.

  10. Simultaneous fabrication of laser-active colour centres and permanent microgratings in lithium fluoride by a single femtosecond pulse

    International Nuclear Information System (INIS)

    Kurobori, Toshio; Kawamura, Ken-ichi; Hirano, Masahiro; Hosono, Hideo

    2003-01-01

    We report, for the first time, simultaneous fabrication of laser-active F 2 and F 3 + colour centres in lithium fluoride and permanent periodic gratings with fringe spacings as fine as sub-micron size by two interfering infrared femtosecond (fs) laser pulses. In particular, the optical properties (absorption and luminescence) of F 2 and F 3 + colour centres produced by a single fs laser pulse are compared with those created by damage from radiation such as x-rays. The present technique of simultaneously fabricating laser-active colour centres and functional fine-periodic structures in photo-insensitive transparent materials may well be a useful method for making miniaturized optical devices. (letter to the editor)

  11. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    International Nuclear Information System (INIS)

    Im, A-Rang; Kim, Jee Young; Kim, Yeong Shik; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie

    2013-01-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds. (paper)

  12. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    Science.gov (United States)

    Im, A.-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

    2013-10-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

  13. In Vitro Evaluation of Colloidal Silver on Immune Function: Anti lymphoproliferative Activity

    International Nuclear Information System (INIS)

    Franco-Molina, M. A.; Mendoza-Gamboa, E.; Zarate-Trivino, D. G.; Coronado-Cerda, E.E.; Alcocer-Gonzalez, J. M.; Resendez-Perez, D.; Rodriguez-Salazar, M.C.; Rivera-Morales, L.G.; Tamez-Guerra, R.; Rodriguez-Padilla, C.

    2016-01-01

    Colloidal silver (AgC) is currently used by humans and it can be internalized through inhalation, injection, ingestion, and dermal contact. However, there is limited information about immunological activity; more investigations using colloidal silver are needed. In the present study, the effects of AgC (17.5 ng/m L) on immunological parameters (proliferation and immuno phenotyping) using human peripheral blood mononuclear cells (PBMC) and macrophages (phagocytosis) and cytotoxicity on leukemia and lymphoma cancer cell lines (1.75 to 17.5 ng/m L) were investigated. AgC was observed to significantly ρ) decrease interleukin-2 (I L-2) production and proliferation induced by phytohemagglutinin or concanavalin A in PBMC without affecting its cell viability but with cytotoxic effect on cancer cells. IL-2, IL-4, IL-6, IL-10, INF-γ, and IL_-17 A cytokines production and CD3"+, CD3"-CD19"+, CD3"+CD4"+, CD3"+CD8"+, and CD16"+CD56"+ PBMC phenotypes were not affected by AgC. The present study demonstrates that colloidal silver is harmless and nontoxic to the immune system cells and its ability to interfere with the immune response by decreasing cell proliferation when stimulated with mitogens demonstrated the anti lymphoproliferative potential of AgC

  14. Facile fabrication of silver nanoparticles with temperature-responsive sizes as highly active SERS substrates

    Science.gov (United States)

    Wu, Jing; Fang, Jinghuai; Cheng, Mingfei; Gong, Xiao

    2016-12-01

    In our work, large-scale silver NPs (nanoparticles) are successfully synthesized on zinc foils with controllable size by regulating the temperature of the displacement reaction. Our results show that when the temperature is 70 °C, the average size of silver NPs is approximately 88 nm in diameter, and they exhibit the strongest SERS activity. The gap between nanoparticles is simultaneously regulated as near as possible, which produces abundant "hot spots" and nanogaps. Crystal violet (CV) was used as probe molecules, and the SERS signals show that the values of relative standard deviation in the intensity of the main vibration modes are less than 10%, demonstrating excellent reproducibility of the silver NPs. Furthermore, the high surface-average enhancement factor of 3.86 × 107 is achieved even when the concentration of CV is 10-7 M, which is sufficient for single-molecule detection. We believe that this low cost and rapid route would get wide applications in chemical synthesis.

  15. Synthesis and evaluation of antiviral activities of novel sonochemical silver nanorods against HIV and HSV viruses

    Directory of Open Access Journals (Sweden)

    Mazyar Etemadzade

    2016-11-01

    Full Text Available Objective: To evaluate the effect of novel sonochemical silver nanorods on HIV and herpes simplex virus type 1 (HSV-1 viruses in human cervical cancer HeLa cells. Methods: The formation of silver nanorods conjugated with sodium 2-mercaptoethane sulfonate (Ag-MES was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analysis. The antiviral activity of this Ag-MES was examined against HIV and HSV-1 virus replication. Results: The characterizations of Ag-MES and physiochemical structure were determined by scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analysis. Approximately entire viral replication was inhibited by Ag-MES at 10 µmol/mL concentration. About 90% of HSV virions failed to replicate in the present of this concentration of nanorods. However, HIV showed more sensitivity to Ag-MES than HSV-1. Conclusions: According to the obtained data, the synthesized sonochemical silver nanorod in this study is a promising candidate for further drug discovery investigation.

  16. In Vitro Evaluation of Colloidal Silver on Immune Function: Antilymphoproliferative Activity

    Directory of Open Access Journals (Sweden)

    M. A. Franco-Molina

    2016-01-01

    Full Text Available Colloidal silver (AgC is currently used by humans and it can be internalized through inhalation, injection, ingestion, and dermal contact. However, there is limited information about immunological activity; more investigations using colloidal silver are needed. In the present study, the effects of AgC (17.5 ng/mL on immunological parameters (proliferation and immunophenotyping using human peripheral blood mononuclear cells (PBMC and macrophages (phagocytosis and cytotoxicity on leukemia and lymphoma cancer cell lines (1.75 to 17.5 ng/mL were investigated. AgC was observed to significantly (p<0.05 decrease interleukin-2 (IL-2 production and proliferation induced by phytohemagglutinin or concanavalin A in PBMC without affecting its cell viability but with cytotoxic effect on cancer cells. IL-2, IL-4, IL-6, IL-10, INF-γ, and IL-17A cytokines production and CD3+, CD3−CD19+, CD3+CD4+, CD3+CD8+, and CD16+CD56+ PBMC phenotypes were not affected by AgC. The present study demonstrates that colloidal silver is harmless and nontoxic to the immune system cells and its ability to interfere with the immune response by decreasing cell proliferation when stimulated with mitogens demonstrated the antilymphoproliferative potential of AgC.

  17. Green Synthesis and Antimicrobial Activities of Silver Nanoparticles using Cell Free-Extracts of Enterococcus species

    Directory of Open Access Journals (Sweden)

    Iyabo C. OLADIPO

    2017-06-01

    Full Text Available Cell-free extracts of six strains of Enterococcus species obtained from fermented foods were used for the green synthesis of silver nanoparticles (AgNPs, which was characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR and transmission electron microscopy (TEM. The biosynthesized AgNPs were dark brown in colour having surface plasmon resonance in the range of 420-442 nm. The spherical shaped AgNPs had sizes of 4-55 nm, whose formations were facilitated by proteins as indicated by the presence of peaks 1,635-1,637 and 3,275-3,313 cm-1 in the FTIR spectra. The energy dispersive x-ray (EDX showed prominent presence of silver in the AgNPs colloidal solution, while the selected area electron diffraction was typified by the face-centred crystalline nature of silver. The particles inhibited the growth of multi-drug resistant clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris, and also potentiated the activities of ampicillin, ciprofloxacin and cefuroxime in the AgNPs-antibiotic synergy studies. In addition, the prospective relevance of the particles as nanopreservative in paints was demonstrated with the inhibition of growth of Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger and A. flavus in AgNPs-paint admixture. This report further demonstrates the green synthesis of AgNPs by strains of Enterococcus species.

  18. Synthesis and characterization of silver nanoparticles using Cynodon dactylon leaves and assessment of their antibacterial activity.

    Science.gov (United States)

    Sahu, Nidhi; Soni, Deepika; Chandrashekhar, B; Sarangi, Bijaya Ketan; Satpute, Devanand; Pandey, Ram Avatar

    2013-07-01

    Many methods of synthesizing silver nanoparticles (Ag-NPs) by reducing Ag⁺ ions using aqueous/organic extracts of various plants have been reported in the past, but the methods are rather slow. In this investigation, silver nanoparticles were quickly synthesized from aqueous silver nitrate through a simple method using leaf extract of a plant--Cynodon dactylon which served as reducing agent, while sunlight acted as a catalyst. The formation of Ag-NPs was indicated by gradual change in colour and pH and confirmed by ultraviolet--visible spectroscopy. The Ag-NPs showed a surface plasmon resonance at 451 nm. Based on the decrease in pH, a possible mechanism of the synthesis of Ag-NPs involving hydroxyl (OH⁻) ions of polyphenols of the leaf extract is postulated. Ag-NPs having (111) and (200) crystal lattices were confirmed by X-ray diffraction. Scanning electron microscopy revealed the spherical nature of the Ag-NPs, while transmission electron microscopy showed that the nanoparticles were polydispersed with a size range of 8-10 nm. The synthesized Ag-NPs also demonstrated their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhimurium.

  19. Antioxidant and anti-inflammatory activities of silver nanoparticles biosynthesized from aqueous leaves extracts of four Terminalia species

    Science.gov (United States)

    El-Rafie, Hanaa Mohamed; Abdel-Aziz Hamed, Manal

    2014-09-01

    The environmentally friendly synthesis of nanoparticles process is a revolutionary step in the field of nanotechnology. In recent years plant mediated biological synthesis of nanoparticles has been gaining importance due to its simplicity and eco-friendliness. In this study, a simple and an efficient eco-friendly approach for the biosynthesis of stable, monodisperse silver nanoparticles using aqueous extracts of four Terminalia species, namely, Terminalia catappa, Terminalia mellueri, Terminalia bentazoe and Terminalia bellerica were described. The silver nanoparticles were characterized in terms of synthesis, capping functionalities (polysaccharides, phenolics and flavonoidal compounds) and microscopic evaluation by UV-visible spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. The results showed a simple and feasible approach for obtaining stable aqueous monodispersive silver nanoparticles. Furthermore, biological activity of the biosynthesized silver nanoparticles was examined. Concerning this, dose-dependent antioxidant activity of silver nanoparticles imparted by the plant phenolic and flavonoidal components was evaluated using in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and found to be comparable to standard ascorbic acid. The same holds true for the anti-inflammatory activity where Terminalia catappa and Terminalia mellueri have a high-test inhibition percentage better than that of ascorbic acid in the carrageenan induced hind paw edema. The results also revealed that the aqueous extract of Terminallia catapa and its silver nanoparticles recorded the most potent in vivo antioxidant effect.

  20. Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

    Science.gov (United States)

    Shimabuku, Quelen Letícia; Arakawa, Flávia Sayuri; Fernandes Silva, Marcela; Ferri Coldebella, Priscila; Ueda-Nakamura, Tânia; Fagundes-Klen, Márcia Regina; Bergamasco, Rosangela

    2017-08-01

    Continuous flow experiments (450 mL min -1 ) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10 5  UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

  1. Nucleolar activity after 3-methylcholanthrene treatment of rat liver cells studied by silver staining procedure

    Energy Technology Data Exchange (ETDEWEB)

    Komaromy, L.; Tigyi, A.

    1986-01-01

    The influence of a single dose of 3-methylcholanthrene (3-MC) was studied in nucleoli of young rat liver cells by means of conventional and ultracytochemical methods. The nucleolar activity was stimulated in the authors experimental conditions: the appearance of the fibrillar centers in the liver cell nucleoli as well as the silver staining protein content of the fibrillar centers and the dense fibrillar component were increased by 3-MC. The results suggest that the activity of ribosomal genes was increased following 3-MC treatment.

  2. Silver nanoparticles anchored reduced graphene oxide for enhanced electrocatalytic activity towards methanol oxidation

    Science.gov (United States)

    Kumar, Sanjeev; Mahajan, Mani; Singh, Rajinder; Mahajan, Aman

    2018-02-01

    In this report, silver nanoparticles (Ag NPs) anchored reduced graphene oxide (rGO) sheets (rGO/Ag) nanohybrid has been explored as anode material in direct methanol fuel cells (DMFCs). The synthesized rGO/Ag nanohybrid is characterized by XRD, XPS, FTIR spectroscopy and HRTEM techniques. Cyclic voltammograms demonstrate that the rGO/Ag nanohybrid exhibits higher electrocatalytic activity in comparison to rGO sheets for methanol oxidation reaction (MOR). This enhancement is attributed to the synergetic effect produced by the presence of more active sites provided by Ag NPs anchored on a conducting network of large surface area rGO sheets.

  3. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    OpenAIRE

    Richard Sauerheber

    2013-01-01

    The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity ...

  4. Photocatalytic, antimicrobial activities of biogenic silver nanoparticles and electrochemical degradation of water soluble dyes at glassy carbon/silver modified past electrode using buffer solution.

    Science.gov (United States)

    Khan, Zia Ul Haq; Khan, Amjad; Shah, Afzal; Chen, Yongmei; Wan, Pingyu; Khan, Arif Ullah; Tahir, Kamran; Muhamma, Nawshad; Khan, Faheem Ullah; Shah, Hidayat Ullah

    2016-03-01

    In the present research work a novel, nontoxic and ecofriendly procedure was developed for the green synthesis of silver nano particle (AgNPs) using Caruluma edulis (C. edulis) extract act as reductant as well as stabilizer agents. The formation of AgNPs was confirmed by UV/Vis spectroscopy. The small and spherical sizes of AgNPs were conformed from high resolution transmission electron microscopy (HRTEM) analysis and were found in the range of 2-10nm, which were highly dispersion without any aggregation. The crystalline structure of AgNPs was conformed from X-ray diffraction (XRD) analysis. For the elemental composition EDX was used and FTIR helped to determine the type of organic compounds in the extract. The potential electrochemical property of modified silver electrode was also studied. The AgNPs showed prominent antibacterial motion with MIC values of 125 μg/mL against Bacillus subtilis and Staphylococcus aureus while 250 μg/mL against Escherichia coli. High cell constituents' release was exhibited by B. subtilis with 2 × MIC value of silver nanoparticles. Silver nanoparticles also showed significant DPPH free radical scavenging activity. This research would have an important implication for the synthesis of more efficient antimicrobial and antioxidant agent. The AgNP modified electrode (GC/AgNPs) exhibited an excellent electro-catalytic activity toward the redox reaction of phenolic compounds. The AgNPs were evaluated for electrochemical degradation of bromothymol blue (BTB) dyes which showed a significant activity. From the strong reductive properties it is obvious that AgNPs can be used in water sanitization and converting some organic perilous in to non-hazardous materials. The AgNPs showed potential applications in the field of electro chemistry, sensor, catalyst, nano-devices and medical. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Determination of Gold Traces in 4th Century B.C. Silver Coins By Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Ronen, Y.; Kubani, G.

    2004-01-01

    A method based on non-destructive neutron activation analysis was developed for measuring traces of gold in silver. This method requires a very small neutron source and, in this study, it was Am-Be of 5μCi. With a small neutron source, the equipment is not expensive and radiation protection problems are reduced. Our method was applied to ancient silver coins from the 4th-3rd centuries B.C. These coins were obols minted in Gaza and Yehud coins minted in Jerusalem. It was found that there is gold in all of them. Their relative gold content was found to be between 7*10 -3 and 8.9*10 - 3 with a relative accuracy of less than 7%. The gold content in silver coins can serve as a ''finger prints' for the origin of the silver

  6. Earliest Results in the Use of Activated Composite Membranes for the Transport of Silver Ions from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Yucundo Mendoza-Tolentino

    2014-01-01

    Full Text Available This paper presents the results concerning the first use of activated composite membranes (ACMs for the facilitated transport of silver ions containing di-(2-ethylhexyl-dithiophosphoric acid (DTPA as the carrier. DTPA was immobilized by interfacial polymerization in a dense layer that was deposited in a porous layer, which was prepared on a nonwoven fabric support by phase inversion. The influence of fundamental parameters affecting the transport of silver ion as the carrier concentration in the membrane phase and stripping agent variation of the stripping solution have been studied. In the optimal conditions, the amount of silver transported across the ACMs was greater than 50%, whereas if the content of the carrier is modified, more than the 90% of the initial silver is removed from the feed phase.

  7. Biogenic silver nanoparticles synthesized with rhamnogalacturonan gum: Antibacterial activity, cytotoxicity and its mode of action

    Directory of Open Access Journals (Sweden)

    Aruna Jyothi Kora

    2018-03-01

    Full Text Available Silver nanoparticles synthesized from gum kondagogu (5 nm were used to evaluate the antibacterial activity against Gram-positive and Gram-negative bacteria. To decipher the mode of antibacterial action of nanoparticles, a comprehensive study was carried out employing a variety of susceptibility assays: micro-broth dilution, antibiofilm activity, growth kinetics, cytoplasmic content leakage, membrane permeabilization, etc. The production of reactive oxygen species (ROS and cell surface damage during bacterial nanoparticle interaction were also demonstrated using dichlorodihydrofluorescein diacetate, N-acetylcysteine; and scanning electron microscopy and energy dispersive X-ray spectra. Further, the biocompatibility with HeLa cell line was also evaluated. Compared to earlier reports, the minimum inhibitory concentration values were lower by 3.2- and 16-folds for Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli strains, respectively. The minimum bactericidal concentration values were lower by 4 and 50-folds. Thus, the biogenic silver nanoparticles were found to be more potent bactericidal agents in terms of concentration. The nanoparticles exhibited significant antibiofilm activity against test strains at 2 μg mL−1, which can have implications in the treatment of drug resistant bacterial infections caused by biofilms. Growth curve in nanoparticle supplemented indicated a faster inhibition in Gram-negative bacteria as compared to Gram-positive. Treatment with nanoparticles caused cytoplasmic content leakage and membrane permeabilization in a dose dependent manner, an evidence for membrane damage. The observations noted in our study substantiated the association of ROS and membrane damage in the antibacterial action of silver nanoparticles. The promising antibacterial activity enables these nanoparticles as potential bactericidal material for various environmental and biomedical applications.

  8. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Directory of Open Access Journals (Sweden)

    Richard Sauerheber

    2013-01-01

    Full Text Available The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.

  9. Physiologic conditions affect toxicity of ingested industrial fluoride.

    Science.gov (United States)

    Sauerheber, Richard

    2013-01-01

    The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.

  10. Molten fluoride fuel salt chemistry

    International Nuclear Information System (INIS)

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1995-01-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed. copyright American Institute of Physics 1995

  11. Antimicrobial activity and cytocompatibility of silver nanoparticles coated catheters via a biomimetic surface functionalization strategy

    Directory of Open Access Journals (Sweden)

    Wu K

    2015-12-01

    Full Text Available Ke Wu,1 Yun Yang,2,3 Yanmei Zhang,2,3 Jiexi Deng,1 Changjian Lin2,31Department of Cardiology, The Affiliated Dongnan Hospital of Xiamen University, Zhangzhou, 2Department of Medical Materials, Beijing Medical Implant Engineering Research Center, Beijing Naton Technology Group, Beijing, 3State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People’s Republic of ChinaAbstract: Catheter-related bloodstream infections are a significant problem in the clinic and may result in a serious infection. Here, we developed a facile and green procedure for buildup of silver nanoparticles (AgNPs on the central venous catheters (CVCs surface. Inspired by mussel adhesive proteins, dopamine was used to form a thin polydopamine layer and induce AgNPs formation without additional reductants or stabilizers. The chemical and physicochemical properties of AgNPs coated CVCs were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and water contact angle. The Staphylococcus aureus culture experiment was used to study the antibacterial properties. The cytocompatibility was assessed by water soluble tetrazolium salts (WST-1 assay, fluorescence staining, and scanning electron microscopy analysis. The results indicated that the CVCs surface was successfully coated with compact AgNPs. AgNPs were significantly well separated and spherical with a size of 30–50 nm. The density of AgNPs could be modulated by the concentration of silver nitrate solution. The antibacterial activity was dependent on the AgNPs dose. The high dose of AgNPs showed excellent antibacterial activity while associated with increased cytotoxicity. The appropriate density of AgNPs coated CVCs could exhibit improved biocompatibility and maintained evident sterilization effect. It is promising to design mussel-inspired silver releasing CVCs with both

  12. Bottled Water and Fluoride

    Science.gov (United States)

    ... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

  13. Other Fluoride Products

    Science.gov (United States)

    ... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

  14. Taurine reverses sodium fluoride-mediated increase in inflammation, caspase-3 activity, and oxidative damage along the brain-pituitary-gonadal axis in male rats.

    Science.gov (United States)

    Adedara, Isaac A; Olabiyi, Bolanle F; Ojuade, TeminiJesu D; Idris, Umar F; Onibiyo, Esther M; Farombi, Ebenezer O

    2017-09-01

    Excessive exposure to fluoride is associated with male reproductive dysfunction in humans and animals. Taurine (2-aminoethane sulfonic acid) is a free intracellular β-amino acid with antioxidant, anti-inflammatory, and neuroprotective properties. However, the effect of taurine on fluoride-induced reproductive toxicity has not been reported. The present study investigated the influence of taurine on sodium fluoride (NaF)-induced functional changes along the brain-pituitary-gonadal axis in male rats. NaF was administered singly in drinking water at 15 mg·L -1 alone or orally co-administered by gavage with taurine at 100 and 200 mg·(kg body mass) -1 for 45 consecutive days. Results showed that taurine significantly prevented NaF-induced increase in oxidative stress indices as well as augmented antioxidant enzymes activities and glutathione level in the brain, testes, and epididymis of the treated rats. Moreover, taurine reversed NaF-induced elevation in inflammatory biomarkers and caspase-3 activity as well as histological damage in the brain, testes, and epididymis of the treated rats. The significant reversal of NaF-induced decreases in testosterone level and testicular activities of acid phosphatase, alkaline phosphatase, and lactate dehydrogenase by taurine was accompanied by enhancement of sperm functional characteristics in the treated rats. Taurine may be a possible chemopreventive candidate against reproductive dysfunction resulting from fluoride exposure.

  15. Antimicrobial activity of cream incorporated with silver nanoparticles biosynthesized from Withania somnifera

    Directory of Open Access Journals (Sweden)

    Marslin G

    2015-09-01

    Full Text Available Gregory Marslin,1 Rajendran K Selvakesavan,1 Gregory Franklin,1 Bruno Sarmento,2,3 Alberto CP Dias11Centre for the Research and Technology of Agro-Environment and Biological Sciences (CITAB-UM, AgroBioPlant Group, Department of Biology, University of Minho, Braga, Portugal; 2Instituto de Engenharia Biomédica (INEB, University of Porto, Porto, Portugal; 3CESPU, Instituto Universitário de Ciências da Saúde, Gandra, PortugalAbstract: We report on the antimicrobial activity of a cream formulation of silver nanoparticles (AgNPs, biosynthesized using Withania somnifera extract. Aqueous extracts of leaves promoted efficient green synthesis of AgNPs compared to fruits and root extracts of W. somnifera. Biosynthesized AgNPs were characterized for their size and shape by physical-chemical techniques such as UV-visible spectroscopy, laser Doppler anemometry, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, and X-ray energy dispersive spectroscopy. After confirming the antimicrobial potential of AgNPs, they were incorporated into a cream. Cream formulations of AgNPs and AgNO3 were prepared and compared for their antimicrobial activity against human pathogens (Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Escherichia coli, and Candida albicans and a plant pathogen (Agrobacterium tumefaciens. Our results show that AgNP creams possess significantly higher antimicrobial activity against the tested organisms.Keywords: Withania somnifera, green synthesis, silver nanoparticles cream, antimicrobial activity

  16. Green synthesis and antibacterial activity screening of silver nanoparticles reduced by papaya (Carica papaya L.) leaves extract

    International Nuclear Information System (INIS)

    Esplana, Camille S.; Cabling, Mercedes Q.

    2013-01-01

    The field of nano technology is the most active area of research in modern material sciences. Though there are many chemical, as well as physical methods, green synthesis is the most emerging method of synthesis. This study aimed to describe a cost effective and environment friendly technique for green synthesis of silver nanoparticles. The synthesis of silver nanoparticles was prepared by adding Carica papaya L. leaves extract to 1mM silver nitrate solution. The color change in reaction mixture (pale yellow to dark brown color was observed during the incubation period , due to excitation of surface plasmon vibrations in silver nanoparticles. Nanoparticles were characterized using UV-Visible absorption spectroscopy, X-Ray Diffraction (XRD) pattern, Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDX) analysis. Absorption spectra of silver nanoparticles formed in the reaction media has absorbance peak at 280 nm, broadening of peak indicates that the particles are poly dispersed. SEM analysis described the morphology and the size of the particles. XRD confirmed the crystalline structure of the nanoparticles. The presence of the elemental silver was observed in the graph obtained from EDX analysis, which also supports the XRD results. The biomass of plants produces their nano materials by a process called bio mineralization. The tests cultures included in the study were Staphylococcus aureus, Escherichia coli and Salmonella. Results showed that the maximum inhibitory effect using 1mM silver nitrates against the microbes were obtained. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy alternative to conventional methods of silver nanoparticles synthesis (author)

  17. EFFECT OF SILVER NANOPARTICLES ON THE PHYSICAL AND CHEMICAL PROPERTIES OF PLANT OILS AND THEIR ANTIMICROBIAL ACTIVITY

    Directory of Open Access Journals (Sweden)

    V. M. Minarchenko

    2017-12-01

    Full Text Available The aim of our research was to investigate the influence of silver nanoparticles on the physical and chemical features of plant oils of dogrose, flax, cedar, amaranth and watermelon and their antimicrobial activity. Plant oils were saturated with silver nanoparticles using electron-beam technology for depositing a molecular stream of metal in a vacuum. To characterize the rancidity of plant oils, the acid, iodine, peroxide, ester and saponification values were determined. A sharp drop in the iodine number and an increase in the peroxide number in oils saturated with silver nanoparticles were observed, as compared to pure oils, indicating a decrease in the number of unsaturated bonds in fatty acids and the formation of peroxides in oils. All pure plant oils and a separate sample of silver nanoparticles suppressed the growth of only E. faecalis colonies. Plant oils that were saturated with silver nanoparticles delayed the growth of S. aureus, S. epidermidis, E. faecalis, E. coli, P. aeruginosa, and C. albicans; the greatest delay in the growth of colonies was caused by flaxseed oil. Thus, the features of the plant oils under study essentially changed after they are aturated with silver nanoparticles. It can be assumed that the metal acted as a catalyst for peroxide oxidation of lipids in the investigated plant oil samples, the products of which caused toxic effects on cultures of bacteria and fungi in the experiment.

  18. Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol.

    Science.gov (United States)

    Naraginti, Saraschandra; Sivakumar, A

    2014-07-15

    The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (111), (200), (222) and (311) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yan-yu [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Yang, Hui, E-mail: 549456369@qq.com [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Wang, Tao [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Wang, Chuang [Department of Highway & Bridge, Shaanxi Railway Institute, Weinan 714000 (China)

    2016-11-25

    Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag{sup +} (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO{sub 3}) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO{sub 3} concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV–vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10–16 nm. FTIR analysis revealed that biological macromolecules with groups of −NH{sub 2}, −OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications. - Highlights: • Monodisperse silver nanoparticles were first prepared by a green synthetical way through Ginkgo Biloba leaf extract. • The synthesized AgNPs is of high crystallinity, stable and good dispersion with smaller sizes between 10–16 nm. • The achieved AgNPs exhibits good antibacterial activities. • The biosynthesis method is advantageous for its cost effectiveness, availability, portability, nontoxic and environmentally benign.

  20. Synthesis and antibacterial activity of water-dispersible silver nanoparticles via micellar nanoreactors

    Science.gov (United States)

    Pofali, Prasad; Shirolikar, Seema; Borde, Lalit; Pattani, Aditya; Dandekar, Prajakta; Jain, Ratnesh

    2018-04-01

    We have synthesized silver nanoparticles (AgNPs) using micelles of sugar fatty acid ester by dissolving the surfactant in a mixture of iso-octane and n-butanol, with solid-liquid extraction. Highly concentrated, water-dispersible AgNPs were obtained after thorough washing with alcohol, to remove excess of sucrose fatty acid ester DK SS and salt, followed by drying. The particles were characterized for their size, morphology and crystallinity using UV-Visible spectrophotometry, Transmission Electron Microscopy and x-ray diffractometry. Antibacterial study, confirmed the activity of nanoparticles against E. coli, P. aeruginosa and S. aureus, which causes diseases including diarrhoea and several life-threatening infections. Antibacterial activity of E. coli and P. aeruginosa was found to be 2.5 fold and for S. aureus 1.6 fold compared to 50 ppm conc. of Silver Nitrate. Our method of producing nanoparticles is employed as a platform technology for synthesizing other inorganic nanoparticles. This is the first report discussing the use of micellar carriers for obtaining silver nanopowder, to the best of our knowledge, which has the potential to overcome limitations during fabrication of AgNPs using reverse/inverse micelles. Our method yielded nano-sized, water-dispersible AgNPs via an easy and economic approach. The one-pot approach possesses advantages in terms of cost and simplicity, as compared with traditional methods of producing powdered AgNPs using energy intensive and expensive techniques like lyophilisation. The developed method, thus, possesses immense potential for commercial synthesis of AgNPs.

  1. Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

    International Nuclear Information System (INIS)

    Ren, Yan-yu; Yang, Hui; Wang, Tao; Wang, Chuang

    2016-01-01

    Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag + (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO 3 ) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO 3 concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV–vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10–16 nm. FTIR analysis revealed that biological macromolecules with groups of −NH 2 , −OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications. - Highlights: • Monodisperse silver nanoparticles were first prepared by a green synthetical way through Ginkgo Biloba leaf extract. • The synthesized AgNPs is of high crystallinity, stable and good dispersion with smaller sizes between 10–16 nm. • The achieved AgNPs exhibits good antibacterial activities. • The biosynthesis method is advantageous for its cost effectiveness, availability, portability, nontoxic and environmentally benign.

  2. Fluoride absorption: independence from plasma fluoride levels

    International Nuclear Information System (INIS)

    Whitford, G.M.; Williams, J.L.

    1986-01-01

    The concept that there are physiologic mechanisms to homeostatically regulate plasma fluoride concentrations has been supported by results in the literature suggesting an inverse relationship between plasma fluoride levels and the absorption of the ion from the gastrointestinal tract of the rat. The validity of the relationship was questioned because of possible problems in the experimental design. The present work used four different methods to evaluate the effect of plasma fluoride levels on the absorption of the ion in rats: (i) the percentage of the daily fluoride intake that was excreted in the urine; (ii) the concentration of fluoride in femur epiphyses; (iii) the net areas under the time-plasma fluoride concentration curves after intragastric fluoride doses; and (iv) the residual amounts or fluoride in the gastrointestinal tracts after the intragastric fluoride doses. None of these methods indicated that plasma fluoride levels influence the rate or the degree or fluoride absorption. It was concluded that, unless extremely high plasma fluoride levels are involved (pharmacologic or toxic doses), the absorption of the ion is independent of plasma levels. The results provide further evidence that plasma fluoride concentrations are not homeostatically regulated

  3. Antibacterial Activity of Electrochemically Synthesized Colloidal Silver Nanoparticles Against Hospital-Acquired Infections

    Science.gov (United States)

    Thuc, Dao Tri; Huy, Tran Quang; Hoang, Luc Huy; Hoang, Tran Huy; Le, Anh-Tuan; Anh, Dang Duc

    2017-06-01

    This study evaluated the antibacterial activity of electrochemically synthesized colloidal silver nanoparticles (AgNPs) against hospital-acquired infections. Colloidal AgNPs were synthesized via a single process using bulk silver bars, bi-distilled water, trisodium citrate, and direct current voltage at room temperature. Colloidal AgNPs were characterized by transmission electron microscopy, field-emission scanning electron microscopy, and energy-dispersive x-ray analyses. The antibacterial activity of colloidal AgNPs against four bacterial strains isolated from clinical samples, including methicillin-resistant Staphylococcus aureus, Escherichia coli O157:H7, multidrug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Klebsiella pneumonia, was evaluated by disc diffusion, minimum inhibitory concentration (MIC), and ultrathin sectioning electron microscopy. The results showed that the prepared AgNPs were 19.7 ± 4.3 nm in size, quasi-spherical, and of high purity. Zones of inhibition approximately 6-10 mm in diameter were found, corresponding to AgNPs concentrations of 50 μg/mL to 100 μg/mL. The MIC results revealed that the antibacterial activity of the prepared AgNPs was strongly dependent on the concentration and strain of the tested bacteria.

  4. Nanoecotoxicity assessment of activated carbon from sugarcane bagasse modified with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Suely Patricia Costa; Strauss, Mathias; Delite, Fabricio Souza; Martinez, Diego Stefani Teodoro, E-mail: suely.goncalves@lnnano.cnpem.br [Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP (Brazil); Clemente, Zaira; Castro, Vera Lucia Scherholz Salgado [Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA), Campinas, SP (Brazil)

    2016-07-01

    Full text: In this work, we performed the preparation and characterization of the activated carbon obtained from pyrolyzed sugarcane bagasse (ACBP) and its modification with silver nanoparticles with diameter around 35 nm (ACBP-AgNPs). The focus was on the correlations between the material physico-chemical properties and its adverse effects/ecotoxicity on three environmental exposure bioindicators (i.e. E. coli, Hydra attenuata, and Lycopersicum esculentum) based on its possible life cycle. The materials were well characterized using integrated techniques (e.g. TEM, SEM-EDS, XPS, BET, DLS, and ICP-OES). The presence of AgNPs on the activated carbon surface was responsible for microbial growth inhibition (E. coli). Besides, ACBP modification with silver nanoparticles has not altered its high adsorption capacity of organic pollutant models (i.e. phenol and methylene blue), making this material promising to environmental remediation and water purification. However, ACPB-AgNPs showed environmental risks, caused a moderate toxicity to the aquatic organism (H. attenuata, 1.94 mg L{sup -1}, LC50) and delayed the tomato (L. esculentum) root development, including oxidative stress induction. Finally, to develop efficient, innovative and safe nanomaterials for environmental remediation technologies, the combination/integration of material physical and chemical methodologies with biological assays (ecotoxicity assessment) appears as a promising and necessary strategy towards a sustainable nanotechnology. (author)

  5. One pot light assisted green synthesis, storage and antimicrobial activity of dextran stabilized silver nanoparticles.

    Science.gov (United States)

    Hussain, Muhammad Ajaz; Shah, Abdullah; Jantan, Ibrahim; Tahir, Muhammad Nawaz; Shah, Muhammad Raza; Ahmed, Riaz; Bukhari, Syed Nasir Abbas

    2014-12-03

    Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report green synthesis of silver nanoparticles (Ag NPs) mediated with dextran. Dextran was used as a stabilizer and capping agent to synthesize Ag NPs using silver nitrate (AgNO3) under diffused sunlight conditions. UV-vis spectra of as synthesized Ag nanoparticles showed characteristic surface plasmon band in the range from ~405-452 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies showed spherical Ag NPs in the size regime of ~50-70 nm. Face centered cubic lattice of Ag NPs was confirmed by powder X-ray diffraction (PXRD). FT-IR spectroscopy confirmed that dextran not only acts as reducing agent but also functionalizes the surfaces of Ag NPs to make very stable dispersions. Moreover, on drying, the solution of dextran stabilized Ag NPs resulted in the formation of thin films which were found stable over months with no change in the plasmon band of pristine Ag NPs. The antimicrobial assay of the as synthesized Ag NPs showed remarkable activity. Being significantly active against microbes, the Ag NPs can be explored for antimicrobial medical devices.

  6. Electrodeposition, characterization, and antibacterial activity of zinc/silver particle composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Vidal, Y.; Suarez-Rojas, R.; Ruiz, C.; Torres, J. [Center of Research and Technological Development in Electrochemistry (CIDETEQ), Parque Tecnológico Sanfandila, Pedro Escobedo, Querétaro, A.P.064, C.P.76703, Querétaro (Mexico); Ţălu, Ştefan [Technical University of Cluj-Napoca, Faculty of Mechanical Engineering, Department of AET, Discipline of Descriptive Geometry and Engineering Graphics, 103-105 B-dul Muncii St., Cluj-Napoca 400641 Cluj (Romania); Méndez, Alia [Centro de Química-ICUAP Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria Puebla, 72530 Puebla (Mexico); Trejo, G., E-mail: gtrejo@cideteq.mx [Center of Research and Technological Development in Electrochemistry (CIDETEQ), Parque Tecnológico Sanfandila, Pedro Escobedo, Querétaro, A.P.064, C.P.76703, Querétaro (Mexico)

    2015-07-01

    Highlights: • Zn/AgPs composites coatings were formed for electrodeposition. • CTAB promotes occlusion of silver particles in the coating. • Zn/AgPs coatings present very good antibacterial activity. - Abstract: Composite coatings consisting of zinc and silver particles (Zn/AgPs) with antibacterial activity were prepared using an electrodeposition technique. The morphology, composition, and structure of the Zn/AgPs composite coatings were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), inductively coupled plasma (ICP) spectrometry, and X-ray diffraction (XRD). The antibacterial properties of the coatings against the microorganisms Escherichia coli as a model Gram-negative bacterium and Staphylococcus aureus as a model Gram-positive bacterium were studied quantitatively and qualitatively. The results revealed that the dispersant cetyltrimethylammonium bromide (CTAB) assisted in the formation of a stable suspension of Ag particles in the electrolytic bath for 24 h. Likewise, a high concentration of CTAB in the electrolytic bath promoted an increase in the number of Ag particles occluded in the Zn/AgPs coatings. The Zn/AgPs coatings that were obtained were compact, smooth, and shiny materials. Antimicrobial tests performed on the Zn/AgPs coatings revealed that the inhibition of bacterial growth after 30 min of contact time was between 91% and 98% when the AgPs content ranged from 4.3 to 14.0 mg cm{sup −3}.

  7. Preparation of Size-Controlled Silver Nanoparticles and Chitin-Based Composites and Their Antimicrobial Activities

    Directory of Open Access Journals (Sweden)

    Vinh Quang Nguyen

    2013-01-01

    Full Text Available A simple method for the preparation of size-controlled spherical silver nanoparticles (Ag NPs was reported for their generation by autoclaving a mixture of silver-containing glass powder and glucose. The particle size is regulated by the glucose concentration, with concentrations of 0.25, 1.0, and 4.0 wt% glucose providing small (3.48±1.83 nm in diameter, medium (6.53±1.78 nm, and large (12.9±2.5 nm particles, respectively. In this study, Ag NP/chitin composites were synthesized by mixing each of these three Ag NP suspensions with a <5% deacetylated (DAc chitin powder (pH 7.0 at room temperature. The Ag NPs were homogenously dispersed and stably adsorbed onto the chitin. The Ag NP/chitin composites were obtained as yellow or brown powders. Approximately 5, 15, and 20 μg of the small, medium, and large Ag NPs, respectively, were estimated to maximally adsorb onto 1 mg of chitin. The bactericidal and antifungal activities of the Ag NP/chitin composites increased as the amount of Ag NPs in the chitin increased. Furthermore, smaller Ag NPs (per weight in the chitin composites provided higher bactericidal and anti-fungal activities.

  8. Green synthesis of Silver and Gold Nanoparticles for Enhanced catalytic and bactericidal activity

    Science.gov (United States)

    Naraginti, S.; Tiwari, N.; Sivakumar, A.

    2017-11-01

    A rapid one step green synthetic method using kiwi fruit extract was employed for preparation of silver and gold nanoparticles. The synthesized nanoparticles were successfully used as green catalysts for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB). They also exhibited excellent antimicrobial activity against clinically isolated Pseudomonas aeruginosa (P.aeruginosa) and Staphylococcus aureus (S.aureus). It was noticed that with increase in concentration of the aqueous silver and gold solutions, particle size of the Ag and Au NPS showed increase as evidenced from UV-Visible spectroscopy and TEM micrograph. The method employed for the synthesis required only a few minutes for more than 90% formation of nanoparticles when the temperature was raised to 80°C. It was also noticed that the catalytic activity of nanoparticles depends upon the size of the particles. These nanoparticles were observed to be crystalline from the clear lattice fringes in the transmission electron microscopic (TEM) images, bright circular spots in the selected area electron diffraction (SAED) pattern and peaks in the X-ray diffraction (XRD) pattern. The Fourier-transform infrared (FTIR) spectrum indicated the presence of different functional groups in the biomolecule capping the nanoparticles.

  9. Nanoecotoxicity assessment of activated carbon from sugarcane bagasse modified with silver nanoparticles

    International Nuclear Information System (INIS)

    Goncalves, Suely Patricia Costa; Strauss, Mathias; Delite, Fabricio Souza; Martinez, Diego Stefani Teodoro; Clemente, Zaira; Castro, Vera Lucia Scherholz Salgado

    2016-01-01

    Full text: In this work, we performed the preparation and characterization of the activated carbon obtained from pyrolyzed sugarcane bagasse (ACBP) and its modification with silver nanoparticles with diameter around 35 nm (ACBP-AgNPs). The focus was on the correlations between the material physico-chemical properties and its adverse effects/ecotoxicity on three environmental exposure bioindicators (i.e. E. coli, Hydra attenuata, and Lycopersicum esculentum) based on its possible life cycle. The materials were well characterized using integrated techniques (e.g. TEM, SEM-EDS, XPS, BET, DLS, and ICP-OES). The presence of AgNPs on the activated carbon surface was responsible for microbial growth inhibition (E. coli). Besides, ACBP modification with silver nanoparticles has not altered its high adsorption capacity of organic pollutant models (i.e. phenol and methylene blue), making this material promising to environmental remediation and water purification. However, ACPB-AgNPs showed environmental risks, caused a moderate toxicity to the aquatic organism (H. attenuata, 1.94 mg L -1 , LC50) and delayed the tomato (L. esculentum) root development, including oxidative stress induction. Finally, to develop efficient, innovative and safe nanomaterials for environmental remediation technologies, the combination/integration of material physical and chemical methodologies with biological assays (ecotoxicity assessment) appears as a promising and necessary strategy towards a sustainable nanotechnology. (author)

  10. Green synthesis of silver nanoparticles using Prosopis juliflora bark extract: reaction optimization, antimicrobial and catalytic activities.

    Science.gov (United States)

    Arya, Geeta; Kumari, R Mankamna; Gupta, Nidhi; Kumar, Ajeet; Chandra, Ramesh; Nimesh, Surendra

    2017-07-18

    In the present study, silver nanoparticles (PJB-AgNPs) have been biosynthesized employing Prosopis juliflora bark extract. The biosynthesis of silver nanoparticles was monitored on UV-vis spectrophotometer. The size, charge and polydispersity index (PDI) of PJB-AgNPs were determined using dynamic light scattering (DLS). Different parameters dictating the size of PJB-AgNPs were explored. Nanoparticles biosynthesis optimization studies suggested efficient synthesis of highly dispersed PJB-AgNPs at 25 °C when 9.5 ml of 1 mM AgNO 3 was reduced with 0.5 ml of bark extract for 40 min. Characterization of PJB-AgNPs by SEM showed spherical-shaped nanoparticles with a size range ∼10-50 nm along with a hydrodynamic diameter of ∼55 nm as evaluated by DLS. Further, characterizations were done by FTIR and EDS to evaluate the functional groups and purity of PJB-AgNPs. The antibacterial potential of PJB-AgNPs was tested against E. coli and P. aeruginosa. The PJB-AgNPs remarkably exhibited anticancer activity against A549 cell line as evidenced by Alamar blue assay. The dye degradation activity was also evaluated against 4-nitrophenol that has carcinogenic effect. The results thus obtained suggest application of PJB-AgNPs as antimicrobial, anticancer and catalytic agents.

  11. Isatis tinctoria mediated synthesis of amphotericin B-bound silver nanoparticles with enhanced photoinduced antileishmanial activity: A novel green approach.

    Science.gov (United States)

    Ahmad, Aftab; Wei, Yun; Syed, Fatima; Khan, Shafiullah; Khan, Gul Majid; Tahir, Kamran; Khan, Arif Ullah; Raza, Muslim; Khan, Faheem Ullah; Yuan, Qiping

    2016-08-01

    After malaria, Leishmaniasis is the most prevalent infectious disease in terms of fatality and geographical distribution. The availability of a limited number of antileishmanial agents, emerging resistance to the available drugs, and the high cost of treatment complicate the treatment of leishmaniasis. To overcome these issues, critical research for new therapeutic agents with enhanced antileishmanial potential and low treatment cost is needed. In this contribution, we developed a green protocol to prepare biogenic silver nanoparticles (AgNPs) and amphotericin B-bound biogenic silver nanoparticles (AmB-AgNPs). Phytochemicals from the aqueous extract of Isatis tinctoria were used as reducing and capping agents to prepare silver nanoparticles. Amphotericin B was successfully adsorbed on the surface of biogenic silver nanoparticles. The prepared nanoparticles were characterized by various analytical techniques. UV-Visible spectroscopy was employed to detect the characteristic localized surface plasmon resonance peaks (LSPR) for the prepared nanoparticles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies revealed the formation of spherical silver nanoparticles with an average particle size of 10-20nm. The cubic crystalline structure of the prepared nanoparticles was confirmed by X-ray diffraction (XRD) study. FTIR spectroscopic analysis revealed that plant polyphenolic compounds are mainly involved in metal reduction and capping. Under visible light irradiation, biogenic silver nanoparticles exhibited significant activity against Leishmania tropica with an IC50 value of 4.2μg/mL. The leishmanicidal activity of these nanoparticles was considerably enhanced by conjugation with amphotericin B (IC50=2.43μg/mL). In conclusion, the findings of this study reveal that adsorption of amphotericin B, an antileishmanial drug, to biogenic silver nanoparticles, could be a safe, more effective and economic alternative to the available

  12. “Synthesis, characterization and studies on antioxidant activity of silver nanoparticles using Elephantopus scaber leaf extract”

    Energy Technology Data Exchange (ETDEWEB)

    Kharat, Sopan N., E-mail: sopankharat@gmail.com; Mendhulkar, Vijay D., E-mail: drmendhulkar@gmail.com

    2016-05-01

    The simple, eco-friendly and cost effective method of green synthesis of silver nanoparticle in the leaf extract of medicinal plant Elephantopus scaber L. is illustrated in the present work. The synthesized silver nanoparticles (AgNPs) were characterized with UV–Vis-spectroscopy, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The UV-spectra show maximum absorbance at 435 nm, NTA analysis shows 78 nm average sizes of nanoparticles, TEM analysis indicates spherical shape of the nanoparticles with the average diameter of 50 nm. The XRD peaks at 2θ range of 30–80° correspond to (111), (200), (220), (311) reflection planes that indicate the structure of metallic silver. FTIR analysis reveals surface capping of phenolic groups. Existence of peaks in the range of 1611 to 1400 cm{sup −1} indicates the presence of aromatic rings in the leaf extract. The peak at 1109 cm{sup −1} is due to the presence of OH groups. The antioxidant activity of synthesized nanoparticles was evaluated performing DPPH assay and it is observed that the photosynthesized nanoparticle also possesses antioxidant potentials. Thus, it can be used as potential free radical scavenger. Silver particles have tremendous applications in the field of diagnostics and therapeutics. To this context, the surface coating of plant metabolite constituents has great potentials. Therefore, the present work has been undertaken to synthesize the AgNPs using leaf extract of medicinal plant, E. scaber, to characterize and access their antioxidant properties. - Highlights: • Green synthesis of silver nanoparticle using leaf extract of medicinal plant Elephantopus scaber L. • Synthesized nanoparticles (SNP's) were characterized by UV-Spectroscopy, NTA, TEM, XRD and FTIR analysis. • Silver nanoparticles (AgNPs) showed average size of 78 nm in NTA analysis and spherical shape in TEM analysis.

  13. Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    Siqi Huang

    2016-06-01

    Full Text Available A facile, efficient, and eco-friendly approach for the preparation of uniform silver nanoparticles (Ag NPs was developed. The synthesis was conducted in an aqueous medium exposed to microwave irradiation for 8 min, using laboratory-prepared, water-soluble quaternized carboxymethyl chitosan (QCMC as a chemical reducer and stabilizer and silver nitrate as the silver source. The structure of the prepared QCMC was characterized using Fourier transform infrared (FT-IR and 1H nuclear magnetic resonance (NMR. The formation, size distribution, and dispersion of the Ag NPs in the QCMC matrix were determined using X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, ultraviolet-visible (UV-Vis, transmission electron microscopy (TEM, and field emission scanning electron microscope (FESEM analysis, and the thermal stability and antibacterial properties of the synthesized QCMC-based Ag NPs composite (QCMC-Ag were also explored. The results revealed that (1 QCMC was successfully prepared by grafting quaternary ammonium groups onto carboxymethyl chitosan (CMC chains under microwave irradiation in water for 90 min and this substitution appeared to have occurred at -NH2 sites on C2 position of the pyranoid ring; (2 uniform and stable spherical Ag NPs could be synthesized when QCMC was used as the reducing and stabilizing agent; (3 Ag NPs were well dispersed in the QCMC matrix with a narrow size distribiution in the range of 17–31 nm without aggregation; and (4 due to the presence of Ag NPs, the thermal stability and antibacterial activity of QCMC-Ag were dramatically improved relative to QCMC.

  14. Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity.

    Science.gov (United States)

    Huang, Siqi; Wang, Jing; Zhang, Yang; Yu, Zhiming; Qi, Chusheng

    2016-06-17

    A facile, efficient, and eco-friendly approach for the preparation of uniform silver nanoparticles (Ag NPs) was developed. The synthesis was conducted in an aqueous medium exposed to microwave irradiation for 8 min, using laboratory-prepared, water-soluble quaternized carboxymethyl chitosan (QCMC) as a chemical reducer and stabilizer and silver nitrate as the silver source. The structure of the prepared QCMC was characterized using Fourier transform infrared (FT-IR) and ¹H nuclear magnetic resonance (NMR). The formation, size distribution, and dispersion of the Ag NPs in the QCMC matrix were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis), transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM) analysis, and the thermal stability and antibacterial properties of the synthesized QCMC-based Ag NPs composite (QCMC-Ag) were also explored. The results revealed that (1) QCMC was successfully prepared by grafting quaternary ammonium groups onto carboxymethyl chitosan (CMC) chains under microwave irradiation in water for 90 min and this substitution appeared to have occurred at -NH₂ sites on C2 position of the pyranoid ring; (2) uniform and stable spherical Ag NPs could be synthesized when QCMC was used as the reducing and stabilizing agent; (3) Ag NPs were well dispersed in the QCMC matrix with a narrow size distribiution in the range of 17-31 nm without aggregation; and (4) due to the presence of Ag NPs, the thermal stability and antibacterial activity of QCMC-Ag were dramatically improved relative to QCMC.

  15. Influences of Silver-Doping on the Crystal Structure, Morphology and Photocatalytic Activity of TiO2 Nanofibers

    DEFF Research Database (Denmark)

    Barakat, Nasser A. M.; Kanjwal, Muzafar Ahmed; Al-Deyab, Salem S.

    2011-01-01

    Doping of titanium dioxide nanofibers by silver nanoparticles revealed distinct improvement in the photocatalytic activ-ity; however other influences have not been investigated. In this work, effect of sliver-doping on the crystal structure, the nanofibrous morphology as well as the photocatalyti...

  16. Synthesis, characterization and catalytic activity of silver nanoparticles using Tribulus terrestris leaf extract.

    Science.gov (United States)

    Ashokkumar, S; Ravi, S; Kathiravan, V; Velmurugan, S

    2014-01-01

    Biomediated silver nanoparticles were synthesized with the aid of an eco-friendly biomaterial, namely, aqueous Tribulus terrestris extract. Silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous T. terrestris leaf extracts as both the reducing and capping agent. Silver ions were rapidly reduced by aqueous T. terrestris leaf extracts, leading to the formation of highly crystalline silver nanoparticles. An attempt has been made and formation of the silver nanoparticles was verified by surface plasmon spectra using an UV-vis (Ultra violet), spectrophotometer. Morphology and crystalline structure of the prepared silver nanoparticles were characterized by TEM (Transmission Electron Microscope) and XRD (X-ray Diffraction), techniques, respectively. FT-IR (Fourier Transform Infrared), analysis suggests that the obtained silver nanoparticles might be stabilized through the interactions of carboxylic groups, carbonyl groups and the flavonoids present in the T. terrestris extract. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Interaction of Silver Nanoparticles with Serum Proteins Affects Their Antimicrobial Activity In Vivo

    Science.gov (United States)

    Gnanadhas, Divya Prakash; Ben Thomas, Midhun; Thomas, Rony; Raichur, Ashok M.

    2013-01-01

    The emergence of multidrug-resistant bacteria is a global threat for human society. There exist recorded data that silver was used as an antimicrobial agent by the ancient Greeks and Romans during the 8th century. Silver nanoparticles (AgNPs) are of potential interest because of their effective antibacterial and antiviral activities, with minimal cytotoxic effects on the cells. However, very few reports have shown the usage of AgNPs for antibacterial therapy in vivo. In this study, we deciphered the importance of the chosen methods for synthesis and capping of AgNPs for their improved activity in vivo. The interaction of AgNPs with serum albumin has a significant effect on their antibacterial activity. It was observed that uncapped AgNPs exhibited no antibacterial activity in the presence of serum proteins, due to the interaction with bovine serum albumin (BSA), which was confirmed by UV-Vis spectroscopy. However, capped AgNPs [with citrate or poly(vinylpyrrolidone)] exhibited antibacterial properties due to minimized interactions with serum proteins. The damage in the bacterial membrane was assessed by flow cytometry, which also showed that only capped AgNPs exhibited antibacterial properties, even in the presence of BSA. In order to understand the in vivo relevance of the antibacterial activities of different AgNPs, a murine salmonellosis model was used. It was conclusively proved that AgNPs capped with citrate or PVP exhibited significant antibacterial activities in vivo against Salmonella infection compared to uncapped AgNPs. These results clearly demonstrate the importance of capping agents and the synthesis method for AgNPs in their use as antimicrobial agents for therapeutic purposes. PMID:23877702

  18. Synergy between Printex nano-carbons and silver nanoparticles for sensitive estimation of antioxidant activity

    International Nuclear Information System (INIS)

    Raymundo-Pereira, Paulo A.; Campos, Anderson M.; Prado, Thiago M.; Furini, Leonardo N.; Boas, Naiza V.; Calegaro, Marcelo L.; Machado, Sergio A.S.

    2016-01-01

    We report on the synthesis, characterization and applications of a Printex L6 carbon-silver hybrid nanomaterial (PC-Ag), which was obtained using a polyol method. In addition, we also highlight the use of Printex L6 nano-carbon as a much cheaper alternative to the use of carbon nanotubes and graphene. The silver nanoparticles (AgNP) were prepared directly on the surface of the Printex 6L carbon “nanocarbon” material using ethylene glycol as the reducing agent. The hybrid nanomaterial was characterized by High-angle annular dark-field transmission electron microscopy (HAADF-TEM), energy–dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), Raman spectroscopy and cyclic voltammetry. Optimized electrocatalytic activity on glassy carbon electrode was reached for the architecture GC/PC-Ag, the silver nanoparticles with size ranging between 1 and 2 nm were well–distributed throughout the hybrid material. The synergy between PC nano-carbons and AgNPs was verified by detection of gallic acid (GA) at a low applied potential (0.091 V vs. Ag/AgCl). GA detection was performed in a concentration range between 5.0 × 10"−"7 and 8.5 × 10"−"6 mol L"−"1, with a detection limit of 6.63 × 10"−"8 mol L"−"1 (66.3 nmol L"−"1), which is considerably lower than similar devices. The approach for fabricating the reproducible GC/PC-Ag electrodes is entirely generic and may be explored for other types of (bio)sensors and devices. - Highlights: • We highlight the use of Printex L6 nano-carbon as a much cheaper alternative to carbon nanotubes and graphene. • The hybrid nanomaterial was completely characterized by MET, EDX, SAED, DRX, RAMAN and cyclic voltammetry. • The silver nanoparticles (size range 1-2 nm) were prepared directly onto the surface of the Printex 6L Carbon “nanocarbon”. • An ultrathin film PC-AgNP nanostructured showed a synergetic effect between PC nanocarbons and AgNP. • Sensitive estimation of

  19. Synergy between Printex nano-carbons and silver nanoparticles for sensitive estimation of antioxidant activity

    Energy Technology Data Exchange (ETDEWEB)

    Raymundo-Pereira, Paulo A., E-mail: pauloaugustoraymundopereira@gmail.com [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, CEP 13566-590 (Brazil); Campos, Anderson M.; Prado, Thiago M. [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, CEP 13566-590 (Brazil); Furini, Leonardo N. [Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, 19060-900 Presidente Prudente, São Paulo (Brazil); Boas, Naiza V.; Calegaro, Marcelo L.; Machado, Sergio A.S. [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, CEP 13566-590 (Brazil)

    2016-07-05

    We report on the synthesis, characterization and applications of a Printex L6 carbon-silver hybrid nanomaterial (PC-Ag), which was obtained using a polyol method. In addition, we also highlight the use of Printex L6 nano-carbon as a much cheaper alternative to the use of carbon nanotubes and graphene. The silver nanoparticles (AgNP) were prepared directly on the surface of the Printex 6L carbon “nanocarbon” material using ethylene glycol as the reducing agent. The hybrid nanomaterial was characterized by High-angle annular dark-field transmission electron microscopy (HAADF-TEM), energy–dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), Raman spectroscopy and cyclic voltammetry. Optimized electrocatalytic activity on glassy carbon electrode was reached for the architecture GC/PC-Ag, the silver nanoparticles with size ranging between 1 and 2 nm were well–distributed throughout the hybrid material. The synergy between PC nano-carbons and AgNPs was verified by detection of gallic acid (GA) at a low applied potential (0.091 V vs. Ag/AgCl). GA detection was performed in a concentration range between 5.0 × 10{sup −7} and 8.5 × 10{sup −6} mol L{sup −1}, with a detection limit of 6.63 × 10{sup −8} mol L{sup −1} (66.3 nmol L{sup −1}), which is considerably lower than similar devices. The approach for fabricating the reproducible GC/PC-Ag electrodes is entirely generic and may be explored for other types of (bio)sensors and devices. - Highlights: • We highlight the use of Printex L6 nano-carbon as a much cheaper alternative to carbon nanotubes and graphene. • The hybrid nanomaterial was completely characterized by MET, EDX, SAED, DRX, RAMAN and cyclic voltammetry. • The silver nanoparticles (size range 1-2 nm) were prepared directly onto the surface of the Printex 6L Carbon “nanocarbon”. • An ultrathin film PC-AgNP nanostructured showed a synergetic effect between PC nanocarbons and AgNP.

  20. Biologically synthesised silver nanoparticles from three diverse family of plant extracts and their anticancer activity against epidermoid A431 carcinoma.

    Science.gov (United States)

    Nayak, Debasis; Pradhan, Sonali; Ashe, Sarbani; Rauta, Pradipta Ranjan; Nayak, Bismita

    2015-11-01

    Biological synthesis of silver nanoparticles is a cost effective natural process where the phytochemicals specifically phenols, flavonoids and terpenoids present in the plant extracts act as capping and reducing agent. Due to their nano size regime the silver nanoparticles may directly bind to the DNA of the pathogenic bacterial strains leading to higher antimicrobial activity. In the current study silver nanoparticles were synthesised using plant extracts from different origin Cucurbita maxima (petals), Moringa oleifera (leaves) and Acorus calamus (rhizome). The synthesised nanoparticles were characterized by UV-visible spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), field emission scanning electron microscopy (Fe-SEM) and Fourier transform infrared spectroscopy (FTIR). Highly crystalline, roughly spherical and cuboidal silver nanoparticles of 30-70 nm in size were synthesised. The nanoparticles provided strong antimicrobial activity against pathogenic strains. The effect of the synthesised nanoparticles against A431 skin cancer cell line was tested for their toxicity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. The IC50 values of 82.39±3.1, 83.57±3.9 and 78.58±2.7 μg/ml were calculated for silver nanoparticles synthesised by C. maxima, M. oleifera and A. calamus respectively. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Studies on the antifungal activities of the novel synthesized chelating co-polymer emulsion lattices and their silver complexes

    Directory of Open Access Journals (Sweden)

    Abd-El-Ghaffar M.A.

    2008-01-01

    Full Text Available The novel binary chelating co-polymers of butyl acrylate with itaconic and maleic acids were prepared by emulsion polymerization process. The chelating co-polymers of butyl acrylate-co-itaconic acid (BuA/IA and butyl acrylate-co-maleic acid (BuA/MA and their silver complexes were characterized and identified using IR spectroscopy and differential scanning calorimetry (DSC measurements. The biological activities of these compounds were studied against various types of fungal species. The dose and the rate of leached silver ions were controlled by the type of the co-polymers used and the solubility in the medium. The results provided laboratory support for the concept that the polymers containing chemically bound biocide are useful for controlling microbial growth. The silver uptake by strains of different fungal species was studied to determine their difference in behavior to the antifungal activities of these compounds. The uptake strategy was examined by transmission electron microscopy (TEM.

  2. Study of multiplet structures of Mn4+ activated in fluoride crystals

    International Nuclear Information System (INIS)

    Novita, Mega; Honma, Tetsuo; Hong, Byungchul; Ohishi, Atsushi; Ogasawara, Kazuyoshi

    2016-01-01

    We investigated the optical properties of Mn 4+ in some fluoride crystals such as Cs 2 MnF 6 , Cs 2 GeF 6 , Rb 2 GeF 6 , Cs 2 SiF 6 , K 2 SiF 6 , Rb 2 MnF 6 , Rb 2 SiF 6 , K 2 GeF 6 , K 2 TiF 6 , Li 2 MnF 6 , Na 2 GeF 6 , Na 2 SiF 6 , and Na 2 TiF 6 based on the first-principle calculation using the discrete-variational multi-electron method. In order to estimate the lattice relaxation, we performed EXAFS measurement of Mn 4+ doped in K 2 SiF 6 , K 2 TiF 6 , and K 2 GeF 6 . The relaxation rates of A 2 BF 6 :Mn 4+ were fixed to be the above estimated values, 102.24%, 107.37% or 96.80% for crystal having Si, Ge, or Ti at the B cation site, respectively. In this work, we also considered some corrections such as configuration dependent correction and correlation correction to improve the theoretical energies. It has been shown that to reproduce multiplet energy levels quantitatively, the lattice relaxation is very important. On the other hand, for a qualitative prediction of the tendencies of the multiplet energies, the combination of lattice relaxation effect, configuration dependent correction, and correlation correction is effective. - Highlights: • Multiplet structures of A 2 BF 6 :Mn 4+ were calculated from first-principles. • Lattice relaxation was estimated based on EXAFS experiment. • Lattice relaxation is important to reproduce multiplet energies quantitatively. • CDC and CC are important to reproduce tendencies of multiplet energies.

  3. Phosphate activity of Poa pratensis seeds. III. Effect of fluoride, citrate, urea and other substances on the activity of acid phosphatase Ia/sub 2/ and Ia/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Lorenc-Kubis, I.; Morawiecka, B.

    1978-01-01

    Effects of fluoride, citrate, urea and other substances on the activity of acid phosphatase a/sub 2/ and a/sub 3/ toward p-nitrophenylphosphate and phenylphosphate were investigated. Both enyzmes were inhibited by fluoride, p-chloro-mercuribenzoate and oxalate. Fluoride inhibited acid phosphatase a/sub 2/ non-competitively with p-nitrophenylphosphate, whereas acid phosphatase a/sub 3/ showed mixed type inhibition. Hydrolysis of phenylphosphate by both acid phosphatases was activated by citrate. Cytosine and uridine inhibited the activity of phosphatase a/sub 2/ toward p-nitrophenylphosphate and phenylphosphate, but no effect was observed in case of acid phosphatase a/sub 3/. After 30 min. incubation with 4 M urea both enzymes lost about 30% of their activity. 11 references, 5 figures, 1 table.

  4. Studies on low-carrier radiofluorination of non-active aromatics with no-carrier-added [{sup 18}F]fluoride; Untersuchungen zur traegerarmen Radiofluorierung nicht-aktiver Aromaten mit n.c.a. [{sup 18}F]Fluorid

    Energy Technology Data Exchange (ETDEWEB)

    Cardinale, Jens

    2013-01-15

    In vivo imaging with positron emission tomography generally demands radiotracers with a high specific activity. In case of fluorine-18 the required no-carrier-added (n.c.a.) starting material is only available in form of fluoride. This and the short half-life of 109.7 minutes of the radionuclide lead to the demand of special methods for radiosyntheses. The only practical procedure for manufacturing n.c.a. [{sup 18}F]fluoro-compounds is therefore nucleophilic substitution. There is, however, still a lack of effective procedures for the labelling of electron rich aromatic molecules starting from n.c.a. [{sup 18}F]fluoride. A process for n.c.a. radiofluorination of these compounds is offered by the reaction of iodonium compounds as starting materials. In this study modern procedures for the synthesis of iodoniumsalts and -ylides were investigated. Several precursor molecules for the versatile synthetic building block 4-[{sup 18}F]fluoroiodobenzene were synthesised. In this course, a new one-pot procedure for the synthesis of iodoniumylides was developed. Further on, the syntheses of suitable iodonium precursors for two fluorophenoxy-derivatives, which are possible antidepressants, were investigated. Due to their binding profile these compounds can be considered as ligands for the serotonin reuptake transporter (SERT) and the norepinephrin reuptake transporter (NET), respectively. The preparation of appropriate iodonium salts proved to be too problematic, while the synthesis of suitable iodoniumylides could be accomplished with satisfactory yields of about 30% and 40 %, respectively. Both compounds were labelled with n.c.a. [{sup 18}F]fluoride and deprotected to the desired target compounds 4-((3-[{sup 18}F]fluorophenoxy)(phenyl)methyl)piperidine and 4-((4-[{sup 18}F]fluorophenoxy)(phenyl)methyl)piperidine in radiochemical yields of about 40 % and 25 %, respectively. Those are now available for preclinical evaluation studies. Furthermore, a process for the palladium

  5. Silver nanoparticles with antimicrobial activities against Streptococcus mutans and their cytotoxic effect

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Díaz, Mario Alberto [Facultad de Ciencias Químicas, UASLP, Álvaro Obregón 64, San Luis Potosí (Mexico); Boegli, Laura; James, Garth [Center for Biofilm Engineering, Montana State University, Bozeman, MT (United States); Velasquillo, Cristina; Sánchez-Sánchez, Roberto [Laboratorio de Biotecnología, Instituto Nacional de Rehabilitación (Mexico); Martínez-Martínez, Rita-Elizabeth; Martínez-Castañón, Gabriel Alejandro [Facultad de Estomatología, Universidad Autónoma de San Luis Potosí (Mexico); Martinez-Gutierrez, Fidel, E-mail: fidel@uaslp.mx [Facultad de Ciencias Químicas, UASLP, Álvaro Obregón 64, San Luis Potosí (Mexico)

    2015-10-01

    Microbial resistance represents a challenge for the scientific community to develop new bioactive compounds. The goal of this research was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) against a clinical isolate of Streptococcus mutans, antibiofilm activity against mature S. mutans biofilms and the compatibility with human fibroblasts. The antimicrobial activity of AgNPs against the planktonic clinical isolate was size and concentration dependent, with smaller AgNPs having a lower minimum inhibitory concentration. A reduction of 2.3 log in the number of colony-forming units of S. mutans was observed when biofilms grown in a CDC reactor were exposed to 100 ppm of AgNPs of 9.5 ± 1.1 nm. However, AgNPs at high concentrations (> 10 ppm) showed a cytotoxic effect upon human dermal fibroblasts. AgNPs effectively inhibited the growth of a planktonic S. mutans clinical isolate and killed established S. mutans biofilms, which suggests that AgNPs could be used for prevention and treatment of dental caries. Further research and development are necessary to translate this technology into therapeutic and preventive strategies. - Highlights: • Biological activities of silver nanoparticles for dental caries purposes • Antimicrobial activity of AgNPs on planktonic cell was size and concentration dependent. • Reduction in the S. mutans biofilm formation was statistically significant. • AgNPs at high concentrations showed a cytotoxic effect upon human dermal fibroblasts. • AgNPs could be used for prevention and treatment of dental caries.

  6. Silver nanoparticles with antimicrobial activities against Streptococcus mutans and their cytotoxic effect

    International Nuclear Information System (INIS)

    Pérez-Díaz, Mario Alberto; Boegli, Laura; James, Garth; Velasquillo, Cristina; Sánchez-Sánchez, Roberto; Martínez-Martínez, Rita-Elizabeth; Martínez-Castañón, Gabriel Alejandro; Martinez-Gutierrez, Fidel

    2015-01-01

    Microbial resistance represents a challenge for the scientific community to develop new bioactive compounds. The goal of this research was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) against a clinical isolate of Streptococcus mutans, antibiofilm activity against mature S. mutans biofilms and the compatibility with human fibroblasts. The antimicrobial activity of AgNPs against the planktonic clinical isolate was size and concentration dependent, with smaller AgNPs having a lower minimum inhibitory concentration. A reduction of 2.3 log in the number of colony-forming units of S. mutans was observed when biofilms grown in a CDC reactor were exposed to 100 ppm of AgNPs of 9.5 ± 1.1 nm. However, AgNPs at high concentrations (> 10 ppm) showed a cytotoxic effect upon human dermal fibroblasts. AgNPs effectively inhibited the growth of a planktonic S. mutans clinical isolate and killed established S. mutans biofilms, which suggests that AgNPs could be used for prevention and treatment of dental caries. Further research and development are necessary to translate this technology into therapeutic and preventive strategies. - Highlights: • Biological activities of silver nanoparticles for dental caries purposes • Antimicrobial activity of AgNPs on planktonic cell was size and concentration dependent. • Reduction in the S. mutans biofilm formation was statistically significant. • AgNPs at high concentrations showed a cytotoxic effect upon human dermal fibroblasts. • AgNPs could be used for prevention and treatment of dental caries

  7. In vitro study of the antibacterial and anticancer activities of silver nanoparticles synthesized from Penicillium brevicompactum (MTCC-1999

    Directory of Open Access Journals (Sweden)

    Shahnaz Majeed

    2016-07-01

    Full Text Available Among the most promising nanomaterials, metallic nanoparticles with antibacterial and antitumor properties are expected to open new avenues to fight and prevent various tumours and infectious diseases. The study of bactericidal nanomaterial is particularly timely considering the recent increase in new resistant strains of bacteria to the most potent antibiotics and the potential role of bactericidal nanomaterial as anticancer agents. This has promoted the research of the well-known activity of silver ions and silver-based compounds, including silver nanoparticles. The present work is the study of silver nanoparticles synthesized from Penicillium brevicompactum (MTCC-1999. The colour of the cell filtrate changes to dark brown upon addition of 1 mM AgNO3, suggesting the formation of silver nanoparticles. These silver nanoparticles (AgNPs were characterized and analyzed by UV–vis spectrophotometric analysis, which showed a peak of absorbance at 420 nm. Fourier transform infrared (FTIR analysis showed amines and amides that are responsible for the stabilization of AgNPs. To determine the particle size, atomic force microscopy (AFM analysis was used, which showed that the nanoparticles are spherical and are 30–50 nm in size. High-resolution transmission electron microscopy (HRTEM showed that AgNPs were well dispersed, spherical, and well within the range of 40–50 nm. These nanoparticles displayed good antibacterial activity and also increased the antibiotic activity of gatifloxacin, tetracycline, and vancomycin. These nanoparticles were further studied for their anticancer activity and showed high toxicity towards the MCF-7 breast cancer cell line.

  8. Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

    Science.gov (United States)

    Shao, Wei; Liu, Xiufeng; Min, Huihua; Dong, Guanghui; Feng, Qingyuan; Zuo, Songlin

    2015-04-01

    In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

  9. Cellulose aerogels functionalized with polypyrrole and silver nanoparticles: In-situ synthesis, characterization and antibacterial activity.

    Science.gov (United States)

    Wan, Caichao; Li, Jian

    2016-08-01

    Green porous and lightweight cellulose aerogels have been considered as promising candidates to substitute some petrochemical host materials to support various nanomaterials. In this work, waste wheat straw was collected as feedstock to fabricate cellulose hydrogels, and a green inexpensive NaOH/polyethylene glycol solution was used as cellulose solvent. Prior to freeze-drying treatment, the cellulose hydrogels were integrated with polypyrrole and silver nanoparticles by easily-operated in-situ oxidative polymerization of pyrrole using silver ions as oxidizing agent. The tri-component hybrid aerogels were characterized by scanning electron microscope, transmission electron microscope, energy dispersive X-ray spectroscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and X-ray diffraction. Moreover, the antibacterial activity of the hybrid aerogels against Escherichia coli (Gram-negative), Staphylococcus aureus (Gram-positive) and Listeria monocytogenes (intracellular bacteria) was qualitatively and quantitatively investigated by parallel streak method and determination of minimal inhibitory concentration, respectively. This work provides an example of combining cellulose aerogels with nanomaterials, and helps to develop novel forms of cellulose-based functional materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Major activated corrosion products cobalt, silver and antimony in the primary coolant of PWR power plants

    International Nuclear Information System (INIS)

    Xu Mingxia

    2012-01-01

    The production of the major activated corrosion products such as cobalt, silver and antimony in the primary coolant of PWR power plants and the impacts on the increase of the dose rates caused by these corrosion products during the shutdown are described in the paper. Investigating the corrosion product behavior during the operation and shutdown periods aims at detecting the appearance of these radiological pollutants in the early time and searching relevant solutions that may enable eventually to decrease the dose rate. The solutions may include: Replacing critical material in the primary system's equipment and components, which contact with primary coolant circuit to possibly limit the source term, Elaborating strictly the specific chemical and shutdown procedure to optimize the purification capacity and to minimize the over-contaminations; Improving purification techniques according to the real operation circumstance, and limiting the impacts of these pollutants. It is obvious in the real practices that implementing appropriate solution will be benefit to decrease or limit the pollutants species like cobalt, silver and antimony. (author)

  11. Biocidal Activity of Plasma Modified Electrospun Polysulfone Mats Functionalized with Polyethyleneimine-Capped Silver Nanoparticles

    KAUST Repository

    Schiffman, Jessica D.

    2011-11-01

    The incorporation of silver nanoparticles (AgNPs) into polymeric nanofibers has attracted a great deal of attention due to the strong antimicrobial activity that the resulting fibers exhibit. However, bactericidal efficacy of AgNP-coated electrospun fibrous mats has not yet been demonstrated. In this study, polysulfone (PSf) fibers were electrospun and surface-modified using an oxygen plasma treatment, which allowed for facile irreversible deposition of cationically charged polyethyleneimine (PEI)-AgNPs via electrostatic interactions. The PSf-AgNP mats were characterized for relative silver concentration as a function of plasma treatment time using ICP-MS and changes in contact angle. Plasma treatment of 60 s was the shortest time required for maximum loss of bacteria (Escherichia coli) viability. Time-dependent bacterial cytotoxicity studies indicate that the optimized PSf-AgNP mats exhibit a high level of inactivation against both Gram negative bacteria, Escherichia coli, and Gram positive bacteria, Bacillus anthracis and Staphylococcus aureus. © 2011 American Chemical Society.

  12. Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

    Science.gov (United States)

    Ren, Yan-yu; Yang, Hui; Wang, Tao; Wang, Chuang

    2016-11-01

    Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag+ (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO3) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO3 concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV-vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10-16 nm. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications.

  13. Anesthetic activity of Brazilian native plants in silver catfish (Rhamdia quelen

    Directory of Open Access Journals (Sweden)

    Lenise de Lima Silva

    Full Text Available There is an increasing demand for inexpensive and safe anesthetics that can reduce fish stress caused by some procedures such as capture and handling. In this context, the present study evaluated the potential of essential oils (EO of three Brazilian native plants (Hesperozygis ringens, Lippia sidoides and Ocotea acutifolia as anesthetics for the silver catfish - Rhamdia quelen. Moreover, an analysis was made of the chemical composition of these oils and their influence on stress parameter. EO of H. ringens and O. acutifolia were effective as anesthetics, without behavioral side effects. EO of O. acutifolia (150 µL L-1 promoted an increase in blood glucose level. Regarding to the composition, pulegone accounts for 96.63% of the EO of H. ringens, and caryophyllene oxide amounts to 56.90% of the EO of O. acutifolia. Two chemotypes, thymol and carvacrol (68.40% and 67.89%, respectively were verified for EO of L. sidoides. Both samples of EO of L. sidoides showed anesthetic activity in silver catfish, but exposure also caused loss of mucus and mortality. Thus, only the EO of H. ringens and O. acutifolia are advised for anesthetic use

  14. Rapid biosynthesis and characterization of silver nanoparticles: an assessment of antibacterial and antimycotic activity

    Science.gov (United States)

    Kanawaria, Sajjan Kumar; Sankhla, Aryan; Jatav, Pradeep Kumar; Yadav, Raghvendra Singh; Verma, Kumar Sambhav; Velraj, Parthiban; Kachhwaha, Sumita; Kothari, Shanker Lal

    2018-04-01

    Bioassisted synthesis provides a facile, convenient, and promising approach to produce many inorganic nanostructures. Herein, we report a rapid biosynthesis of silver nanoparticles (AgNPs) using Thuja occidentalis (L.) leaf extract with an emphasis on their antibacterial and antimycotic activity. Interestingly, the synthesis of AgNPs was completed in a short duration of 35-40 min. The electron micrographs showed AgNPs with particles Bacillus subtilis. An AgNP solution with 30 µg/ml concentration arrested the growth of bacterial strains making a zone of inhibition > 15 mm. The antimycotic activity against Aspergillus niger, Fusarium spp., and Alternaria alternata species increased monotonically with nanoparticle concentration in the growth media. A 10 ppm solution of AgNP was detrimental to fungal growth. Thus, the technique provides an avenue to synthesize antibiotic AgNPs without use of other external agents.

  15. Antimicrobial activity of silver nanoparticles encapsulated in poly-N-isopropylacrylamide-based polymeric nanoparticles.

    Science.gov (United States)

    Qasim, Muhammad; Udomluck, Nopphadol; Chang, Jihyun; Park, Hansoo; Kim, Kyobum

    2018-01-01

    In this study, we analyzed the antimicrobial activities of poly- N -isopropylacrylamide (pNIPAM)-based polymeric nanoparticles encapsulating silver nanoparticles (AgNPs). Three sizes of AgNP-encapsulating pNIPAM- and pNIPAM-NH 2 -based polymeric nanoparticles were fabricated. Highly stable and uniformly distributed AgNPs were encapsulated within polymeric nanoparticles via in situ reduction of AgNO 3 using NaBH 4 as the reducing agent. The formation and distribution of AgNPs was confirmed by UV-visible spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometry, respectively. Both polymeric nanoparticles showed significant bacteriostatic activities against Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria depending on the nanoparticle size and amount of AgNO 3 used during fabrication.

  16. Experimental studies on excitation functions of the proton-induced activation reactions on silver

    International Nuclear Information System (INIS)

    Uddin, M.S.; Hagiwara, M.; Baba, M.; Tarkanyi, F.; Ditroi, F.

    2005-01-01

    Excitation functions were measured for the production of 106m,105 Ag, 103,101,100 Pd, 105,102,101m,100,99 Rh and 97 Ru via proton-induced activation reactions on natural silver using a stacked foil technique in the energy range 11-80 MeV. The residual activity measurements were carried out nondestructively by the high-resolution HPGe γ-ray spectroscopy. Thick target integral yields were deduced using the measured cross-sections from the respective threshold energies of the investigated reactions up to 80 MeV. The present work gives new results for the investigated radionuclides. The data in MENDL-2P deduced with the theoretical model code ALICE-IPPE are consistent in shape with the measured values, but show disagreement in magnitude

  17. Silver nanoparticles and dissolved silver activate contrasting immune responses and stress-induced heat shock protein expression in sea urchin.

    Science.gov (United States)

    Magesky, Adriano; de Oliveira Ribeiro, Ciro A; Beaulieu, Lucie; Pelletier, Émilien

    2017-07-01

    Using immune cells of sea urchin Strongylocentrotus droebachiensis in early development as a model, the cellular protective mechanisms against ionic and poly(allylamine)-coated silver nanoparticle (AgNPs; 14 ± 6 nm) treatments at 100 μg L -1 were investigated. Oxidative stress, heat shock protein expression, and pigment production by spherulocytes were determined as well as AgNP translocation pathways and their multiple effects on circulating coelomocytes. Sea urchins showed an increasing resilience to Ag over time because ionic Ag is accumulated in a steady way, although nanoAg levels dropped between 48 h and 96 h. A clotting reaction emerged on tissues injured by dissolved Ag (present as chloro-complexes in seawater) between 12 h and 48 h. Silver contamination and nutritional state influenced the production of reactive oxygen species. After passing through coelomic sinuses and gut, AgNPs were found in coelomocytes. Inside blood vessels, apoptosis-like processes appeared in coelomocytes highly contaminated by poly(allylamine)-coated AgNPs. Increasing levels of Ag accumulated by urchins once exposed to AgNPs pointed to a Trojan-horse mechanism operating over 12-d exposure. However, under short-term treatments, physical interactions of poly(allylamine)-coated AgNPs with cell structures might be, at some point, predominant and responsible for the highest levels of stress-related proteins detected. The present study is the first report detailing nano-translocation in a marine organism and multiple mechanisms by which sea urchin cells can deal with toxic AgNPs. Environ Toxicol Chem 2017;36:1872-1886. © 2016 SETAC. © 2016 SETAC.

  18. Prevalence, molecular characterization of Staphylococcus aureus isolated from cheese and in vitro antibacterial activity of silver nanoparticles against such strains

    Directory of Open Access Journals (Sweden)

    Karima G. Abdel Hameed

    2015-07-01

    Full Text Available Aim: The aim was to investigate cheese samples for the prevalence of Staphylococcus aureus, evaluate multiplex polymerase chain reaction (PCR methods for S. aureus identification, as well as to determine the antibacterial activity of silver nanoparticles against such strains. Materials and Methods: Total of 100 random locally manufactured cheese samples were collected from Qena dairy markets, Egypt, and examined conventionally for the prevalence of S. aureus then, confirmation of these isolates were done using multiplex PCR. The antibacterial activity of silver nanoparticles against such isolates was also checked. Results: Lower prevalence of S. aureus in Damietta cheese (54% than in Kareish cheese (62% was recorded. As well lower frequency distribution for both S. aureus (36% and CNS (8% was also reported for Damietta cheese. Using of multiplex PCR method for S. aureus identification have been confirmed all 58 S. aureus stains that were identified conventionally by detection of two PCR products on agarose gel: The 791 bp and the 638 bp. The correlation coefficient between conventional and multiplex PCR method was 0.91 and was significant at p≤0.001. Regarding antibacterial activity of silver nanoparticles using disk diffusion method on Baird Parker agar it was found that inhibition zone of silver nanoparticles against S. aureus, was 19.2±0.91 mm and it was higher than that produced by gentamicin (400 units/ml 15.2±0.89 mm. Conclusions: The present study illustrated the higher prevalence of S. aureus in cheese samples that may constitute a public health hazard to consumers. According to the results, it can be concluded that silver nanoparticles can be used as an effective antibacterial against S. aureus. Thereby, there is a need for an appropriate study for using silver nanoparticles in cleaning and disinfection of equipment and in food packaging.

  19. Widespread genetic switches and toxicity resistance proteins for fluoride.

    Science.gov (United States)

    Baker, Jenny L; Sudarsan, Narasimhan; Weinberg, Zasha; Roth, Adam; Stockbridge, Randy B; Breaker, Ronald R

    2012-01-13

    Most riboswitches are metabolite-binding RNA structures located in bacterial messenger RNAs where they control gene expression. We have discovered a riboswitch class in many bacterial and archaeal species whose members are selectively triggered by fluoride but reject other small anions, including chloride. These fluoride riboswitches activate expression of genes that encode putative fluoride transporters, enzymes that are known to be inhibited by fluoride, and additional proteins of unknown function. Our findings indicate that most organisms are naturally exposed to toxic levels of fluoride and that many species use fluoride-sensing RNAs to control the expression of proteins that alleviate the deleterious effects of this anion.

  20. Functioned silver nanoparticle loaded activated carbon for the recovery of bioactive molecule from bacterial fermenter for its bactericidal activity

    Science.gov (United States)

    Arivizhivendhan, Villalan; Mahesh, Mannacharaju; Boopathy, Ramasamy; Karthikeyan, Sekar; Mary, Rathanasamy Regina; Sekaran, Ganesan

    2018-01-01

    A novel continuous production and extraction of bacterial bioactive prodigiosin (PG) from fermented using silver nanoparticle impregnated functioned activated carbon composite is proposed for cost-effective and ecofriendly microbial technique. Hence, in this investigation silver nanoparticle was impregnated onto functioned activated carbon ([AC]F) as a support matrix and to enable the separation of PG conjugated silver nanoparticle from the fermented medium. A laboratory scale experiment was carried out to evaluate the continuous production and recovery of PG using [AC@Ag]F. Ag nanoparticle impregnated [AC]F ([AC@Ag]F) characterized by FT-IR, XRD, TGA, DSC and SEM. Instrumental analyses confirmed that Ag nanoparticles significantly impregnated on AC through the functionalization of AC with diethanolamine and it enhances the binding capacity between AC and Ag. The various process parameters, such as contact time, pH, and mass of [AC@Ag]F, were statistically optimized for the recovery of PG using Response Surface Methodology (RSM). The maximum extraction of PG in [AC@Ag]F was found to be 16.2 ± 0.2 mg g-1, its twofold higher than [AC]F. Further, PG conjugated [AC@Ag]F and ([AC@Ag]F-PG) were checked for the growth inhibition of gram negative and gram positive bacteria without formation of biofilm upto 96 h. Hence, the developed matrix could be eco-friendly, viable and lower energy consumption step for separation of the bacterial bioactive PG from fermented broth. In additionally, [AC@Ag]F-PG was used as an antifouling matrix without formation of biofilm.

  1. Antibacterial activity of silver nanoparticles stabilized on tannin-grafted collagen fiber

    Energy Technology Data Exchange (ETDEWEB)

    He Li [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Gao Siying; Wu Hao [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); Liao Xuepin, E-mail: xpliao@scu.edu.cn [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); He Qiang [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Shi Bi, E-mail: sibitannin@vip.163.com [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China) and Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China)

    2012-07-01

    Bayberry tannin (BT), a typical plant polyphenol, was grafted on collagen fiber (CF) in different mass ratios. Subsequently, the BT-grafted CF (BT-CF) was used as carrier and stabilizer to prepare BT-CF stabilized silver nanoparticles (BT-CF-AgNPs). Scanning Electron Microscopy image of BT-CF-AgNPs showed that the BT-CF-AgNPs was in ordered fibrous state. X-ray Diffraction patterns and Transmission Electron Microscopy images offered evidence that the Ag nanoparticles were well dispersed on BT-CF. Fourier Transform-Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) investigations revealed that the Ag NPs were stabilized by the phenolic hydroxyls and quinones of BT on CF through electron donation/acception interaction. Antibacterial experiments demonstrated that BT-CF-AgNPs exhibited high antibacterial activity. When cell suspensions of Escherichia coli and Staphylococcus aureus (10{sup 4}-10{sup 5} cfu/mL) were contacted with BT{sub 0.19}-CF-AgNPs (mass ratio of BT to CF = 0.19, conc. of Ag = 8 {mu}g/mL) at 310 K under constant shaking, the number of cells went down to zero within 2 h. In addition, the minimal inhibitory concentration of BT{sub 0.19}-CF-AgNPs against Escherichia coli, Staphylococcus aureus, Penicillium glaucum and Saccharomyces cerevisiae was 2 {mu}g/mL, 4 {mu}g/mL, 6 {mu}g/mL and 12 {mu}g/mL Ag, respectively. During recycling use, the antibacterial activity of BT{sub 0.19}-CF-AgNPs against Escherichia coli can last for 5 cycles. These facts suggest that BT-CF-AgNPs can be used as a new and effective antibacterial agent. - Highlights: Black-Right-Pointing-Pointer Bayberry tannin-grafted collagen fiber can be acted as carrier and stabilizer for the preparation of nano-silver (AgNPs) with different particle size. Black-Right-Pointing-Pointer Bayberry tannin-grafted collagen fiber stabilized silver nanoparticles (BT-CF-AgNPs) were characterized by SEM, XRD, TEM, FTIR and XPS. Black-Right-Pointing-Pointer BT-CF-AgNPs has the

  2. Silver Nanoparticles Complexed with Bovine Submaxillary Mucin Possess Strong Antibacterial Activity and Protect against Seedling Infection.

    Science.gov (United States)

    Makarovsky, Daria; Fadeev, Ludmila; Salam, Bolaji Babajide; Zelinger, Einat; Matan, Ofra; Inbar, Jacob; Jurkevitch, Edouard; Gozin, Michael; Burdman, Saul

    2018-02-15

    A simple method for the synthesis of nanoparticles (NPs) of silver (Ag) in a matrix of bovine submaxillary mucin (BSM) was reported previously by some of the authors of this study. Based on mucin characteristics such as long-lasting stability, water solubility, and surfactant and adhesive characteristics, we hypothesized that these compounds, named BSM-Ag NPs, may possess favorable properties as potent antimicrobial agents. The goal of this study was to assess whether BSM-Ag NPs possess antibacterial activity, focusing on important plant-pathogenic bacterial strains representing both Gram-negative ( Acidovorax and Xanthomonas ) and Gram-positive ( Clavibacter ) genera. Growth inhibition and bactericidal assays, as well as electron microscopic observations, demonstrate that BSM-Ag NPs, at relatively low concentrations of silver, exert strong antimicrobial effects. Moreover, we show that treatment of melon seeds with BSM-Ag NPs effectively prevents seed-to-seedling transmission of Acidovorax citrulli , one of the most threatening pathogens of cucurbit production worldwide. Overall, our findings demonstrate strong antimicrobial activity of BSM-Ag NPs and their potential application for reducing the spread and establishment of devastating bacterial plant diseases in agriculture. IMPORTANCE Bacterial plant diseases challenge agricultural production, and the means available to manage them are limited. Importantly, many plant-pathogenic bacteria have the ability to colonize seeds, and seed-to-seedling transmission is a critical route by which bacterial plant diseases spread to new regions and countries. The significance of our study resides in the following aspects: (i) the simplicity of the method of BSM-Ag NP synthesis, (ii) the advantageous chemical properties of BSM-Ag NPs, (iii) the strong antibacterial activity of BSM-Ag NPs at relatively low concentrations of silver, and (iv) the fact that, in contrast to most studies on the effects of metal NPs on plant pathogens

  3. Green synthesis and characterization of monodispersed silver nanoparticles using root bark aqueous extract of Annona muricata Linn and their antimicrobial activity

    Science.gov (United States)

    Ezealisiji, K. M.; Noundou, X. S.; Ukwueze, S. E.

    2017-11-01

    In recent time, various phytosynthetic methods have been employed for the fabrication of silver nanoparticles; these unique metal nanoparticles are used in several applications which include pharmaceuticals and material engineering. The current research reports a rapid and simple synthetic partway for silver nanoparticles (AgNPs) using root bark aqueous extract of Annona muricata and the evaluation of its antimicrobial efficacy against pathogenic microorganisms. The root bark extract was treated with aqueous silver nitrate solution. Silver ions were reduced to silver atoms which on aggregation gave Silver nanoparticles; the biosynthesized AgNPs were characteristically spherical, discreet and stabilized by phytochemical entities and were characterized using ultraviolet visible spectroscopy, transmission electron microscope (TEM) and photon correlation microscopy. The aqueous plant extract-AgNPs suspension was subjected to Fourier transform infrared spectroscopy. TEM result for the average particle size is 22 ± 2 nm. The polydispersity index and zeta-potential were found to be 0.44 ± 0.02 and - 27.90 ± 0.01 mV, respectively (Zeta-Sizer). The antimicrobial evaluation result showed that the synthesized silver nanoparticles at different concentration were very active against the Gram-positive bacteria ( B. subtilis, S. aureous) and Gram-negative bacteria ( K. Pneumonia, E. Coli and Pseudomonas aeruginosa), P. aeruginosa being most susceptible to the anti microbial effect of the silver nanoparticles. Stable silver nanoparticles with antimicrobial activity were obtained through biosynthesis.

  4. Synthesis, characterization and antibacterial activity against Gram positive and Gram negative bacteria of biomimetically coated silver nanoparticles.

    Science.gov (United States)

    Amato, Elvio; Diaz-Fernandez, Yuri A; Taglietti, Angelo; Pallavicini, Piersandro; Pasotti, Luca; Cucca, Lucia; Milanese, Chiara; Grisoli, Pietro; Dacarro, Cesare; Fernandez-Hechavarria, Jose M; Necchi, Vittorio

    2011-08-02

    In the present work, we describe a simple procedure to produce biomimetically coated silver nanoparticles (Ag NPs), based on the postfunctionalization and purification of colloidal silver stabilized by citrate. Two biological capping agents have been used (cysteine Cys and glutathione GSH). The composition of the capped colloids has been ascertained by different techniques and antibacterial tests on GSH-capped Ag NPs have been conducted under physiological conditions, obtaining values of Minimum Inhibitory Concentration (MIC) of 180 and 15 μg/mL for Staphylococcus aureus and Escherichia coli, respectively. The antibacterial activity of these GSH capped NPs can be ascribed to the direct action of metallic silver NPs, rather than to the bulk release of Ag(+).

  5. Study of the behavior of high activity waste produced during the regeneration of fast reactor fuel elements by the gaseous fluoride method

    International Nuclear Information System (INIS)

    Kiriolovich, A.P.; Dem'yanovich, M.A.; Lavrinovich, Yu.G.; Skiba, O.V.; Gazizov, R.K.; Vorobey, M.P.

    The composition and certain physicochemical and radiation properties of waste obtained from reprocessing BOR-60 fuel by the gaseous fluoride method were studied on an experimental stand. It was found that from 80 to 85 percent of the total activity is concentrated in the fluorination cakes. From thermographic analysis, measurement of radiation-induced gas evolution and composition of the gaseous phase, it is concluded that the waste must be canned. Compatibility of carbon steel, austenitic steel, and nickel with low-activity fluoride cakes was studied. It is shown that the corrosion of these materials increases with temperature and moisture content of the medium. In the first stage of waste disposal, hermetic storage in special containers of stainless steel or nickel is recommended. From their corrosion resistance in low-activity fluoride cakes, the wall temperatures of containers made of St. 3 should not exceed 100 0 C, Kh18N10T 230 0 C, and nickel 300 0 C. Later, after cooling and a decrease in the γ activity of the waste (10 to 15 years), they can be reprocessed to recover valuable components (Am, Cm, etc.) and then buried. 5 tables

  6. Influence of silver on photocatalytic activity of TiO2

    International Nuclear Information System (INIS)

    Kisen, Carla Yuri; Teodoro, Vinicius; Zaghete, Maria Ap.; Perazolli, Leinig Antonio; Longo, Elson

    2016-01-01

    Full text: This work studied the influence of silver on photo activity of TiO 2 , prepared by Pechini method, in the photodegradation of Rhodamine-B. The catalysts were prepared with different percentage of silver (0.0, 0.5 and 1.0 %) and different calcination temperatures (500, 600 and 700°C), characterized by X-ray diffraction (DRX) and field emission gun - scanning electron microscopy (FEG-SEM), The powders' photo catalytic activity was defined by Rhodamine-B decolorisation test. The solution containing the dye and the catalyst, in the concentration of 0,01 mmol L -1 e 1,0 g L -1 respectively, were submitted to radiation with 9W germicidal lamp for 120 minutes. The control samples, for comparison effects, were made with TiO 2 anatase (Synth brand) and photolysis tests. In the micrographs, obtained by SEM, all the temperatures and compositions employed presented similar morphologies, it is assumed the calcination temperature rise leads to a decreased apparent porosity and the generation of particles clusters. The X-ray diffractograms indicates the calcination temperature influence in the generation of distinct TiO 2 phases during the catalysts synthesis. Regardless of the TiO 2 proportions, the only actual phase with 500°C calcination is the anatase. At 600°C, the rutile phase coexisting with the anatase phase disappears, and the rutile phase predominates. Among the catalysts, what presented greater activity was the TiO 2 with 0.5% Ag and calcination temperature of 500°C, which degraded around 100% in 60 minutes. References: [1] P. Cozolli, E. Fanizza and A. Agostiano. J. Phys.Chem. B108, 9623-9630, 2004. (author)

  7. Photobiosynthesis of stable and functional silver/silver chloride nanoparticles with hydrolytic activity using hyperthermophilic β-glucosidases with industrial potential.

    Science.gov (United States)

    Araújo, Juscemácia N; Tofanello, Aryane; da Silva, Viviam M; Sato, Juliana A P; Squina, Fabio M; Nantes, Iseli L; Garcia, Wanius

    2017-09-01

    The β-glucosidases are important enzymes employed in a large number of processes and industrial applications, including biofuel production from biomass. Therefore, in this study, we reported for the first time the photobiosynthesis of stable and functional silver/silver chloride nanoparticles (Ag/AgCl-NPs) using two hyperthermostable bacterial β-glucosidases with industrial potential. The syntheses were straightforward and rapid processes carried out by mixing β-glucosidase and silver nitrate (in buffer 10mM Tris-HCl, pH 8) under irradiation with light (over a wavelength range of 450-600nm), therefore, compatible with the green chemistry procedure. Synthesized Ag/AgCl-NPs were characterized using a series of physical techniques. Absorption spectroscopy showed a strong absorption band centered at 460nm due to surface plasmon resonance of the Ag-NPs. X-ray diffraction analysis revealed that the Ag/AgCl-NPs were purely crystalline in nature. Under electron microscopy, Ag/AgCl-NPs of variable diameter ranging from 10 to 100nm can be visualized. Furthermore, electron microscopy, zeta potential and Fourier transform infrared spectroscopy results confirmed the presence of β-glucosidases coating and stabilizing the Ag/AgCl-NPs. Finally, the results showed that the enzymatic activities were maintained in the β-glucosidases assisted Ag/AgCl-NPs. The information described here should provide a useful basis for future studies of β-glucosidases assisted Ag/AgCl-NPs, including biotechnological applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Optimization for extracellular biosynthesis of silver nanoparticles by Penicillium aculeatum Su1 and their antimicrobial activity and cytotoxic effect compared with silver ions.

    Science.gov (United States)

    Ma, Liang; Su, Wei; Liu, Jian-Xin; Zeng, Xiao-Xi; Huang, Zhi; Li, Wen; Liu, Zheng-Chun; Tang, Jian-Xin

    2017-08-01

    The present study addresses an eco-friendly and energy-saving method for extracellular biosynthesis of silver nanoparticles (AgNPs) using a cell free filtrate of the fungus strain Penicillium aculeatum Su1 as a reducing agent. Parametric optimization of the biosynthesis process demonstrated different effects on the size, distribution, yield, and synthesis rate of biosynthesized AgNPs. The transmission electron microscopy (TEM) measurements demonstrated that AgNPs were spherical or approximately spherical, with a size between 4 and 55nm. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses indicated that AgNPs were nanocrystalline by nature, with the character of a face-centered cubic (fcc). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the existence of protein molecules that acted as a reducing agent and a capping agent during the biosynthesis process. Furthermore, the biosynthesized AgNPs exhibited higher antimicrobial activity than silver ions against Gram negative bacteria, Gram positive bacteria and fungi. Compared with silver ions, the biosynthesized AgNPs presented higher biocompatibility toward human bronchial epithelial (HBE) cells and high cytotoxicity in a dose-dependent manner with an IC 50 of 48.73μg/mL toward A549 cells. These results demonstrate that Penicillium aculeatum Su1 is a potential bioresource that can be used to produce low-cost and eco-friendly AgNPs as efficient antimicrobial agent, drug delivery vehicle or anticancer drug for clinic treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. 77 FR 43238 - Takes of Marine Mammals Incidental to Specified Activities; Navy Training Conducted at the Silver...

    Science.gov (United States)

    2012-07-24

    ... which case the animal's hearing threshold will recover over time (Southall et al. 2007). Since marine... et al. 2002). However, in order for marine mammals to experience TTS or PTS, the animals have to be... Marine Mammals Incidental to Specified Activities; Navy Training Conducted at the Silver Strand Training...

  10. Antibacterial Activity of Silver-Graphene Quantum Dots Nanocomposites Against Gram-Positive and Gram-Negative Bacteria

    Science.gov (United States)

    Habiba, Khaled (Inventor); Makarov, Vladimir (Inventor); Weiner, Brad R (Inventor); Morell, Gerardo (Inventor)

    2018-01-01

    The invention provides a composite of silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) using pulsed laser synthesis. The nanocomposites were functionalized with polyethylene glycol (PEG). A concentration of 150 .mu.g/mL of Ag-GQDs, a non-toxic level for human cells, exhibits strong antibacterial activity against both Gram-Positive and Gram-Negative Bacteria.

  11. TTC- Based Test as an Efficient Method to Determine Antibiofilm Activity of Silver Nanoparticles

    OpenAIRE

    Chojniak Joanna; Biedroń Izabela; Płaza Grażyna

    2017-01-01

    Among metal nanoparticles, silver nanoparticles are a widely used in various life sectors such as in biomedical applications, air and water purification, food production, cosmetics, garments and in various household products. There are several methods for production of silver nanoparticles. Generally, silver nanoparticles can be prepared by chemical methods such as chemical reduction and electrochemical techniques, physical methods, and biological methods such as the use of microorganisms. Th...

  12. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

  13. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

    International Nuclear Information System (INIS)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

    2016-01-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

  14. Radiation dosimetry by neutron or X ray fluorescence activation of residual silver in ionographic emulsions

    International Nuclear Information System (INIS)

    Heilmann, C.

    1987-01-01

    A global measuring technique which is sensitive enough to detect small silver contents in films for dosimetry applications is presented. The applications studied are neutron dosimetry by measuring residual silver due to recoil protons in developed emulsions and high dose dosimetry by the detection of photolytic silver in fixed emulsions. An individual fast neutron dosimeter which can be used in radiation protection was developed, along with an automatic data analysis and readout system. Application of this technique to the measurement of high radiation doses (100 to 1 million Gy) via the measurement of photolytic silver in fixed, but undeveloped, emulsions confirms the usefulness of the method [fr

  15. Biosynthesis Of Silver Nanoparticles From Marine Seaweed Sargassum Cinereum And Their Antibacterial Activity

    Digital Repository Service at National Institute of Oceanography (India)

    Mohandass, C.; VijayRaj, A.S.; Rajasabapathy, R.; SatheeshBabu, S.; Rao, S.V.; Shiva, C.; De-Mello, I.

    the biosynthesis of gold and silver nanoparticles using various plant sources and obtained a good nanoparticles with an average size of 20‑30 nm[10‑13]. Green synthesis of nanoparticles provides advancement over chemical and physical methods as it is cost... that hygienic benefits have been associated with the use of silver for considerably longer. Records show that Hippocrates recognised the role of silver in the prevention of disease and accounts exist that, the Romans stored wine in silver vessels to prevent...

  16. Tryptophan-Assisted Synthesis Reduces Bimetallic Gold/Silver Nanoparticle Cytotoxicity and Improves Biological Activity

    Directory of Open Access Journals (Sweden)

    Igor O. Shmarakov

    2014-10-01

    Full Text Available Aiming to reduce the potential in vivo hepato-and nephrotoxicity of Ag/Au bimetallic nanoparticles (NPs stabilized by sodium dodecyl sulphate (SDS, an approach involving a simultaneous reduction of silver nitrate and tetrachlorauratic acid using tryptophan (Trp as a reducing/stabilizing agent was applied during NP synthesis. The obtained Ag/Au/Trp NPs (5–15 nm sized were able to form stable aggregates with an average size of 370–450 nm and were potentially less toxic than Ag/Au/SDS in relation to a mouse model system based on clinical biochemical parameters and oxidative damage product estimation. Ag/Au/Trp NPs were shown to exhibit anticancer activity in relation to a Lewis lung carcinoma model. The data generated from the present study support the fact that the use of tryptophan in NP synthesis is effective in attenuating the potential hepatotoxicity and nephrotoxicity of NPs during their in vivo application.

  17. Preparation and characterization of HMSPP/MMT/silver nanocomposite films with antibacterial activity

    International Nuclear Information System (INIS)

    Oliani, Washington Luiz; Komatsu, Luiz Gustavo Hiroki; Berenguer, Isabelle; Lugao, Ademar Benevolo; Parra, Duclerc Fernandes; Lincopan, Nilton

    2015-01-01

    The aim of study was to use nanocomposites for bactericide packing for food. The polypropylene modified by irradiation in acetylene at dose of 12.5 kGy, also known as high-melt-strength-polypropylene (HMSPP), with montmorillonite (MMT) and silver nanoparticles (AgNPs) composed a mix to process by melt intercalation in a twin-screw extruder. As compatibilizer agent it has been used a propylene graft maleic anhydride copolymer (PP-g-MA). The nanocomposites were evaluated by Fourier Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and determination of antibacterial activity. The results indicate the formation of microstructures predominantly intercalated and flocculated. Further, the antibacterial properties of the films were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. (author)

  18. Preparation and characterization of HMSPP/MMT/silver nanocomposite films with antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Oliani, Washington Luiz; Komatsu, Luiz Gustavo Hiroki; Berenguer, Isabelle; Lugao, Ademar Benevolo; Parra, Duclerc Fernandes, E-mail: washoliani@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Lincopan, Nilton [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola de Farmacia. Dept. de Analises Clinicas; Rangari, Vijaya Kumar [Center For Advanced Materials Science and Engineering Tuskegee University, AL (United States)

    2015-07-01

    The aim of study was to use nanocomposites for bactericide packing for food. The polypropylene modified by irradiation in acetylene at dose of 12.5 kGy, also known as high-melt-strength-polypropylene (HMSPP), with montmorillonite (MMT) and silver nanoparticles (AgNPs) composed a mix to process by melt intercalation in a twin-screw extruder. As compatibilizer agent it has been used a propylene graft maleic anhydride copolymer (PP-g-MA). The nanocomposites were evaluated by Fourier Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and determination of antibacterial activity. The results indicate the formation of microstructures predominantly intercalated and flocculated. Further, the antibacterial properties of the films were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. (author)

  19. Parametric study on removal efficiency of impregnated activated charcoal and silver zeolite for radioactive methyl iodide

    International Nuclear Information System (INIS)

    Shiomi, H.; Yuasa, Y.; Tani, A.; Ohki, M.; Nakagawa, T.

    1983-01-01

    The removal efficiency of impregnated activated charcoal and silver zeolite for radioactive methyl iodide is influenced by various parameters such as temperature, relative humidity, face velocity and packing density. This study is to evaluate the dependency of the removal efficiency on each parameter and these combined parameters, quantitatively. Four types of adsorbents, BC-727, AgX, CHC-50 and SS 208C 5KI 3 , were tested. From experimental data and mass transfer theory, an experimental equation for evaluating the removal efficiency of adsorbents was derived under a series of experiments for radioactive methyl iodine-131. It was concluded that the removal efficiency calculated from the experimental equation agreed well with the experimental value. Effects of experimental specific parameters, such as Pre-flow time, methyl iodide injection time and After-flow time, on the removal efficiency of adsorbent are also described

  20. Tea waste biomass activated carbon electrode for simultaneous removal of Cr(VI) and fluoride by capacitive deionization.

    Science.gov (United States)

    Gaikwad, Mahendra S; Balomajumder, Chandrajit

    2017-10-01

    Capacitive deionization is promising less energy based desalination technique to achieve pure water. In the present study microporous activated carbon was prepared from tea waste biomass by chemical and thermal modification. Further TWBAC was used for preparation of the electrode. The TWBAC electrode was applied in the self-made CDI set up for simultaneous removal of hexavalent chromium [Cr(VI)] and fluoride (F) form mixed feed solution of Cr(VI) and F. The performance of TWBAC electrode was found effective for simultaneous removal of Cr(VI) and F from mixed feed solution. The maximum electrosorption capacity of Cr(VI) and F were found 0.77 and 0.74 mg g -1 for 10 mg L -1 and 2.83 and 2.49 mg g -1 for 100 mg L -1 mixed feed solution respectively. The higher removal of Cr(VI) was found due to the electrosorption selectivity of the divalent CrO 4 2- is higher than that of the monovalent F - . Multicomponent isotherm modeling and kinetic study were carried out in this study. TWBAC CDI electrode could be useful for treatment of a low concentrated Cr(VI) and F containing wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effects of CO{sub 2} activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seul-Yi; Park, Soo-Jin, E-mail: sjpark@inha.ac.kr

    2013-11-15

    In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO{sub 2} gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO{sub 2} activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO{sub 2} activation had developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO{sub 2} activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m{sup 2}/g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO{sub 2} activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs.

  2. Effects of CO2 activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

    International Nuclear Information System (INIS)

    Lee, Seul-Yi; Park, Soo-Jin

    2013-01-01

    In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO 2 gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO 2 activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO 2 activation had developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO 2 activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m 2 /g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO 2 activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs

  3. Polyelectrolyte Multilayer Film Coated Silver Nanorods: An Effective Carrier System for Externally Activated Drug Delivery

    Science.gov (United States)

    Paramasivam, Gokul; Sharma, Varsha; Sundaramurthy, Anandhakumar

    2017-08-01

    Nanoparticle anisotropy offers unique functions and features in comparison with spherical nanoparticles (NPs) and makes anisotropic nanoparticles (ANPs) promising candidates in applications like drug delivery, imaging, biosensing and theranostics. Presence of surface active groups (e.g. amine, and carboxylate groups) on their surface provides binding sites for ligands or other biomolecules, and hence, this could be targeted for specific part or cells in our body. In the quest of such surface modification, functionalization of ANPs along Layer-by-Layer (LbL) coating of oppositely charged polyelectrolytes (PE) reduces cellular toxicity and promotes easy encapsulation of drugs. In this work, we report the silver nanorods (AgNRs) synthesis by adsorbate directed synthetic approach using cetyltrimethyl ammonium bromide (CTAB). The formed ANPs is investigated by scanning electron microscopy (SEM) and UV-Visible (UV-Vis) spectroscopy revealing the shaping of AgNRs of 3-16 nm aspect ratio with some presence of triangles. These NRs were further coated with bio polymers of chitosan (CH) and dextran sulphate (DS) through LbL approach and used for encapsulation of water soluble anti-bacterial drugs like ciprofloxacin hydrochloride (CFH). The encapsulation of drugs and profiles of drug release were investigated and compared to that of spherical silver nanoparticles (AgNPs). The added advantages of the proposed drug delivery system (DDS) can be externally activated to release the loaded drug and used as contrast agents for biological imaging under exposure to NIR light. Such system shows unique and attractive characteristics required for drug delivery and bioimaging thus offering the scope for further development as theranostic material.

  4. Piper nigrum Leaf and Stem Assisted Green Synthesis of Silver Nanoparticles and Evaluation of Its Antibacterial Activity Against Agricultural Plant Pathogens

    Directory of Open Access Journals (Sweden)

    Kanniah Paulkumar

    2014-01-01

    Full Text Available Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM, energy dispersive X-ray analysis (EDAX, and Fourier Transform Infrared Spectroscopy (FTIR. The observation of the peak at 460 nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7–50 nm and 9–30 nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology.

  5. In Vitro and In Vivo Osteogenic Activity of Titanium Implants Coated by Pulsed Laser Deposition with a Thin Film of Fluoridated Hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Luyuan Chen

    2018-04-01

    Full Text Available To enhance biocompatibility, osteogenesis, and osseointegration, we coated titanium implants, by krypton fluoride (KrF pulsed laser deposition, with a thin film of fluoridated hydroxyapatite (FHA. Coating was confirmed by scanning electron microscopy (SEM and scanning probe microscopy (SPM, while physicochemical properties were evaluated by attenuated reflectance Fourier transform infrared spectroscopy (ATR-FTIR. Calcium deposition, osteocalcin production, and expression of osteoblast genes were significantly higher in rat bone marrow mesenchymal stem cells seeded on FHA-coated titanium than in cells seeded on uncoated titanium. Implantation into rat femurs also showed that the FHA-coated material had superior osteoinductive and osseointegration activity in comparison with that of traditional implants, as assessed by microcomputed tomography and histology. Thus, titanium coated with FHA holds promise as a dental implant material.

  6. Fluoride varnish or fluoride mouth rinse?

    DEFF Research Database (Denmark)

    Keller, M K; Klausen, BJ; Twetman, S

    2016-01-01

    OBJECTIVE: In many Danish communities, school-based fluoride programs are offered to children with high caries risk in adjunct to tooth brushing. The purpose of this field trial was to compare the caries-preventive effectiveness of two different fluoride programs in 6-12 year olds. BASIC RESEARCH...... different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. INTERVENTIONS: One group received a semi-annual fluoride varnish applications (FV) and the other group continued with an existing program with fluoride mouth rinses once per...... in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program....

  7. Green Synthesized Silver Nanoparticles Exhibit Reduced Toxicity to Mammalian Cells and Retain Antimicrobial Activity

    Science.gov (United States)

    The interest in silver nanoparticles (AgNPs) and silver nanomaterial stems from their antimicrobial properties. AgNPs are being added to clothing, paint, refrigerators, washing machines and a variety of other commercially available items. Recent in vitro and in vivo studies, howe...

  8. Biosynthesis of silver nanoparticles using Reseda Luteola L. and their antimicrobial activity

    NARCIS (Netherlands)

    Nasiriboroumand, Majid Nasiri; Montazer, Majid; Dutschk, Victoria

    2013-01-01

    Among different methods to synthesize silver nanoparticles (SNPs), the biological method has been the most extensively investigated. This study presents a facile and rapid method for biosynthesis of silver nanoparticles from Weld (Reseda Luteola L.) as a natural dye. An aqueous extract of the dye

  9. Silver nanoparticle accumulation by aquatic organisms – neutron activation as a tool for the environmental fate of nanoparticles tracing

    Directory of Open Access Journals (Sweden)

    Asztemborska Monika

    2014-12-01

    Full Text Available Water environments are noted as being some of the most exposed to the influence of toxic nanoparticles (NPs. Therefore, there is a growing need for the investigation of the accumulation and toxicity of NPs to aquatic organisms. In our studies neutron activation followed by gamma spectrometry and liquid scintillation counting were used for studying the accumulation of silver nanoparticles (AgNPs by freshwater larvae of Chironomus and fish Danio rerio. The influence of exposition time, concentration and the source of nanoparticles on the efficiency of AgNP accumulation were studied. It was found that AgNPs are efficiently accumulated by Chironomid larvae for the first 30 hours of exposition; then, the amount of silver nanoparticles decreases. The silver content in larvae increases together with the NP concentration in water. Larvae which have accumulated AgNPs can be a source of nanoparticles for fish and certainly higher levels of Ag in the trophic chain. In comparison with water contamination, silver nanoparticles are more efficiently accumulated if fish are fed with AgNP-contaminated food. Finally, it was concluded that the applied study strategy, including neutron activation of nanoparticles, is very useful technique for tracing the uptake and accumulation of NPs in organisms

  10. Nonactivated titanium-dioxide nanoparticles promote the growth of Chlamydia trachomatis and decrease the antimicrobial activity of silver nanoparticles.

    Science.gov (United States)

    Bogdanov, A; Janovák, L; Lantos, I; Endrész, V; Sebők, D; Szabó, T; Dékány, I; Deák, J; Rázga, Z; Burián, K; Virok, D P

    2017-11-01

    Chlamydia trachomatis and herpes simplex virus (HSV) are the most prevalent bacterial and viral sexually transmitted infections. Due to the chronic nature of their infections, they are able to interact with titanium-dioxide (TiO 2 ) nanoparticles (NPs) applied as food additives or drug delivery vehicles. The aim of this study was to describe the interactions of these two prevalent pathogens with the TiO 2 NPs. Chlamydia trachomatis and HSV-2 were treated with nonactivated TiO 2 NPs, silver NPs and silver decorated TiO 2 NPs before infection of HeLa and Vero cells. Their intracellular growth was monitored by quantitative PCR. Unexpectedly, the TiO 2 NPs (100 μg ml -1 ) increased the growth of C. trachomatis by approximately fourfold, while the HSV-2 replication was not affected. Addition of TiO 2 to silver NPs decreased their antimicrobial activity against C. trachomatis up to 27·92-fold. In summary, nonactivated TiO 2 NPs could increase the replication of C. trachomatis and decrease the antimicrobial activity of silver NPs. The food industry or drug delivery use of TiO 2 NPs could enhance the growth of certain intracellular pathogens and potentially worsen disease symptoms, a feature that should be further investigated. © 2017 The Society for Applied Microbiology.

  11. Innate catalytic and free radical scavenging activities of silver nanoparticles synthesized using Dillenia indica bark extract.

    Science.gov (United States)

    Mohanty, Alfa S; Jena, Bhabani S

    2017-06-15

    A green approach was envisaged for the rapid synthesis of stable silver nanoparticles in an aqueous medium using phenolic rich ethanolic bark extract from D. indica with marked free radical scavenging and reducing ability. Biosynthesis of silver nanoparticles (AgNPs) was confirmed and characterized by using UV-visible spectroscopy, particle size analyzer, X-ray diffractometry (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FT-IR). Bio-reduction of Ag+ was confirmed with the appearance of golden yellow coloration within 5-10min at 45°C with maximum absorbance at 421nm. XRD analysis of AgNPs indicated the crystalline nature of metallic Ag. As analyzed by TEM, AgNPs were found to be spherical in shape, well dispersed and size varied from 15 to 35nm and dynamic light scattering (DLS) studies showed the average particle size of 29nm with polydispersity index (PDI) of 0.280. Synthesized AgNPs were showing surface functionalization as revealed through FTIR studies. These AgNPs were observed to be highly stable at room temperature (28±2°C) for more than 3months, thereby indicating the ethanolic extract of D. indica was a reducing as well as a capping agent for stabilization of AgNPs. Moreover, these green synthesized AgNPs showed enhanced free radical scavenging and excellent catalytic activities when used in the reduction of 4-nitrophenol and methylene blue dye, at room temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Exploiting silver nanoparticles with PMAA against aedes aegypti larvae development: potential larvicidal activity

    Science.gov (United States)

    Carvalho, Mariana T.; de Santana, Gisele S.; de Andrade, Audrey N.; Cabral, Amanda; da Silva Rosa-Leão, Nairane; de Melo-Santos, Maria Alice V.; Gomes, Anderson S. L.

    2018-02-01

    Aedes aegypti is one of the mosquito species with major epidemiological importance in Brazil, involved with the transmission of the arboviruses such as Dengue, Chikungunya and Zika. Since the mosquito is well adapted to the urban environments, where there are large amounts of breeding sites for larvae and pupae, its control has become increasingly difficult. Since 1996, the usual control is made by using chemical larvicides, but the continued use of some of these compounds has led to the selection of A. aegypti resistant populations. Therefore, the search for new insecticidal substances is necessary to guarantee the control of this specie. Our goal is to establish a new larvicide with high toxicity without the drawback of resistance. For this, we developed a low-cost green synthesized silver nanoparticles with a poly(methacrylic acid) outer layer, catalyzed with ultra violet light. We tested nanoparticles samples produced from different batches in laboratory bioassays against fourth-instar larvae. The results showed a desired toxic activity, presenting 10% to 100% of mortalities in concentrations ranging from 0.01 to 1.1 ppm, and from the bioassay we have obtained LC50 = 0.027 ppm and LC90 = 0.044 ppm, after 24 hours of exposure. Imaging the threated larvae by optical microscopy and optical coherence tomography helped to clarify the potential larvae death mechanism. These results associated with the simplicity and low cost of production of these silver nanoparticles, reveal their great potential for the development of products to control of A. aegypti larvae.

  13. Gamma-Irradiation modified polypropylene and nano silver hybrid films: antibacterial activity

    International Nuclear Information System (INIS)

    Oliani, Washigton L.; Alcantara, Mara T.S.; Lima, Luis F.C.P. de; Bueno, Nelson R.; Rogero, Sizue O.; Lugao, Ademar B.; Parra, Duclerc F.; Huenuman, Nilton E.L.; Santos, Priscila M. dos

    2013-01-01

    This paper presents a study of films based on blends of polypropylene (PP) with radiation modified PP and insertion of silver nanoparticles aiming bactericide effect. The use of silver (Ag) gives important antibacterial properties since silver is highly toxic for bacteria. The blend of 50/50 PP and gamma irradiated PP was processed in a twin screw extruder. The polypropylene was processed for five PP-Nanocomposite AgNPs in different concentrations of 0.25%; 0.5%; 1.0%; 2.0% and 4.0% in wt%. The material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), cytotoxicity assay and reduction colony-forming unit (CFU). The analyzed films showed agglomeration of silver particles and regions with homogeneous distribution of the particles. The interactions of the nano silver bactericidal effect with E. coli and S. aureus were assessed. (author)

  14. Gamma-Irradiation modified polypropylene and nano silver hybrid films: antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Oliani, Washigton L.; Alcantara, Mara T.S.; Lima, Luis F.C.P. de; Bueno, Nelson R.; Rogero, Sizue O.; Lugao, Ademar B.; Parra, Duclerc F., E-mail: washoliani@usp.br [Instituto de Pesquisas Energeticas Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil); Huenuman, Nilton E.L.; Santos, Priscila M. dos [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Dept. of Microbiologia; Riella, Humberto G. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2013-07-01

    This paper presents a study of films based on blends of polypropylene (PP) with radiation modified PP and insertion of silver nanoparticles aiming bactericide effect. The use of silver (Ag) gives important antibacterial properties since silver is highly toxic for bacteria. The blend of 50/50 PP and gamma irradiated PP was processed in a twin screw extruder. The polypropylene was processed for five PP-Nanocomposite AgNPs in different concentrations of 0.25%; 0.5%; 1.0%; 2.0% and 4.0% in wt%. The material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), cytotoxicity assay and reduction colony-forming unit (CFU). The analyzed films showed agglomeration of silver particles and regions with homogeneous distribution of the particles. The interactions of the nano silver bactericidal effect with E. coli and S. aureus were assessed. (author)

  15. Shape-dependent antibacterial activity of silver nanoparticles on Escherichia coli and Enterococcus faecium bacterium

    Science.gov (United States)

    Alshareef, A.; Laird, K.; Cross, R. B. M.

    2017-12-01

    Silver nanoparticles (AgNPs) have been shown to exhibit strong antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria including antibiotic resistant strains. This study aims to compare the bactericidal effect of different shaped AgNPs (spherical and truncated octahedral) against Escherichia coli and Enterococcus faecium. The antimicrobial activity of a range of concentrations (50, 100, 1000 μg/ml) was determined over 24 h using both optical density and viable counts. Truncated octahedral AgNPs (AgNOct) were found to be more active when compared with spherical AgNPs (AgNS). The difference in shape resulted in differences in efficacy which may be due to the higher surface area of AgNOct compared to AgNS, and differences in active facets and surface energies, with AgNPs having a bacteriostatic effect and AgNOct being bactericidal after 4 h. The results suggest that AgNPs can be used as effective growth inhibitors in different microorganisms, rendering them applicable to various medical devices and antimicrobial control systems.

  16. Size-dependent antibacterial activities of silver nanoparticles against oral anaerobic pathogenic bacteria.

    Science.gov (United States)

    Lu, Zhong; Rong, Kaifeng; Li, Ju; Yang, Hao; Chen, Rong

    2013-06-01

    Dental caries and periodontal disease are widespread diseases for which microorganism infections have been identified as the main etiology. Silver nanoparticles (Ag Nps) were considered as potential control oral bacteria infection agent due to its excellent antimicrobial activity and non acute toxic effects on human cells. In this work, stable Ag Nps with different sizes (~5, 15 and 55 nm mean values) were synthesized by using a simple reduction method or hydrothermal method. The Nps were characterized by powder X-ray diffraction, transmission electron microscopy and UV-vis absorption spectroscopy. The antibacterial activities were evaluated by colony counting assay and growth inhibition curve method, and corresponding minimum inhibitory concentration (MIC) against five anaerobic oral pathogenic bacteria and aerobic bacteria E. coli were determined. The results showed that Ag Nps had apparent antibacterial effects against the anaerobic oral pathogenic bacteria and aerobic bacteria. The MIC values of 5-nm Ag against anaerobic oral pathogenic bacteria A. actinomycetemcomitans, F. nuceatum, S. mitis, S. mutans and S. sanguis were 25, 25, 25, 50 and 50 μg/mL, respectively. The aerobic bacteria were more susceptible to Ag NPs than the anaerobic oral pathogenic bacteria. In the mean time, Ag NPs displayed an obvious size-dependent antibacterial activity against the anaerobic bacteria. The 5-nm Ag presents the highest antibacterial activity. The results of this work indicated a potential application of Ag Nps in the inhibition of oral microorganism infections.

  17. The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study

    International Nuclear Information System (INIS)

    Abbaszadegan, A.; Ghahramani, Y.; Nabavizadeh, M.; Gholami, A.; Hemmateenejad, I.; Dorostkar, S.; Sharghi, H.

    2014-01-01

    The bactericidal efficiency of various positively and negatively charged silver nanoparticles has been extensively evaluated in literature, but there is no report on efficacy of neutrally charged silver nanoparticles. The goal of this study is to evaluate the role of electrical charge at the surface of silver nanoparticles on antibacterial activity against a panel of microorganisms. Three different silver nanoparticles were synthesized by different methods, providing three different electrical surface charges (positive, neutral, and negative). The antibacterial activity of these nanoparticles was tested against gram-positive (i.e., Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes) and gram-negative (i.e., Escherichia coli and Proteus vulgaris) bacteria. Well diffusion and micro-dilution tests were used to evaluate the bactericidal activity of the nanoparticles. According to the obtained results, the positively-charged silver nanoparticles showed the highest bactericidal activity against all microorganisms tested. The negatively charged silver nanoparticles had the least and the neutral nanoparticles had intermediate antibacterial activity. The most resistant bacteria were Proteus vulgaris. We found that the surface charge of the silver nanoparticles was a significant factor affecting bactericidal activity on these surfaces. Although the positively charged nanoparticles showed the highest level of effectiveness against the organisms tested, the neutrally charged particles were also potent against most bacterial species.

  18. Preparation and characterization of uniform-sized chitosan/silver microspheres with antibacterial activities

    Energy Technology Data Exchange (ETDEWEB)

    An, Jing; Ji, Zhenxing; Wang, Desong, E-mail: dswang06@126.com; Luo, Qingzhi; Li, Xueyan

    2014-03-01

    The chitosan/silver microspheres (CAgMs), which possess effective inhibitory on microorganisms, were prepared by an inverse-emulsification cross-linking method using CS/Ag sol as dispersed phase, whiteruss as continuous phase, and glutaraldehyde as crosslinking agent. The size and shape of CAgMs, greatly affecting their antibacterial activities, were controlled by varying the concentrations of cross-linking agent, emulsifier and CS/Ag colloid. The preparation conditions for obtaining uniform-sized microspheres were optimized. The morphology of CAgMs was characterized by scanning electron microscopy (SEM) and laser particle size analysis. The spherical CAgMs with smooth surface in the mean size of ca. 5 μm exhibited a narrow particle size distribution. Energy Dispersive X-ray spectroscopy (EDX) revealed the elemental composition of the microspheres. Transmission electron micrographs (TEM) and Fourier transform infrared spectroscopy (FTIR) of the microspheres confirmed the formation of silver nanoparticles (AgNPs). The X-ray diffraction (XRD) patterns and UV–Visible diffuse reflectance spectroscopy (UV–vis DRS) of the sample showed that AgNPs with the diameter no more than 20 nm were face-centered cubic crystallites. X-ray photoelectron spectroscopy (XPS) proved that Ag-O bond existed in the microspheres. Thermogravimetric analysis (TGA) showed that the starting decomposition temperature of CAgMs (ca. 260 °C) was much higher than that of CS (ca. 160 °C), suggesting that the as-prepared CAgMs possessed better thermal stability than original CS did. Antimicrobial assays were performed using typical Gram bacteria and fungi. The inhibitory effect indicated that the as-prepared microspheres exerted a stronger antibacterial activity as the concentration of the AgNPs is increasing, and the microspheres in smaller size had much better antibacterial activity than those in the larger size. The antimicrobial mechanism of CAgMs was discussed. - Highlights: • CAgM was

  19. Calcium fluoride

    International Nuclear Information System (INIS)

    King, C.W.; Nestor, O.H.

    1989-01-01

    A new process for producing large, single, oriented crystals of calcium fluoride (CaF 2 ) has been developed which overcomes the limitations of current growing methods. This process has been reduced to practice and has yielded oriented crystals 17.5 x 17.5 x 5 cm 3 . Currently nearing completion is a system for producing 35 x 35 x 7.5 cm 3 single crystals. A scale up to one-meter-square is considered feasible. This crystal growing process makes possible the fabrication of very large CaF 2 windows. Suitability for very high power lasers, however, requires attention to properties beyond mere size. A process to generate higher purity growth stock (starting material) was also developed. The additional purification of the growth stock contributes to lower bulk absorption, the absence of color centers and increased radiation hardness. Also identified were several specific impurities which correlate with radiation hardness. A correlation was found between color centers induced by laser radiation and ionizing radiation. Other CaF 2 crystal properties such as tensile strength, absorption and laser damage thresholds were studied and are discussed

  20. Toxic influence of silver and uranium salts on activated sludge of wastewater treatment plants and synthetic activated sludge associates modeled on its pure cultures.

    Science.gov (United States)

    Tyupa, Dmitry V; Kalenov, Sergei V; Skladnev, Dmitry A; Khokhlachev, Nikolay S; Baurina, Marina M; Kuznetsov, Alexander Ye

    2015-01-01

    Toxic impact of silver and uranium salts on activated sludge of wastewater treatment facilities has been studied. Some dominating cultures (an active nitrogen fixer Agrobacterium tumifaciens (A.t) and micromyces such as Fusarium nivale, Fusarium oxysporum, and Penicillium glabrum) have been isolated and identified as a result of selection of the activated sludge microorganisms being steadiest under stressful conditions. For these cultures, the lethal doses of silver amounted 1, 600, 50, and 300 µg/l and the lethal doses of uranium were 120, 1,500, 1,000, and 1,000 mg/l, respectively. A.tumifaciens is shown to be more sensitive to heavy metals than micromyces. Synthetic granular activated sludge was formed on the basis of three cultures of the isolated micromyces steadiest against stress. Its granules were much more resistant to silver than the whole native activated sludge was. The concentration of silver causing 50 % inhibition of synthetic granular activated sludge growth reached 160-170 μg/l as far as for the native activated sludge it came only to 100-110 μg/l.

  1. Story of Fluoridation

    Science.gov (United States)

    ... Home Health Info Health Topics Fluoride Share The Story of Fluoridation It started as an observation, that ... this time using photospectrographic analysis, a more sophisticated technology than that used by McKay. Churchill asked an ...

  2. Fluoride in diet

    Science.gov (United States)

    Diet - fluoride ... bones and teeth. Too much fluoride in the diet is very rare. Rarely, infants who get too ... of essential vitamins is to eat a balanced diet that contains a variety of foods from the ...

  3. Silver Nanoparticles Synthesized Using Wild Mushroom Show Potential Antimicrobial Activities against Food Borne Pathogens

    Directory of Open Access Journals (Sweden)

    Yugal Kishore Mohanta

    2018-03-01

    Full Text Available The present study demonstrates an economical and eco-friendly method for the synthesis of silver nanoparticles (AgNPs using the wild mushroom Ganoderma sessiliforme. The synthesis of AgNPs was confirmed and the products characterized by UV-visible spectroscopy, dynamic light scattering spectroscopy and X-ray diffraction analysis. Furthermore, Fourier transform infrared spectroscopy (ATR-FTIR analysis was performed to identify the viable biomolecules involved in the capping and active stabilization of AgNPs. Moreover, the average sizes and morphologies of AgNPs were analyzed by field emission scanning electron microscopy (FE-SEM. The potential impacts of AgNPs on food safety and control were evaluated by the antimicrobial activity of the synthesized AgNPs against common food-borne bacteria, namely, Escherichia coli, Bacillus subtilis, Streptococcus faecalis, Listeria innocua and Micrococcus luteus. The results of this study revealed that the synthesized AgNPs can be used to control the growth of food-borne pathogens and have potential application in the food packaging industry. Moreover, the AgNPs were evaluated for antioxidant activity (DPPH, for biocompatibility (L-929, normal fibroblast cells, and for cytotoxic effects on human breast adenosarcoma cells (MCF-7 & MDA-MB231 to highlight their potential for use in a variety of bio-applications.

  4. PEG capped methotrexate silver nanoparticles for efficient anticancer activity and biocompatibility.

    Science.gov (United States)

    Muhammad, Zarmina; Raza, Abida; Ghafoor, Sana; Naeem, Ayesha; Naz, Syeda Sohaila; Riaz, Sundus; Ahmed, Wajiha; Rana, Nosheen Fatima

    2016-08-25

    Nanocarriers endow tremendous benefits to the drug delivery systems depending upon the specific properties of either component. These benefits include, increase in the drug blood retention time, reduced efflux, additional toxicity and targeted delivery. Methotrexate (MTX) is clinically used for cancer treatment. Higher dosage of MTX results in hepatic and renal toxicity. In this study methotrexate silver nanoparticles (Ag-MTX) coated with polyethylene glycol (PEG) are synthesized and characterized. Their anticancer activity and biocompatibility is also evaluated. Ag-MTX nanoparticles are synthesized by chemical reduction method. They are characterized by Ultraviolet-Visible Spectroscopy and Fourier Transform Infrared Spectroscopy. Average size of PEG coated Ag-MTX nanoparticles (PEG-Ag-MTX nanoparticles) is 12nm. These particles exhibited improved anticancer activity against MCF-7 cell line. Hemolytic activity of these particles was significantly less than MTX. PEG-Ag-MTX nanoparticles are potential nanocarrier of methotrexate which may offer MTX based cancer treatment with reduced side effects. In-vivo investigations should be carried out to explore them in detail. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Silver nanoparticles with antimicrobial activities against Streptococcus mutans and their cytotoxic effect.

    Science.gov (United States)

    Pérez-Díaz, Mario Alberto; Boegli, Laura; James, Garth; Velasquillo, Cristina; Sánchez-Sánchez, Roberto; Martínez-Martínez, Rita-Elizabeth; Martínez-Castañón, Gabriel Alejandro; Martinez-Gutierrez, Fidel

    2015-10-01

    Microbial resistance represents a challenge for the scientific community to develop new bioactive compounds. The goal of this research was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) against a clinical isolate of Streptococcus mutans, antibiofilm activity against mature S. mutans biofilms and the compatibility with human fibroblasts. The antimicrobial activity of AgNPs against the planktonic clinical isolate was size and concentration dependent, with smaller AgNPs having a lower minimum inhibitory concentration. A reduction of 2.3 log in the number of colony-forming units of S. mutans was observed when biofilms grown in a CDC reactor were exposed to 100 ppm of AgNPs of 9.5±1.1 nm. However, AgNPs at high concentrations (>10 ppm) showed a cytotoxic effect upon human dermal fibroblasts. AgNPs effectively inhibited the growth of a planktonic S. mutans clinical isolate and killed established S. mutans biofilms, which suggests that AgNPs could be used for prevention and treatment of dental caries. Further research and development are necessary to translate this technology into therapeutic and preventive strategies. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Silver nanoparticles incorporated into nanostructured biopolymer membranes produced by electrospinning: a study of antimicrobial activity

    Directory of Open Access Journals (Sweden)

    Karen Segala

    2015-12-01

    Full Text Available abstract This study examines the antimicrobial activity of silver nanoparticles incorporated into nanostructured membranes made of cellulose acetate (CA and blends of chitosan/poly-(ethylene oxide, CTS/PEO and prepared by electrospinning. The formation of chemically synthesized Ag nanoparticles (AgNPs was monitored by UV-visible spectroscopy (UV-Vis and characterized by transmission electron microscopy (TEM. The size distribution of the AgNPs was measured by dynamic light scattering (DLS, with an average size of approximately 20 nm. The presence of AgNPs on the surface of electrospun nanofibers was observed by field emission electron microscopy (FEG and confirmed by TEM. The antimicrobial activity of AgNPs incorporated into nanostructured membranes made of CA and CTS/PEO electrospun nanofibers was evaluated in the presence of both Gram-positive bacteria, such as Staphylococcus aureus ATCC 29213 and Propionibacterium acnes ATCC 6919, and Gram-negative bacteria, such as Escherichia coli ATCC 25992 and Pseudomonas aeruginosa ATCC 17933. Microbiological results showed that the presence of AgNPs in CA and CTS/PEO nanostructured membranes has significant antimicrobial activity for the Gram-positive bacteria Escherichia coli and Propionibacterium acnes.

  7. Silver nanoparticles: Antimicrobial activity, cytotoxicity, and synergism with N-acetyl cysteine.

    Science.gov (United States)

    Hamed, Selwan; Emara, Mohamed; Shawky, Riham M; El-Domany, Ramadan A; Youssef, Tareq

    2017-08-01

    The fast progression of nanotechnology has led to novel therapeutic interventions. Antimicrobial activities of silver nanoparticles (Ag NPs) were tested against standard ATCC strains of Staphylococcus aureus (ATCC 9144), Escherichia coli (O157:H7), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 90028) in addition to 60 clinical isolates collected from cancer patients. Antimicrobial activity was tested by disk diffusion method and MIC values for Ag NPs alone and in combination with N-acetylcysteine (NAC) against tested pathogens were determined by broth microdilution method. Ag NPs showed a robust antimicrobial activity against all tested pathogens and NAC substantially enhanced the antimicrobial activity of Ag NPs against all tested pathogens. Synergism between Ag NPs and NAC has been confirmed by checkerboard assay. The effect of Ag NPs on tested pathogens was further scrutinized by Transmission Electron Microscope (TEM) which showed disruption of cell wall in both bacteria and fungi. Ag NPs abrogated the activity of respiratory chain dehydrogenase of all tested pathogens and released muramic acid content from S. aureus in culture. The cytotoxic effect of Ag NPs alone and in combination with NAC was examined using human HepG2 cells and this revealed no cytotoxicity at MIC values of Ag NPs and interestingly, NAC reduced the cytotoxic effect of Ag NPs at concentrations higher than their MIC values. Taken together, Ag NPs have robust antimicrobial activity and NAC substantially enhances their antimicrobial activities against MDR pathogens which would provide a novel safe, effective, and inexpensive therapeutic approach to control the prevalence of MDR pathogens. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Comparative catalytic activity of PET track-etched membranes with embedded silver and gold nanotubes

    Science.gov (United States)

    Mashentseva, Anastassiya; Borgekov, Daryn; Kislitsin, Sergey; Zdorovets, Maxim; Migunova, Anastassiya

    2015-12-01

    Irradiated by heavy ions nanoporous polyethylene terephthalate track-etched membranes (PET TeMs) after +15Kr84 ions bombardment (1.75 MeV/nucl with the ion fluency of 1 × 109 cm-2) and sequential etching was applied in this research as a template for development of composites with catalytically enriched properties. A highly ordered silver and gold nanotubes arrays were embedded in 100 nm pores of PET TeMs via electroless deposition technique at 4 °C during 1 h. All "as-prepared" composites were examined for catalytic activity using reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride as a common reaction to test metallic nanostructures catalysts. The effect of temperature on the catalytic activity was investigated in range of 292-313 K and activation energy were calculated. Kapp of Ag/PET composites linearly increase with an increase of the temperature thus normal Arrhenius behavior have been seen and the activation energy was calculated to be 42.13 kJ/mol. Au/PET composites exhibit not only more powerful catalytic activity but also non-linear dependence of rate constant from temperature. Kapp increased with increasing temperature throughout the 292-308 K temperature range; the reaction had an activation energy 65.32 kJ/mol. In range 311-313 K rate constant dramatically decreased and the apparent activation energy at this temperature rang was -91.44 kJ/mol due some structural changes, i.e. agglomeration of Au nanoparticles on the surface of composite.

  9. Fluoride metabolism in plants

    Energy Technology Data Exchange (ETDEWEB)

    Peters, R; Shorthouse, M

    1964-04-04

    Grass seedlings exposed to inorganic fluoride solutions do not take up appreciable amounts of fluoride until concentrations of more than 1.0 mM (19 p.p.m.) are used. No formation of organic fluoride has been found, even with exposure to 15.75 mM fluoride, indicating that there is no formation of fluoroacetate or similar compounds. 8 references, 2 tables.

  10. Effects of mouthrinses with chlorhexidine and zinc ions combined with fluoride on the viability and glycolytic activity of dental plaque.

    Science.gov (United States)

    Giertsen, E; Scheie, A A

    1995-10-01

    Inhibition of plaque acidogenicity by a mouthrinse with chlorhexidine (CHX) or zinc ions has been ascribed to a prolonged bacteriostasis due to substantive properties of the agents. The present aim was to study the effects of mouthrinses with CHX and Zn ions combined with fluoride on the viability and glycolytic activity of dental plaque in order to assess the bacteriostatic versus possible bactericidal effects. Following 2 d of plaque accumulation, 4 groups of 10 students rinsed with either 12 mM NaF (F), 0.55 mM CHX diacetate+F (F-CHX), 10 mM Zn acetate+F (F-Zn), or with the three agents in combination (F-CHX-Zn). Plaque samples were collected before and 90 min after mouthrinsing. Thereafter, the in vivo plaque pH response to sucrose was monitored in each student using touch microelectrodes. F-CHX and F-CHX-Zn reduced the in vivo pH fall significantly as compared with F, whereas F-Zn exerted a non-significant inhibition. Pooled pre- and post-rinse plaque samples were used to measure the pH fall during fermentation of [14C]-glucose, and the glycolytic profiles were analyzed by HPLC. Bacterial viability was assessed by counting the colony-forming units (CFU). All mouthrinses except F reduced glucose consumption and acid formation and thus the pH fall. F-CHX reduced the CFU equal to the reduction of glucose consumption, indicating that inhibition of plaque acidogenicity was due to a bactericidal rather than a bacteriostatic effect. F and F-Zn did not reduce the CFU, thus F-Zn decreased glucose metabolism without affecting plaque viability. F-CHX-Zn reduced both the CFU and glucose metabolism of surviving plaque microorganisms.

  11. Preparation and characterization of uniform-sized chitosan/silver microspheres with antibacterial activities.

    Science.gov (United States)

    An, Jing; Ji, Zhenxing; Wang, Desong; Luo, Qingzhi; Li, Xueyan

    2014-03-01

    The chitosan/silver microspheres (CAgMs), which possess effective inhibitory on microorganisms, were prepared by an inverse-emulsification cross-linking method using CS/Ag sol as dispersed phase, whiteruss as continuous phase, and glutaraldehyde as crosslinking agent. The size and shape of CAgMs, greatly affecting their antibacterial activities, were controlled by varying the concentrations of cross-linking agent, emulsifier and CS/Ag colloid. The preparation conditions for obtaining uniform-sized microspheres were optimized. The morphology of CAgMs was characterized by scanning electron microscopy (SEM) and laser particle size analysis. The spherical CAgMs with smooth surface in the mean size of ca. 5 μm exhibited a narrow particle size distribution. Energy Dispersive X-ray spectroscopy (EDX) revealed the elemental composition of the microspheres. Transmission electron micrographs (TEM) and Fourier transform infrared spectroscopy (FTIR) of the microspheres confirmed the formation of silver nanoparticles (AgNPs). The X-ray diffraction (XRD) patterns and UV-Visible diffuse reflectance spectroscopy (UV-vis DRS) of the sample showed that AgNPs with the diameter no more than 20 nm were face-centered cubic crystallites. X-ray photoelectron spectroscopy (XPS) proved that AgO bond existed in the microspheres. Thermogravimetric analysis (TGA) showed that the starting decomposition temperature of CAgMs (ca. 260°C) was much higher than that of CS (ca. 160°C), suggesting that the as-prepared CAgMs possessed better thermal stability than original CS did. Antimicrobial assays were performed using typical Gram bacteria and fungi. The inhibitory effect indicated that the as-prepared microspheres exerted a stronger antibacterial activity as the concentration of the AgNPs is increasing, and the microspheres in smaller size had much better antibacterial activity than those in the larger size. The antimicrobial mechanism of CAgMs was discussed. Copyright © 2013 Elsevier B.V. All

  12. Green synthesis and characterization of silver nanoparticles using alcoholic flower extract of Nyctanthes arbortristis and in vitro investigation of their antibacterial and cytotoxic activities

    International Nuclear Information System (INIS)

    Gogoi, Nayanmoni; Babu, Punuri Jayasekhar; Mahanta, Chandan; Bora, Utpal

    2015-01-01

    Here we report the synthesis of silver nanoparticles using ethanolic flower extract of Nyctanthes arbortristis, UVvisible spectra and TEM indicated the successful formation of silver nanoparticles. Crystalline nature of the silver nanoparticles was confirmed by X-ray diffraction. Fourier Transform Infra-Red Spectroscopy analysis established the capping of the synthesized silver nanoparticles with phytochemicals naturally occurring in the ethanolic flower extract of N. arbortristis. The synthesized silver nanoparticles showed antibacterial activity against the pathogenic strain of Escherichia coli MTCC 443. Furthermore, cytotoxicity of the silver nanoparticles was tested on mouse fibroblastic cell line (L929) and found to be non-toxic, which thus proved their biocompatibility. Antibacterial activity and cytotoxicity assay carried out in this study open up an important perspective of the synthesized silver nanoparticles. - Highlights: • The present study depicts the green synthesis of AgNPs using Nyctanthes arbortristis. • AuNPs found to be biocompatible and can be used for biomedical applications. • The FTIR, TGA and DTA results showed that AgNPs are bounded by organic coating. • The synthesized AgNPs showed antibacterial activity on E. Coli MTCC 443. • We investigated the antioxidant activity for both EFE and AgNPs

  13. Polylactic acid (PLA)/Silver-NP/VitaminE bionanocomposite electrospun nanofibers with antibacterial and antioxidant activity

    Science.gov (United States)

    Munteanu, Bogdanel Silvestru; Aytac, Zeynep; Pricope, Gina M.; Uyar, Tamer; Vasile, Cornelia

    2014-10-01

    The antibacterial property of silver nanoparticles (Ag-NPs) and the antioxidant activity of Vitamin E have been combined by incorporation of these two active components within polylactic acid (PLA) nanofibers via electrospinning (PLA/Ag-NP/VitaminE nanofibers). The morphological and structural characterizations of PLA/Ag-NP/VitaminE nanofibers were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy and X-ray diffraction. The average fiber diameter was 140 ± 60 nm, and the size of the Ag-NP was 2.7 ± 1.5 nm. PLA/Ag-NP/VitaminE nanofibers inhibited growth of Escherichia coli, Listeria monocytogenes and Salmonella typhymurium up to 100 %. The amount of released Ag ions from the nanofibers immersed in aqueous solution was determined by Inductively Coupled Plasma Mass Spectrometry, and it has been observed that the release of Ag ions was kept approximately constant after 10 days of immersion. The antioxidant activity of PLA/Ag-NP/VitaminE nanofibers was evaluated according to DPPH (2,2-diphenyl-1-picrylhydrazyl) method and determined as 94 %. The results of the tests on fresh apple and apple juice indicated that the PLA/Ag/VitaminE nanofiber membrane actively reduced the polyphenol oxidase activity. The multifunctional electrospun PLA nanofibers incorporating Ag-NP and Vitamin E may be quite applicable in food packaging due to the extremely large surface area of nanofibers along with antibacterial and antioxidant activities. These materials could find application in food industry as a potential preservative packaging for fruits and juices.

  14. OBTAINING AND ACTIVITY OF SILVER NANOPARTICLES BASED ON THE EXOPOLYSACCHARIDE OF DIAZOTROPHIC STRAIN Bradyrhizobium japonicum 36 AND AgNO3

    Directory of Open Access Journals (Sweden)

    B. A. Rasulov

    2014-12-01

    Full Text Available The aim of the research was to obtain silver nanoparticles and to study of its antibacterial activity against pathogenic cultures Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538. Obtained complex was characterized by UV-Vis spectroscopy, X-ray diffraction (XRD and transmission electron microscopy (TEM. Colloid solutions of the complex absorbed radiation in the visible regions of 420–460 nm, which confirmed the formation of silver nanoparticles. The size of synthesized SNP varied from 6 to 50 nm. There has been confirmed presence in them of atomic silver. Obtained compound possessed antibacterial activity against pathogens, such as Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538.

  15. Synthesis of poly acrylic acid modified silver nanoparticles and their antimicrobial activities

    International Nuclear Information System (INIS)

    Ni, Zhihui; Wang, Zhihua; Sun, Lei; Li, Binjie; Zhao, Yanbao

    2014-01-01

    Poly acrylic acid modified silver (Ag/PAA) nanoparticles (NPs) have been successfully synthesized in the aqueous solution by using tannic acid as a reductant. The structure, morphology and composition of Ag/PAA NPs were characterized by various techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectroscopy (UV–vis) and thermogravimetry analysis (TGA). The results show that PAA/Ag NPs have a quasi-ball shape with an average diameter of 10 nm and exhibit well crystalline, and the reaction conditions have some effect on products morphology and size distribution. In addition, the as-synthesized Ag/PAA NPs antimicrobial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were evaluated by the methods of broth dilution, cup diffusion, optical density (OD600) and electron microscopy observation. The as-synthesized Ag/PAA NPs exhibit excellent antibacterial activity. The antimicrobial mechanism may be attributed to the damaging of bacterial cell membrane and causing leakage of cytoplasm. - Highlights: • Dispersed Ag/PAA NPs with small size were synthesized. • Ag/PAA NPs exhibited excellent antimicrobial properties. • Interaction mechanism between Ag/PAA NPs and bacteria was verified

  16. Synthesis of poly acrylic acid modified silver nanoparticles and their antimicrobial activities.

    Science.gov (United States)

    Ni, Zhihui; Wang, Zhihua; Sun, Lei; Li, Binjie; Zhao, Yanbao

    2014-08-01

    Poly acrylic acid modified silver (Ag/PAA) nanoparticles (NPs) have been successfully synthesized in the aqueous solution by using tannic acid as a reductant. The structure, morphology and composition of Ag/PAA NPs were characterized by various techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis) and thermogravimetry analysis (TGA). The results show that PAA/Ag NPs have a quasi-ball shape with an average diameter of 10 nm and exhibit well crystalline, and the reaction conditions have some effect on products morphology and size distribution. In addition, the as-synthesized Ag/PAA NPs antimicrobial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were evaluated by the methods of broth dilution, cup diffusion, optical density (OD600) and electron microscopy observation. The as-synthesized Ag/PAA NPs exhibit excellent antibacterial activity. The antimicrobial mechanism may be attributed to the damaging of bacterial cell membrane and causing leakage of cytoplasm. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. SERS activity of silver and gold nanostructured thin films deposited by pulsed laser ablation

    Science.gov (United States)

    Agarwal, N. R.; Tommasini, M.; Fazio, E.; Neri, F.; Ponterio, R. C.; Trusso, S.; Ossi, P. M.

    2014-10-01

    Nanostructured Au and Ag thin films were obtained by nanosecond pulsed laser ablation in presence of a controlled Ar atmosphere. Keeping constant other deposition parameters such as target-to-substrate distance, incidence angle, laser wavelength and laser fluence, the film morphology, revealed by SEM, ranges from isolated NPs to island structures and sensibly depends on gas pressure (10-100 Pa) and on the laser pulse number (500-3 × 10). The control of these two parameters allows tailoring the morphology and correspondingly the optical properties of the films. The position and width of the surface plasmon resonance peak, in fact, can be varied with continuity. The films showed remarkable surface-enhanced Raman activity (SERS) that depends on the adopted deposition conditions. Raman maps were acquired on micrometer-sized areas of both silver and gold substrates selected among those with the strongest SERS activity. Organic dyes of interest in cultural heritage studies (alizarin, purpurin) have been also considered for bench marking the substrates produced in this work. Also the ability to detect the presence of biomolecules was tested using lysozyme in a label free configuration.

  18. Neutron activation determination of iridium, gold, platinum, and silver in geologic samples

    International Nuclear Information System (INIS)

    Millard, H.T.

    1986-01-01

    Low-level methods for the determination of iridium and other noble metals have been important in recent years due to interest in locating abundance anomalies associated with the Cretaceous/Tertiary (K/T) boundary. Typical iridium anomalies are in the range of 1 to 100 ppb. Thus methods with detection limits near 0.1 ppb should be adequate to detect K/T boundary anomalies. Radiochemical neutron activation analysis methods continue to be required although instrumental neutron activation analysis techniques employing elaborate gamma-counters are under development. In the procedure employed in this study samples irradiated in the epithermal neutron facility of the U.S. Geological Survey TRIGA Reactor are treated with a mini-fire assay technique. The iridium, gold, and silver are collected in a 1-gram metallic lead button. Primary contaminants at this stage are arsenic and antimony. These can be removed by heating the button with a mixture of sodium peroxide and sodium hydroxide. The resulting 0.2-gram lead bead is counted in a Compton suppression spectrometer. Carrier yields are determined by reirradiation of the lead beads. This procedure has been applied to the U.S.G.S. Standard Rock PCC-1. and samples from K/T boundary sites in the Western Interior of North America. (author)

  19. Synthesis of poly acrylic acid modified silver nanoparticles and their antimicrobial activities

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Zhihui [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Wang, Zhihua [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Sun, Lei, E-mail: sunlei@henu.edu.cn [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Li, Binjie [Key Laboratory of Cellular and Molecular Immunology, Henan University, Kaifeng 475004 (China); Zhao, Yanbao [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China)

    2014-08-01

    Poly acrylic acid modified silver (Ag/PAA) nanoparticles (NPs) have been successfully synthesized in the aqueous solution by using tannic acid as a reductant. The structure, morphology and composition of Ag/PAA NPs were characterized by various techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectroscopy (UV–vis) and thermogravimetry analysis (TGA). The results show that PAA/Ag NPs have a quasi-ball shape with an average diameter of 10 nm and exhibit well crystalline, and the reaction conditions have some effect on products morphology and size distribution. In addition, the as-synthesized Ag/PAA NPs antimicrobial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were evaluated by the methods of broth dilution, cup diffusion, optical density (OD600) and electron microscopy observation. The as-synthesized Ag/PAA NPs exhibit excellent antibacterial activity. The antimicrobial mechanism may be attributed to the damaging of bacterial cell membrane and causing leakage of cytoplasm. - Highlights: • Dispersed Ag/PAA NPs with small size were synthesized. • Ag/PAA NPs exhibited excellent antimicrobial properties. • Interaction mechanism between Ag/PAA NPs and bacteria was verified.

  20. Calcium phosphate coating containing silver shows high antibacterial activity and low cytotoxicity and inhibits bacterial adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Yoshiki, E-mail: andoy@jmmc.jp [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Miyamoto, Hiroshi [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Noda, Iwao; Sakurai, Nobuko [Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Akiyama, Tomonori [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Yonekura, Yutaka; Shimazaki, Takafumi; Miyazaki, Masaki; Mawatari, Masaaki; Hotokebuchi, Takao [Department of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan)

    2010-01-01

    Surgical site infection is one of the serious complications of orthopedic implants. In order to reduce the incidence of implant-associated infections, we developed a novel coating technology of calcium phosphate (CP) containing silver (Ag), designated Ag-CP coating, using a thermal spraying technique. In this study, we evaluated the antibacterial efficacy and biological safety of this coating. In vitro antibacterial activity tests showed that the growths of Escherichia coli, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) are completely suppressed on Ag-CP coating. In vitro bacterial adherence tests revealed that the number of adherent bacteria on the surface of this coating is significantly less (p < 0.02) than that on the surface of the CP coating. Moreover, the Ag-CP coating completely inhibits MRSA adhesion [<10 colony-forming units (CFU)] when 10{sup 2} CFU MRSA is inoculated. On the other hand, V79 Chinese hamster lung cells were found to grow on the Ag-CP coating as well as on the CP coating in a cytotoxicity test. These results indicate that the Ag-CP coating on the surface of orthopedic implants exhibits antibacterial activity and inhibits bacterial adhesion without cytotoxicity.

  1. Strontium (Sr) and silver (Ag) loaded nanotubular structures with combined osteoinductive and antimicrobial activities.

    Science.gov (United States)

    Cheng, Hao; Xiong, Wei; Fang, Zhong; Guan, Hanfeng; Wu, Wei; Li, Yong; Zhang, Yong; Alvarez, Mario Moisés; Gao, Biao; Huo, Kaifu; Xu, Jiangwen; Xu, Na; Zhang, Chengcheng; Fu, Jijiang; Khademhosseini, Ali; Li, Feng

    2016-02-01

    Two frequent problems are associated with the titanium surfaces of bone/dental implants: lack of native tissue integration and associated infection. These problems have prompted a significant body of research regarding the modification of these surfaces. The present study describes a hydrothermal treatment for the fabrication of strontium (Sr) and silver (Ag) loaded nanotubular structures with different tube diameters on titanium surfaces. The Sr loading from a Sr(OH)2 solution was regulated by the size of the inner diameter of the titanium nanotubes (NT) (30nm or 80nm, formed at 10V or 40V, respectively). The quantity of Ag was adjusted by immersing the samples in 1.5 or 2.0M AgNO3 solutions. Sr and Ag were released in a controllable and prolonged matter from the NT-Ag.Sr samples, with negligible cytotoxicity. Prominent antibacterial activity was observed due to the release of Ag. Sr incorporation enhanced the initial cell adhesion, migration, and proliferation of preosteoblast MC3T3-E1 cells. Sr release also up-regulated the expression of osteogenic genes and induced mineralization, as suggested by the presence of more mineralized calcium nodules in cells cultured on NT-Ag.Sr surfaces. In vivo experiments showed that the Sr-loaded samples accelerated the formation of new bone in both osteoporosis and bone defect models, as confirmed by X-ray, Micro-CT evaluation, and histomorphometric analysis of rats implanted with NT-Ag.Sr samples. The antibacterial activity and outstanding osteogenic properties of NT-Ag.Sr samples highlight their excellent potential for use in clinical applications. Two frequent problems associated with Ti surfaces, widely used in orthopedic and dental arenas, are their lack of native tissue integration and risk of infection. We describe a novel approach for the fabrication of strontium (Sr) and silver (Ag) loaded nanotubular structures on titanium surfaces. A relevant aspect of this work is the demonstration of long-lasting and controllable

  2. Artificial caries formation around fluoride-releasing restorations in roots.

    Science.gov (United States)

    Dionysopoulos, P; Kotsanos, N; Papadogiannis, Y; Konstantinidis, A

    1998-11-01

    Secondary caries is one of the most important factors leading to replacement of dental restorations. This investigation assessed the capacity of fluoride-releasing restorative materials to resist caries in vitro when used in roots. Class 5 cavities were prepared in the buccal and lingual surfaces of 30 extracted premolars. The six materials used were: glass-ionomer cement (Fuji), glass-ionomer cement with silver particles added (Ketac-silver), fluoride-containing composite resin (Tetric), composite resin (Silux plus), fluoride-containing amalgam (Fluor-Alloy) and high-copper amalgam (Dispersalloy). After 5 weeks in an acid gel for caries-like lesion formation, the teeth were sectioned longitudinally and examined with polarized light. The results showed that repair with glass-ionomer materials of a carious lesion may be of great importance in the prevention of secondary caries around the restorations in roots.

  3. In vitro screening of silver nanoparticles and ionic silver using neural networks yields differential effects on spontaneous activity and pharmacological responses.

    Science.gov (United States)

    Silver nanoparticles (AgNPs) are used in a wide range of consumer and medical products because of their antimicrobial and antifungal properties. Numerous studies have demonstrated that silver can translocate to distal organs following exposure to AgNPs. Therefore, it is essential...

  4. Studies on Bacterial Synthesis of Silver Nanoparticles Using Gamma Radiation and Their Activity against Some Pathogenic Microbes

    International Nuclear Information System (INIS)

    Hallol, M.M.A.M.A.

    2013-01-01

    Synthesis of nanoparticles as an emerging highlight of the intersection of nano technology and biotechnology has received increasing attention due to a growing need to develop environmentally-benign technologies in material synthesis. The metallic nanoparticles are the most promising as they show good antibacterial properties due to their large surface area to volume ratio, which is coming up as the current interest in research due to the growing microbial resistance against metal ions, antibiotics and the development of resistant strains (Fayaz et al., 2010). Silver has long been known to exhibit a strong toxicity to a wide range of 116 micro-organisms (Liau et al., 1997) for these reasons silver-based compounds have been used extensively in many bactericidal applications (Gupta et al., 1998 and Nomiya et al., 2004). Several salts of silver and their derivatives are commercially employed as antimicrobial agents. The bactericidal effect of silver ions on microorganisms is very well known; however, the bactericidal mechanism is only partially understood. It has been proposed that ionic silver strongly interacts with thiol groups of vital enzymes and inactivates them (Gupta et al., 1998). Experimental evidence suggests that DNA loses its replication ability once the bacteria have been treated with silver ions. Other studies have shown evidence of structural changes in the cell membrane as well as the formation of small electron-dense granules formed by silver and sulfur (Singh et al., 2008). Metal particles in the nanometer size range exhibit physical properties that are different from both the ion and the bulk material. This makes them exhibit remarkable properties such as increased catalytic activity due to morphologies with highly active facets (Singh et al., 2008). Microorganisms, such as bacteria and fungi, now play an important role in the remediation of toxic metals through the reduction of the metal ions (Kalishwaralal et al., 2008). Response surface

  5. Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum β-lactamase producing (ESBL) strains of Enterobacteriaceae

    International Nuclear Information System (INIS)

    Banu, Afreen; Rathod, Vandana; Ranganath, E.

    2011-01-01

    Highlights: → Silver nanoparticle production by using Rhizopus stolonifer. → Antibacterial activity of silver nanoparticles against extended spectrum β-lactamase producing (ESBL) strains of Enterobacteriaceae. → Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. → Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silver nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.

  6. Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

    Energy Technology Data Exchange (ETDEWEB)

    Banu, Afreen [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India); Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India); Ranganath, E. [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India)

    2011-09-15

    Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silver nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.

  7. Hydroxyapatites and europium(III) doped hydroxyapatites as a carrier of silver nanoparticles and their antimicrobial activity.

    Science.gov (United States)

    Wiglusz, Rafal J; Kedziora, Anna; Lukowiak, Anna; Doroszkiewicz, Wlodzimierz; Strek, Wieslaw

    2012-08-01

    Hydroxyapatites (Ca10(PO4)6(OH)2 and Eu3+:Ca10(PO4)6(OH)2) were synthesized by aqueous synthesis route. Hydroxyapatites were impregnated with silver ions that were subsequently reduced. XRD, TEM, and SAED measurements were used in order to determine the crystal structure and morphology of the final products. The results showed the well crystallized hydroxyapatite grains with diameter of about 35 nm and with silver nanoparticles on their surface. The antimicrobial activity of the nanoparticles against: Staphylococcus aureus ATCC 6538 as model of the Gram-positive bacteria, Escherichia coli ATCC 11229, and Klebsiella pneumoniae ATCC 4352 as model of Gram-negative bacteria, were shown with the best activity against K. pneumoniae. These nanocomposite powders can be a promising antimicrobial agent and a fluorescent material for biodetection due to their optical and bioactive properties.

  8. Synthesis and Catalytic Activity of Pluronic Stabilized Silver-Gold Bimetallic Nanoparticles

    OpenAIRE

    Holden, Megan S.; Nick, Kevin E.; Hall, Mia; Milligan, Jamie R.; Chen, Qiao; Perry, Christopher C.

    2014-01-01

    In this report, we demonstrate a rapid, simple, and green method for synthesizing silver-gold (Ag-Au) bimetallic nanoparticles (BNPs). We used a novel modification to the galvanic replacement reaction by suspending maltose coated silver nanoparticles (NPs) in ≈ 2% aqueous solution of EO100PO65EO100 (Pluronic F127) prior to HAuCl4 addition. The Pluronic F127 stabilizes the BNPs, imparts biocompatibility, and mitigates the toxicity issues associated with other surfactant stabilizers. BNPs with ...

  9. Antimicrobial Activities of Silver Nanoparticles Synthesized by Using Water Extract of Arnicae anthodium

    OpenAIRE

    Dobrucka, Renata; Długaszewska, Jolanta

    2015-01-01

    Green synthesis of nanoparticles has gained significant importance in recent years and has become the one of the most preferred methods. Also, green synthesis of nanoparticles is valuable branch of nanotechnology. Plant extracts are eco-friendly and can be an economic option for synthesis of nanoparticles. This study presents method the synthesis of silver nanoparticles using water extract of Arnicae anthodium. Formation of silver nanoparticles was confirmed by UV–visble spectroscopy, Fourier...

  10. In vitro cytotoxicity and antibacterial activity of silver-coated electrospun polycaprolactone/gelatine nanofibrous scaffolds

    OpenAIRE

    Lim, Mim Mim; Sultana, Naznin

    2016-01-01

    The development of nano-sized scaffolds with antibacterial properties that mimic the architecture of tissue is one of the challenges in tissue engineering. In this study, polycaprolactone (PCL) and PCL/gelatine (Ge) (70:30) nanofibrous scaffolds were fabricated using a less toxic and common solvent, formic acid and an electrospinning technique. Nanofibrous scaffolds were coated with silver (Ag) in different concentrations of silver nitrate (AgNO3) aqueous solution (1.25, 2.5, 5, and 10?%) by ...

  11. Fluoride glass fiber optics

    CERN Document Server

    Aggarwal, Ishwar D

    1991-01-01

    Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

  12. Study of mechanism of enhanced antibacterial activity by green synthesis of silver nanoparticles

    Science.gov (United States)

    Parashar, Upendra Kumar; Kumar, Vinod; Bera, Tanmay; Saxena, Preeti S.; Nath, Gopal; Srivastava, Sunil K.; Giri, Rajiv; Srivastava, Anchal

    2011-10-01

    The extensive use of silver nanoparticles needs a synthesis process that is greener without compromising their properties. The present study describes a novel green synthesis of silver nanoparticles using Guava (Psidium guajava) leaf extract. In order to compare with the conventionally synthesized ones, we also prepared Ag-NPs by chemical reduction. Their optical and morphological characteristics were thoroughly investigated and tested for their antibacterial properties on Escherichia coli. The green synthesized silver nanoparticles showed better antibacterial properties than their chemical counterparts even though there was not much difference between their morphologies. Fourier transform infrared (FTIR) spectroscopic analysis of the used extract and as-synthesized silver nanoparticles suggests the possible reduction of Ag + by the water-soluble ingredients of the guava leaf like tannins, eugenol and flavonoids. The possible reaction mechanism for the reduction of Ag + has been proposed and discussed. The time-dependent electron micrographs and the simulation studies indicated that a physical interaction between the silver nanoparticles and the bacterial cell membrane may be responsible for this effect. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is not just an environmentally viable technique but it also opens up scope to improve their antibacterial properties.

  13. Preparation and characterization of chitosan–silver nanocomposite films and their antibacterial activity against Staphylococcus aureus

    International Nuclear Information System (INIS)

    Regiel, Anna; Irusta, Silvia; Arruebo, Manuel; Santamaria, Jesus; Kyzioł, Agnieszka

    2013-01-01

    In this work different variables have been analyzed in order to optimize the bactericidal properties of chitosan films loaded with silver nanoparticles. The goal was to achieve complete elimination of antibiotic resistant and biofilm forming strains of Staphylococcus aureus after short contact times. The films were produced by solution casting using chitosan as both a stabilizing and reducing agent for the in situ synthesis of embedded silver nanoparticles. We have applied an innovative approach: the influence of the chitosan molecular weight and its deacetylation degree (DD) were analyzed together with the influence of the bacterial concentration and contact time. The best results were obtained with high DD chitosan where a fast reduction was favored; leading to smaller nanoparticles (nucleation is promoted), and a sufficiently high polymer viscosity prevented the resulting nanoparticles from undesired agglomeration. In addition, for the first time, potential detachment of the silver nanoparticles from the films was evaluated and neglected, demonstrating that uncontrolled release of silver nanoparticles from the chitosan films is prevented. The influence of the ionic silver released from the films, silver loading, nanoparticle sizes, contact, and initial number of bacteria was also analyzed to elucidate the mechanism responsible for the strong bactericidal action observed. (paper)

  14. Study of mechanism of enhanced antibacterial activity by green synthesis of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Parashar, Upendra Kumar; Srivastava, Sunil K; Srivastava, Anchal [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumar, Vinod; Saxena, Preeti S [Department of Zoology, Banaras Hindu University, Varanasi 22005 (India); Bera, Tanmay [Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Nath, Gopal [Department of Microbiology, Institute of Medical Science, Banaras Hindu University, Varanasi 22005 (India); Giri, Rajiv, E-mail: anchalbhu@gmail.com [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)

    2011-10-14

    The extensive use of silver nanoparticles needs a synthesis process that is greener without compromising their properties. The present study describes a novel green synthesis of silver nanoparticles using Guava (Psidium guajava) leaf extract. In order to compare with the conventionally synthesized ones, we also prepared Ag-NPs by chemical reduction. Their optical and morphological characteristics were thoroughly investigated and tested for their antibacterial properties on Escherichia coli. The green synthesized silver nanoparticles showed better antibacterial properties than their chemical counterparts even though there was not much difference between their morphologies. Fourier transform infrared (FTIR) spectroscopic analysis of the used extract and as-synthesized silver nanoparticles suggests the possible reduction of Ag{sup +} by the water-soluble ingredients of the guava leaf like tannins, eugenol and flavonoids. The possible reaction mechanism for the reduction of Ag{sup +} has been proposed and discussed. The time-dependent electron micrographs and the simulation studies indicated that a physical interaction between the silver nanoparticles and the bacterial cell membrane may be responsible for this effect. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is not just an environmentally viable technique but it also opens up scope to improve their antibacterial properties.

  15. Synthesis, characterization and antimicrobial activity of the micro/nano structured biogenic silver doped calcium phosphate

    Science.gov (United States)

    Supraja, N.; Prasad, T. N. V. K. V.; David, Ernest

    2016-01-01

    Scale formation in PVC pipelines reduces the water flow efficiency and enhances microbial contamination. A bio-based composite material comprising of silver doped calcium phosphate (Cp-Ag) was synthesized using a simple technique (photo catalysis) and herein, we report for the first time on preparation and evaluation of the antimicrobial efficacy of silver doped calcite extracted from the scale in drinking water pipe lines. Five concentrations of silver doped calcite materials viz,5, 10, 15, 20 and 25 ppm were prepared using chemical ammonia mediated synthetic method. The material Cp-Ag was characterized by using the techniques UV-Visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, Raman spectroscopy, Thermo gravimetric analysis, X-ray photo electron spectroscopy (XPS), Nuclear magnetic resonance spectrometer and X-ray flouresence microscopy (XRF). Typical rhombohedral structure of the silver doped calcite was observed. XRF and XPS studies confirmed the presence of both calcium and silver in the composite material (Cp-Ag). The silver doped calcite material exhibited enhanced inhibition against Escherichia coli and staphylococcus aureus (Kirby-Bauer discs diffusion assay) which is also dependent on the concentration of the Cp-Ag material.

  16. Preparation and characterization of chitosan-silver nanocomposite films and their antibacterial activity against Staphylococcus aureus

    Science.gov (United States)

    Regiel, Anna; Irusta, Silvia; Kyzioł, Agnieszka; Arruebo, Manuel; Santamaria, Jesus

    2013-01-01

    In this work different variables have been analyzed in order to optimize the bactericidal properties of chitosan films loaded with silver nanoparticles. The goal was to achieve complete elimination of antibiotic resistant and biofilm forming strains of Staphylococcus aureus after short contact times. The films were produced by solution casting using chitosan as both a stabilizing and reducing agent for the in situ synthesis of embedded silver nanoparticles. We have applied an innovative approach: the influence of the chitosan molecular weight and its deacetylation degree (DD) were analyzed together with the influence of the bacterial concentration and contact time. The best results were obtained with high DD chitosan where a fast reduction was favored; leading to smaller nanoparticles (nucleation is promoted), and a sufficiently high polymer viscosity prevented the resulting nanoparticles from undesired agglomeration. In addition, for the first time, potential detachment of the silver nanoparticles from the films was evaluated and neglected, demonstrating that uncontrolled release of silver nanoparticles from the chitosan films is prevented. The influence of the ionic silver released from the films, silver loading, nanoparticle sizes, contact, and initial number of bacteria was also analyzed to elucidate the mechanism responsible for the strong bactericidal action observed.

  17. Determination of silver, gold, zinc and copper in mineral samples by various techniques of instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Rodriguez R, N. I.; Rios M, C.; Pinedo V, J. L.; Yoho, M.; Landsberger, S.

    2015-09-01

    Using the method of instrumental neutron activation analysis, mineral exploration samples were analyzed in order to determine the concentrations of silver, gold, zinc and copper; these minerals being the main products of benefit of Tizapa and Cozamin mines. Samples were subjected to various techniques, where the type of radiation and counting methods were chosen based on the specific isotopic characteristics of each element. For calibration and determination of concentrations the comparator method was used, certified standards were subjected to the same conditions of irradiation and measurement that the prospecting samples. The irradiations were performed at the research reactor TRIGA Mark II of the University of Texas at Austin. The silver concentrations were determined by Cyclical Epithermal Neutron Activation Analysis. This method in combination with the transfer pneumatic system allowed a good analytical precision and accuracy in prospecting for silver, from photo peak measurement 657.7 keV of short half-life radionuclide 110 Ag. For the determination of gold and zinc, Epithermal Neutron Activation Analysis was used, the photo peaks analyzed corresponded to the energies 411.8 keV of radionuclide 199 Au and 438.6 keV of metastable radionuclide 69m Zn. On the other hand, copper quantification was based on the photo peak analysis of 1039.2 keV produced by the short half-life radionuclide 66 Cu, by Thermal Neutron Activation Analysis. The photo peaks measurement corresponding to gold, zinc and copper was performed using a Compton suppression system, which allowed an improvement in the signal to noise relationship, so that better detection limits and low uncertainties associated with the results were obtained. Comparing elemental concentrations the highest values in silver, zinc and copper was for samples of mine Tizapa. Regarding gold values were found in the same range for both mines. To evaluate the precision and accuracy of the methods used, various geological

  18. Enhancing the antibacterial activity of the gold standard intracanal medicament with incorporation of silver zeolite: An in vitro study

    OpenAIRE

    Ghatole, Kiran; Gowdra, Ramesh Halebathi Giriyappa; Azher, Samer; Sabharwal, Sumit; Singh, Veerandar T.; Sundararajan, Bharath Vardhana

    2016-01-01

    Background: Enterococcus faecalis is a persistent organism that plays a major role in the etiology of persistent periradicular lesions after root canal treatment has been associated with different forms of periradicular disease including primary endodontic infections and persistent infections. The present study compares the antibacterial activities of calcium hydroxide, calcium hydroxide mixed with silver zeolite, and calcium hydroxide mixed with 2% chlorhexidine against E. faecalis using dir...

  19. Analysis for iodide in groundwater by x-ray fluorescence spectrometry after collection as silver iodide on activated charcoal

    International Nuclear Information System (INIS)

    Howe, P.T.

    1980-01-01

    The report describes the determination of microgram quantities of iodide in water by X-ray fluorescence spectrometry. The iodide is concentrated by precipitation as silver iodide on activated charcoal. If a 60-mL sample is available, a concentration of 0.12 mg/L can be detected. Precision (2σ) at the 1-mg/L level is +- 0.08 mg/L. (auth)

  20. Cytotoxicity and antiviral activity of electrochemical - synthesized silver nanoparticles against poliovirus.

    Science.gov (United States)

    Huy, Tran Quang; Hien Thanh, Nguyen Thi; Thuy, Nguyen Thanh; Chung, Pham Van; Hung, Pham Ngoc; Le, Anh-Tuan; Hong Hanh, Nguyen Thi

    2017-03-01

    Silver nanoparticles (AgNPs) have been proven to have noticeable cytotoxicity in vitro and antiviral activity against some types of enveloped viruses. This paper presents the cytotoxicity and antiviral activity of pure AgNPs synthesized by the electrochemical method, towards cell culture and poliovirus (a non-enveloped virus). Prepared AgNPs were characterized by ultraviolet-visible spectroscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. Before incubation with poliovirus, different concentrations of AgNPs were added to human rhabdomyosarcoma (RD) cell monolayers seeded in 96 well plates for testing their cytotoxicity. The in vitro cytotoxicity and anti-poliovirus activity of AgNPs were daily assessed for cytopathic effect (CPE) through inverted light microscopy. CPE in the tested wells was determined in comparison with those in wells of negative and positive control. Structure analysis showed that AgNPs were formed with a quasi-spherical shape with mean size about 7.1nm and high purity. No CPE of RD cells was seen in wells at the time point of 48h post-incubation with AgNPs at concentration up to 100ppm. The anti-poliovirus activity of AgNPs was determined at 3.13ppm corresponding to the viral concentration of 1TCID 50 (Tissue Culture Infective Dose) after 30min, and 10TCID 50 after 60min, the cell viability was found up to 98% at 48h post-infection, with no CPE found. Whereas, a strong CPE of RD cells was found at 48h post-infection with the mixture of AgNPs and poliovirus at concentration of 100TCID 50 , and in wells of positive controls. With mentioned advantages, electrochemical-synthesized AgNPs are promising candidate for advanced biomedical and disinfection applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Antimicrobial Activity and Mechanism of inhibition of Silver Nanoparticles against Extreme Halophilic Archaea

    Directory of Open Access Journals (Sweden)

    Rebecca Thombre

    2016-09-01

    Full Text Available Haloarchaea are salt-loving halophilic microorganism’s that inhabit marine environments, sea water, salterns, and lakes. The resistance of haloarchaea to physical extremities that challenge organismic survival is ubiquitous. Metal and antibiotic resistance of haloarchaea has been on an upsurge due to the exposure of these organisms to metal sinks and drug resistance genes augmented in their natural habitats due to anthropogenic activities and environmental pollution. The efficacy of silver nanoparticles (SNPs as a potent and broad spectrum inhibitory agent is known however, there are no reports on the inhibitory activity of SNPs against haloarchaea. In the present study, we have investigated the antimicrobial potentials of SNPs synthesized using aqueous leaf extract of Cinnamomum tamala against antibiotic resistant haloarchaeal isolates Haloferax prahovense RR8, Haloferax lucentense RR15, Haloarcula argentinensis RR10 and Haloarcula tradensis RR13. The synthesized SNPs were characterized by UV-Vis spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, dynamic light scattering, X-ray diffraction and Fourier transform infrared spectroscopy. The SNPs demonstrated potent antimicrobial activity against the haloarchaea with a minimum inhibitory concentration of 300- 400µg/ml. Growth kinetics of haloarchaea in the presence of SNPs was studied by employing the Baranyi mathematical model for microbial growth using the DMFit curve fitting programme. The C. tamala SNPs also demonstrated cytotoxic activity against human lung adenocarcinoma epithelial cell line (A540 and human breast adenocarcinoma cell line (MCF-7. The mechanism of inhibition of haloarchaea by the SNPs was investigated. The plausible mechanism proposed is the alterations and disruption of haloarchaeal membrane permeability by turbulence, inhibition of respiratory dehydrogenases and lipid peroxidation causing cellular and DNA damage resulting in cell death.

  2. Bioengineered silver nanoparticles using Curvularia pallescens and its fungicidal activity against Cladosporium fulvum

    Directory of Open Access Journals (Sweden)

    Abdallah M. Elgorban

    2017-11-01

    Full Text Available Microorganisms based biosynthesis of nanomaterials has triggered significant attention, due to their great potential as vast source of the production of biocompatible nanoparticles (NPs. Such biosynthesized functional nanomaterials can be used for various biomedical applications. The present study investigates the green synthesis of silver nanoparticles (Ag NPs using the fungus Curvularia pallescens (C. pallescens which is isolated from cereals. The C. pallescens cell filtrate was used for the reduction of AgNO3 to Ag NPs. To the best of our knowledge C. pallescens is utilized first time for the preparation of Ag NPs. Several alkaloids and proteins present in the phytopathogenic fungus C. pallescens were mainly responsible for the formation of highly crystalline Ag NPs. The as-synthesized Ag NPs were characterized by using UV–Visible spectroscopy, X-ray diffraction and transmission electron microscopy (TEM. The TEM micrographs have revealed that spherical shaped Ag NPs with polydisperse in size were obtained. These results have clearly suggested that the biomolecules secreted by C. pallescens are mainly responsible for the formation and stabilization of nanoparticles. Furthermore, the antifungal activity of the as-prepared Ag NPs was tested against Cladosporium fulvum, which is the major cause of a serious plant disease, known as tomato leaf mold. The synthesized Ag NPs displayed excellent fungicidal activity against the tested fungal pathogen. The extreme zone of reduction occurred at 50 μL, whereas, an increase in the reduction activity is observed with increasing the concentration of Ag NPs. These encouraging results can be further exploited by employing the as synthesized Ag NPs against various pathogenic fungi in order to ascertain their spectrum of fungicidal activity.

  3. Scavenger receptor B1 facilitates macrophage uptake of silver nanoparticles and cellular activation

    Energy Technology Data Exchange (ETDEWEB)

    Aldossari, Abdullah A.; Shannahan, Jonathan H. [The University of Colorado Anschutz Medical Campus, Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences (United States); Podila, Ramakrishna [Clemson University, Department of Physics and Astronomy (United States); Brown, Jared M., E-mail: jared.brown@ucdenver.edu [The University of Colorado Anschutz Medical Campus, Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences (United States)

    2015-07-15

    Due to increased use of silver nanoparticles (AgNPs) for their antimicrobial activity, concerns have risen regarding potential adverse human health effects. Scavenger receptor B1 (SR-B1), a major receptor for high-density lipoprotein (HDL), is expressed by macrophages and has also been reported to play a role in recognition of negatively charged particles. We, therefore, hypothesized that SR-B1 mediates macrophage uptake of AgNPs and inflammatory activation. To test this hypothesis, we exposed a mouse macrophage cell line RAW264.7 (RAW) and bone marrow-derived macrophages (BMDM) to 20 nm citrate-suspended AgNPs. To verify the role of the SR-B1 receptor, we utilized a SR-B1 inhibitor (Blt2). In vitro studies demonstrated uptake of AgNPs and HDL-coated AgNPs by macrophages which were significantly reduced following pretreatment with Blt2. Inflammatory cytokine arrays revealed that macrophages exposed to AgNPs up-regulated expression of Tnf-α, Oncostatin m (OSM), Ccl4, Il17f, Ccl7, and Ccl2, whereas Il16 was found to be down-regulated. Macrophage activation was observed following AgNP and HDL-coated AgNP exposure as measured by OSM protein production and increased surface expression of CD86. These markers of activation were reduced with Blt2 pretreatment. The in vitro findings were confirmed in vivo through pulmonary instillation of AgNPs in mice. Pulmonary instillation of AgNPs resulted in a recruitment of inflammatory cells that were reduced in SR-B1-deficient mice or following Blt2 pretreatment. This study suggests that SR-B1 plays a major role in cellular recognition of AgNPs and the induction of cell responses that could contribute to inflammation caused by AgNP exposure.

  4. Scavenger receptor B1 facilitates macrophage uptake of silver nanoparticles and cellular activation

    Science.gov (United States)

    Aldossari, Abdullah A.; Shannahan, Jonathan H.; Podila, Ramakrishna; Brown, Jared M.

    2015-07-01

    Due to increased use of silver nanoparticles (AgNPs) for their antimicrobial activity, concerns have risen regarding potential adverse human health effects. Scavenger receptor B1 (SR-B1), a major receptor for high-density lipoprotein (HDL), is expressed by macrophages and has also been reported to play a role in recognition of negatively charged particles. We, therefore, hypothesized that SR-B1 mediates macrophage uptake of AgNPs and inflammatory activation. To test this hypothesis, we exposed a mouse macrophage cell line RAW264.7 (RAW) and bone marrow-derived macrophages (BMDM) to 20 nm citrate-suspended AgNPs. To verify the role of the SR-B1 receptor, we utilized a SR-B1 inhibitor (Blt2). In vitro studies demonstrated uptake of AgNPs and HDL-coated AgNPs by macrophages which were significantly reduced following pretreatment with Blt2. Inflammatory cytokine arrays revealed that macrophages exposed to AgNPs up-regulated expression of Tnf- α, Oncostatin m (OSM), Ccl4, Il17f, Ccl7, and Ccl2, whereas Il16 was found to be down-regulated. Macrophage activation was observed following AgNP and HDL-coated AgNP exposure as measured by OSM protein production and increased surface expression of CD86. These markers of activation were reduced with Blt2 pretreatment. The in vitro findings were confirmed in vivo through pulmonary instillation of AgNPs in mice. Pulmonary instillation of AgNPs resulted in a recruitment of inflammatory cells that were reduced in SR-B1-deficient mice or following Blt2 pretreatment. This study suggests that SR-B1 plays a major role in cellular recognition of AgNPs and the induction of cell responses that could contribute to inflammation caused by AgNP exposure.

  5. Egg extract of apple snail for eco-friendly synthesis of silver nanoparticles and their antibacterial activity.

    Science.gov (United States)

    Janthima, Ratima; Khamhaengpol, Arunrat; Siri, Sineenat

    2018-03-01

    Green synthesis of silver nanoparticles (AgNPs) provides the alternative method with cost effectiveness and the eco-friendly process by using natural biomolecules as reducing and stabilizing agents. Alternative to the most studies of plant extracts, this work demonstrated a use of egg extract of apple snail (Pomacea canaliculata) for an eco-friendly production of AgNPs. The extract contained at least six proteins with the molecular weight in a range of 24-65 kDa that exhibited the reducing activity. The dispersive AgNPs were produced in the reaction containing only the extract and silver nitrate, as determined by the characteristic surface plasmon resonance peak of silver at 412 nm. The synthesized AgNPs were spherical with the average diameter of 9.0 ± 5.9 nm. The X-ray diffraction pattern and selected area electron diffraction (SAED) analyses confirmed the face-cubic centre (fcc) unit cell structure of AgNPs. The synthesized AgNPs exhibited the antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Results of this work clearly showed the potential use of the egg extract of apple snail for a green synthesis of small size AgNPs exhibiting the antibacterial activity.

  6. Synthesis, characterization and antimicrobial activities of novel silver(I) complexes with coumarin substituted N-heterocyclic carbene ligands.

    Science.gov (United States)

    Karataş, Mert Olgun; Olgundeniz, Begüm; Günal, Selami; Özdemir, İlknur; Alıcı, Bülent; Çetinkaya, Engin

    2016-02-15

    Eight new coumarin substituted silver(I) N-heterocyclic carbene (NHC) complexes were synthesized by the interaction of the corresponding imidazolium or benzimidazolium chlorides and Ag2O in dichloromethane at room temperature. Structures of these complexes were established on the basis of elemental analysis, (1)H NMR, (13)C NMR, IR and mass spectroscopic techniques. The antimicrobial activities of carbene precursors and silver NHC complexes were tested against standard strains: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungi Candida albicans and Candida tropicalis. Results showed that all the compounds inhibited the growth of the all bacteria and fungi strains and some complexes performed good activities against different microorganisms. Among all the compounds, the most lipophilic complex bis[1-(4-methylene-6,8-dimethyl-2H-chromen-2-one)-3-(naphthalene-2-ylmethyl)benzimidazol-2-ylidene]silver(I) dichloro argentate (5e) was found out as the most active one. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Eco-friendly approach for nanoparticles synthesis and mechanism behind antibacterial activity of silver and anticancer activity of gold nanoparticles.

    Science.gov (United States)

    Patil, Maheshkumar Prakash; Kim, Gun-Do

    2017-01-01

    This review covers general information about the eco-friendly process for the synthesis of silver nanoparticles (AgNP) and gold nanoparticles (AuNP) and focuses on mechanism of the antibacterial activity of AgNPs and the anticancer activity of AuNPs. Biomolecules in the plant extract are involved in reduction of metal ions to nanoparticle in a one-step and eco-friendly synthesis process. Natural plant extracts contain wide range of metabolites including carbohydrates, alkaloids, terpenoids, phenolic compounds, and enzymes. A variety of plant species and plant parts have been successfully extracted and utilized for AgNP and AuNP syntheses. Green-synthesized nanoparticles eliminate the need for a stabilizing and capping agent and show shape and size-dependent biological activities. Here, we describe some of the plant extracts involved in nanoparticle synthesis, characterization methods, and biological applications. Nanoparticles are important in the field of pharmaceuticals for their strong antibacterial and anticancer activity. Considering the importance and uniqueness of this concept, the synthesis, characterization, and application of AgNPs and AuNPs are discussed in this review.

  8. Bactericidal activity of bio-synthesized silver nanoparticles against human pathogenic bacteria

    International Nuclear Information System (INIS)

    Abalkhil, Tarad Abdulaziz; Alharbi, Sulaiman Ali; Salmen, Saleh Hussein; Wainwright, Milton

    2017-01-01

    Green synthesis is an attractive and eco-friendly approach to generate potent antibacterial silver nanoparticles (Ag-NPs). Such particles have long been used to fight bacteria and represent a promising tool to overcome the emergence of antibiotic-resistant bacteria. In this study, green synthesis of Ag-NPs was attempted using plant extracts of Aloe vera, Portulaca oleracea and Cynodon dactylon. The identity and size of Ag-NPs was characterized by ultraviolet–visible spectrophotometer and scanning electron microscopy. Monodispersed Ag-NPs were produced with a range of different sizes based on the plant extract used. The bactericidal activity of Ag-NPs against a number of human pathogenic bacteria was determined using the disc diffusion method. The results showed that Gram positive bacteria were more susceptible than Gram negative ones to these antibacterial agents. The minimum inhibitory concentration was determined using the 96- well plate method. Finally, the mechanism by which Ag-NPs affect bacteria was investigated by SEM analysis. Bacteria treated with Ag-NPs were seen to undergo shrinkage and to lose their viability. This study provides evidence for a cheap and effective method for synthesizing potent bactericidal Ag-NPs and demonstrates their effectiveness against human pathogenic bacteria

  9. Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities.

    Directory of Open Access Journals (Sweden)

    Palaniyandi Velusamy

    Full Text Available In the current study, facile synthesis of carboxymethyl cellulose (CMC and sodium alginate capped silver nanoparticles (AgNPs was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%, volumes of reducing agent (50, 100, 150 μL, and duration of heat treatment (30 s to 240 s. The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications.

  10. Green synthesis, characterization and catalytic activity of silver nanoparticles using Cassia auriculata flower extract separated fraction

    Science.gov (United States)

    Muthu, Karuppiah; Priya, Sethuraman

    2017-05-01

    Cassia auriculata L., the flower aqueous extract was fractionated by separating funnel using n-hexane (A1), chloroform (A2), ethyl acetate (A3) and triple distilled water (A4). The A4 fraction was concentrated and determined the presence of preliminary phytochemicals such as tannins, flavonoids, glycosides, carbohydrates and polyphenolic compounds. These phytochemical compounds acted as reducing as well as a stabilizing agent in the green synthesis of Ag NPs from aqueous silver ions. Initially, the colour change and UV-vis absorbance surface Plasmon resonance strong, wide band located at 435 nm has confirmed the synthesis of Ag NPs. The X-ray diffraction (XRD) pattern of Ag NPs shows a face-centered cubic crystal structure. The observed values were calculated by Debye-Scherrer equation to theoretical confirms the particle size of 18 nm. The surface morphology of Ag NPs was viewed by HRTEM, the particles are spherical and triangle shapes with sizes from 10 to 35 nm. Further, the Ag NPs was effective catalytic activity in the reduction of highly environmental polluted organic compounds of 4-nitrophenol and methyl orange. The green synthesis of Ag NPs seems to eco-friendly, cost-effective, conventional one spot synthesis and greater performance of catalytic degradation of environmentally polluted organic dyes.

  11. Biomimetic synthesis of silver nanoparticles and evaluation of their catalytic activity towards degradation of methyl orange

    Science.gov (United States)

    Manjari Mishra, Pravat; Bihari Pani, Khirod

    2017-11-01

    This paper described the significant effect of process variables like reductant concentrations, substrate concentration, reaction pH and reaction temperature on the size, morphology and yield of the silver nanoparticles (AgNPs) synthesized using aqueous leaf extract of a medicinal plant Momordica charantia (Bitter guard). By means of UV-vis spectroscopy, XRD analysis, TEM analysis and Fluorescence analysis, it is observed that the reaction solution containing 10-3 M of AgNO3 of pH 5.3  +  10 ml of aqueous leaf extract at normal room temperature, was optimum for synthesis of stable, polydisperse, predominantly spherical AgNPs with average size of 12.15 nm. FT-IR and TEM studies confirmed the stability of AgNPs was due to the capping of phytoconstituents present in the leaf extract. The aqueous solution of leaf extract containing AgNPs showed remarkable catalytic activity towards degradation of methyl orange (MO) in aqueous medium.

  12. Field-assisted synthesis of SERS-active silver nanoparticles using conducting polymers

    Science.gov (United States)

    Xu, Ping; Jeon, Sea-Ho; Mack, Nathan H.; Doorn, Stephen K.; Williams, Darrick J.; Han, Xijiang; Wang, Hsing-Lin

    2010-08-01

    A gradient of novel silver nanostructures with widely varying sizes and morphologies is fabricated on a single conducting polyaniline-graphite (P-G) membrane with the assistance of an external electric field. It is believed that the formation of such a silver gradient is a synergetic consequence of the generation of a silver ion concentration gradient along with an electrokinetic flow of silver ions in the field-assisted model, which greatly influences the nucleation and growth mechanism of Ag particles on the P-G membrane. The produced silver dendrites, flowers and microspheres, with sharp edges, intersections and bifurcations, all present strong surface enhanced Raman spectroscopy (SERS) responses toward an organic target molecule, mercaptobenzoic acid (MBA). This facile field-assisted synthesis of Ag nanoparticles via chemical reduction presents an alternative approach to nanomaterial fabrication, which can yield a wide range of unique structures with enhanced optical properties that were previously inaccessible by other synthetic routes.A gradient of novel silver nanostructures with widely varying sizes and morphologies is fabricated on a single conducting polyaniline-graphite (P-G) membrane with the assistance of an external electric field. It is believed that the formation of such a silver gradient is a synergetic consequence of the generation of a silver ion concentration gradient along with an electrokinetic flow of silver ions in the field-assisted model, which greatly influences the nucleation and growth mechanism of Ag particles on the P-G membrane. The produced silver dendrites, flowers and microspheres, with sharp edges, intersections and bifurcations, all present strong surface enhanced Raman spectroscopy (SERS) responses toward an organic target molecule, mercaptobenzoic acid (MBA). This facile field-assisted synthesis of Ag nanoparticles via chemical reduction presents an alternative approach to nanomaterial fabrication, which can yield a wide range

  13. Enhancing the antibacterial activity of the gold standard intracanal medicament with incorporation of silver zeolite: An in vitro study.

    Science.gov (United States)

    Ghatole, Kiran; Gowdra, Ramesh Halebathi Giriyappa; Azher, Samer; Sabharwal, Sumit; Singh, Veerandar T; Sundararajan, Bharath Vardhana

    2016-01-01

    Enterococcus faecalis is a persistent organism that plays a major role in the etiology of persistent periradicular lesions after root canal treatment has been associated with different forms of periradicular disease including primary endodontic infections and persistent infections. The present study compares the antibacterial activities of calcium hydroxide, calcium hydroxide mixed with silver zeolite, and calcium hydroxide mixed with 2% chlorhexidine against E. faecalis using direct contact test. The test materials of the in vitro experimental study were grouped as group 1-calcium hydroxide mixed with sterile water, group 2-2% silver zeolite added in calcium hydroxide mixed with sterile water, and group 3-calcium hydroxide mixed with 2% chlorhexidine. The bottom of microtiter plate were coated with freshly mixed tested material and a 10 μL of bacterial suspension was placed. After 1 h of incubation at 37°C, brain-heart infusion (BHI) broth (245 μL) was added and mixed for 2 min. These were designated as "subgroup 1" wells. A volume of 15 μL of broth then transferred from subgroup 1 wells to an adjacent set of four wells containing fresh BHI medium (215 μL); these wells were designated as "subgroup 2"' wells. The optical density was measured by a spectrophotometer after the first day, third day, and seventh day. One-way analysis of variance (ANOVA) and Tukey tests were performed for the analysis. Calcium hydroxide mixed with silver zeolite showed maximum antibacterial activity. Silver zeolite can be added in calcium hydroxide to enhance the latter's antibacterial activity against E. faecalis.

  14. Antileishmanial effect of silver nanoparticles and their enhanced antiparasitic activity under ultraviolet light

    Directory of Open Access Journals (Sweden)

    Allahverdiyev AM

    2011-11-01

    Full Text Available Adil M Allahverdiyev1, Emrah Sefik Abamor1, Malahat Bagirova1, Cem B Ustundag2, Cengiz Kaya2, Figen Kaya2, Miriam Rafailovich3 1Department of Bioengineering; 2Department of Metallurgical and Materials Engineering, Yildiz Technical University, Esenler, Istanbul, Turkey; 3Department of Materials Science and Engineering, Stony Brook University, Stony Brook, NY, USA Abstract: Leishmaniasis is a protozoan vector-borne disease and is one of the biggest health problems of the world. Antileishmanial drugs have disadvantages such as toxicity and the recent development of resistance. One of the best-known mechanisms of the antibacterial effects of silver nanoparticles (Ag-NPs is the production of reactive oxygen species to which Leishmania parasites are very sensitive. So far no information about the effects of Ag-NPs on Leishmania tropica parasites, the causative agent of leishmaniasis, exists in the literature. The aim of this study was to investigate the effects of Ag-NPs on biological parameters of L. tropica such as morphology, metabolic activity, proliferation, infectivity, and survival in host cells, in vitro. Consequently, parasite morphology and infectivity were impaired in comparison with the control. Also, enhanced effects of Ag-NPs were demonstrated on the morphology and infectivity of parasites under ultraviolet (UV light. Ag-NPs demonstrated significant antileishmanial effects by inhibiting the proliferation and metabolic activity of promastigotes by 1.5- to threefold, respectively, in the dark, and 2- to 6.5-fold, respectively, under UV light. Of note, Ag-NPs inhibited the survival of amastigotes in host cells, and this effect was more significant in the presence of UV light. Thus, for the first time the antileishmanial effects of Ag-NPs on L. tropica parasites were demonstrated along with the enhanced antimicrobial activity of Ag-NPs under UV light. Determination of the antileishmanial effects of Ag-NPs is very important for the further

  15. PENGGUNAAN SILVER DIAMINA FLUORIDA (SDF 38% SEBAGAI Arresting Caries Treatment (ACT PADA ANAK-ANAK

    Directory of Open Access Journals (Sweden)

    Lendrawati Lendrawati

    2011-09-01

    was not perfect and still less saliva buffer so that a more proteolytic activity in the mouth. Fluor is a mineral substance that used as an ingredient that effectively prevent the occurrence of dental caries and can make enamel resistant to decay caused by acid dissolution email. TINJAUAN PUSTAKA99Strategy of caries prevention is more effective since the introduction of silver diamine fluoride (SDF which is a colorless liquid containing fluoride ions are used to induce the process of remineralization mineral of tooth that is hidoksiapatit. SDF is a method of Arresting Caries Treatment (ACT. That combines the strengthening tooth effects of sodium fluoride (NaF and the effect of nitrate perak. Used of 38% concentration of SDF solution (44,800 ppm fluoride ion are effective to inhibit the development of caries in primary teeth of children, especially children who are difficult to be treated. SDF use is simple, easy to apply and use costs cheaper. SDF is a good material to be used in the public dental health problems, especially in children.Key word : dental caries, silver diamine fluoride, Arresting Caries Treatment, topical

  16. Evaluation of dose dependent antimicrobial activity of self-assembled chitosan, nano silver and chitosan-nano silver composite against several pathogens.

    Science.gov (United States)

    Tareq, Foysal Kabir; Fayzunnesa, Mst; Kabir, Md Shahariar; Nuzat, Musrat

    2018-01-01

    The aim of this investigation to preparation of silver nanoparticles organized chitosan nano polymer, which effective against microbial and pathogens, when apply to liquid medium and edible food products surface, will rescue the growth of microbes. Self-assembly approach used to synthesis of silver nanoparticles and silver nanoparticles organized chitosan nano polymer. Silver nanoparticles and silver nanoparticles organized chitosan nano polymer and film characterized using Ultra-violate visible spectrometer (UV-vis), X-ray diffraction (X-ray), and Scanning electronic microscope (SEM). The crystalline structured protein capped nano silver successfully synthesized at range of 12 nm-29 nm and organized into chitosan nano polymer. Antimicrobial ingredient in liquid medium and food product surface provide to rescue oxidative change and growth of microorganism to provide higher safety. The silver nanoparticles organized chitosan nano polymer caused the death of microorganism. The materials in nano scale synthesized successfully using self-assembly method, which showed good antimicrobial properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Silver nanoparticles-loaded activated carbon fibers using chitosan as binding agent: Preparation, mechanism, and their antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chengli, E-mail: tcl-lily@mail.zjxu.edu.cn [College of Mechanical and Electrical Engineering, Jiaxing University, Jiaxing 314001 (China); Hu, Dongmei [College of Mechanical Science and Engineering, Jilin University, Changchun 130022 (China); Cao, Qianqian [College of Mechanical and Electrical Engineering, Jiaxing University, Jiaxing 314001 (China); Yan, Wei [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xing, Bo [College of Mechanical and Electrical Engineering, Jiaxing University, Jiaxing 314001 (China)

    2017-02-01

    Highlights: • Chitosan was firstly introduced as binding agent for AgNPs loading on ACF surface. • Molecular dynamics simulation was used to explore the AgNPs loading mechanism. • Loading mechanism was proposed based on the experimental and simulation results. • Antibacterial AgNPs-loaded ACF showed use potential for water disinfection. - Abstract: The effective and strong adherence of silver nanoparticles (AgNPs) to the substrate surface is pivotal to the practical application of those AgNPs-modified materials. In this work, AgNPs were synthesized through a green and facile hydrothermal method. Chitosan was introduced as the binding agent for the effective loading of AgNPs on activated carbon fibers (ACF) surface to fabricate the antibacterial material. Apart from conventional instrumental characterizations, i. e., scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), zeta potential and Brunauer-Emmett-Teller (BET) surface area measurement, molecular dynamics simulation method was also applied to explore the loading mechanism of AgNPs on the ACF surface. The AgNPs-loaded ACF material showed outstanding antibacterial activity for S. aureus and E. coli. The combination of experimental and theoretical calculation results proved chitosan to be a promising binding agent for the fabrication of AgNPs-loaded ACF material with excellent antibacterial activity.

  18. Fluoride-induced foliar injury in Solanum pseudo-capsicum: its induction in the dark and activation in the light

    Energy Technology Data Exchange (ETDEWEB)

    MacLean, D.C.; Schneider, R.C.; Weinstein, L.H.

    1982-09-01

    The differential responses of plants exposed to hydrogen fluoride (HF) in continuous light or darkness were investigated in Jerusalem cherry Solanum pseudo-capsicum L. Plants exposed to HF in the dark develop few, if any, foliar symptoms by the end of the exposure period, but severe foliar injury develops rapidly upon transfer to the light after exposure. The results suggest that light is required for the expression of responses induced by exposure to HF in the dark.

  19. Fluoride-induced foliar injury in Solanum pseudo-capsicum: its induction in the dark and activation in the light

    Energy Technology Data Exchange (ETDEWEB)

    MacLean, D.C.; Schneider, R.E.; Weinstein, L.H.

    1982-01-01

    The differential responses of plants exposed to hydrogen fluoride (HF) in continuous light or darkness were investigated in Jerusalem cherry Solanum pseudo-capsicum L. Plants exposed to HF in the dark develop few, if any, foliar symptoms by the end of the exposure period, but severe folia injury develops rapidly upon transfer to the light after exposure. The results suggest that light is required for the expression of responses induced by exposure to HF in the dark.

  20. Antibacterial and hemolysis activity of polypyrrole nanotubes decorated with silver nanoparticles by an in-situ reduction process.

    Science.gov (United States)

    Upadhyay, J; Kumar, A; Gogoi, B; Buragohain, A K

    2015-09-01

    Polypyrrole nanotube-silver nanoparticle nanocomposites (PPy-NTs:Ag-NPs) have been synthesized by in-situ reduction of silver nitrate (AgNO3) to suppress the agglomeration of Ag-NPs. The morphology and chemical structure of the nanocomposites have been studied by HRTEM, SEM, XRD, FTIR and UV-vis spectroscopy. The average diameter of the polypyrrole nanotubes (PPy-NTs) is measured to be 130.59±5.5 nm with their length in the micrometer range, while the silver nanoparticles (Ag-NPs) exhibit spherical shape with an average diameter of 23.12±3.23 nm. In-vitro blood compatibility of the nanocomposites has been carried out via hemolysis assay. Antimicrobial activity of the nanocomposites has been investigated with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. The results depict that the hemolysis and antimicrobial activities of the nanocomposites increase with increasing Ag-NP concentration that can be controlled by the AgNO3 precursor concentration in the in-situ process. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Biosynthesis and evaluation of the characteristics of silver nanoparticles using Cassia fistula fruit aqueous extract and its antibacterial activity

    Science.gov (United States)

    Ghafoori, Seyed Mohammad; Entezari, Maliheh; Taghva, Arefeh; Tayebi, Zahra

    2017-12-01

    There are several ways to produce nanoparticles, but the biological method of nanoparticle production is considered most efficient by researchers due to its eco-friendly and energy saving properties. In this study, the biosynthesis of silver nanoparticles (AgNPs) via Cassia fistula fruit pulp extract was examined. Furthermore, its antibacterial effects were investigated both in vitro and in vivo. To achieve biosynthesis, 10 ml of C. fistula extract was added to 90 ml of aqueous solution of 1 mM silver nitrate. The solution was incubated in darkness overnight, at room temperature. After changing the color of solution, the production of AgNPs was examined by UV-Vis spectrophotometry, XRD and DLS methods. Finally, the antibacterial activity of AgNPs was investigated by using three methods: (1) agar well diffusion, (2) MIC determining and (3) effect on prevention of infection in wound on rat models. The results revealed that synthesized silver nanoparticles have strong antibacterial activity in vitro and in vivo conditions. Undeniably, further research is required to investigate the side effects of such particles.

  2. Antimicrobial and anticancer activities of porous chitosan-alginate biosynthesized silver nanoparticles.

    Science.gov (United States)

    Venkatesan, Jayachandran; Lee, Jin-Young; Kang, Dong Seop; Anil, Sukumaran; Kim, Se-Kwon; Shim, Min Suk; Kim, Dong Gyu

    2017-05-01

    The main aim of this study was to obtain porous antimicrobial composites consisting of chitosan, alginate, and biosynthesized silver nanoparticles (AgNPs). Chitosan and alginate were used owing to their pore-forming capacity, while AgNPs were used for their antimicrobial property. The developed porous composites of chitosan-alginate-AgNPs were characterized using Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The FT-IR results revealed the presence of a strong chemical interaction between chitosan and alginate due to polyelectrolyte complex; whereas, the XRD results confirmed the presence of AgNPs in the composites. The dispersion of AgNPs in the porous membrane was uniform with a pore size of 50-500μm. Antimicrobial activity of the composites was checked with Escherichia coli and Staphylococcus aureus. The developed composites resulted in the formation of a zone of inhibition of 11±1mm for the Escherichia coli, and 10±1mm for Staphylococcus aureus. The bacterial filtration efficiency of chitosan-alginate-AgNPs was 1.5-times higher than that of the chitosan-alginate composite. The breast cancer cell line MDA-MB-231 was used to test the anticancer activity of the composites. The IC 50 value of chitosan-alginate-AgNPs on MDA-MB-231 was 4.6mg. The developed chitosan-alginate-AgNPs composite showed a huge potential for its applications in antimicrobial filtration and cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Enhancement of visible-light photocatalytic activity of silver and mesoporous carbon co-modified Bi2WO6

    International Nuclear Information System (INIS)

    Zhao, Qian; Gong, Ming; Liu, Wangping; Mao, Yulin; Le, Shukun; Ju, Shang; Long, Fei; Liu, Xiufang; Liu, Kai; Jiang, Tingshun

    2015-01-01

    Graphical abstract: - Highlights: • Silver and mesoporous carbon co-modified Bi 2 WO 6 (Ag/Bi 2 WO 6 /CMK-3) composite was prepared. • Photocatalytic activity of Bi 2 WO 6 was remarkably enhanced by co-modification of silver and mesoporous carbon. • The degradation rate of MB can reach ca. 95.1% under visible light irradiation. • The Ag/Bi 2 WO 6 /CMK-3 composite has good stability and potential application prospects. - Abstract: Ordered mesoporous carbon CMK-3 was prepared by hard template method using SBA-15 as template, sucrose as carbon source. Flower/sphere-like Bi 2 WO 6 and CMK-3/Bi 2 WO 6 photocatalysts were synthesized by hydrothermal method, and then Ag/Bi 2 WO 6 and Ag/Bi 2 WO 6 /CMK-3 composite photocatalysts were prepared via a photoreduction process. The samples were characterized by XRD, UV–vis, TEM (HR-TEM), SEM, N 2 physical adsorption and PL and their photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) under visible light irradiation. The results show that both incorporating of CMK-3 and Ag loading greatly improved the photocatalytic activity of Bi 2 WO 6 , and the content of CMK-3 and silver have an impact on the photocatalytic activity of Bi 2 WO 6 . The photocatalytic activity of Ag/Bi 2 WO 6 /CMK-3 photocatalyst is superior to the activities of CMK-3/Bi 2 WO 6 and Ag/Bi 2 WO 6 under comparable conditions, and Ag/Bi 2 WO 6 /CMK-3 photocatalyst has high stability and is easy to be recycled. Also, the mechanism for the enhancement of the photocatalytic activity of CMK-3 and Ag co-modified Bi 2 WO 6 was also investigated

  4. Characterization of engineered nanoparticles in commercially available spray disinfectant products advertised to contain colloidal silver

    Science.gov (United States)

    Given the potential for human exposure to silver nanoparticles from spray disinfectants and dietary supplements, we characterized the silver-containing nanoparticles in 22 commercial products that advertised the use of silver or colloidal silver as the active ingredient. Characte...

  5. Purification of Drinking Water from Fluorides by Reverse Osmosis

    Directory of Open Access Journals (Sweden)

    Aleksander A.

    2018-03-01

    Full Text Available Introduction: An important task in the sphere of sanitary and epidemiological welfare of the population of the Russian Federation is provision of drinking water. Tap water must not contain pathogenic bacteria and dangerous chemicals. Purification systems regulate the concentration of fluoride ions in drinking water. The aim of this paper is to study the possibility of purifying tap water from fluoride ions by reverse osmosis. Materials and Methods: We used the Alfa Laval PilotUnit 2.5 "RO/NF with a set of spiral-type membrane elements RO99-2517/48 to remove fluoride ions. We measured the concentration of fluoride ions by the potentiometric method using the Hanna HI 2211 (pH/mV/T. Fluoride-selective electrode ELIS 131 F was used as an indicator electrode and the standard chloride-silver electrode EVL-1M3 was used as a reference electrode. Both the calibration and buffer solutions were prepared from chemically pure reagents and A. R. purity for analysis reagents according to GOST 4386-89. Results: A single passage of water through the reverse osmosis membrane reduced the concentration of fluoride ions from 2.29 ± 0.02 to 0.240 ± 0.015 mg/l. Double passage of water reduced the concentration by a factor of two. As the concentration of fluoride ions increased in the retentate, the concentration in the filtrate slightly increased too. Purification of water reduced the concentration of fluoride ions from 20 mg/l, to 0.5 mg/l. Discussion and Conclusions: Thus, using the Alfa Laval PilotUnit 2.5" RO/NF with a set of spiral-type membrane elements RO99-2517/48 filters tap water of ions of fluoride to the maximum allowable concentration. This study opens the perspective of using reverse osmosis to purify tap water with high concentration of fluoride ions.

  6. Aeromonas caviae alters the cytosolic and mitochondrial creatine kinase activities in experimentally infected silver catfish: Impairment on renal bioenergetics.

    Science.gov (United States)

    Baldissera, Matheus D; Souza, Carine F; Júnior, Guerino B; Verdi, Camila Marina; Moreira, Karen L S; da Rocha, Maria Izabel U M; da Veiga, Marcelo L; Santos, Roberto C V; Vizzotto, Bruno S; Baldisserotto, Bernardo

    2017-09-01

    Cytosolic and mitochondrial creatine kinases (CK), through the creatine kinase-phosphocreatine (CK/PCr) system, provide a temporal and spatial energy buffer to maintain cellular energy homeostasis. However, the effects of bacterial infections on the kidney remain poorly understood and are limited only to histopathological analyses. Thus, the aim of this study was to investigate the involvement of cytosolic and mitochondrial CK activities in renal energetic homeostasis in silver catfish experimentally infected with Aeromonas caviae. Cytosolic CK activity decreased in infected animals, while mitochondrial CK activity increased compared to uninfected animals. Moreover, the activity of the sodium-potassium pump (Na + , K + -ATPase) decreased in infected animals compared to uninfected animals. Based on this evidence, it can be concluded that the inhibition of cytosolic CK activity by A. caviae causes an impairment on renal energy homeostasis through the depletion of adenosine triphosphate (ATP) levels. This contributes to the inhibition of Na + , K + -ATPase activity, although the mitochondrial CK activity acted in an attempt to restore the cytosolic ATP levels through a feedback mechanism. In summary, A. caviae infection causes a severe energetic imbalance in infected silver catfish, which may contribute to disease pathogenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Facile pyrolysis preparation of rosin-derived biochar for supporting silver nanoparticles with antibacterial activity

    DEFF Research Database (Denmark)

    Huang, Jian Fei; Shi, Qing Shan; Feng, Jin

    2017-01-01

    -step preparation process and a low loading capacity of nanoparticles. A facile preparation route for the preparation of antibacterial metallic nanocomposites would be especially beneficial for industrial fabrication. In this study, we provided a facile strategy for the preparation of a rosin-derived biochar matrix...... loaded with silver nanoparticles (Ag NPs) as the fillers. The results demonstrated that the preparation of these rosin-derived biochar silver nanocomposites (Rc/Ag nanocomposites) was achieved by a rapid pyrolysis process and a large amount of Ag NPs were in-situ obtained and homogeneously dispersed...

  8. Green chemistry focus on optimization of silver nanoparticles using response surface methodology (RSM) and mosquitocidal activity: Anopheles stephensi (Diptera: Culicidae).

    Science.gov (United States)

    Ondari Nyakundi, Erick; Padmanabhan, M Nalini

    2015-01-01

    There is an exigent necessity for development of environmental friendly bio-control agent(s) for elimination of mosquito due to increased resistance resurgence against synthetic control agents. Mosquito control strategy will lay a strong foundation to malaria exclusion or it can be curbed to certain level especially in the developing nations. In this study, silver nanoparticles were synthesized by green chemistry approach using Tridax procumbens leaf extract as a reducing agent. The reaction medium involved in the synthesis process was optimized by statistical experimental design using response surface methodology to obtain better yield, uniform size, shape and stability. Further, these synthesized nanoparticles were confirmed through UV-Visible, FT-IR spectroscopy, PSA and SEM Subsequently, the bioefficacy of these particles were investigated on Anopheles stephensi for larvicidal and pupicidal activity. Interestingly, time period of 90 min, temperature of 76±2 °C, pH 7.2±2, 2 mM silver nitrate (AgNO3), 3mM PEG and 2mM PVP showed excellent parameters for bioprocess design for large scale production of stabilized nanoparticles. A concentration of 5 ppm of PVP stabilized nanoparticles exhibited 100% mortality. Thus, the obtained results clearly suggest that silver nanoparticles stabilized by PEG and PVP may have important function as stabilizers, dispersants as well as larvicides for mosquito control. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. A facile biomimetic preparation of highly stabilized silver nanoparticles derived from seed extract of Vigna radiata and evaluation of their antibacterial activity

    Science.gov (United States)

    Choudhary, Manoj Kumar; Kataria, Jyoti; Cameotra, Swaranjit Singh; Singh, Jagdish

    2016-01-01

    The significant antibacterial activity of silver nanoparticles draws the major attention toward the present nanobiotechnology. Also, the use of plant material for the synthesis of metal nanoparticles is considered as a green technology. In this context, a non-toxic, eco-friendly, and cost-effective method has been developed for the synthesis of silver nanoparticles using seed extract of mung beans ( Vigna radiata). The synthesized nanoparticles have been characterized by UV-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS), and X-ray diffraction (XRD). The UV-visible spectrum showed an absorption peak at around 440 nm. The different types of phytochemicals present in the seed extract synergistically reduce the Ag metal ions, as each phytochemical is unique in terms of its structure and antioxidant function. The colloidal silver nanoparticles were observed to be highly stable, even after 5 months. XRD analysis showed that the silver nanoparticles are crystalline in nature with face-centered cubic geometry and the TEM micrographs showed spherical particles with an average size of 18 nm. Further, the antibacterial activity of silver nanoparticles was evaluated by well-diffusion method and it was observed that the biogenic silver nanoparticles have an effective antibacterial activity against Escherichia coli and Staphylococcus aureus. The outcome of this study could be useful for nanotechnology-based biomedical applications.

  10. Biosynthesis of silver nanoparticles from Catharanthus roseus leaf extract and assessing their antioxidant, antimicrobial, and wound-healing activities.

    Science.gov (United States)

    Al-Shmgani, Hanady S A; Mohammed, Wasnaa H; Sulaiman, Ghassan M; Saadoon, Ali H

    2017-09-01

    Biosynthesis of silver nanoparticles (AgNPs) from Catharanthus roseus leaf extract was carried out, and their characterization, as well as antioxidant, antimicrobial, and wound-healing activities were evaluated. Color change, UV-vis spectrum, XRD, FTIR, and AFM assessments supported the biosynthesis and characterization of AgNPs. The synthesized AgNPs showed strong in vitro antioxidant and antimicrobial activities against various pathogens. The in vivo assessment of wound healing in AgNPs-treated mice revealed their effectiveness in closuring and reducing size of wounds. Such potent bioactivity may justify their biomedical use as antioxidant and antimicrobial agents for controlling various health-related diseases, particularly in wound healing.

  11. Green Synthesis and Antibacterial Activities of Silver Nanoparticles Using Extracellular Laccase of Lentinus edodes

    Directory of Open Access Journals (Sweden)

    Agbaje LATEEF

    2015-12-01

    Full Text Available This study reports the multi-step mutagenesis of Lentinus edodes towards optimization of the production of laccase and novel application of laccase in the biosynthesis of silver nanoparticles (AgNPs which could be used to develop an eco-friendly method for the rapid biosynthesis of AgNPs. The wild strain of L. edodes was subjected to UV irradiation at 254 nm and the resultant viable mutant was further treated with acridine orange, a chemical mutagen. The strains were evaluated for the production of laccase and the crude laccase of the UV mutant (UV10 was used for the green synthesis of AgNPs. The particles were characterized by UV-Visible spectroscopy, Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. Laccase activities of wild, UV10 and UV10ACR8 strains of L. edodes were obtained as 2.6, 10.6 and 2.8 U/ml/min respectively after 7 days of fermentation, showing laccase yield improvement of 4.08-fold for UV10 mutant. UV-Visible spectroscopy indicated the formation of AgNPs at absorption band of 430 nm. FTIR result indicated that proteins were responsible for AgNP synthesis, while SEM analysis confirmed the formation of walnut-shaped nanoparticles with size range of 50-100 nm. The biosynthesized nanoparticles revealed effective inhibition against clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. To the best of the authors’ knowledge, this result represents the first report on the biosynthesis of AgNPs using L. edodes metabolite. The report adds to the growing relevance of L. edodes as potential industrially viable organism, used for diverse biotechnological applications.

  12. Fluoride and Oral Health.

    Science.gov (United States)

    O'Mullane, D M; Baez, R J; Jones, S; Lennon, M A; Petersen, P E; Rugg-Gunn, A J; Whelton, H; Whitford, G M

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.

  13. Private Well Water and Fluoride

    Science.gov (United States)

    ... Private Wells Infant Formula Fluorosis Public Health Service Recommendation Water Operators & Engineers Water Fluoridation Additives Shortages of Fluoridation Additives Drinking Water Pipe Systems CDC-Sponsored Water Fluoridation Training Links to Other ...

  14. Characterization, antibacterial, antioxidant, antidiabetic, anti-inflammatory and antityrosinase activity of green synthesized silver nanoparticles using Calophyllum tomentosum leaves extract

    Science.gov (United States)

    Govindappa, M.; Hemashekhar, B.; Arthikala, Manoj-Kumar; Ravishankar Rai, V.; Ramachandra, Y. L.

    2018-06-01

    The current research study is to develop an easy and eco-friendly method for the synthesis of AgNPs using aqueous leaf extract of Calophyllum tomentosum (CtAgNPs) and evaluated the extract to know the effects of anti-bacterial, antioxidant, anti-diabetic, anti-inflammatory and anti-tyrosinase activity. Using UV-vis spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) characterized the Calophyllum tomentosum mediated silver nanoparticles. The leaf extract of C. tomentosum yielded flavonoids, saponins, tannins, alkaloids, glycosides, phenols, terpenoids and coumarins. AgNPs formation was confirmed by UV-vis spectra at 438 nm. Crystalline structure with a face centered cubic (fcc) of AgNPs was observed in XRD. FTIR had shown that the phytochemicals were responsible for the reduction and capping material of silver nanoparticles. The size and shape of the AgNPs were determined using SEM. From EDX study analysed the strong absorption property of AgNPs. The CtAgNPs have showed significant antibacterial activity on multi drug resistance bacteria. The CtAgNPs had shown strong antioxidant (DPPH, H2O2 scavenging, nitric oxide scavenging power, reducing power) activities. The CtAgNPs had strongly inhibited the α-glucosidase and DPPIV compared to α-amylase. The CtAgNPs exhibited strong anti-inflammatory activity (albumin denaturation, membrane stabilization, heat haemolytic, protein inhibitory, lipoxygenase, xanthine oxidase) and tyrosinase inhibitory activity. To our best knowledge, this is the first attempt on the synthesis of silver nanoparticles using Calophyllum tomentosum leaves extract. Hence, to validate our results the in vivo studies at molecular level are needed to develop an antioxidant, anti-diabetic and anti-inflammatory agent.

  15. Community water fluoridation on the Internet and social media.

    Science.gov (United States)

    Mertz, Aaron; Allukian, Myron

    2014-01-01

    In the United States, 95 percent of teens and 85 percent of adults use the Internet. Two social media outlets, Facebook and Twitter, reach more than 150 billion users. This study describes anti-fluoridation activity and dominance on the Internet and social media, both of which are community water fluoridation (CWF) information sources. Monthly website traffic to major fluoridation websites was determined from June 2011 to May 2012. Facebook, Twitter, and YouTube fluoridation activity was categorized as "proCWF" or "anti-CWF." Twitter's anti-CWF tweets were further subcategorized by the argument used against CWF. Anti-CWF website traffic was found to exceed proCWF activity five- to sixty-fold. Searching "fluoride" and "fluoridation" on Facebook resulted in 88 to 100 percent anti-CWF groups and pages; "fluoridation" on Twitter and YouTube resulted in 64 percent anti-CWF tweets and 99 percent anti-CWF videos, respectively. "Cancer, " "useless, " and "poisonous" were the three major arguments used against fluoridation. Anti-fluoridation information significantly dominates the Internet and social media. Thousands of people are being misinformed daily about the safety, health, and economic benefits of fluoridation.

  16. Green production of microalgae-based silver chloride nanoparticles with antimicrobial activity against pathogenic bacteria.

    Science.gov (United States)

    da Silva Ferreira, Veronica; ConzFerreira, Mateus Eugenio; Lima, Luís Maurício T R; Frasés, Susana; de Souza, Wanderley; Sant'Anna, Celso

    2017-02-01

    Silver nanoparticles are powerful antimicrobial agents. Here, the synthesis of silver chloride nanoparticles (AgCl-NPs) was consistently evidenced from a commercially valuable microalgae species, Chlorella vulgaris. Incubation of C. vulgaris conditioned medium with AgNO 3 resulted in a medium color change to yellow/brown (with UV-vis absorbance at 415nm), indicative of silver nanoparticle formation. Energy-dispersive X-ray spectroscopy (EDS) of purified nanoparticles confirmed the presence of both silver and chlorine atoms, and X-ray diffraction (XRD) showed the typical pattern of cubic crystalline AgCl-NPs. Transmission electron microscopy (TEM) showed that most particles (65%) were spherical, with average diameter of 9.8±5.7nm. Fourier transform infrared spectroscopy (FTIR) of purified nanoparticle fractions suggested that proteins are the main molecular entities involved in AgCl-NP formation and stabilization. AgCl-NPs (from 10μg/mL) decreased by 98% the growth of Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae bacterial pathogens, and had a dose-dependent effect on cell viability, which was measured by automated image-based high content screening (HCS). Ultrastructural analysis of treated bacteria by TEM revealed the abnormal arrangement of the chromosomal DNA. Our findings strongly indicated that the AgCl-NPs from C. vulgaris conditioned medium is a promising 'green' alternative for biomedical application as antimicrobials. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Nanosilver and the microbiological activity of the particulate solids versus the leached soluble silver.

    Science.gov (United States)

    Faiz, Merisa B; Amal, Rose; Marquis, Christopher P; Harry, Elizabeth J; Sotiriou, Georgios A; Rice, Scott A; Gunawan, Cindy

    2018-04-01

    Nanosilver (Ag NPs) is currently one of the most commercialized antimicrobial nanoparticles with as yet, still unresolved cytotoxicity origins. To date, research efforts have mostly described the antimicrobial contribution from the leaching of soluble silver, while the undissolved solid Ag particulates are often considered as being microbiologically inert, serving only as source of the cytotoxic Ag ions. Here, we show the rapid stimulation of lethal cellular oxidative stress in bacteria by the presence of the undissolved Ag particulates. The cytotoxicity characteristics are distinct from those arising from the leached soluble Ag, the latter being locked in organic complexes. The work also highlights the unique oxidative stress-independent bacterial toxicity of silver salt. Taken together, the findings advocate that future enquiries on the antimicrobial potency and also importantly, the environmental and clinical impact of Ag NPs use, should pay attention to the potential bacterial toxicological responses to the undissolved Ag particulates, rather than just to the leaching of soluble silver. The findings also put into question the common use of silver salt as model material for evaluating bacterial toxicity of Ag NPs.

  18. Gold and silver thin film analysis by optical and neutron activation techniques

    International Nuclear Information System (INIS)

    Moharram, B.M.; El-Khatib, A.M.; Ammar, E.A.

    1989-01-01

    Thicknesses of gold and silver thin films have been determined by NAA technique. Reasonable agreement with conventional optical methods has been obtained, but the lower detection limit in the case of NAA is far better than in the optical method. (author)

  19. Mechanism of bactericidal activity of Silver Nitrate - a concentration dependent bi-functional molecule

    Directory of Open Access Journals (Sweden)

    Sureshbabu Ram Kumar Pandian

    2010-10-01

    Full Text Available Silver nitrate imparts different functions on bacteria depending upon its concentration. At lower concentration it induced synthesis of nanoparticles, whereas at higher concentrations it induced cell death. Bacillus licheniformis was used as model system. The MIC was 5 mM, and it induced catalase production, apoptotic body formation and DNA fragmentation.

  20. Evaluation of antibacterial activities of silver nanoparticles green-synthesized using pineapple leaf (Ananas comosus).

    Science.gov (United States)

    Emeka, Elemike Elias; Ojiefoh, Oseghale Charles; Aleruchi, Chuku; Hassan, Labulo Ayomide; Christiana, Owoseni Mojisola; Rebecca, Mfon; Dare, Enock Olugbenga; Temitope, Adesuji Elijah

    2014-02-01

    Pineapple leaf was used in this study for the synthesis of silver nanoparticles based on the search for sustainable synthetic means. Indeed, this offered an economical and sustainable synthetic route relative to expensive and toxic chemical methods. The leaf extract was used and the corresponding nanoparticles obtained were subjected to UV-vis analysis at different times. The UV-vis was used to monitor the silver nanoparticle formation through sampling at time intervals. The formation of silver nanoparticles was apparently displayed within 2 min with evidence of surface plasmon bands (SPB) between 440 and 460 nm. The crystals was equally characterized using FTIR, X-ray diffraction methods and TEM. The different results obtained suggested the appearance of silver nanoparticles (SNPs) as determined by the process parameters with a particle size of 12.4 nm. The sample was further screened against Staphylococcus aureus, Streptococcus pneumoniae, Proteus mirabilis and Escherichia coli using Gentamicin as control. From the results, there is evidence of inhibition towards bacteria growth. It can now be inferred from the studies that biosynthesis of nanoparticles could be a gateway to our numerous health issues. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Synthesis of positively charged hybrid PHMB-stabilized silver nanoparticles: the search for a new type of active substances used in plant protection products

    Science.gov (United States)

    Krutyakov, Yurii A.; Kudrinsky, Alexey A.; Gusev, Alexander A.; Zakharova, Olga V.; Klimov, Alexey I.; Yapryntsev, Alexey D.; Zherebin, Pavel M.; Shapoval, Olga A.; Lisichkin, Georgii V.

    2017-07-01

    Modern agriculture calls for a decrease in pesticide application, particularly in order to decrease the negative impact on the environment. Therefore the development of new active substances and plant protection products (PPP) to minimize the chemical load on ecosystems is a very important problem. Substances based on silver nanoparticles are a promising solution of this problem because of the fact that in correct doses such products significantly increase yields and decrease crop diseases while displaying low toxicity to humans and animals. In this paper we for the first time propose application of polymeric guanidine compounds with varying chain lengths (from 10 to 130 elementary links) for the design and synthesis of modified silver nanoparticles to be used as the basis of a new generation of PPP. Colloidal solutions of nanocrystalline silver containing 0.5 g l-1 of silver and 0.01-0.4 g l-1 of polyhexamethylene biguanide hydrochloride (PHMB) were obtained by reduction of silver nitrate with sodium borohydride in the presence of PHMB. The field experiment has shown that silver-containing solutions have a positive effect on agronomic properties of potato, wheat and apple. Also the increase in activity of such antioxidant system enzymes as peroxidase and catalase in the tissues of plants treated with nanosilver has been registered.

  2. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite.

    Science.gov (United States)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Controllable synthesis of Eu{sup 3+}/Tb{sup 3+} activated lutetium fluorides nanocrystals and their photophysical properties

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jintai; Huo, Jiansheng [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Cai, Yuepeng [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Qianming, E-mail: qmwang@scnu.edu.cn [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

    2013-12-15

    In this paper, phosphors of LuF{sub 3}:Eu{sup 3+}/Tb{sup 3+} have been successfully synthesized with small chelator ethylenediaminetetra acetic acid (EDTA) or amphiphilic polymer (polyethylene glycol, PEG-1000) as templates via a hydrothermal method. X-ray powder diffraction (XRD), scanning electronic microscope (SEM), and photo-luminescent spectra techniques (PL) were used to characterize the as-prepared samples. XRD patterns showed that well crystallized lanthanide fluorides with hexagonal phase were achieved. SEM images revealed that different regular microstructures were achieved. The photo-luminescent properties of LuF{sub 3}:Eu{sup 3+} demonstrated that there are significant energy transfers from fluorides to Eu{sup 3+}. The results presented that EDTA as the template will lead to the highest emission intensities. -- Highlights: • Various templates were used to synthesize LuF{sub 3}:Eu{sup 3+}/Tb{sup 3+}. • All the phosphors were red or green emissive. • Different morphologies were acquired and controllable.

  4. Antimicrobial activity of biopolymeric thin films containing flavonoid natural compounds and silver nanoparticles fabricated by MAPLE: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Visan, A.; Socol, G. [National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Surdu, A.V.; Oprea, A.E.; Grumezescu, A.M. [Faculty of Applied Chemistry and Materials Science, Politehnica University of Bucharest, 1–7 Polizu Street, Bucharest, 011061 Romania (Romania); Chifiriuc, M.C. [Microbiology Immunology Department, Faculty of Biology, Research Institute of the University of Bucharest - ICUB, Bucharest, 77206 (Romania); Boehm, R.D.; Yamaleyeva, D.; Taylor, M.; Narayan, R.J. [Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC (United States); Chrisey, D.B. [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA (United States)

    2016-06-30

    Highlights: • We successfully deposited composite quercetin dehydrate-, resveratrol- and silver nanoparticle-polyvinylpyrrolidone thin coatings with chemical structure close to that of the starting materials by MAPLE. • Thin film morphology studies revealed a uniform surface without aggregates or grains on the top of the surface. • MAPLE-deposited thin films exhibited antibacterial activity against Gram-positive and Gram-negative bacterial strains. • We demonstrated the potential use of these hybrid systems and MAPLE deposition method for the development of new harmless, ecological antimicrobial strategies. - Abstract: The purpose of this study was to investigate the interactions between microorganisms, including the planktonic and adherent organisms, and biopolymer (polyvinylpyrrolidone), flavonoid (quercetin dihydrate and resveratrol)-biopolymer, and silver nanoparticles-biopolymer composite thin films that were deposited using matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF{sup *} excimer laser source was used to deposit the aforementioned composite thin films, which were characterized using Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The antimicrobial activity of thin films was quantified using an adapted disk diffusion assay against Gram-positive and Gram-negative bacteria strains. FT-IR, AFM and SEM studies confirmed that MAPLE may be used to fabricate thin films with chemical properties corresponding to the input materials as well as surface properties that are appropriate for medical use. The silver nanoparticles and flavonoid-containing films exhibited an antimicrobial activity both against Gram-positive and Gram-negative bacterial strains demonstrating the potential use of these hybrid systems for the development of novel antimicrobial strategies.

  5. Antimicrobial activity of biopolymeric thin films containing flavonoid natural compounds and silver nanoparticles fabricated by MAPLE: A comparative study

    International Nuclear Information System (INIS)

    Cristescu, R.; Visan, A.; Socol, G.; Surdu, A.V.; Oprea, A.E.; Grumezescu, A.M.; Chifiriuc, M.C.; Boehm, R.D.; Yamaleyeva, D.; Taylor, M.; Narayan, R.J.; Chrisey, D.B.

    2016-01-01

    Highlights: • We successfully deposited composite quercetin dehydrate-, resveratrol- and silver nanoparticle-polyvinylpyrrolidone thin coatings with chemical structure close to that of the starting materials by MAPLE. • Thin film morphology studies revealed a uniform surface without aggregates or grains on the top of the surface. • MAPLE-deposited thin films exhibited antibacterial activity against Gram-positive and Gram-negative bacterial strains. • We demonstrated the potential use of these hybrid systems and MAPLE deposition method for the development of new harmless, ecological antimicrobial strategies. - Abstract: The purpose of this study was to investigate the interactions between microorganisms, including the planktonic and adherent organisms, and biopolymer (polyvinylpyrrolidone), flavonoid (quercetin dihydrate and resveratrol)-biopolymer, and silver nanoparticles-biopolymer composite thin films that were deposited using matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF * excimer laser source was used to deposit the aforementioned composite thin films, which were characterized using Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The antimicrobial activity of thin films was quantified using an adapted disk diffusion assay against Gram-positive and Gram-negative bacteria strains. FT-IR, AFM and SEM studies confirmed that MAPLE may be used to fabricate thin films with chemical properties corresponding to the input materials as well as surface properties that are appropriate for medical use. The silver nanoparticles and flavonoid-containing films exhibited an antimicrobial activity both against Gram-positive and Gram-negative bacterial strains demonstrating the potential use of these hybrid systems for the development of novel antimicrobial strategies.

  6. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Song, Cunfeng [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chang, Ying; Cheng, Ling; Xu, Yiting [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Xiaoling, E-mail: tinachen0628@163.com [Department of Endodontics, Xiamen Stomatology Hospital, Teaching Hospital of Fujian Medical University, Xiamen 361003 (China); Zhang, Long; Zhong, Lina [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Dai, Lizong, E-mail: lzdai@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Esch