In vivo magnetic resonance and fluorescence dual imaging of tumor sites by using dye-doped silica-coated iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Jang, Haeyun; Lee, Chaedong [Seoul National University, Program in Nano Science and Technology, Graduate School of Convergence Science and Technology (Korea, Republic of); Nam, Gi-Eun [University of Ulsan College of Medicine, Department of Radiology, Asan Medical Center (Korea, Republic of); Quan, Bo [Seoul National University, Program in Nano Science and Technology, Graduate School of Convergence Science and Technology (Korea, Republic of); Choi, Hyuck Jae [University of Ulsan College of Medicine, Department of Radiology, Asan Medical Center (Korea, Republic of); Yoo, Jung Sun [Seoul National University, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Smart Humanity Convergence Center (Korea, Republic of); Piao, Yuanzhe, E-mail: parkat9@snu.ac.kr [Seoul National University, Program in Nano Science and Technology, Graduate School of Convergence Science and Technology (Korea, Republic of)

2016-02-15

The difficulty in delineating tumor is a major obstacle for better outcomes in cancer treatment of patients. The use of single-imaging modality is often limited by inadequate sensitivity and resolution. Here, we present the synthesis and the use of monodisperse iron oxide nanoparticles coated with fluorescent silica nano-shells for fluorescence and magnetic resonance dual imaging of tumor. The as-synthesized core–shell nanoparticles were designed to improve the accuracy of diagnosis via simultaneous tumor imaging with dual imaging modalities by a single injection of contrast agent. The iron oxide nanocrystals (∼11 nm) were coated with Rhodamine B isothiocyanate-doped silica shells via reverse microemulsion method. Then, the core–shell nanoparticles (∼54 nm) were analyzed to confirm their size distribution by transmission electron microscopy and dynamic laser scattering. Photoluminescence spectroscopy was used to characterize the fluorescent property of the dye-doped silica shell-coated nanoparticles. The cellular compatibility of the as-prepared nanoparticles was confirmed by a trypan blue dye exclusion assay and the potential as a dual-imaging contrast agent was verified by in vivo fluorescence and magnetic resonance imaging. The experimental results show that the uniform-sized core–shell nanoparticles are highly water dispersible and the cellular toxicity of the nanoparticles is negligible. In vivo fluorescence imaging demonstrates the capability of the developed nanoparticles to selectively target tumors by the enhanced permeability and retention effects and ex vivo tissue analysis was corroborated this. Through in vitro phantom test, the core/shell nanoparticles showed a T2 relaxation time comparable to Feridex{sup ®} with smaller size, indicating that the as-made nanoparticles are suitable for imaging tumor. This new dual-modality-nanoparticle approach has promised for enabling more accurate tumor imaging.

Magnetic, Fluorescence and Transition Metal Ion Response Properties of 2,6-Diaminopyridine Modified Silica-Coated Fe3O4 Nanoparticles

Directory of Open Access Journals (Sweden)

Yunhui Zhai

2016-08-01

Full Text Available Multi-functional nanoparticles possessing magnetic, fluorescence and transition metal ion response properties were prepared and characterized. The particles have a core/shell structure that consists of silica-coated magnetic Fe3O4 and 2,6-diaminopyridine anchored on the silica surface via organic linker molecules. The resultant nanoparticles were found by transmission electron microscopy to be well-dispersed spherical particles with an average diameter of 10–12 nm. X-ray diffraction analysis suggested the existence of Fe3O4 and silica in/on the particle. Fourier transform infrared spectra revealed that 2,6-diaminopyridine molecules were successfully covalently bonded to the surface of magnetic composite nanoparticles. The prepared particles possessed an emission peak at 364 nm with an excitation wavelength of 307 nm and have a strong reversible response property for some transition metal ions such as Cu2+ and Zn2+. This new material holds considerable promise in selective magneto separation and optical determination applications.

Magnet-induced temporary superhydrophobic coatings from one-pot synthesized hydrophobic magnetic nanoparticles.

Science.gov (United States)

Fang, Jian; Wang, Hongxia; Xue, Yuhua; Wang, Xungai; Lin, Tong

2010-05-01

In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe(3)O(4) magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe(2+)/Fe(3+) under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172 degrees , and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is the formation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas.

Silica-coated Gd(DOTA)-loaded protein nanoparticles enable magnetic resonance imaging of macrophages

Science.gov (United States)

Bruckman, Michael A.; Randolph, Lauren N.; Gulati, Neetu M.; Stewart, Phoebe L.; Steinmetz, Nicole F.

2015-01-01

The molecular imaging of in vivo targets allows non-invasive disease diagnosis. Nanoparticles offer a promising platform for molecular imaging because they can deliver large payloads of imaging reagents to the site of disease. Magnetic resonance imaging (MRI) is often preferred for clinical diagnosis because it uses non-ionizing radiation and offers both high spatial resolution and excellent penetration. We have explored the use of plant viruses as the basis of for MRI contrast reagents, specifically Tobacco mosaic virus (TMV), which can assemble to form either stiff rods or spheres. We loaded TMV particles with paramagnetic Gd ions, increasing the ionic relaxivity compared to free Gd ions. The loaded TMV particles were then coated with silica maintaining high relaxivities. Interestingly, we found that when Gd(DOTA) was loaded into the interior channel of TMV and the exterior was coated with silica, the T1 relaxivities increased by three-fold from 10.9 mM−1 s−1 to 29.7 mM−1s−1 at 60 MHz compared to uncoated Gd-loaded TMV. To test the performance of the contrast agents in a biological setting, we focused on interactions with macrophages because the active or passive targeting of immune cells is a popular strategy to investigate the cellular components involved in disease progression associated with inflammation. In vitro assays and phantom MRI experiments indicate efficient targeting and imaging of macrophages, enhanced contrast-to-noise ratio was observed by shape-engineering (SNP > TMV) and silica-coating (Si-TMV/SNP > TMV/SNP). Because plant viruses are in the food chain, antibodies may be prevalent in the population. Therefore we investigated whether the silica-coating could prevent antibody recognition; indeed our data indicate that mineralization can be used as a stealth coating option to reduce clearance. Therefore, we conclude that the silica-coated protein-based contrast agent may provide an interesting candidate material for further investigation

Magnetic heating by silica-coated Co–Zn ferrite particles

Czech Academy of Sciences Publication Activity Database

Veverka, Miroslav; Závěta, K.; Kaman, Ondřej; Veverka, Pavel; Knížek, Karel; Pollert, Emil; Burian, M.; Kašpar, P.

2014-01-01

Roč. 47, č. 6 (2014), "065503-1"-"065503-11" ISSN 0022-3727 R&D Projects: GA ČR GAP204/10/0035; GA ČR(CZ) GAP108/11/0807 Institutional support: RVO:68378271 Keywords : cobalt–zinc ferrite * magnetic nanoparticles * coprecipitation * silica coating * hysteresis loops * calorimetric measurements * hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.721, year: 2014 http://stacks.iop.org/0022-3727/47/065503

Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

Energy Technology Data Exchange (ETDEWEB)

Tong, Yue; Zhang, Min, E-mail: congmingyang123@163.com; Xia, Peixiong; Wang, Linlin; Zheng, Jing; Li, Weizhen; Xu, Jingli, E-mail: xujingli@sues.edu.cn

2016-05-15

Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N{sub 2} adsorption–desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO{sub 2}-coated maghemite/CNTs nanoparticles (CNTs/Fe{sub 3}O{sub 4}@SiO{sub 2} composites) were synthesized by the combination of high temperature decomposition process and an sol–gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO{sub 2}, respectively. The CNTs/Fe{sub 3}O{sub 4}@SiO{sub 2} composites revealed a core–shell structure, Then, CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature. - Graphical abstract: Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis, which can be a good adsorbent for the organic pollutant in the ambient temperature. - Highlights: • The surface of CNTs/Fe{sub 3}O{sub 4} is hydrophilic, which facilitates the silica coating. • The CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} was synthesized by a facile method. • The CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} can be a good adsorbent for the organic pollutant.

Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

International Nuclear Information System (INIS)

Perrier, Marine; Gary-Bobo, Magali; Lartigue, Lenaïc; Brevet, David; Morère, Alain; Garcia, Marcel; Maillard, Philippe; Raehm, Laurence; Guari, Yannick; Larionova, Joulia; Durand, Jean-Olivier; Mongin, Olivier; Blanchard-Desce, Mireille

2013-01-01

An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

Energy Technology Data Exchange (ETDEWEB)

Perrier, Marine [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Gary-Bobo, Magali [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Lartigue, Lenaiec; Brevet, David [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Morere, Alain; Garcia, Marcel [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Maillard, Philippe [Universite Paris-Sud, UMR 176 CNRS, Institut Curie (France); Raehm, Laurence; Guari, Yannick, E-mail: yannick.guari@um2.fr; Larionova, Joulia; Durand, Jean-Olivier, E-mail: durand@univ-montp2.fr [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Mongin, Olivier [Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, CNRS UMR 6226 (France); Blanchard-Desce, Mireille [Universite Bordeaux, Institut des Sciences Moleculaires, UMR CNRS 5255 (France)

2013-05-15

An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

Evaluation of superparamagnetic and biocompatible properties of mesoporous silica coated cobalt ferrite nanoparticles synthesized via microwave modified Pechini method

Energy Technology Data Exchange (ETDEWEB)

Gharibshahian, M. [Faculty of New Sciences and Technologies, Semnan University, Semnan (Iran, Islamic Republic of); Mirzaee, O., E-mail: O_mirzaee@semnan.ac.ir [Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Nourbakhsh, M.S. [Faculty of New Sciences and Technologies, Semnan University, Semnan (Iran, Islamic Republic of)

2017-03-01

Cobalt ferrite nano particles were synthesized by Pechini sol-gel method and calcined at 700 °C in electrical and microwave furnace. The microwave calcined sample was coated with mesoporous silica by hydrothermal method. Characterization was performed by XRD, FESEM, TEM, VSM, BET and FTIR analysis. The cytotoxicity was evaluated by MTT assay with 3T3 fibroblast cells. The XRD and FTIR results confirmed spinal formation in both cases and verified the formation of silica coating on the nanoparticles. For microwave calcination, The XRD and SEM results demonstrated smaller and flat adhesion forms of nanoparticles with the average size of 15 nm. The VSM results demonstrated nearly superparamagnetic nanoparticles with significant saturation magnetization equal to 64 emu/g. By coating, saturation magnetization was decreased to 36 emu/g. Moreover, the BET results confirmed the formation of mesoporous coating with the average pore diameters of 2.8 nm and average pore volume of 0.82 cm{sup 3} g{sup −1}. Microwave calcined nanoparticles had the best structural and magnetic properties. - Highlights: • CoFe{sub 2}O{sub 4} nanoparticles were synthesized using the microwave modified Pechini method. • The Effect of calcination route and silica coating on NPs properties was studied. • The nearly superparamagnetic nanoparticles were achieved by microwave calcination. • MFC NPs had the best magnetic properties and MTT assay showed no toxicity for MFC-MSC NPs. • A useful scheme was designed to achieve biological superparamagnetic core/shell NPs.

Optical properties of silica-coated Y2O3:Er,Yb nanoparticles in the presence of polyvinylpyrrolidone

International Nuclear Information System (INIS)

Fujii, Kunio; Kitamoto, Yoshitaka; Hara, Masahiko; Odawara, Osamu; Wada, Hiroyuki

2014-01-01

The optical properties of polyvinylpyrrolidone (PVP)-adsorbed and silica-coated Y 2 O 3 :Er,Yb nanoparticles produced by using PVP were studied for potential bio-applications of upconversion nanoparticles. We utilized PVP to better disperse Y 2 O 3 :Er,Yb nanoparticles in solution and to prepare silica-coated Y 2 O 3 :Er,Yb nanoparticles. The fluorescent intensity of PVP-adsorbed Y 2 O 3 :Er,Yb nanoparticles was 1.25 times higher than non-adsorbed Y 2 O 3 :Er,Yb nanoparticles, which was probably due to surface defects in Y 2 O 3 :Er,Yb nanoparticles being covered by the PVP. However, the fluorescent intensity of silica-coated Y 2 O 3 :Er,Yb nanoparticles decreased as silica layer thickness increased. This could be ascribed to the higher vibrational energy of PVP than that of the silica structure. Therefore, the optimum silica layer thickness is important in bio-applications to avoid deterioration of the optical properties of Y 2 O 3 :Er,Yb nanoparticles. - Highlights: • We prepared the silica-coated upconversion nanoparticles by using PVP. • We showed that PVP played an important role in coating nanoparticles. • PL intensity of silica-coated nanoparticles decreased as silica layer thickness increased

Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers

Directory of Open Access Journals (Sweden)

Junpeng Liu

2016-12-01

Full Text Available A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

Design of water-repellant coating using dual scale size of hybrid silica nanoparticles on polymer surface

Science.gov (United States)

Conti, J.; De Coninck, J.; Ghazzal, M. N.

2018-04-01

The dual-scale size of the silica nanoparticles is commonly aimed at producing dual-scale roughness, also called hierarchical roughness (Lotus effect). In this study, we describe a method to build a stable water-repellant coating with controlled roughness. Hybrid silica nanoparticles are self-assembled over a polymeric surface by alternating consecutive layers. Each one uses homogenously distributed silica nanoparticles of a particular size. The effect of the nanoparticle size of the first layer on the final roughness of the coating is studied. The first layer enables to adjust the distance between the silica nanoparticles of the upper layer, leading to a tuneable and controlled final roughness. An optimal size nanoparticle has been found for higher water-repellency. Furthermore, the stability of the coating on polymeric surface (Polycarbonate substrate) is ensured by photopolymerization of hybridized silica nanoparticles using Vinyl functional groups.

Iodinated oil-loaded, fluorescent mesoporous silica-coated iron oxide nanoparticles for magnetic resonance imaging/computed tomography/fluorescence trimodal imaging

Directory of Open Access Journals (Sweden)

Xue S

2014-05-01

Full Text Available Sihan Xue,1 Yao Wang,1 Mengxing Wang,2 Lu Zhang,1 Xiaoxia Du,2 Hongchen Gu,1 Chunfu Zhang1,31School of Biomedical Engineering and Med-X Research Institute, Shanghai Jiao Tong University, 2Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, 3State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, People’s Republic of ChinaAbstract: In this study, a novel magnetic resonance imaging (MRI/computed tomography (CT/fluorescence trifunctional probe was prepared by loading iodinated oil into fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (i-fmSiO4@SPIONs. Fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs were prepared by growing fluorescent dye-doped silica onto superparamagnetic iron oxide nanoparticles (SPIONs directed by a cetyltrimethylammonium bromide template. As prepared, fmSiO4@SPIONs had a uniform size, a large surface area, and a large pore volume, which demonstrated high efficiency for iodinated oil loading. Iodinated oil loading did not change the sizes of fmSiO4@SPIONs, but they reduced the MRI T2 relaxivity (r2 markedly. I-fmSiO4@SPIONs were stable in their physical condition and did not demonstrate cytotoxic effects under the conditions investigated. In vitro studies indicated that the contrast enhancement of MRI and CT, and the fluorescence signal intensity of i-fmSiO4@SPION aqueous suspensions and macrophages, were intensified with increased i-fmSiO4@SPION concentrations in suspension and cell culture media. Moreover, for the in vivo study, the accumulation of i-fmSiO4@SPIONs in the liver could also be detected by MRI, CT, and fluorescence imaging. Our study demonstrated that i-fmSiO4@SPIONs had great potential for MRI/C/fluorescence trimodal imaging.Keywords: multifunctional probe, SPIONs, mesoporous silica

Silica Nanoparticles Functionalized with Zwitterionic Sulfobetaine Siloxane for Application as a Versatile Antifouling Coating System.

Science.gov (United States)

Knowles, Brianna R; Wagner, Pawel; Maclaughlin, Shane; Higgins, Michael J; Molino, Paul J

2017-06-07

The growing need to develop surfaces able to effectively resist biological fouling has resulted in the widespread investigation of nanomaterials with potential antifouling properties. However, the preparation of effective antifouling coatings is limited by the availability of reactive surface functional groups and our ability to carefully control and organize chemistries at a materials' interface. Here, we present two methods of preparing hydrophilic low-fouling surface coatings through reaction of silica-nanoparticle suspensions and predeposited silica-nanoparticle films with zwitterionic sulfobetaine (SB). Silica-nanoparticle suspensions were functionalized with SB across three pH conditions and deposited as thin films via a simple spin-coating process to generate hydrophilic antifouling coatings. In addition, coatings of predeposited silica nanoparticles were surface functionalized via exposure to zwitterionic solutions. Quartz crystal microgravimetry with dissipation monitoring was employed as a high throughput technique for monitoring and optimizing reaction to the silica-nanoparticle surfaces. Functionalization of nanoparticle films was rapid and could be achieved over a wide pH range and at low zwitterion concentrations. All functionalized particle surfaces presented a high degree of wettability and resulted in large reductions in adsorption of bovine serum albumin protein. Particle coatings also showed a reduction in adhesion of fungal spores (Epicoccum nigrum) and bacteria (Escherichia coli) by up to 87 and 96%, respectively. These results indicate the potential for functionalized nanosilicas to be further developed as versatile fouling-resistant coatings for widespread coating applications.

Phospholipid-Coated Mesoporous Silica Nanoparticles Acting as Lubricating Drug Nanocarriers

OpenAIRE

Tao Sun; Yulong Sun; Hongyu Zhang

2018-01-01

Osteoarthritis (OA) is a severe disease caused by wear and inflammation of joints. In this study, phospholipid-coated mesoporous silica nanoparticles (MSNs@lip) were prepared in order to treat OA at an early stage. The phospholipid layer has excellent lubrication capability in aqueous media due to the hydration lubrication mechanism, while mesoporous silica nanoparticles (MSNs) act as effective drug nanocarriers. The MSNs@lip were characterized by scanning electron microscope, transmission el...

Morphology and orientational behavior of silica-coated spindle-type hematite particles in a magnetic field probed by small-angle X-ray scattering.

Science.gov (United States)

Reufer, Mathias; Dietsch, Hervé; Gasser, Urs; Hirt, Ann; Menzel, Andreas; Schurtenberger, Peter

2010-04-15

Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core-shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The orientational order is determined from the SAXS data and compared to the orientational order obtained from magnetometry. The direct access to both, the orientational order of the particles, and the magnetic moments allow one to determine the magnetic properties of the individual spindle-type hematite particles. We study the influence of the silica coating on the magnetic properties and find a fundamentally different behavior of silica-coated particles. The silica coating reduces the effective magnetic moment of the particles. This effect is enhanced with field strength and can be explained by superparamagnetic relaxation in the highly porous particles.

Synthesis and characterization of uniform silica nanoparticles on nickel substrate by spin coating and sol-gel method

Science.gov (United States)

Ngoc Thi Le, Hien; Jeong, Hae Kyung

2014-01-01

Spin coating and sol-gel methods are proposed for the preparation of silica nanoparticles on a nickel substrate using silicon tetrachloride, 2-methoxyethanol, and four different types of alkaline solutions. The effects of the type of alkaline solution, concentration of silica solution, and speed of spin coating on the properties of silica nanoparticles are investigated systematically. Uniform spherical shape of silica nanoparticles on Ni with the smallest size are obtained with sodium carbonate among the alkaline solutions after stirring at 70 °C for 6 h and spin-coating at 7000 rpm. Physical and electrochemical properties of the silica particles are investigated.

Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

Energy Technology Data Exchange (ETDEWEB)

Sodipo, Bashiru Kayode, E-mail: bashirsodipo@gmail.com [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia)

2016-10-15

Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION. - Highlights: • We present recent advances in synthesis of SPION and various routes of producing silica coated SPION • The synthetic routes of producing SPION can be classified into three: physical, chemical and biological methods. • The chemical method is the most cited method of producing SPION and it sub-classified into liquid and gas phase. • The techniques of producing silica coated SPION is grouped into seeded and non-seeded methods.

Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

International Nuclear Information System (INIS)

Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

2016-01-01

Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION. - Highlights: • We present recent advances in synthesis of SPION and various routes of producing silica coated SPION • The synthetic routes of producing SPION can be classified into three: physical, chemical and biological methods. • The chemical method is the most cited method of producing SPION and it sub-classified into liquid and gas phase. • The techniques of producing silica coated SPION is grouped into seeded and non-seeded methods.

A novel method for the synthesis of monodisperse gold-coated silica nanoparticles

International Nuclear Information System (INIS)

English, Michael D.; Waclawik, Eric R.

2012-01-01

Monodisperse silica nanoparticles were synthesised by the well-known Stober protocol, then dispersed in acetonitrile (ACN) and subsequently added to a bisacetonitrile gold(I) coordination complex ([Au(MeCN) 2 ] + ) in ACN. The silica hydroxyl groups were deprotonated in the presence of ACN, generating a formal negative charge on the siloxy groups. This allowed the [Au(MeCN) 2 ] + complex to undergo ligand exchange with the silica nanoparticles and form a surface coordination complex with reduction to metallic gold (Au 0 ) proceeding by an inner sphere mechanism. The residual [Au(MeCN) 2 ] + complex was allowed to react with water, disproportionating into Au 0 and Au(III), respectively, with the Au 0 adding to the reduced gold already bound on the silica surface. The so-formed metallic gold seed surface was found to be suitable for the conventional reduction of Au(III) to Au 0 by ascorbic acid (ASC). This process generated a thin and uniform gold coating on the silica nanoparticles. The silica NPs batches synthesised were in a size range from 45 to 460 nm. Of these silica NP batches, the size range from 400 to 480 nm were used for the gold-coating experiments.

Sensing behavior study of silica-coated Ag nanoparticles deposited on glassy carbon toward nitrobenzene

Energy Technology Data Exchange (ETDEWEB)

Devi, Pooja; Reddy, Pramod [CSIR, Sector-30C, Central Scientific Instruments Organization (India); Arora, Swati [Shri Mata Vaishno Devi University (India); Singh, Suman; Ghanshyam, C.; Singla, M. L., E-mail: singla_min@yahoo.co.in [CSIR, Sector-30C, Central Scientific Instruments Organization (India)

2012-10-15

In this study, we report the synthesis and characterization of silica-coated silver core/shell nanostructures (NSs) and their sensing behavior when deposited on glassy carbon (GC) electrode for nitrobenzene (NB) detection. Synthesized silica-coated silver core/shell NSs were characterized for their chemical, structural and morphological properties. TEM analysis confirmed that the silica-coated silver nanoparticles (size {approx}200 nm) are spherical in shape and the core diameter is {approx}38 nm. FT-IR spectra also confirmed the coating of silica on the surface of silver nanoparticles. Cyclic voltammetry studies of NB with silica-coated silver core-shell nanoparticles-modified GC electrodes revealed two cathodic peaks at -0.74 V (C{sub 1}) and -0.34 V (C{sub 2}) along with two anodic peaks at -0.64 V (A{sub 1}) and -0.2 V (A{sub 2}). Enhanced cathodic peak current (C{sub 1}, I{sub P}) of the core-shell NSs-modified electrode is observed relative to bare and silica-modified electrodes. Amperometric studies revealed a very high current sensitivity (114 nA/nM) and linearly dependent reduction current with NB amount in the low concentration range and a detection limit of 25 nM. Moreover, the core-shell NSs-modified electrode showed good reproducibility and selectivity toward NB in the presence of many cationic, anionic, and organic interferents.

Sensing behavior study of silica-coated Ag nanoparticles deposited on glassy carbon toward nitrobenzene

International Nuclear Information System (INIS)

Devi, Pooja; Reddy, Pramod; Arora, Swati; Singh, Suman; Ghanshyam, C.; Singla, M. L.

2012-01-01

In this study, we report the synthesis and characterization of silica-coated silver core/shell nanostructures (NSs) and their sensing behavior when deposited on glassy carbon (GC) electrode for nitrobenzene (NB) detection. Synthesized silica-coated silver core/shell NSs were characterized for their chemical, structural and morphological properties. TEM analysis confirmed that the silica-coated silver nanoparticles (size ∼200 nm) are spherical in shape and the core diameter is ∼38 nm. FT-IR spectra also confirmed the coating of silica on the surface of silver nanoparticles. Cyclic voltammetry studies of NB with silica-coated silver core–shell nanoparticles-modified GC electrodes revealed two cathodic peaks at −0.74 V (C 1 ) and −0.34 V (C 2 ) along with two anodic peaks at −0.64 V (A 1 ) and −0.2 V (A 2 ). Enhanced cathodic peak current (C 1 , I P ) of the core–shell NSs-modified electrode is observed relative to bare and silica-modified electrodes. Amperometric studies revealed a very high current sensitivity (114 nA/nM) and linearly dependent reduction current with NB amount in the low concentration range and a detection limit of 25 nM. Moreover, the core–shell NSs-modified electrode showed good reproducibility and selectivity toward NB in the presence of many cationic, anionic, and organic interferents.

Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters

CERN Document Server

Dash, Monika

2013-01-01

Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

Controlled surface functionalization of silica-coated magnetic nanoparticles with terminal amino and carboxyl groups

International Nuclear Information System (INIS)

Kralj, Slavko; Drofenik, Miha; Makovec, Darko

2011-01-01

General and versatile methods for the functionalization of superparamagnetic, silica-coated, maghemite nanoparticles by surface amino and/or carboxyl groups have been established. The nanoparticles were synthesized using co-precipitation from aqueous solutions and coated with a thin layer of silica using the hydrolysis and condensation of tetraethoxysilane (TEOS). For the amino functionalization, 3-(2-aminoethylamino)propylmethyldimethoxysilane (APMS) was grafted onto the nanoparticle surfaces in their aqueous suspensions. The grafting process was followed by measurements of the ζ-potential and a determination of the concentration of the surface amino groups with conductometric titrations. The surface concentration of the amino groups could be varied by increasing the amount of APMS in the grafting process up to approximately 2.3 –NH 2 groups per nm 2 . The carboxyl functionalization was obtained in two ways: (i) by a ring-opening linker elongation reaction of the surface amines at the functionalized nanoparticles with succinic anhydride (SA) in non-aqueous medium, and (ii) by reacting the APMS and SA first, followed by grafting of the carboxyl-terminated reagent onto the nanoparticle surfaces. Using the first method, the SA only reacted with the terminal primary amino groups (–NH 2 ) of the surface-grafted APMS molecules. Infra-red spectroscopy (ATR FTIR) and mass spectrometry (HRMS) showed that the second method enables the bonding of up to two SA molecules per one APMS molecule, since the SA reacted with both the primary (–NH 2 ) and secondary amino (–NH–) groups of the APMS molecule. When using both methods, the ratio between the surface amino and carboxyl groups can be controlled.

Thiol-modified gold nanoparticles deposited on silica support using dip coating

International Nuclear Information System (INIS)

Magura, Jozef; Zeleňáková, Adriana; Zeleňák, Vladimír; Kaňuchová, Maria

2014-01-01

Graphical abstract: - Highlights: • Thin layers of gold were deposited on glass substrate. • Layers were modified by two different ligands, 1,4-dithiothreitol and L-glutathione. • Red shift of SPR band was observed in spectra after modification of Au by thiols. • Charge transfer between Au and S atoms leads to ferromagnetic behaviour of samples. - Abstract: In our work, we have prepared thin layers of gold nanoparticles deposited via dip coating technique on silica glass substrate. The prepared thin layers were modified by two different ligands, namely 1,4-dithiothreitol (sample Au-DTT NPs) and L-glutathione (sample Au-GSH NPs). The spectral, structural and magnetic properties of the prepared samples were investigated. The modification of Au nanoparticles with thiol ligands leads to change of their plasmon resonance fields, as indicated by UV–vis spectra. The magnetic measurements showed that the magnetization of the samples is composed from two magnetic contributions: diamagnetic contribution and low field ferromagnetic contribution. Our experimental results show that the charge transfer between Au and S atoms gives rise to the ferromagnetic behaviour of prepared thin layers

Pore fabrication in various silica-based nanoparticles by controlled etching

KAUST Repository

Zhao, Lan

2010-07-20

A novel method based on controlled etching was developed to fabricate nanopores on preformed silica nanoparticles (<100 nm in diameter). The obtained monodisperse nanoporous particles could form highly stable homogeneous colloidal solution. Fluorescent silica nanoparticles and magnetic silica-coated γ-Fe 2O 3 nanoparticles were investigated as examples to illustrate that this strategy could be generally applied to various silica-based functional nanoparticles. The results indicated that this method was effective for generating pores on these nanoparticles without altering their original functionalities. The obtained multifunctional nanoparticles would be useful for many biological and biomedical applications. These porous nanoparticles could also serve as building blocks to fabricate three-dimensionally periodic structures that have the potential to be used as photonic crystals. © 2010 American Chemical Society.

Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

Energy Technology Data Exchange (ETDEWEB)

Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei, E-mail: weidong@njust.edu.cn

2016-11-30

Highlights: • Fe{sub 3}O{sub 4}@SiO{sub 2}@EDPS with uniform size and good dispersity is prepared. • We fabricated MMSN@EDPS with distinct core-shell–shell triple-layer composition. • DNA adsorption capacity of MMSN@EDPS is considerable. - Abstract: We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

Silica-coated magnetic nanoparticles impair proteasome activity and increase the formation of cytoplasmic inclusion bodies in vitro

Science.gov (United States)

Phukan, Geetika; Shin, Tae Hwan; Shim, Jeom Soon; Paik, Man Jeong; Lee, Jin-Kyu; Choi, Sangdun; Kim, Yong Man; Kang, Seong Ho; Kim, Hyung Sik; Kang, Yup; Lee, Soo Hwan; Mouradian, M. Maral; Lee, Gwang

2016-01-01

The potential toxicity of nanoparticles, particularly to neurons, is a major concern. In this study, we assessed the cytotoxicity of silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye (MNPs@SiO2(RITC)) in HEK293 cells, SH-SY5Y cells, and rat primary cortical and dopaminergic neurons. In cells treated with 1.0 μg/μl MNPs@SiO2(RITC), the expression of several genes related to the proteasome pathway was altered, and proteasome activity was significantly reduced, compared with control and with 0.1 μg/μl MNPs@SiO2(RITC)-treated cells. Due to the reduction of proteasome activity, formation of cytoplasmic inclusions increased significantly in HEK293 cells over-expressing the α–synuclein interacting protein synphilin-1 as well as in primary cortical and dopaminergic neurons. Primary neurons, particularly dopaminergic neurons, were more vulnerable to MNPs@SiO2(RITC) than SH-SY5Y cells. Cellular polyamines, which are associated with protein aggregation, were significantly altered in SH-SY5Y cells treated with MNPs@SiO2(RITC). These findings highlight the mechanisms of neurotoxicity incurred by nanoparticles. PMID:27378605

Fluorescent magnetic nanoparticles for cell labeling: flux synthesis of manganite particles and novel functionalization of silica shell

Czech Academy of Sciences Publication Activity Database

Kačenka, Michal; Kaman, Ondřej; Kikerlová, S.; Pavlů, B.; Jirák, Zdeněk; Jirák, D.; Herynek, Vít; Černý, J.; Chaput, F.; Laurent, S.; Lukeš, I.

2015-01-01

Roč. 47, Jun (2015), s. 97-106 ISSN 0021-9797 R&D Projects: GA ČR(CZ) GAP108/11/0807; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : manganites * magnetic nanoparticles * molten salt synthesis * silica coating * dual probes * MRI * cell labeling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.782, year: 2015

Targeting to carcinoma cells with chitosan- and starch-coated magnetic nanoparticles for magnetic hyperthermia.

Science.gov (United States)

Kim, Dong-Hyun; Kim, Kyoung-Nam; Kim, Kwang-Mahn; Lee, Yong-Keun

2009-01-01

The delivery of hyperthermic thermoseeds to a specific target site with minimal side effects is an important challenge in targeted hyperthermia, which employs magnetic method and functional polymers. An external magnetic field is used to control the site-specific targeting of the magnetic nanoparticles. Polymer-coated magnetic nanoparticles can confer a higher affinity to the biological cell membranes. In this study, uncoated, chitosan-coated, and starch-coated magnetic nanoparticles were synthesized for use as a hyperthermic thermoseed. Each sample was examined with respect to their applications to hyperthermia using XRD, VSM, and FTIR. In addition, the temperature changes under an alternating magnetic field were observed. As in vitro tests, the magnetic responsiveness of chitosan- and starch-coated magnetite was determined by a simple blood vessel model under various intensities of magnetic field. L929 normal cells and KB carcinoma cells were used to examine the cytotoxicity and affinity of each sample using the MTT method. The chitosan-coated magnetic nanoparticles generated a higher DeltaT of 23 degrees C under an AC magnetic field than the starch-coated magnetite, and the capturing rate of the particles was 96% under an external magnetic field of 0.4 T. The highest viability of L929 cells was 93.7%. Comparing the rate of KB cells capture with the rate of L929 cells capture, the rate of KB cells capture relatively increased with 10.8% in chitosan-coated magnetic nanoparticles. Hence, chitosan-coated magnetic nanoparticles are biocompatible and have a selective affinity to KB cells. The targeting of magnetic nanoparticles in hyperthermia was improved using a controlled magnetic field and a chitosan-coating. Therefore, chitosan-coated magnetic nanoparticles are expected to be promising materials for use in magnetic targeted hyperthermia. 2008 Wiley Periodicals, Inc.

Effects of cadmium chloride as inhibitor on stability and kinetics of immobilized Lactoperoxidase(LPO on silica-coated magnetite nanoparticles versus free LPO

Directory of Open Access Journals (Sweden)

Narges Babadaie Samani

2016-10-01

Full Text Available Objective(s: Enzyme immobilization via nanoparticles is perfectly compatible against the other chemical or biological approximate to improve enzyme functions and stability. In this study lactoperoxidase was immobilized onto silica-coated magnetite nanoparticles to improve enzyme properties in the presence of cadmium chloride as an inhibitor. Materials and Methods:  The process consists of the following steps: (1 preparing magnetic iron oxide nanoparticles using the co-precipitation method, (2 coating NP with silica (SiO2 by sol–gel reaction, (3 characterizations of NPs were examined by FT-IR, XRD, AGFM and TEM. (4 Immobilization of LPO on the magnetite NPs, (5 Study kinetic and stability of both free and immobilized LPO in the presence of various concentrations of cadmium chloride. Results:  The size of the Fe3O4 and silica-coated magnetite nanoparticles were about 9 nm and 12 nm, respectively. The results showed that the highest immobilization yield, nearly 90 %, was attained at 240 to 300 µg of LPO at 15h. It was found that the concentration of cadmium chloride directly affects the LPO activity and changes the kinetic parameters of it. Also, the results showed that immobilized LPO has better tolerance than the free LPO, so that after immobilization, Vmax of immobilized LPO was increased and Km of immobilized LPO was decreased. Conclusion: The results demonstrating that the effect of immobilized lactoperoxidase on silica-coated magnetite nanoparticles increases the stability of the LPO in the presence of cadmium chloride as inhibitor. Michaelis–Menten parameters (Km and Vmax also revealed the considerable improvement of immobilized.

Canted spin structure and the first order magnetic transition in CoFe{sub 2}O{sub 4} nanoparticles coated by amorphous silica

Energy Technology Data Exchange (ETDEWEB)

Lyubutin, I.S. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Starchikov, S.S., E-mail: sergey.s.starchikov@gmail.com [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Gervits, N.E.; Korotkov, N.Yu.; Dmitrieva, T.V. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Lin, Chun-Rong, E-mail: crlinspin@gmail.com [Department of Applied Physics, National Pingtung University, Pingtung County 90003, Taiwan (China); Tseng, Yaw-Teng [Department of Applied Physics, National Pingtung University, Pingtung County 90003, Taiwan (China); Shih, Kun-Yauh [Department of Applied Chemistry, National Pingtung University, Pingtung County 90003, Taiwan (China); Lee, Jiann-Shing [Department of Applied Physics, National Pingtung University, Pingtung County 90003, Taiwan (China); Wang, Cheng-Chien [Department of Chemical and Materials Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan (China)

2016-10-01

The functional polymer (PMA-co-MAA) latex microspheres were used as a core template to prepare magnetic hollow spheres consisting of CoFe{sub 2}O{sub 4}/SiO{sub 2} composites. The spinel type crystal structure of CoFe{sub 2}O{sub 4} ferrite is formed under annealing, whereas the polymer cores are completely removed after annealing at 450 °C. Magnetic and Mössbauer spectroscopy measurements reveal very interesting magnetic properties of the CoFe{sub 2}O{sub 4}/SiO{sub 2} hollow spheres strongly dependent on the particle size which can be tuned by the annealing temperature. In the ground state of low temperatures, the CoFe{sub 2}O{sub 4} nanoparticles are in antiferromagnetic state due to the canted magnetic structure. Under heating in the applied field, the magnetic structure gradually transforms from canted to collinear, which increases the magnetization. The Mössbauer data revealed that the small size CoFe{sub 2}O{sub 4}/SiO{sub 2} particles (2.2–4.3 nm) do not show superparamagnetic behavior but transit from the magnetic to the paramagnetic state by a jump-like magnetic transition of the first order This effect is a specific property of the magnetic nanoparticles isolated by inert material, and can be initiated by internal pressure creating at the particle surface. The suggested method of synthesis can be modified with various bio-ligands on the silane surface, and such materials can find many applications in diagnostics and bio-separation. - Highlights: • CoFe{sub 2}O{sub 4}/SiO{sub 2} nanocomposites in shell of hollow microcapsules designed for biomedical applications • The CoFe{sub 2}O{sub 4} particle size and magnetic properties can be tuned by thermal treatment • Canted spin structure in the CoFe{sub 2}O{sub 4} nanoparticles coated by SiO{sub 2} • The first order magnetic transition in the CoFe{sub 2}O{sub 4} nanoparticles coated by silica.

Tunable thick porous silica coating fabricated by multilayer-by-multilayer bonding of silica nanoparticles for open-tubular capillary chromatographic separation.

Science.gov (United States)

Qu, Qishu; Liu, Yuanyuan; Shi, Wenjun; Yan, Chao; Tang, Xiaoqing

2015-06-19

A simple coating procedure employing a multilayer-by-multilayer process to modify the inner surface of bare fused-silica capillaries with silica nanoparticles was established. The silica nanoparticles were adsorbed onto the capillary wall via a strong electrostatic interaction between amino functional groups and silica particles. The thickness of the coating could be tuned from 130 to 600 nm by increasing the coating cycles from one to three. Both the retention factor and the resolution were greatly increased with increasing coating cycles. The loading capacity determined by naphthalene in the column with three coating cycles is 152.1 pmol. The effects of buffer concentration and pH value on the stability of the coating were evaluated. The retention reproducibility of the separation of toluene was 0.8, 1.2, 2.3, and 4.5%, respectively, for run-to-run, day-to-day, column-to-column, and batch-to-batch, respectively. The chromatographic performance of these columns was evaluated by both capillary liquid chromatography and open-tubular capillary electrochromatography (OT-CEC). Separation of aromatic hydrocarbons in the column with three coating cycles provided high theoretical plate numbers (up to 269,280 plates m(-1) for toluene) and short separation time (<15 min) by using OT-CEC mode. The method was also used to separate egg white proteins. Both acidic and basic proteins as well as four glycoisoforms were separated in a single run. Copyright © 2015 Elsevier B.V. All rights reserved.

Titania-coated manganite nanoparticles: Synthesis of the shell, characterization and MRI properties

Energy Technology Data Exchange (ETDEWEB)

Jirák, Zdeněk; Kuličková, Jarmila [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Herynek, Vít [Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Praha 4 (Czech Republic); Maryško, Miroslav [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Koktan, Jakub [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Chemistry and Technology, Prague, Technická 5, 166 28 Praha 6 (Czech Republic); Kaman, Ondřej, E-mail: kamano@seznam.cz [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic)

2017-04-01

Novel procedure for coating of oxide nanoparticles with titania, employing hydrolysis and polycondensation of titanium alkoxides under high-dilution conditions and cationic surfactants, is developed and applied to magnetic cores of perovskite manganite. Bare particles of the ferromagnetic La{sub 0.65}Sr{sub 0.35}MnO{sub 3} phase, possessing high magnetization, M{sub 10} {sub kOe}(4.5 K) = 63.5 emu g{sup −1}, and Curie temperature, T{sub C} = 355 K, are synthesized by sol-gel procedure and subsequently coated with titania. Further, a comparative silica-coated product is prepared. In order to analyse the morphology, colloidal stability, and surface properties of these two types of coated particles, a detailed study by means of transmission electron microscopy, dynamic light scattering, zeta-potential measurements, and IR spectroscopy is carried out. The experiments on the titania-coated sample reveal a continuous though porous character of the TiO{sub 2} shell, the nature of which is amorphous but can be transformed to anatase at higher temperatures. Finally, the relaxometric study at the magnetic field of 0.5 T, performed to quantity the transverse relaxivity and its temperature dependence, reveals important differences between the titania-coated and silica-coated nanoparticles. - Highlights: • Magnetic nanoparticles of perovskite La{sub 0.65}Sr{sub 0.35}MnO{sub 3} phase are coated with TiO{sub 2}. • The titania forms a continuous and amorphous shell and provides colloidal stability. • Morphology and surface properties are compared to a silica-coated product. • MRI properties of both the titania- and silica-coated particles are studied at 0.5 T. • The temperature dependence of r{sub 2} is strongly affected by the type of coating.

Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

Energy Technology Data Exchange (ETDEWEB)

Yoncheva, K., E-mail: krassi.yoncheva@gmail.com [Department of Pharmaceutical Technology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia (Bulgaria); Popova, M. [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria); Szegedi, A.; Mihaly, J. [Institute of Nanochemistry and Catalysis, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út. 59-67, 1025 Budapest (Hungary); Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V. [Department of Pharmaceutical Technology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia (Bulgaria); Pessina, F.; Valoti, M. [Dipartimento di Scienze della Vita, Universita di Siena, via Aldo Moro 2, Siena (Italy)

2014-03-15

Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide. -- Graphical abstract: Silica mesoporous MCM-41 particles were amino-functionalized, loaded with budesonide and post-coated with bioadhesive polymer (carbopol) in order to achieve prolonged residence of anti-inflammatory drug in GIT. Highlights: • Higher drug loading in amino-functionalized mesoporous silica. • Amino-functionalization and post-coating of the nanoparticles sustained drug release. • Achievement of higher cytoprotective effect with drug loaded into the nanoparticles.

Hydrophilic nano-silica coating agents with platinum and diamond nanoparticles for denture base materials.

Science.gov (United States)

Yoshizaki, Taro; Akiba, Norihisa; Inokoshi, Masanao; Shimada, Masayuki; Minakuchi, Shunsuke

2017-05-31

Preventing microorganisms from adhering to the denture surface is important for ensuring the systemic health of elderly denture wearers. Silica coating agents provide high hydrophilicity but lack durability. This study investigated solutions to improve the durability of the coating layer, determine an appropriate solid content concentration of SiO 2 in the silica coating agent, and evaluate the effect of adding platinum (Pt) and diamond nanoparticles (ND) to the agent. Five coating agents were prepared with different SiO 2 concentrations with/without Pt and ND additives. The contact angle was measured, and the brush-wear test was performed. Scanning electron microscopy was used to investigate the silica coating layer. The appropriate concentration of SiO 2 was found to be 0.5-0.75 wt%. The coating agents with additives showed significantly high hydrophilicity immediately after coating and after the brush-wear test. The coating agents with/without additives formed a durable coating layer even after the brush-wear test.

Synthesis and characterization of the superparamagnetic iron oxide nanoparticles modified with cationic chitosan and coated with silica shell

Energy Technology Data Exchange (ETDEWEB)

Lewandowska-Łańcucka, Joanna, E-mail: lewandow@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Staszewska, Magdalena; Szuwarzyński, Michał; Kępczyński, Mariusz [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Romek, Marek [Department of Cytology and Histology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow (Poland); Tokarz, Waldemar [Department of Solid State Physics, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow (Poland); Szpak, Agnieszka; Kania, Gabriela; Nowakowska, Maria [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

2014-02-15

Highlights: • The new, facile methodology for synthesis of silica covered SPIONs is proposed. • The SPIONs was modified with cationic chitosan and coated with silica shell. • Negatively charged, rounded in shape particles of ca. 330 nm were obtained. • The product exhibits the superparamagnetic properties. • The product properties imply its potential applications in biomedicine areas. -- Abstract: Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPION) modified with a cationic chitosan (CCh) and coated with a silica shell, SPION-CCh-SiO{sub 2} was developed. The process was carried out in two steps. In the first step the chitosan coated SPIONs were obtained by co-precipitation of Fe{sup 2+} and Fe{sup 3+} with ammonium hydroxide in aqueous solution of CCh. In the second one, the silica shell is formed on their surfaces. The formation of SPION-CCh-SiO{sub 2} was achieved by direct decomposition of tetraethoxysilane (TEOS) adsorbed on a surface of SPION-CCh dispersed in aqueous phase under sonication and mechanical stirring at room temperature. The chemical composition and physicochemical properties of the materials were determined using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and zeta potential measurements. The morphology of the particles was evaluated by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Magnetic properties were confirmed using Atomic Force Microscopy/Magnetic Force Microscopy (AFM/MFM) and magnetization measurements. The resulting products are negatively charged, rounded in shape and exhibit the superparamagnetic properties what implies their potential applications in engineering and biomedicine areas.

Synthesis and characterization of the superparamagnetic iron oxide nanoparticles modified with cationic chitosan and coated with silica shell

International Nuclear Information System (INIS)

Lewandowska-Łańcucka, Joanna; Staszewska, Magdalena; Szuwarzyński, Michał; Kępczyński, Mariusz; Romek, Marek; Tokarz, Waldemar; Szpak, Agnieszka; Kania, Gabriela; Nowakowska, Maria

2014-01-01

Highlights: • The new, facile methodology for synthesis of silica covered SPIONs is proposed. • The SPIONs was modified with cationic chitosan and coated with silica shell. • Negatively charged, rounded in shape particles of ca. 330 nm were obtained. • The product exhibits the superparamagnetic properties. • The product properties imply its potential applications in biomedicine areas. -- Abstract: Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPION) modified with a cationic chitosan (CCh) and coated with a silica shell, SPION-CCh-SiO 2 was developed. The process was carried out in two steps. In the first step the chitosan coated SPIONs were obtained by co-precipitation of Fe 2+ and Fe 3+ with ammonium hydroxide in aqueous solution of CCh. In the second one, the silica shell is formed on their surfaces. The formation of SPION-CCh-SiO 2 was achieved by direct decomposition of tetraethoxysilane (TEOS) adsorbed on a surface of SPION-CCh dispersed in aqueous phase under sonication and mechanical stirring at room temperature. The chemical composition and physicochemical properties of the materials were determined using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and zeta potential measurements. The morphology of the particles was evaluated by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Magnetic properties were confirmed using Atomic Force Microscopy/Magnetic Force Microscopy (AFM/MFM) and magnetization measurements. The resulting products are negatively charged, rounded in shape and exhibit the superparamagnetic properties what implies their potential applications in engineering and biomedicine areas

Ceria nanoparticles vis-à-vis cerium nitrate as corrosion inhibitors for silica-alumina hybrid sol-gel coating

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, R.V. [Surface Engineering Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, HAL Airport Road, Kodihalli, Bengaluru 560017 (India); Aruna, S.T., E-mail: staruna194@gmail.com [Surface Engineering Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, HAL Airport Road, Kodihalli, Bengaluru 560017 (India); Sampath, S. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560012 (India)

2017-01-30

Highlights: • Corrosion protection efficiency comparison of ceria nanoparticles and cerium nitrate. • Silica-alumina hybrid coating exhibited good barrier protection. • Detailed XPS study confirm the hybrid structure and presence of Ce species in coating. • Loss of cerium ions not prevalent in ceria doped coating unlike that of cerium nitrate. • Ceria increased the coating integrity, corrosion inhibition and barrier protection. - Abstract: The present work provides a comparative study on the corrosion protection efficiency of defect free sol-gel hybrid coating containing ceria nanoparticles and cerium nitrate ions as corrosion inhibitors. Less explored organically modified alumina-silica hybrid sol-gel coatings are synthesized from 3-glycidoxypropyltrimethoxysilane and aluminium-tri-sec-butoxide. The microemulsion derived nanoparticles and the hybrid coatings are characterized and compared with coatings containing cerium nitrate. Corrosion inhibiting capability is assessed using electrochemical impedance spectroscopy. Scanning Kelvin probe measurements are also conducted on the coatings for identifying the apparent corrosion prone regions. Detailed X-ray photoelectron spectroscopy (XPS) analysis is carried out to comprehend the bonding and corrosion protection rendered by the hybrid coatings.

Nanoparticles affect PCR primarily via surface interactions with PCR components: using amino-modified silica-coated magnetic nanoparticles as a main model

Science.gov (United States)

Nanomaterials have been widely reported to affect the polymerase chain reaction (PCR). However, many studies in which these effects were observed were not comprehensive, and many of the proposed mechanisms have been primarily speculative. In this work, we used amino-modified silica-coated magnetic n...

Antimicrobial activity of silica coated silicon nano-tubes (SCSNT) and silica coated silicon nano-particles (SCSNP) synthesized by gas phase condensation.

Science.gov (United States)

Tank, Chiti; Raman, Sujatha; Karan, Sujoy; Gosavi, Suresh; Lalla, Niranjan P; Sathe, Vasant; Berndt, Richard; Gade, W N; Bhoraskar, S V; Mathe, Vikas L

2013-06-01

Silica-coated, silicon nanotubes (SCSNTs) and silica-coated, silicon nanoparticles (SCSNPs) have been synthesized by catalyst-free single-step gas phase condensation using the arc plasma process. Transmission electron microscopy and scanning tunneling microscopy showed that SCSNTs exhibited a wall thickness of less than 1 nm, with an average diameter of 14 nm and a length of several 100 nm. Both nano-structures had a high specific surface area. The present study has demonstrated cheaper, resistance-free and effective antibacterial activity in silica-coated silicon nano-structures, each for two Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) was estimated, using the optical densitometric technique, and by determining colony-forming units. The MIC was found to range in the order of micrograms, which is comparable to the reported MIC of metal oxides for these bacteria. SCSNTs were found to be more effective in limiting the growth of multidrug-resistant Staphylococcus aureus over SCSNPs at 10 μg/ml (IC 50 = 100 μg/ml).

Effect of the size of silica nanoparticles on wettability and surface chemistry of sol–gel superhydrophobic and oleophobic nanocomposite coatings

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, R.V., E-mail: lakshmi_rv@nal.res.in; Bera, Parthasarathi; Anandan, C.; Basu, Bharathibai J.

2014-11-30

Highlights: • Superhydrophobic coatings from Cab-O-Sil EH5 and M5 particles in MTEOS sol. • Particle size of Cab-O-Sil influenced its optimum concentration in coating. • FAS-13 modification improved the oleophobicity of the coating. • Coating surface exhibited porous structure with nanovoids and microscale bumps. • Coatings with Cab-O-Sil EH5 retained water repelling property for a long time. - Abstract: Superhydrophobic sol–gel nanocomposite coatings have been fabricated by incorporating silica nanoparticles with different particle sizes separately in an acid-catalyzed sol of methyltriethoxysilane (MTEOS). Water contact angle (WCA) of the coatings increased with increase in the concentration of silica nanoparticles in both the cases. The coatings became superhydrophobic at an optimum silica concentration. The water repellency was further improved by the addition of fluoroalkylsilane (FAS). The optimum silica concentration was found to depend on the size of silica nanoparticles and FAS content and the coatings exhibited WCA of about 160° and water sliding angle (WSA) of <2°. FAS addition also improved the oleophobicity of the coatings. The coatings exhibited oil-repellency with a lubricant oil contact angle of 126° and ethylene glycol contact angle of 153.3°. Surface morphology of the coatings analyzed using field emission scanning electron microscopy (FESEM) showed a rough surface with microscale bumps and nanoscale pores. XPS was used to study the surface composition of the coatings. The superhydrophobic property of the coatings was due to the synergistic effect of surface chemistry and surface microstructure and can be explained using Cassie-Baxter model.

Phospholipid-Coated Mesoporous Silica Nanoparticles Acting as Lubricating Drug Nanocarriers

Directory of Open Access Journals (Sweden)

Tao Sun

2018-05-01

Full Text Available Osteoarthritis (OA is a severe disease caused by wear and inflammation of joints. In this study, phospholipid-coated mesoporous silica nanoparticles (MSNs@lip were prepared in order to treat OA at an early stage. The phospholipid layer has excellent lubrication capability in aqueous media due to the hydration lubrication mechanism, while mesoporous silica nanoparticles (MSNs act as effective drug nanocarriers. The MSNs@lip were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectrum, X-ray photoelectron spectrum, thermogravimetric analysis and dynamic light scattering techniques to confirm that the phospholipid layer was coated onto the surface of MSNs successfully. A series of tribological tests were performed under different experimental conditions, and the results showed that MSNs@lip with multi-layers of phospholipids greatly reduced the friction coefficient in comparison with MSNs. Additionally, MSNs@lip demonstrated sustained drug release behavior and were biocompatible based on CCK-8 assay using MC3T3-E1 cells. The MSNs@lip developed in the present study, acting as effective lubricating drug nanocarriers, may represent a promising strategy to treat early stage OA by lubrication enhancement and drug delivery therapy.

Blocked-micropores, surface functionalized, bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

International Nuclear Information System (INIS)

Darbandi, Masih; Laurent, Sophie; Busch, Martin; Li Zian; Yuan Ying; Krüger, Michael; Farle, Michael; Winterer, Markus; Vander Elst, Luce; Muller, Robert N.; Wende, Heiko

2013-01-01

Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. In this article, a systematic study of the design and development of surface-modification schemes for silica-coated iron oxide nanoparticles (IONP) via a one-pot, in situ method at room temperature is presented. Silica-coated IONP were prepared in a water-in-oil microemulsion, and subsequently the surface was modified via addition of organosilane reagents to the microemulsion system. The structure and the morphology of the as synthesized nanoparticles have been investigated by means of transmission electron microscopy (TEM) and measurement of N 2 adsorption–desorption. Electron diffraction and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the IONP structures. Nitrogen adsorption indicates microporous and blocked-microporous structures for the silica-coated and amine functionalized silica-coated IONP, respectively which could prove less cytotoxicity of the functionalized final product. Besides, the colloidal stability of the final product and the presence of the modified functional groups on top of surface layer have been proven by zeta-potential measurements. Owing to the benefit from the inner IONP core and the hydrophilic silica shell, the as-synthesized nanocomposites were exploited as an MRI contrast enhancement agent. Relaxometric results prove that the surface functionalized IONP have also signal enhancement properties. These surface functionalized nanocomposites are not only potential candidates for highly efficient contrast agents for MRI, but could also be used as ultrasensitive biological-magnetic labels, because they are in nanoscale size, having magnetic properties, blocked-microporous and are well dispersible in biological environment.

188Re labeling and biodistribution of magnetic nanoparticles for the tumor targeting

International Nuclear Information System (INIS)

Li Guiping; Zhang Hui; Wang Yongxian; Zhang Chunfu

2006-01-01

Objective: To prepare 188 Re labeled monoclonal antibody (Herceptin)-coated magnetic nanoparticles for tumor targeting and to study its biodistribution in mice. Methods: Herceptin and histidine were covalently linked to the amine group upon silica-coated magnetic nanoparticles modified by N-[3-(trimethyoxysilyl)prowl]-ethylenediamine using glutaraldehyde method. The Herceptin-coated magnetic nanoparticles and Herceptin were radiolabeled with 188 Re by a direct labelling method, whereas the histidine-coated magnetic nanoparticles was radiolabeled with 188 Re using fac-[ 188 Re(CO) 3 (H 2 0) 3 ] + as a precursor. The labelling efficiency and immunoreactivity as well as labelling stability were determined. Also, the biodistribution of 188 Re-magnetic and 188 Re-Herceptin-magnetic nanoparticles were observed in mice. Results: Herceptin-coated magnetic nanoparticles was characterized by transmission electron microscope (TEM) with diameter about 60 nm, while histidine-coated magnetic nanoparticles about 30 nm. The labeling efficiency for 188 Re-Herceptin, 188 Re-magnetic nanoparticles and 188 Re-Herceptin-magnetic nanoparticles were all > 90% and had a better stability in vitro. The immunoreactivity of Herceptin linked to magnetic nanoparticles was still high. The biodistribution in mice was shown that 188 Re-magnetic nanoparticles and 188 Re-Herceptin- magnetic nanoparticles had higher radioactivity levels in blood. Magnetic nanoparticles with diameter of 30 or 60 nm had a long half-life in blood stream and were accumulated in liver. Conclusion: The efficiency and stability of labelling Herceptin-coated magnetic nanoparticles and labelling magnetic nanoparticles with 188 Re are suitable for in vivo study in tumor-beating nude mice models. (authors)

Multifunctional EuYVO4 nanoparticles coated with mesoporous silica

International Nuclear Information System (INIS)

Justino, Larissa G.; Nigoghossian, Karina; Capote, Ticiana S.O.; Scarel-Caminaga, Raquel M.; Ribeiro, Sidney J.L.; Caiut, José Maurício A.

2016-01-01

Mesoporous structures are interesting materials for the incorporation of dyes, drugs, and luminescent systems, leading to materials with important multifunctionalities. In a very unique way, these guest/host materials combine the high stability of inorganic systems, new guest-structuring features, and adsorption mechanisms in their well-defined pores. This work evaluates the luminescent properties of rare earth-doped YVO 4 nanoparticles coated with a mesoporous silica shell. The use of two different synthesis methodologies allowed for particle size control. The crystalline phase emerged without further heat treatment. The mesoporous shell decreased undesirable quenching effects on YVO 4 :Eu 3+ nanoparticles and rendered them biocompatible. The materials prepared herein could have interesting applications as luminescent markers or drug release systems.

Synthesis of a colloid solution of silica-coated gold nanoparticles for X-ray imaging applications

Science.gov (United States)

Kobayashi, Yoshio; Nagasu, Ryoko; Shibuya, Kyosuke; Nakagawa, Tomohiko; Kubota, Yohsuke; Gonda, Kohsuke; Ohuchi, Noriaki

2014-08-01

This work proposes a method for fabricating silica-coated gold (Au) nanoparticles, surface modified with poly(ethylene glycol) (PEG) (Au/SiO2/PEG), with a particle size of 54.8 nm. X-ray imaging of a mouse is performed with the colloid solution. A colloid solution of 17.9 nm Au nanoparticles was prepared by reducing Au ions (III) with sodium citrate in water at 80 °C. The method used for silica-coating the Au nanoparticles was composed of surface-modification of the Au nanoparticles with (3-aminopropyl)-trimethoxysilane (APMS) and a sol-gel process. The sol-gel process was performed in the presence of the surface-modified Au nanoparticles using tetraethylorthosilicate, APMS, water, and sodium hydroxide, in which the formation of silica shells and the introduction of amino groups to the silica-coated particles took place simultaneously (Au/SiO2-NH2). Surface modification of the Au/SiO2-NH2 particles with PEG, or PEGylation of the particle surface, was performed by adding PEG with a functional group that reacted with an amino group in the Au/SiO2-NH2 particle colloid solution. A computed tomography (CT) value of the aqueous colloid solution of Au/SiO2/PEG particles with an actual Au concentration of 0.112 M was as high as 922 ± 12 Hounsfield units, which was higher than that of a commercial X-ray contrast agent with the same iodine concentration. Injecting the aqueous colloid solution of Au/SiO2/PEG particles into a mouse increased the light contrast of tissues. A CT value of the heart rose immediately after the injection, and this rise was confirmed for up to 6 h.

Surface spins disorder in uncoated and SiO2 coated maghemite nanoparticles

International Nuclear Information System (INIS)

Zeb, F.; Nadeem, K.; Shah, S. Kamran Ali; Kamran, M.; Gul, I. Hussain; Ali, L.

2017-01-01

We studied the surface spins disorder in uncoated and silica (SiO 2 ) coated maghemite (γ-Fe 2 O 3 ) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO 2 coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (T B ) for SiO 2 coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (M s ) of SiO 2 coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO 2 coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1− BT b )) was fitted well for both uncoated and SiO 2 coated nanoparticles and yields: B =3×10 −7 K -b , b=2.22 and B=0.0127 K -b , b=0.57 for uncoated and SiO 2 coated nanoparticles, respectively. Higher value of B for SiO 2 coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO 2 coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO 2 coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO 2 coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface spins disorder in SiO 2 coated nanoparticles than in uncoated γ-Fe 2 O 3 nanoparticles

Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater

Energy Technology Data Exchange (ETDEWEB)

Li, Dien, E-mail: dien.li@srs.gov [Savannah River National Laboratory, Aiken, SC 29808 (United States); Egodawatte, Shani [Department of Chemistry, University of Iowa, Iowa City, IA 52242 (United States); Kaplan, Daniel I. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Larsen, Sarah C. [Department of Chemistry, University of Iowa, Iowa City, IA 52242 (United States); Serkiz, Steven M. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Seaman, John C. [Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 (United States)

2016-11-05

Highlights: • Magnetic mesoporous silica nanoparticles were functionalized with organic molecules. • The functionalized nanoparticles had high surface areas and consistent pore sizes. • The functionalized nanoparticles were easily separated due to their magnetism. • They exhibited high capacity for uranium removal from low- or high-pH groundwater. - Abstract: U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N{sub 2} adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), {sup 13}C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100–200 nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0 nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38 mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133 mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

Enhanced lifetime characteristics in flexible polymer light-emitting devices by encapsulation of epoxy/silica-coated gold nanoparticles resin (ESGR)

International Nuclear Information System (INIS)

Chiu, Pin-Hsiang; Huang, Chien-Jung; Yang, Cheng-Fu; Meen, Teen-Hang; Wang, Yeong-Her

2010-01-01

This paper reports the effects of a new multilayer encapsulation for the lifetime of flexible PLEDs on plastic substrate. The multilayer encapsulation consisted of a novel epoxy/silica-coated gold nanoparticles resin (ESGR) as the pre-encapsulation layer and a SiO 2 layer as the encapsulation cap. The ESGR was prepared by mixing UV-curable epoxy resin and powders of silica-coated gold nanoparticles. The silica-coated gold nanoparticles is a necessity because the epoxy resin is not a good moisture barrier. The flexible PLEDs with multilayer encapsulation exhibited no dark spots after being stored for over 300 h at 25 deg. C and 60% relative humidity. Also, the operational half-luminance decay time of device was 1360 h, seven times longer than that of a device without encapsulation. These results confirmed that the multilayer encapsulation, which restricted the moisture that penetrated into the devices, could be applied to the encapsulation of flexible PLEDs.

Development of Antibody-Coated Magnetite Nanoparticles for Biomarker Immobilization

Directory of Open Access Journals (Sweden)

Christian Chapa Gonzalez

2014-01-01

Full Text Available Magnetic nanoparticles (MNPs have great potential in biomedical applications because of their magnetic response offers the possibility to direct them to specific areas and target biological entities. Magnetic separation of biomolecules is one of the most important applications of MNPs because their versatility in detecting cancer biomarkers. However, the effectiveness of this method depends on many factors, including the type of functionalization onto MNPs. Therefore, in this study, magnetite nanoparticles have been developed in order to separate the 5′-nucleotidase enzyme (5eNT. The 5eNT is used as a bio-indicator for diagnosing diseases such as hepatic ischaemia, liver tumor, and hepatotoxic drugs damage. Magnetic nanoparticles were covered in a core/shell type with silica, aminosilane, and a double shell of silica-aminosilane. A ScFv (fragment antibody and anti-CD73 antibody were attached to the coated nanoparticles in order to separate the enzyme. The magnetic separation of this enzyme with fragment antibody was found to be 28% higher than anti-CD73 antibody and the enzyme adsorption was improved with the double shell due to the increased length of the polymeric chain. Magnetite nanoparticles with a double shell (silica-aminosilane were also found to be more sensitive than magnetite with a single shell in the detection of biomarkers.

Mesoporous Silica Nanoparticle-Coated Microneedle Arrays for Intradermal Antigen Delivery.

Science.gov (United States)

Tu, Jing; Du, Guangsheng; Reza Nejadnik, M; Mönkäre, Juha; van der Maaden, Koen; Bomans, Paul H H; Sommerdijk, Nico A J M; Slütter, Bram; Jiskoot, Wim; Bouwstra, Joke A; Kros, Alexander

2017-08-01

To develop a new intradermal antigen delivery system by coating microneedle arrays with lipid bilayer-coated, antigen-loaded mesoporous silica nanoparticles (LB-MSN-OVA). Synthesis of MSNs with 10-nm pores was performed and the nanoparticles were loaded with the model antigen ovalbumin (OVA), and coated with a lipid bilayer (LB-MSN-OVA). The uptake of LB-MSN-OVA by bone marrow-derived dendritic cells (BDMCs) was studied by flow cytometry. The designed LB-MSN-OVA were coated onto pH-sensitive pyridine-modified microneedle arrays and the delivery of LB-MSN-OVA into ex vivo human skin was studied. The synthesized MSNs demonstrated efficient loading of OVA with a maximum loading capacity of about 34% and the lipid bilayer enhanced the colloidal stability of the MSNs. Uptake of OVA loaded in LB-MSN-OVA by BMDCs was higher than that of free OVA, suggesting effective targeting of LB-MSN-OVA to antigen-presenting cells. Microneedles were readily coated with LB-MSN-OVA at pH 5.8, yielding 1.5 μg of encapsulated OVA per microneedle array. Finally, as a result of the pyridine modification, LB-MSN-OVA were effectively released from the microneedles upon piercing the skin. Microneedle arrays coated with LB-MSN-OVA were successfully developed and shown to be suitable for intradermal delivery of the encapsulated protein antigen.

Structural dependence of the efficiency of functionalization of silica-coated FeOx magnetic nanoparticles studied by ATR-IR

International Nuclear Information System (INIS)

Vargas, Angelo; Shnitko, Ivan; Teleki, Alexandra; Weyeneth, Stephen; Pratsinis, Sotiris E.; Baiker, Alfons

2011-01-01

The efficiency of propylamino functionalization of magnetic silica-coated FeO x nanoparticles prepared by different methods, including coprecipitation and flame aerosol synthesis, has been evaluated by attenuated total reflection infrared spectroscopy (ATR-IR) combined with a specific surface reaction, thus revealing the availability of the grafted functional groups. Large differences in the population of reactive groups were observed for the investigated materials, underlining the tight relation between the structure of nanoparticles and their suitability for organic functionalization. The materials possessed different core structure, surface area, and porosity, as evidenced by transmission electron microscopy and nitrogen adsorption-desorption isotherms. Grafting of aminopropyl groups using a standard procedure based on reaction with (3-aminopropyl)trimethoxysilane as source of the propylamino groups was performed, followed by classical dry analysis methods to determine the specific concentration of the organic functional groups (in mmol g -1 of material). ATR-IR spectroscopy in a specially constructed reactor cell was applied as wet methodology to determine the chemically available amount of such functional groups, showing that the materials possess largely different loading capacity, with a variability of up to 70% in the chemical availability of the organic functional group. The amount of (3-aminopropyl)trimethoxysilane used for functionalization was optimized, thus reaching a saturation limit characteristic of the material.

Effective Uranium (VI) Sorption from Alkaline Solutions Using Bi-Functionalized Silica-Coated Magnetic Nanoparticles

International Nuclear Information System (INIS)

Chen, X.; He, L.; Liu, B.; Tang, Y.

2015-01-01

High temperature gas reactor is one of generation IV reactors that can adapt the future energy market, of which the preparation of fuel elements will produce a large amount of radioactive wastewater with uranium and high-level ammonia. Sorption treatment is one of the most important method to recover uranium from wastewater. However, there are few report on uranium sorbent that can directly be applied in wastewater with ammonia. Therefore, the development of a sorbent that can recover uranium in basic environment will greatly decrease the cost of fuel element production and the risk of radioactive pollution. In this work, ammonium-phosphonate-bifunctionalized silica-coated magnetic nanoparticles has been developed for effective sorption of uranium from alkaline media, which are not only advantaged in the uranium separation from liquid phase, but also with satisfactory adsorption rate, amount and reusability. The as-prepared sorbent is found to show a maximum uranium sorption capacity of 70.7 mg/g and a fast equilibrium time of 2 h at pH 9.5 under room temperature. Compared with the mono-functionalized (phosphonate alone and ammonium alone) particles, the combination of the bi-functionalized groups gives rise to an excellent ability to remove uranium from basic environment. The sorbent can be used as a promising solid phase candidate for highly-efficient removal of uranium from basic solution. (author)

Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

International Nuclear Information System (INIS)

Behzadi, Abed; Mohammadi, Aliasghar

2016-01-01

Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

Energy Technology Data Exchange (ETDEWEB)

Behzadi, Abed; Mohammadi, Aliasghar, E-mail: amohammadi@sharif.edu [Sharif University of Technology, Department of Chemical and Petroleum Engineering (Iran, Islamic Republic of)

2016-09-15

Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

Highly hydrated poly(allylamine)/silica magnetic resin

International Nuclear Information System (INIS)

Johnson, Andrew K.; Kaczor, Jozef; Han, Hongmei; Kaur, Maninder; Tian, Guoxin; Rao, Linfeng; Qiang, You; Paszczynski, Andrzej J.

2011-01-01

The creation of multifunctional nanomaterials by combining organic and inorganic components is a growing trend in nanoscience. The unique size-dependent properties of magnetic nanoparticles (MNPs) make them amenable to numerous applications such as carriers of expensive biological catalysts, in magnetically assisted chemical separation of heavy metals and radionuclides from contaminated water sources. The separation of minor actinides from high-level radionuclide waste requires a sorbent stable in acidic pH, with ease of surface functionalization, and a high capacity for binding the molecules of interest. For the described experiments, the MNPs with 50 nm average size were used (size distribution from 20 to 100 nm and an iron content of 80–90 w/w%). The MNPs that have been double coated with an initial silica coating for protection against iron solubilization and oxidation in nitric acid solution (pH 1) and a second silica/polymer composite coating incorporating partially imbedded poly(allylamine) (PA). The final product is magnetic, highly swelling, containing >95% water, with >0.5 mmol amines g −1 available for functionalization. The amine groups of the magnetic resin were functionalized with the chelating molecules diethylenetriaminepentaacetic acid (DTPA) and N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) for separation of minor actinides from used nuclear fuel.

Molecularly imprinted layer-coated silica nanoparticles for selective solid-phase extraction of bisphenol A from chemical cleansing and cosmetics samples

International Nuclear Information System (INIS)

Zhu Rong; Zhao Wenhui; Zhai Meijuan; Wei Fangdi; Cai Zheng; Sheng Na; Hu Qin

2010-01-01

Highly selective molecularly imprinted layer-coated silica nanoparticles for bisphenol A (BPA) were synthesized by molecular imprinting technique with a sol-gel process on the supporter of silica nanoparticles. The BPA-imprinted silica nanoparticles were characterized by fourier transform infrared spectrometer, transmission electron microscope, dynamic adsorption and static adsorption tests. The equilibrium association constant, K a , and the apparent maximum number of binding sites, Q max , were estimated to be 1.25 x 10 5 mL μmol -1 and 16.4 μmol g -1 , respectively. The BPA-imprinted silica nanoparticles solid-phase extraction (SPE) column had higher selectivity for BPA than the commercial C18-SPE column. The results of the study indicated that the prepared BPA-imprinted silica nanoparticles exhibited high adsorption capacity and selectivity, and offered a fast kinetics for the rebinding of BPA. The BPA-imprinted silica nanoparticles were successfully used in SPE to selectively enrich and determine BPA from shampoo, bath lotion and cosmetic cream samples.

Magnetic properties of GdMnO3 nanoparticles embedded in mesoporous silica

Science.gov (United States)

Tajiri, Takayuki; Mito, Masaki; Deguchi, Hiroyuki; Kohno, Atsushi

2018-05-01

Perovskite manganite GdMnO3 nanoparticles were synthesized using mesoporous silica as a template, and their magnetic properties and crystal structure were investigated. Powder X-ray diffraction data indicated successful synthesis of the GdMnO3 nanoparticles, with mean particle sizes of 13.9 and 20.9 nm. The lattice constants for the nanoparticles were slightly different from those for the bulk material and varied with the particle size. The magnetic transition temperatures for the nanoparticles were higher than those of the bulk crystal. The synthesized GdMnO3 nanoparticles exhibited superparamagnetic behaviors: The blocking temperature, coercive field, and transition temperature depended on the particle size. Magnetic measurements and crystal structure analysis suggest that the changes in the magnetic properties for GdMnO3 nanoparticles can be attributed to the modulation of the crystallographic structure.

Electrochemical analysis of gold-coated magnetic nanoparticles for detecting immunological interaction

International Nuclear Information System (INIS)

Pham, Thao Thi-Hien; Sim, Sang Jun

2010-01-01

An electrochemical impedance immunosensor was developed for detecting the immunological interaction between human immunoglobulin (IgG) and protein A from Staphylococcus aureus based on the immobilization of human IgG on the surface of modified gold-coated magnetic nanoparticles. The nanoparticles with an Au shell and Fe oxide cores were functionalized by a self-assembled monolayer of 11-mercaptoundecanoic acid. The electrochemical analysis was conducted on the modified magnetic carbon paste electrodes with the nanoparticles. The magnetic nanoparticles were attached to the surface of the magnetic carbon paste electrodes via magnetic force. The cyclic voltammetry technique and electrochemical impedance spectroscopy measurements of the magnetic carbon paste electrodes coated with magnetic nanoparticles-human IgG complex showed changes in its alternating current (AC) response both after the modification of the surface of the electrode and the addition of protein A. The immunological interaction between human IgG on the surface of the modified magnetic carbon paste electrodes and protein A in the solution could be successfully monitored.

Selective porous gates made from colloidal silica nanoparticles

Directory of Open Access Journals (Sweden)

Roberto Nisticò

2015-11-01

Full Text Available Highly selective porous films were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol–gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS, and using polystyrene-block-poly(ethylene oxide (PS-b-PEO copolymers as soft-templating agents. Nanoparticles synthesis was carried out in a mixed solvent system. After spin-coating onto a macroporous silicon nitride support, silica nanoparticles were calcined under controlled conditions. An organized nanoporous layer was obtained characterized by a depth filter-like structure with internal porosity due to interparticle voids. Permeability and size-selectivity were studied by monitoring the diffusion of probe molecules under standard conditions and under the application of an external stimulus (i.e., electric field. Promising results were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution.

Magnetic properties of Ni nanoparticles on microporous silica spheres

International Nuclear Information System (INIS)

Godsell, Jeffrey F.; Donegan, Keith P.; Tobin, Joseph M.; Copley, Mark P.; Rhen, Fernando M.F.; Otway, David J.; Morris, Michael A.; O'Donnell, Terence; Holmes, Justin D.; Roy, Saibal

2010-01-01

Ni nanoparticles (∼32 nm particle diameter) have been synthesized on the walls of microporous (∼1 nm pore diameter) silica spheres (∼2.6 μm sphere diameter) and characterised magnetically to potentially produce a new class of core (silica micro-spheres)-shell (nanometallic)-type nanocomposite material. These magnetic nanocomposite materials display a characteristic increase in coercivity with reducing temperature. The average particle size has been used to calculate the anisotropy constant for the system, K. The discussion postulates the potential mechanisms contributing to the difference between the calculated K value and the magnetocrystalline anisotropy constant of bulk Ni. Various factors such as surface anisotropy and interparticle interactions are discussed as possible contributing factors to the anisotropy values calculated in the paper.

Multifunctional EuYVO{sub 4} nanoparticles coated with mesoporous silica

Energy Technology Data Exchange (ETDEWEB)

Justino, Larissa G. [Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP (Brazil); Nigoghossian, Karina [Inst. of Chemistry – São Paulo State University- UNESP, 14801-970 Araraquara, SP (Brazil); Capote, Ticiana S.O.; Scarel-Caminaga, Raquel M. [Department of Morphology, Dental School at Araraquara, Univ. Estadual Paulista – UNESP, Araraquara, SP (Brazil); Ribeiro, Sidney J.L. [Inst. of Chemistry – São Paulo State University- UNESP, 14801-970 Araraquara, SP (Brazil); Caiut, José Maurício A., E-mail: caiut@ffclrp.usp.br [Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP (Brazil)

2016-11-15

Mesoporous structures are interesting materials for the incorporation of dyes, drugs, and luminescent systems, leading to materials with important multifunctionalities. In a very unique way, these guest/host materials combine the high stability of inorganic systems, new guest-structuring features, and adsorption mechanisms in their well-defined pores. This work evaluates the luminescent properties of rare earth-doped YVO{sub 4} nanoparticles coated with a mesoporous silica shell. The use of two different synthesis methodologies allowed for particle size control. The crystalline phase emerged without further heat treatment. The mesoporous shell decreased undesirable quenching effects on YVO{sub 4}:Eu{sup 3+} nanoparticles and rendered them biocompatible. The materials prepared herein could have interesting applications as luminescent markers or drug release systems.

One-Step Method for Preparation of Magnetic Nanoparticles Coated with Chitosan

Directory of Open Access Journals (Sweden)

Karla M. Gregorio-Jauregui

2012-01-01

Full Text Available Preparation of magnetic nanoparticles coated with chitosan in one step by the coprecipitation method in the presence of different chitosan concentrations is reported here. Obtaining of magnetic superparamagnetic nanoparticles was confirmed by X-ray diffraction and magnetic measurements. Scanning transmission electron microscopy allowed to identify spheroidal nanoparticles with around 10-11 nm in average diameter. Characterization of the products by Fourier transform infrared spectroscopy demonstrated that composite chitosan-magnetic nanoparticles were obtained. Chitosan content in obtained nanocomposites was estimated by thermogravimetric analysis. The nanocomposites were tested in Pb2+ removal from a PbCl2 aqueous solution, showing a removal efficacy up to 53.6%. This work provides a simple method for chitosan-coated nanoparticles obtaining, which could be useful for heavy metal ions removal from water.

Surface spins disorder in uncoated and SiO{sub 2} coated maghemite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zeb, F. [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Nadeem, K., E-mail: kashif.nadeem@iiu.edu.pk [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Shah, S. Kamran Ali; Kamran, M. [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Gul, I. Hussain [School of Chemical & Materials Engineering, National University of Sciences and Technology (NUST), H-12, 44000 Islamabad, Pakistan (Pakistan); Ali, L. [Materials Research Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan)

2017-05-01

We studied the surface spins disorder in uncoated and silica (SiO{sub 2}) coated maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO{sub 2} coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (T{sub B}) for SiO{sub 2} coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (M{sub s}) of SiO{sub 2} coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO{sub 2} coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1− BT{sup b})) was fitted well for both uncoated and SiO{sub 2} coated nanoparticles and yields: B =3×10{sup −7} K{sup -b}, b=2.22 and B=0.0127 K{sup -b}, b=0.57 for uncoated and SiO{sub 2} coated nanoparticles, respectively. Higher value of B for SiO{sub 2} coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO{sub 2} coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO{sub 2} coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO{sub 2} coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface

Molecularly imprinted layer-coated silica nanoparticles for selective solid-phase extraction of bisphenol A from chemical cleansing and cosmetics samples

Energy Technology Data Exchange (ETDEWEB)

Zhu Rong; Zhao Wenhui; Zhai Meijuan; Wei Fangdi; Cai Zheng; Sheng Na [School of Pharmacy, Nanjing Medical University, Hanzhong Road 140, Nanjing, Jiangsu 210029 (China); Hu Qin, E-mail: huqin@njmu.edu.cn [School of Pharmacy, Nanjing Medical University, Hanzhong Road 140, Nanjing, Jiangsu 210029 (China)

2010-01-25

Highly selective molecularly imprinted layer-coated silica nanoparticles for bisphenol A (BPA) were synthesized by molecular imprinting technique with a sol-gel process on the supporter of silica nanoparticles. The BPA-imprinted silica nanoparticles were characterized by fourier transform infrared spectrometer, transmission electron microscope, dynamic adsorption and static adsorption tests. The equilibrium association constant, K{sub a}, and the apparent maximum number of binding sites, Q{sub max}, were estimated to be 1.25 x 10{sup 5} mL {mu}mol{sup -1} and 16.4 {mu}mol g{sup -1}, respectively. The BPA-imprinted silica nanoparticles solid-phase extraction (SPE) column had higher selectivity for BPA than the commercial C18-SPE column. The results of the study indicated that the prepared BPA-imprinted silica nanoparticles exhibited high adsorption capacity and selectivity, and offered a fast kinetics for the rebinding of BPA. The BPA-imprinted silica nanoparticles were successfully used in SPE to selectively enrich and determine BPA from shampoo, bath lotion and cosmetic cream samples.

Increased osteoblast density in the presence of novel calcium phosphate coated magnetic nanoparticles

International Nuclear Information System (INIS)

Pareta, Rajesh A; Webster, Thomas J; Taylor, Erik

2008-01-01

Bone diseases (including osteoporosis, osteoarthritis and bone cancer) are of great concern to the medical world. Drugs are available to treat such diseases, but often these drugs are not specifically targeted to the site of the disease and, thus, lack an immediate directed therapeutic effect. The optimal drug delivery system should enhance healthy bone growth with high specificity to the site of bone disease. It has been previously shown that magnetic nanoparticles can be directed in the presence of a magnetic field to any part of the body, allowing for site-specific drug delivery and possibly an immediate increase in bone density. The objective of the present study was to build off of this evidence and determine the density of osteoblasts (bone forming cells) in the presence of various uncoated and coated magnetic nanoparticles that could eventually be used in drug delivery applications. Results showed that some magnetic nanoparticles (specifically, γ-Fe 2 O 3 ) significantly promoted osteoblast density (that is, cells per well) after 5 and 8 days of culture compared to controls (no particles). These magnetic nanoparticles were further coated with calcium phosphate (CaP; the main inorganic component of bone) to tailor them for treating various bone diseases. The coatings were conducted in the presence of either bovine serum albumin (BSA) or citric acid (CA) to reduce magnetic nanoparticle agglomeration, a common problem resulting from the use of nanoparticles which decreases their effectiveness. Results with these coatings showed that magnetic nanoparticles, specifically (γ-Fe 2 O 3 ), coated in the presence of BSA significantly increased osteoblast density compared to controls after 1 day. In this manner, this study provided unexpected evidence that CaP-coated γ-Fe 2 O 3 magnetic nanoparticles increased osteoblast density (compared to no particles) and, thus, should be further studied to treat numerous bone diseases

Reducing ZnO nanoparticles toxicity through silica coating

Directory of Open Access Journals (Sweden)

Sing Ling Chia

2016-10-01

Full Text Available ZnO NPs have good antimicrobial activity that can be utilized as agents to prevent harmful microorganism growth in food. However, the use of ZnO NPs as food additive is limited by the perceived high toxicity of ZnO NPs in many earlier toxicity studies. In this study, surface modification by silica coating was used to reduce the toxicity of ZnO NPs by significantly reducing the dissolution of the core ZnO NPs. To more accurately recapitulate the scenario of ingested ZnO NPs, we tested our as synthesized ZnO NPs in ingestion fluids (synthetic saliva and synthetic gastric juice to determine the possible forms of ZnO NPs in digestive system before exposing the products to colorectal cell lines. The results showed that silica coating is highly effective in reducing toxicity of ZnO NPs through prevention of the dissociation of ZnO NPs to zinc ions in both neutral and acidic condition. The silica coating however did not alter the desired antimicrobial activity of ZnO NPs to E. coli and S. aureus. Thus, silica coating offered a potential solution to improve the biocompatibility of ZnO NPs for applications such as antimicrobial agent in foods or food related products like food packaging. Nevertheless, caution remains that high concentration of silica coated ZnO NPs can still induce undesirable cytotoxicity to mammalian gut cells. This study indicated that upstream safer-by-design philosophy in nanotechnology can be very helpful in a product development.

Synthesis and characterization of multifunctional silica core-shell nanocomposites with magnetic and fluorescent functionalities

International Nuclear Information System (INIS)

Ma Zhiya; Dosev, Dosi; Nichkova, Mikaela; Dumas, Randy K.; Gee, Shirley J.; Hammock, Bruce D.; Liu Kai; Kennedy, Ian M.

2009-01-01

Multifunctional core-shell nanocomposites with a magnetic core and a silica shell doped with lanthanide chelate have been prepared by a simple method. First, citric acid-modified magnetite nanoparticles were synthesized by a chemical coprecipitation method. Then the magnetite nanoparticles were coated with silica shells doped with terbium (Tb 3+ ) complex by a modified Stoeber method based on hydrolyzing and condensation of tetraethyl orthosilicate (TEOS) and a silane precursor. These multifunctional nanocomposites are potentially useful in a variety of biological areas such as bio-imaging, bio-labeling and bioassays because they can be simultaneously manipulated with an external magnetic field and exhibit unique phosphorescence properties.

Synthesis and characterization of thiolated pectin stabilized gold coated magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Arora, Varun, E-mail: varun.arora3986@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka, New Delhi 110078 (India); Sood, Ankur, E-mail: ankursood02@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka, New Delhi 110078 (India); Shah, Jyoti, E-mail: shah.jyoti1@gmail.com [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Kotnala, R.K., E-mail: rkkotnala@nplindia.org [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Jain, Tapan K., E-mail: tapankjain@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka, New Delhi 110078 (India)

2016-04-15

Core–shell nanoparticles, magnetic core and gold shell, were synthesized by reduction of gold chloride on the surface of magnetic nanoparticles; using tyrosine as a reducing agent. The formation of gold shell on magnetic nanoparticles was confirmed by X-ray diffraction (XRD) and UV-Visible spectroscopy. The core–shell nanoparticles (CSn) were conjugated with thiolated pectin to form a stable aqueous dispersion. The hydrodynamic size of thiolated pectin stabilized core–shell nanoparticles (TP-CSn) measured by Dynamic light scattering (DLS) was 160.5 nm with a poly dispersity index (PDI) of 0.302, whereas the mean particle size of TP-CSn calculated by high resolution transmission electron microscopy (HRTEM) was 10.8 ± 2.7 nm. The value of zeta potential for TP-CSn was −13.6 mV. There was a decrease in the value of saturation magnetization upon formation of the gold shell on magnetic nanoparticles. The amount of thiolated pectin bound to the surface of core–shell nanoparticles, calculated using Thermogravimetric analysis (TGA), was 6% of sample weight. - Highlights: • Use of side group of tyrosine (phenol) as a pH dependent reducing agent to synthesize gold coated magnetic nanoparticles. • Successful coating of gold shell on magnetic nanoparticles core. • Synthesis of thiolated pectin and stabilization of aqueous dispersion of core–shell nanoparticles with thiolated pectin. • The superparamagnetic behaviour of magnetic nanoparticles is retained after shell formation.

Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

Energy Technology Data Exchange (ETDEWEB)

Akbaba, Hasan; Karagöz, Uğur [Ege University, Faculty of Pharmacy, Department of Pharmaceutical Biotechnology, 35100 Izmir (Turkey); Selamet, Yusuf [Izmir Institute of Technology, Faculty of Science, Department of Physics, 35433 Izmir (Turkey); Kantarcı, A. Gülten, E-mail: gulten.kantarci@ege.edu.tr [Ege University, Faculty of Pharmacy, Department of Pharmaceutical Biotechnology, 35100 Izmir (Turkey)

2017-03-15

The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15–17 emu g{sup −1} for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting. - Highlights: • A novel iron oxide nanoparticle synthesis method with in-situ surface coating. • Combining advantages of microemulsions and multiple emulsion methods. • Multiple emulsions were used as microreactors for magnetic nanoparticle synthesis. • Superparamagnetic iron oxide particles synthesized in the core of cationic lipids. • Possible delivery systems for nucleic acids, oil soluble compounds or drugs.

Silica encapsulation of luminescent silicon nanoparticles: stable and biocompatible nanohybrids

Energy Technology Data Exchange (ETDEWEB)

Maurice, Vincent [CEA Saclay, DSM/IRAMIS/SPAM-LFP (France); Rivolta, Ilaria [University of Milano-Bicocca, Department of Experimental Medicine (DIMS) (Italy); Vincent, Julien [CEA Saclay, DSM/IRAMIS/SPAM-LFP (France); Raccurt, Olivier [CEA Grenoble, Department of Nano Materials, NanoChemistry and NanoSafety Laboratory (DRT/LITEN/DTNM/LCSN) (France); Rouzaud, Jean-Noel [Ecole Normale superieure de Paris, Laboratoire de Geologie (France); Miserrochi, Giuseppe [University of Milano-Bicocca, Department of Experimental Medicine (DIMS) (Italy); Doris, Eric [CEA, Service de Chimie Bioorganique et de Marquage, iBiTecS (France); Reynaud, Cecile; Herlin-Boime, Nathalie, E-mail: nathalie.herlin@cea.fr [CEA Saclay, DSM/IRAMIS/SPAM-LFP (France)

2012-02-15

This article presents a process for surface coating and functionalization of luminescent silicon nanoparticles. The particles were coated with silica using a microemulsion process that was adapted to the fragile silicon nanoparticles. The as-produced core-shell particles have a mean diameter of 35 nm and exhibit the intrinsic photoluminescence of the silicon core. The silica layer protects the core from aqueous oxidation for several days, thus allowing the use of the nanoparticles for biological applications. The nanoparticles were further coated with amines and functionalized with polyethylene glycol chains and the toxicity of the particles has been evaluated at the different stages of the process. The core-shell nanoparticles exhibit no acute toxicity towards lung cells, which is promising for further development.

Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

Science.gov (United States)

Akbaba, Hasan; Karagöz, Uğur; Selamet, Yusuf; Kantarcı, A. Gülten

2017-03-01

The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15-17 emu g-1 for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting.

Monomer functionalized silica coated with Ag nanoparticles for enhanced SERS hotspots

Science.gov (United States)

Newmai, M. Boazbou; Verma, Manoj; Kumar, P. Senthil

2018-05-01

Mesoporous silica (SiO2) spheres are well-known for their excellent chromatographic properties such as the relatively high specific surface, large pore volume, uniform particle size, narrow pore size distribution with favorable pore connectivity; whereas the noble metal Ag nanoparticles have unique size/shape dependant surface plasmon resonance with wide ranging applications. Thus, the desire to synchronize both their properties for specific applications has naturally prompted research in the design and synthesis of core-shell type novel nanoAg@mesoSiO2 nanocomposites, which display potential utility in applications such as photothermal therapy, photocatalysis, molecular sensing, and photovoltaics. In the present work, SiO2 spheres were carefully functionalized with the monomer, N-vinyl pyrrolidone (NVP), which cohesively controls the uniform mass transfer of Ag+ metal ions, thereby enabling its sequential reduction to zerovalent Ag (in the presence of slightly excess NaOH) by electron transfer from nucleophilic attack of the NVP vinyl group by the water molecules even under ambient conditions. Complete metal nanoshell coverage of the silica surface was obtained after multiple Ag deposition cycles, as systematically confirmed from the BET, TEM, optical and FTIR characterization. Our present Ag-coated silica spheres were directly utilized as viable SERS substrates with high sensitivity in contrast with other long chain polymer/surfactant coated silica spheres, owing to the presence of significant number of nanogaps enhanced SERS 'hotspots', which were methodically analyzed utilizing two example analytes, such as crystal violet (CV) and calendula officinalis (CaF).

Structural dependence of the efficiency of functionalization of silica-coated FeO{sub x} magnetic nanoparticles studied by ATR-IR

Energy Technology Data Exchange (ETDEWEB)

Vargas, Angelo; Shnitko, Ivan [Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang Pauli Strasse 10, Hoenggerberg, HCI, 8093 Zurich (Switzerland); Teleki, Alexandra [Institute of Process Engineering, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich (Switzerland); Weyeneth, Stephen [Physik-Institut der Universitaet Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Pratsinis, Sotiris E. [Institute of Process Engineering, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich (Switzerland); Baiker, Alfons, E-mail: baiker@chem.ethz.ch [Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang Pauli Strasse 10, Hoenggerberg, HCI, 8093 Zurich (Switzerland)

2011-01-15

The efficiency of propylamino functionalization of magnetic silica-coated FeO{sub x} nanoparticles prepared by different methods, including coprecipitation and flame aerosol synthesis, has been evaluated by attenuated total reflection infrared spectroscopy (ATR-IR) combined with a specific surface reaction, thus revealing the availability of the grafted functional groups. Large differences in the population of reactive groups were observed for the investigated materials, underlining the tight relation between the structure of nanoparticles and their suitability for organic functionalization. The materials possessed different core structure, surface area, and porosity, as evidenced by transmission electron microscopy and nitrogen adsorption-desorption isotherms. Grafting of aminopropyl groups using a standard procedure based on reaction with (3-aminopropyl)trimethoxysilane as source of the propylamino groups was performed, followed by classical dry analysis methods to determine the specific concentration of the organic functional groups (in mmol g{sup -1} of material). ATR-IR spectroscopy in a specially constructed reactor cell was applied as wet methodology to determine the chemically available amount of such functional groups, showing that the materials possess largely different loading capacity, with a variability of up to 70% in the chemical availability of the organic functional group. The amount of (3-aminopropyl)trimethoxysilane used for functionalization was optimized, thus reaching a saturation limit characteristic of the material.

Magnetic Nanoparticles Coated with a Thermosensitive Polymer with Hyperthermia Properties

Directory of Open Access Journals (Sweden)

Felisa Reyes-Ortega

2017-12-01

Full Text Available Magnetic nanoparticles (MNPs have been widely used to increase the efficacy of chemotherapeutics, largely through passive accumulation provided by the enhanced permeability and retention effect. Their incorporation into biopolymer coatings enables the preparation of magnetic field-responsive, biocompatible nanoparticles that are well dispersed in aqueous media. Here we describe a synthetic route to prepare functionalized, stable magnetite nanoparticles (MNPs coated with a temperature-responsive polymer, by means of the hydrothermal method combined with an oil/water (o/w emulsion process. The effects of both pH and temperature on the electrophoretic mobility and surface charge of these MNPs are investigated. The magnetite/polymer composition of these systems is detected by Fourier Transform Infrared Spectroscopy (FTIR and quantified by thermogravimetric analysis. The therapeutic possibilities of the designed nanostructures as effective heating agents for magnetic hyperthermia are demonstrated, and specific absorption rates as high as 150 W/g, with 20 mT magnetic field and 205 kHz frequency, are obtained. This magnetic heating response could provide a promising nanoparticle system for combined diagnostics and cancer therapy.

Fabrication, Light Emission, and Magnetism of Silica Nanoparticles Hybridized with AIE Luminogens and Inorganic Nanostructures

Science.gov (United States)

Faisal, Mahtab

Much research efforts have been devoted in developing new synthetic approaches for fluorescent silica nanoparticles (FSNPs) due to their potential high-technological applications. However, light emissions from most of the FSNPs prepared so far have been rather weak. This is due to the emission quenching caused by the aggregation of fluorophores in the solid state. We have observed a novel phenomenon of aggregation-induced emission (AIE): a series of propeller-shaped molecules such as tetraphenylethene (TPE) and silole are induced to emit efficiently by aggregate formation. Thus, they are ideal fluorophors for the construction of FSNPs and my thesis work focuses on the synthesis of silica nanoparticles containing these luminogens and magnetic nanostructures. Highly emissive FSNPs with core-shell structures are fabricated by surfactant-free sol-gel reactions of tetraphenylethene- (TPE) and silole-functionalized siloxanes followed by the reactions with tetraethoxysilane. The FSNPs are uniformly sized, surface-charged and colloidally stable. The diameters of the FSNPs are tunable in the range of 45--295 nm by changing the reaction conditions. Whereas their TPE and silole precursors are non-emissive, the FSNPs emit strong visible lights, thanks to the novel aggregation-induced emission characteristics of the TPE and silole aggregates in the hybrid nanoparticles. The FSNPs pose no toxicity to living cells and can be utilized to selectively image cytoplasm of HeLa cells. Applying the same tool in the presence of citrate-coated magnetite nanoparticles, uniform magnetic fluorescent silica nanoparticles (MFSNPs) with smooth surfaces are fabricated. These particles exhibit appreciable surface charges and hence good colloidal stability. They are superparamagnetic, exhibiting no hysteresis at room temperature. UV irradiation of a suspension of MFSNPs in ethanol gives strong blue and green emissions. The MFSNPs can selectively stain the cytoplasmic regions of the living cells

Magnetic nanoparticles coated with polyaniline to stabilize immobilized trypsin

Energy Technology Data Exchange (ETDEWEB)

Maciel, J. C., E-mail: jackeline-maciel@hotmail.com [Universidade Federal de Roraima (Brazil); Mercês, A. A. D.; Cabrera, M. [Universidade Federal de Pernambuco, Laboratório de Imunopatologia Keizo Asami (Brazil); Shigeyosi, W. T. [Universidade Federal de São Carlos, Departamento de Física (Brazil); Souza, S. D. de; Olzon-Dionysio, M.; Fabris, J. D. [Universidade Federal dos Vales de Jequitinhonha e Mucuri (Brazil); Cardoso, C. A. [Universidade Federal de São Carlos, Departamento de Física (Brazil); Neri, D. F. M. [Universidade Federal do Vale do São Francisco (Brazil); Silva, M. P. C.; Carvalho, L. B. [Universidade Federal de Pernambuco, Laboratório de Imunopatologia Keizo Asami (Brazil)

2016-12-15

It is reported the synthesis of magnetic nanoparticles via the chemical co-precipitation of Fe {sup 3+} ions and their preparation by coating them with polyaniline. The electronic micrograph analysis showed that the mean diameter for the nanoparticles is ∼15 nm. FTIR, powder X-ray diffraction and Mössbauer spectroscopy were used to understand the chemical, crystallographic and {sup 57}Fe hyperfine structures for the two samples. The nanoparticles, which exhibited magnetic behavior with relatively high spontaneous magnetization at room temperature, were identified as being mainly formed by maghemite (γFe{sub 2}O{sub 3}). The coated magnetic nanoparticles (sample labeled “mPANI”) presented a real ability to bind biological molecules such as trypsin, forming the magnetic enzyme derivative (sample “mPANIG-Trypsin”). The amount of protein and specific activity of the immobilized trypsin were found to be 13±5 μg of protein/mg of mPANI (49.3 % of immobilized protein) and 24.1±0.7 U/mg of immobilized protein, respectively. After 48 days of storage at 4 {sup ∘}C, the activity of the immobilized trypsin was found to be 89 % of its initial activity. This simple, fast and low-cost procedure was revealed to be a promising way to prepare mPANI nanoparticles if technological applications addressed to covalently link biomolecules are envisaged. This route yields chemically stable derivatives, which can be easily recovered from the reaction mixture with a magnetic field and recyclable reused.

Magnetic silica hybrids modified with guanidine containing co-polymers for drug delivery applications

Energy Technology Data Exchange (ETDEWEB)

Timin, Alexander S., E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); RASA Center in Tomsk, Tomsk Polytechnic University, 30, Lenin Avenue, 634500 Tomsk (Russian Federation); Khashirova, Svetlana Yu. [Kabardino-Balkar State University, ul. Chernyshevskogo 173, Nal' chik, 360004 Kabardino-Balkaria (Russian Federation); Rumyantsev, Evgeniy V.; Goncharenko, Alexander A. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation)

2016-07-01

Guanidine containing co-polymers grafted onto silica nanoparticles to form core-shell structure were prepared by sol-gel method in the presence of γ-Fe{sub 2}O{sub 3} nanoparticles. The morphological features for uncoated and coated silica particles have been characterized with scanning electron microscopy. The results show that the polymer coated silicas exhibit spherical morphology with rough polymeric surface covered by γ-Fe{sub 2}O{sub 3} nanoparticles. The grafting amount of guanidine containing co-polymers evaluated by thermogravimetric analysis was in the range from 17 to 30%. Then, the drug loading properties and cumulative release of silica hybrids modified with guanidine containing co-polymers were evaluated using molsidomine as a model drug. It was shown that after polymer grafting the loading content of molsidomine could reach up to 3.42 ± 0.21 and 2.34 ± 0.14 mg/g respectively. The maximum drug release of molsidomine is achieved at pH 1.6 (approximately 71–75% release at 37 °C), whereas at pH 7.4 drug release is lower (50.4–59.6% release at 37 °C). These results have an important implication that our magneto-controlled silica hybrids modified with guanidine containing co-polymers are promising as drug carriers with controlled behaviour under influence of magnetic field. - Highlights: • Polymer coated silica hybrids containing γ-Fe{sub 2}O{sub 3} were prepared via sol–gel method. • Polymer grafting influences pH-response and surface properties of final products. • Molsidomine as a model drug was effectively loaded into polymer coated silicas. • The drug loading depends on the nature of grafted polymer and its content.

Ultrasonic electrodeposition of silver nanoparticles on dielectric silica spheres

International Nuclear Information System (INIS)

Tang Shaochun; Tang Yuefeng; Gao Feng; Liu Zhiguo; Meng Xiangkang

2007-01-01

In the present study, a facile and one-step ultrasonic electrodeposition method is first applied to controllably coat colloidal silica spheres with silver nanoparticles. This method is additive-free and very direct, because processes necessary in many other approaches, such as pretreatment of the silica sphere surface and pre-preparation of silver nanoparticles, are not involved in it. Furthermore, it makes possible the coating of dielectric substrates with metal through an electrodeposition route. Under appropriate conditions, silver nanoparticles with sizes of 8-10 nm in diameter can be relatively homogeneously deposited onto the surface of preformed colloidal silica spheres. Silver particles with different sizes and dispersive uniformity on silica sphere surfaces can also be obtained by adjusting the current density (I), the concentration of electrolyte (C) and the electrolysis time (t). The possible ultrasonic electrodeposition mechanism is also suggested according to the experimental results

Surface hydrophobic co-modification of hollow silica nanoparticles toward large-area transparent superhydrophobic coatings.

Science.gov (United States)

Gao, Liangjuan; He, Junhui

2013-04-15

The present paper reports a novel, simple, and efficient approach to fabricate transparent superhydrophobic coatings on glass substrates by spray-coating stearic acid (STA) and 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) co-modified hollow silica nanoparticles (SPHSNs), the surfaces of which were hydrophobic. The surface wettability of coatings was dependent on the conditions of post-treatment: the water contact angle of coating increased and then leveled off with increase in either the drying temperature or the drying time. When the coating was treated at 150°C for 5h, the water contact angle was as high as 160° and the sliding angle was lower than 1°, reaching excellent superhydrophobicity. They remained 159° and ≤1°, respectively, even after 3months storage under indoor conditions (20°C, 20%RH), demonstrating the long time stability of coating superhydrophobicity. The coating was robust both to the impact of water droplets (297 cm/s) and to acidic (pH=1) and basic (pH=14) droplets. It showed good transparency in the visible-near infrared spectral range, and the maximum transmittance reached as high as 89%. Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis were used to investigate the interactions among STA, POTS, and hollow silica nanoparticles (HSNs). Scanning electron microscopy and atomic force microscopy were used to observe and estimate the morphology and surface roughness of coatings. Optical properties were characterized by a UV-visible-near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The enhancement of hydrophobicity to superhydrophobicity by post-treatment was discussed based on the transition from the Wenzel state to the Cassie state. Copyright © 2013 Elsevier Inc. All rights reserved.

Nonadhesive, silica nanoparticles-based brush-coated contact lens casesCompromising between ease of cleaning and microbial transmission to contact lenses

NARCIS (Netherlands)

Qu, Wenwen; Hooymans, Johanna M. M.; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C.; Busscher, Henk J.

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based

Facile synthesis of novel magnetic silica nanoparticles functionalized with layer-by-layer detonation nanodiamonds for secretome study.

Science.gov (United States)

Li, Hong; Wang, Yi; Zhang, Lei; Lu, Haojie; Zhou, Zhongjun; Wei, Liming; Yang, Pengyuan

2015-12-07

Novel magnetic silica nanoparticles functionalized with layer-by-layer detonation nanodiamonds (dNDs) were prepared by coating single submicron-size magnetite particles with silica and subsequently modified with dNDs. The resulting layer-by-layer dND functionalized magnetic silica microspheres (Fe3O4@SiO2@[dND]n) exhibit a well-defined magnetite-core-silica-shell structure and possess a high content of magnetite, which endow them with high dispersibility and excellent magnetic responsibility. Meanwhile, dNDs are known for their high affinity and biocompatibility towards peptides or proteins. Thus, a novel convenient, fast and efficient pretreatment approach of low-abundance peptides or proteins was successfully established with Fe3O4@SiO2@[dND]n microspheres. The signal intensity of low-abundance peptides was improved by at least two to three orders of magnitude in mass spectrometry analysis. The novel microsphere also showed good tolerance to salt. Even with a high concentration of salt, peptides or proteins could be isolated effectively from samples. Therefore, the convenient and efficient enrichment process of this novel layer-by-layer dND-functionalized microsphere makes it a promising candidate for isolation of protein in a large volume of culture supernatant for secretome analysis. In the application of Fe3O4@SiO2@[dND]n in the secretome of hepatoma cells, 1473 proteins were identified and covered a broad range of pI and molecular weight, including 377 low molecular weight proteins.

Silica nanoparticles with a substrate switchable luminescence

International Nuclear Information System (INIS)

Bochkova, O D; Mustafina, A R; Fedorenko, S V; Konovalov, A I

2011-01-01

Silica nanoparticles with visible (Tb and Ru doped), near IR (Yb doped) and dual visible-near IR luminescence (Ru-Yb doped) were obtained by reverse w/o microemulsion procedure. Plenty of luminescent complexes (from 4900 to 10000) encapsulated into each nanoparticle ensures the intensive luminescence of nanoparticles and their applicability as biomarkers. The silica surface decoration by definite anchor groups is the required step for the gaining to these nanoparticles marking and sensing functions. Thus covalent and non-covalent surface modification of these nanoparticles was developed to provide the binding with biotargets and sensing of anions. The dicationic surfactant coating of negatively charged Tb(III)-TCAS doped silica nanoparticles was chosen as the basis for the anion responsible system. The reversible insertion of the quenching anions (namely phenol red) into the surfactant based layer at the surface of luminescent nanoparticles switches off the Tb-centered luminescence. In turn the reversible reestablishment of the luminescence results from the competitive insertion of the non-quenching anions into the surfactant layer at the silica/water interface. The hydrophobic anions exemplified by dodecylsulfates versus hydrophilic ones (hydrophosphates) are preferable in the competition with phenol red anions.

A facile one-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica: Aqueous hydration of nitriles to amides

Science.gov (United States)

One-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium hydroxide immobilization; the hydration of nitriles occurs in high yield and excellent selectivity using this...

Study of Physical Properties of Nano-Silica Coated Cotton Textiles

OpenAIRE

Sidra Saleemi; Farooq Ahmed; Samandar Malik

2015-01-01

This research was aimed to investigate the effect of silica sol-gel coating on air permeability, stiffness and tensile properties of dyed cotton fabric. Various concentrations of silica nanoparticles were applied on dyed cotton substrate using two different cross-linkers through sol-gel method. The homogenous sol-gel coating dispersions were prepared by using an ultrasonicator. Coated samples were tested for mechanical and comfort properties such as tensile strength, stiffness, crease recover...

Synthesis of internally functionalized silica nanoparticles for theranostic applications

Science.gov (United States)

Walton, Nathan Isaac

This thesis addresses the synthesis and characterization of novel inorganic silica nanoparticle hybrids. It focuses in large part on their potential applications in the medical field. Silica acts as a useful carrier for a variety of compounds and this thesis silica will demonstrate its use as a carrier for boron or gadolinium. Boron-10 and gadolinium-157 have been suggested for the radiological treatment of tumor cells through the process called neutron capture therapy (NCT). Gadolinium is also commonly used as a Magnetic Resonance Imaging (MRI) contrast agent. Particles that carry it have potential theranostic applications of both imaging and treating tumors. Chapter 1 presents a background on synthetic strategies and usages of silica nanoparticles, and NCT theory. Chapter 2 describes a procedure to create mesoporous metal chelating silica nanoparticles, mDTTA. This is achieved via a co-condensation of tetraethoxysilane (TEOS) and 3-trimethoxysilyl-propyl diethylenetriamine (SiDETA) followed by a post-synthesis modification step with bromoacetic acid (BrAA). These particles have a large surface area and well-defined pores of ~2 nm. The mDTTA nanoparticles were used to chelate the copper(II), cobalt(II) and gadolinium(III). The chelating of gadolinium is the most interesting since it can be used as a MRI contrast agent and a neutron capture therapeutic. The synthetic procedure developed also allows for the attachment of a fluorophore that gives the gadolinium chelating mDTTA nanoparticles a dual imaging modality. Chapter 3 presents the synthetic method used to produce two classes of large surface area organically modified silica (ORMOSIL) nanoparticles. Condensating the organosilane vinyltrimethoxysilane in a micellar solution results in nanoparticles that are either surface rough (raspberry-like) or mesoporous nanoparticles, which prior to this thesis has not been demonstrated in ORMOSIL chemistry. Furthermore, the vinyl functionalities are modified, using

Fabrication of Magnetite/Silica/Titania Core-Shell Nanoparticles

Directory of Open Access Journals (Sweden)

Suh Cem Pang

2012-01-01

Full Text Available Fe3O4/SiO2/TiO2 core-shell nanoparticles were synthesized via a sol-gel method with the aid of sonication. Fe3O4 nanoparticles were being encapsulated within discrete silica nanospheres, and a layer of TiO2 shell was then coated directly onto each silica nanosphere. As-synthesized Fe3O4/SiO2/TiO2 core-shell nanoparticles showed enhanced photocatalytic properties as evidenced by the enhanced photodegradation of methylene blue under UV light irradiation.

Mn-Zn ferrite nanoparticles with silica and titania coatings: synthesis, transverse relaxivity and cytotoxicity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kuličková, Jarmila; Maryško, Miroslav; Veverka, Pavel; Herynek, V.; Havelek, R.; Královec, K.; Kubániová, D.; Kohout, J.; Dvořák, P.; Jirák, Zdeněk

2017-01-01

Roč. 53, č. 11 (2017), s. 1-8, č. článku 5300908. ISSN 0018-9464 R&D Projects: GA ČR GA16-04340S Institutional support: RVO:68378271 Keywords : amorphous titania * silica * magnetic nanoparticles * Mn-Zn ferrite * transverse relaxivity * cytotoxicity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.243, year: 2016

Magnetic and optical properties of Ag@SiO{sub 2}-FITC-Fe{sub 3}O{sub 4} hybrid nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sui, Ning [Université de Lyon, Institut des Nanotechnologies de Lyon–INL, UMR CNRS 5270, Site Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully Cedex (France); College of Material Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Monnier, Virginie, E-mail: virginie.monnier@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon–INL, UMR CNRS 5270, Site Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully Cedex (France); Salvia, Marie-Virginie; Chevolot, Yann; Souteyrand, Eliane [Université de Lyon, Institut des Nanotechnologies de Lyon–INL, UMR CNRS 5270, Site Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully Cedex (France)

2014-03-15

Highlights: • New magnetic/fluorescent nanoparticles were synthesized. • The silver core led to a maximum 4-fold enhanced fluorescence of fluorophore. • Maximum enhancement factor was obtained when metal-fluorophore distance is 5 nm. • Magnetism and fluorescence appeared simultaneously for nanoparticles in solution. -- Abstract: Nanoparticles composed of a silver core coated with a silica shell (Ag@SiO{sub 2}) were prepared. A dye, fluorescein isothiocyanate (FITC), was further encapsulated during the growth of a second silica shell onto Ag@SiO{sub 2} nanoparticles. The proximity of silver nanoparticles led to a 4-fold maximal enhancement in the fluorescence of FITC when the first silica shell thickness was set at 5 nm. After amino-functionalization of Ag@SiO{sub 2}-FITC nanoparticles, iron oxide nanoparticles were bonded to their surface. The magnetic and metal-enhanced fluorescence properties appeared simultaneously when Ag@SiO{sub 2}-FITC-Fe{sub 3}O{sub 4} hybrid nanoparticles were dispersed in a solution.

Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Covarrubias, Cristian, E-mail: ccovarrubias@odontologia.uchile.cl [Laboratory of Nanobiomaterials, Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago (Chile); Mattmann, Matías [Laboratory of Nanobiomaterials, Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago (Chile); Von Marttens, Alfredo [Department of Prosthesis, Faculty of Dentistry, University of Chile, Santiago (Chile); Caviedes, Pablo; Arriagada, Cristián [Laboratory of Cell Therapy, ICBM, Faculty of Medicine, University of Chile (Chile); Valenzuela, Francisco [Laboratory of Nanobiomaterials, Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago (Chile); Rodríguez, Juan Pablo [Laboratory of Cell Biology, INTA, University of Chile, Santiago (Chile); Corral, Camila [Department of Restorative Dentistry, Faculty of Dentistry, University of Chile, Santiago (Chile)

2016-02-15

Graphical abstract: - Highlights: • The fabrication of a coating for osseointegration of titanium implant is presented. • The coating consists of nanoporous silica loaded with bioactive glass nanoparticles. • Coating accelerates the in vitro formation of apatite in simulated body fluid. • Coating promotes the osteogenic differentiation of stem cells. • Coating accelerates the formation of bone tissue in the periphery of the implant. - Abstract: The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol–gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

International Nuclear Information System (INIS)

Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

2016-01-01

Graphical abstract: - Highlights: • The fabrication of a coating for osseointegration of titanium implant is presented. • The coating consists of nanoporous silica loaded with bioactive glass nanoparticles. • Coating accelerates the in vitro formation of apatite in simulated body fluid. • Coating promotes the osteogenic differentiation of stem cells. • Coating accelerates the formation of bone tissue in the periphery of the implant. - Abstract: The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol–gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Trewyn, Brian G. [Iowa State Univ., Ames, IA (United States)

2006-01-01

The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). Mesoporous silica nanoparticles organically functionalized shown to undergo endocytosis in cancer cells and drug release from the pores was controlled intracellularly and intercellularly. Transmission electron microscopy investigations demonstrated the variety of morphologies produced in this field of mesoporous silica nanomaterial synthesis. A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both KeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the

Hybrid Organometallic-Inorganic Nanomaterial: Acetyl Ferrocene Schiff base Immobilized on Silica Coated Magnetite Nanoparticles

Directory of Open Access Journals (Sweden)

M. Masteri-Farahani

2015-10-01

Full Text Available In  this  work,  a  new  hybrid  organometallic-inorganic  hybrid nanomaterial was prepared by immobilization of acetyl ferrocene on the  surface  of magnetite  nanoparticles. Covalent  grafting of silica coated magnetite nanoparticles (SCMNPs with 3-aminopropyl triethoxysilane gave aminopropyl-modified magnetite nanoparticles (AmpSCMNPs. Then, Schiff base condensation  of AmpSCMNPs with acetyl  ferrocene resulted in the preparation of acferro-SCMNPs hybrid nanomaterial. Characterization of the prepared nanomaterial was performed with different physicochemical methods such as Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, vibrating sample magnetometry (VSM, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. VSM analysis showed superparamagnetic properties of the prepared nanomaterial and TEM and SEM analyses indicated the relatively spherical nanoparticles with 15 nm average size.

Cellular interactions of lauric acid and dextran-coated magnetite nanoparticles

International Nuclear Information System (INIS)

Pradhan, Pallab; Giri, Jyotsnendu; Banerjee, Rinti; Bellare, Jayesh; Bahadur, Dhirendra

2007-01-01

In vitro cytocompatibility and cellular interactions of lauric acid and dextran-coated magnetite nanoparticles were evaluated with two different cell lines (mouse fibroblast and human cervical carcinoma). Lauric acid-coated magnetite nanoparticles were less cytocompatible than dextran-coated magnetite nanoparticles and cellular uptake of lauric acid-coated magnetic nanoparticles was more than that of dextran-coated magnetite nanoparticles. Lesser cytocompatibility and higher uptake of lauric acid-coated magnetite nanoparticles as compared to dextran-coated magnetic nanoparticles may be due to different cellular interactions by coating material. Thus, coating plays an important role in modulation of biocompatibility and cellular interaction of magnetic nanoparticles

Magnetic properties of Co and Ni based alloy nanoparticles dispersed in a silica matrix

Energy Technology Data Exchange (ETDEWEB)

De Julian Fernandez, C. E-mail: dejulian@padova.infm.it; Sangregorio, C.; Mattei, G.; Maurizio, C.; Battaglin, G.; Gonella, F.; Lascialfari, A.; Lo Russo, S.; Gatteschi, D.; Mazzoldi, P.; Gonzalez, J.M.; D' Acapito, F

2001-04-01

A comparative study of the magnetic properties of Co and Ni based alloy nanoparticles (Ni-Co, Ni-Cu and Co-Cu) formed in a silica matrix by ion implantation is presented. Different ion doses and implantation sequences were realized in order to obtain different nanostructures. The structural and magnetic properties observed for the Cu{sub 50}Ni{sub 50} nanoparticles are similar to those of the Cu{sub 60}Ni{sub 40} bulk alloy. The crystal structure of Co{sub x}Ni{sub 1-x} (0{<=}x{<=}1) nanoparticles is similar to that of the corresponding bulk alloy. The magnetic properties depend on the ion-implanted dose and on the alloy composition. The samples prepared by implanting a 15x10{sup 16} ions/cm{sup 2} total dose contain nanoparticles, which are superparamagnetic at room temperature and their magnetic behavior is influenced by dipolar interparticle interactions. The magnetization of the CoNi samples at high magnetic field is larger than that of the corresponding bulk alloy and follows the same composition dependence of that quantity measured in the alloy.

Magnetic properties of Co and Ni based alloy nanoparticles dispersed in a silica matrix

International Nuclear Information System (INIS)

De Julian Fernandez, C.; Sangregorio, C.; Mattei, G.; Maurizio, C.; Battaglin, G.; Gonella, F.; Lascialfari, A.; Lo Russo, S.; Gatteschi, D.; Mazzoldi, P.; Gonzalez, J.M.; D'Acapito, F.

2001-01-01

A comparative study of the magnetic properties of Co and Ni based alloy nanoparticles (Ni-Co, Ni-Cu and Co-Cu) formed in a silica matrix by ion implantation is presented. Different ion doses and implantation sequences were realized in order to obtain different nanostructures. The structural and magnetic properties observed for the Cu 50 Ni 50 nanoparticles are similar to those of the Cu 60 Ni 40 bulk alloy. The crystal structure of Co x Ni 1-x (0≤x≤1) nanoparticles is similar to that of the corresponding bulk alloy. The magnetic properties depend on the ion-implanted dose and on the alloy composition. The samples prepared by implanting a 15x10 16 ions/cm 2 total dose contain nanoparticles, which are superparamagnetic at room temperature and their magnetic behavior is influenced by dipolar interparticle interactions. The magnetization of the CoNi samples at high magnetic field is larger than that of the corresponding bulk alloy and follows the same composition dependence of that quantity measured in the alloy

Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

Science.gov (United States)

Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

2018-05-01

We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

Caveolin-1 and CDC42 mediated endocytosis of silica-coated iron oxide nanoparticles in HeLa cells

Directory of Open Access Journals (Sweden)

Nils Bohmer

2015-01-01

Full Text Available Nanomedicine is a rapidly growing field in nanotechnology, which has great potential in the development of new therapies for numerous diseases. For example iron oxide nanoparticles are in clinical use already in the thermotherapy of brain cancer. Although it has been shown, that tumor cells take up these particles in vitro, little is known about the internalization routes. Understanding of the underlying uptake mechanisms would be very useful for faster and precise development of nanoparticles for clinical applications. This study aims at the identification of key proteins, which are crucial for the active uptake of iron oxide nanoparticles by HeLa cells (human cervical cancer as a model cell line. Cells were transfected with specific siRNAs against Caveolin-1, Dynamin 2, Flotillin-1, Clathrin, PIP5Kα and CDC42. Knockdown of Caveolin-1 reduces endocytosis of superparamagnetic iron oxide nanoparticles (SPIONs and silica-coated iron oxide nanoparticles (SCIONs between 23 and 41%, depending on the surface characteristics of the nanoparticles and the experimental design. Knockdown of CDC42 showed a 46% decrease of the internalization of PEGylated SPIONs within 24 h incubation time. Knockdown of Dynamin 2, Flotillin-1, Clathrin and PIP5Kα caused no or only minor effects. Hence endocytosis in HeLa cells of iron oxide nanoparticles, used in this study, is mainly mediated by Caveolin-1 and CDC42. It is shown here for the first time, which proteins of the endocytotic pathway mediate the endocytosis of silica-coated iron oxide nanoparticles in HeLa cells in vitro. In future studies more experiments should be carried out with different cell lines and other well-defined nanoparticle species to elucidate possible general principles.

Self-cleaning behavior in polyurethane/silica coatings via formation of a hierarchical packed morphology of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Hejazi, Iman [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box 15875/4413, Tehran (Iran, Islamic Republic of); Mir Mohamad Sadeghi, Gity, E-mail: Gsadeghi@aut.ac.ir [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box 15875/4413, Tehran (Iran, Islamic Republic of); Seyfi, Javad [Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Jafari, Seyed-Hassan [School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Khonakdar, Hossein Ali [Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of)

2016-04-15

Graphical abstract: - Highlights: • Self-cleaning behavior was imparted to the hydrophilic polyurethane. • A hierarchical packed morphology is responsible for the superhydrophobicity. • Prolonged pressing process cannot lead to superhydrophobicity due to migration of TPU. • Samples exhibited excellent stability against media with a wide range of pH values. - Abstract: In the current research, a hierarchical morphology comprising of packed assembly of nanoparticles was induced in thermoplastic polyurethane (TPU)/silica nanocomposite coatings in order to achieve self-cleaning behavior. Moderately hydrophilic behavior of TPU hinders its transforming to a superhydrophobic material. In the presented method, a very thin layer of silica nanoparticles is applied to the surface of TPU sheets under elevated temperature and pressure. As temperature and pressure of the process remain unchanged, processing time was considered as a main variable. Based on scanning electron microscopy and confocal microscopy results, it was found that at a certain processing time, nanoparticles can form an utterly packed morphology leading to a self-cleaning behavior. Once the process was prolonged, TPU macromolecules found the chance to migrate onto the coating's top layer due to the enhanced mobility of chains at high temperature. This observation was further proved by X-ray photoelectron spectroscopy analysis and cross-sectional morphology. The presented method has promising potentials in transforming intrinsically hydrophilic polymers into superhydrophobic materials with self-cleaning behavior.

Nonadhesive, silica nanoparticles-based brush-coated contact lens cases--compromising between ease of cleaning and microbial transmission to contact lenses.

Science.gov (United States)

Qu, Wenwen; Hooymans, Johanna M M; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C; Busscher, Henk J

2013-05-01

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs. Copyright © 2013 Wiley Periodicals, Inc.

Influence of layer eccentricity on the resonant properties of cylindrical active coated nano-particles

DEFF Research Database (Denmark)

Thorsen, R. O.; Arslanagic, Samel

2015-01-01

We report on the influence of the layer eccentricity on the resonant properties of active coated nano-particles made of a silver core and gain impregnated silica shell illuminated by a near-by magnetic line source. For a fixed over-all size of the particle, designs with small and large cores...

Effect of surfactant coating on magnetic properties of Fe3O4 nanoparticles: ESR study

International Nuclear Information System (INIS)

Koeseoglu, Yueksel

2006-01-01

Magnetic properties of surfactant-coated and uncoated superparamagnetic iron oxide nanoparticles, Fe 3 O 4 (SPION) were investigated by electron spin resonance (ESR) technique. For all samples, a strong and broad single ESR signal has been observed at all temperatures. A strong temperature dependence of ESR linewidth and resonance field is observed. Also, there is a strong effect of surfactant coating on magnetic properties of Fe 3 O 4 nanoparticles. While the resonance field is decreasing by coating, the linewidth of the ESR spectra is increasing. These changes in resonance field and the linewidth are attributed to the decrease in effective magnetic moment due to a non-collinear spin structure originated from the pinning of the surface spins and coated surfactant at the interface of nanoparticles. Also, the changes are due to the contribution of the volume of the diamagnetic coating mass to the sample volume

Chitosan-coated magnetic nanoparticles prepared in one step by reverse microemulsion precipitation.

Science.gov (United States)

López, Raúl G; Pineda, María G; Hurtado, Gilberto; León, Ramón Díaz de; Fernández, Salvador; Saade, Hened; Bueno, Darío

2013-09-27

Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 °C and 80 °C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ≈4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle size. The chitosan coating on nanoparticles was inferred from Fourier transform infrared spectrometry measurements; furthermore, the carbon concentration in the nanoparticles allowed an estimation of chitosan content in CMNP of 6%-7%. CMNP exhibit a superparamagnetic behavior with relatively high final magnetization values (≈49-53 emu/g) at 20 kOe and room temperature, probably due to a higher magnetite content in the mixture of magnetic nanoparticles. In addition, a slight direct effect of precipitation temperature on magnetization was identified, which was ascribed to a possible higher degree of nanoparticles crystallinity as temperature at which they are obtained increases. Tested for Pb2+ removal from a Pb(NO3)2 aqueous solution, CMNP showed a recovery efficacy of 100%, which makes them attractive for using in heavy metals ion removal from waste water.

Recent Advances in the Application of Magnetic Nanoparticles as a Support for Homogeneous Catalysts

Science.gov (United States)

Govan, Joseph; Gun’ko, Yurii K.

2014-01-01

Magnetic nanoparticles are a highly valuable substrate for the attachment of homogeneous inorganic and organic containing catalysts. This review deals with the very recent main advances in the development of various nanocatalytic systems by the immobilisation of homogeneous catalysts onto magnetic nanoparticles. We discuss magnetic core shell nanostructures (e.g., silica or polymer coated magnetic nanoparticles) as substrates for catalyst immobilisation. Then we consider magnetic nanoparticles bound to inorganic catalytic mesoporous structures as well as metal organic frameworks. Binding of catalytically active small organic molecules and polymers are also reviewed. After that we briefly deliberate on the binding of enzymes to magnetic nanocomposites and the corresponding enzymatic catalysis. Finally, we draw conclusions and present a future outlook for the further development of new catalytic systems which are immobilised onto magnetic nanoparticles. PMID:28344220

Magnetic polymer-silica composites as bioluminescent sensors for bilirubin detection

Energy Technology Data Exchange (ETDEWEB)

Timin, Alexander S., E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation); RASA Center in Tomsk, Tomsk Polytechnic University, pros. Lenina, 30, Tomsk (Russian Federation); Solomonov, Alexey V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation); Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001 (Israel); Kumagai, Akiko; Miyawaki, Atsushi [Cell Function Dynamics, Brain Science Institute RIKEN, 2-1 Hirosawa, Wako-city, Saitama, 351-0198 (Japan); Khashirova, Svetlana Yu; Zhansitov, Azamat [Kabardino-Balkar State University, 173 Chernyshevskogo St., Nal' chik, 360004, Kabardino-Balkaria (Russian Federation); Rumyantsev, Evgeniy V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation)

2016-11-01

The synthesis of multifunctional nano-sized materials is leading to the rapid development of key application, including improved drug delivery, bioimaging and protein separation. In this work, magnetic silica particles modified with novel guanidine containing co-polymers were manufactured via sol-gel method. To evaluate the chemical composition of our prepared samples, FT-IR spectroscopy and thermogravimetry were conducted. Scanning electron microscopy was used in order to investigate the morphology of final products after modification by guanidine containing co-polymers and iron nanoparticles. In addition, the surface of polymer-silica composites was functionalized by the novel bilirubin-inducible fluorescent protein UnaG. In an aqueous bilirubin solution, the silica particles decorated with the polymer-UnaG have showed bright fluorescence. Synthesis and characterization of these hybrid materials allow developing of new multifunctional nano-sized materials, which will be used for detection and separation of bilirubin, a lipophilic heme catabolite that is a clinical diagnostic for liver function. - Highlights: • Novel magnetic silicas grafted by guanidine containing co-polymers were prepared. • Unag protein was effectively loaded into polymer coated silicas. • The fluorescent properties depend on content of bilirubin.

Magnetic polymer-silica composites as bioluminescent sensors for bilirubin detection

International Nuclear Information System (INIS)

Timin, Alexander S.; Solomonov, Alexey V.; Kumagai, Akiko; Miyawaki, Atsushi; Khashirova, Svetlana Yu; Zhansitov, Azamat; Rumyantsev, Evgeniy V.

2016-01-01

The synthesis of multifunctional nano-sized materials is leading to the rapid development of key application, including improved drug delivery, bioimaging and protein separation. In this work, magnetic silica particles modified with novel guanidine containing co-polymers were manufactured via sol-gel method. To evaluate the chemical composition of our prepared samples, FT-IR spectroscopy and thermogravimetry were conducted. Scanning electron microscopy was used in order to investigate the morphology of final products after modification by guanidine containing co-polymers and iron nanoparticles. In addition, the surface of polymer-silica composites was functionalized by the novel bilirubin-inducible fluorescent protein UnaG. In an aqueous bilirubin solution, the silica particles decorated with the polymer-UnaG have showed bright fluorescence. Synthesis and characterization of these hybrid materials allow developing of new multifunctional nano-sized materials, which will be used for detection and separation of bilirubin, a lipophilic heme catabolite that is a clinical diagnostic for liver function. - Highlights: • Novel magnetic silicas grafted by guanidine containing co-polymers were prepared. • Unag protein was effectively loaded into polymer coated silicas. • The fluorescent properties depend on content of bilirubin.

Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

Science.gov (United States)

Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

2017-06-01

Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

Influence of dextran coating on the magnetic behaviour of iron oxide nanoparticles

International Nuclear Information System (INIS)

Dutz, Silvio; Andrae, Wilfried; Hergt, Rudolf; Mueller, Robert; Oestreich, Christiane; Schmidt, Christopher; Toepfer, Jorg; Zeisberger, Matthias; Bellemann, Matthias E.

2007-01-01

Magnetic iron oxide nanoparticles with mean diameters in the range from 10 to 30 nm were prepared by modified chemical precipitation routes. The particles were suspended in an aqueous solution by coating of the particles with carboxymethyldextran. A stability against agglomeration was achieved over a period of more than 7 days. In the present investigation, the structural and the magnetic properties of the nanoparticles were investigated. The influence of the dextran shell on the strength of the dipole-dipole interactions between the neighbouring particles was determined by investigation of the remanence behaviour (Henkel plot) of coated as well as of uncoated particles

Effect of hydrophobic coating on the magnetic anisotropy and radiofrequency heating of γ-Fe2O3 nanoparticles

International Nuclear Information System (INIS)

Singh, Mandeep; Ulbrich, Pavel; Prokopec, Vadym; Svoboda, Pavel; Šantavá, Eva; Štěpánek, František

2013-01-01

The effect of a hydrophobic (oleic acid) coating on the magnetic properties of maghemite (γ-Fe 2 O 3 ) nanoparticles was investigated. The nanoparticles were prepared by a novel bi-phasic co-precipitation route and their properties compared with uncoated nanoparticles and nanoparticles prepared by a standard single-phase process. The oleic acid coated nanoparticles had a mean diameter of 6 nm when the two-phase precipitation procedure was used compared to 12 nm for nanoparticles prepared in a single phase under otherwise identical conditions. Super Quantum Interference Device measurements show superparamagnetism of the nanoparticles, with a saturation magnetization at 4 K to be 66.4 emu/g and 89.0 emu/g for the coated nanoparticles obtained by two- and single-phase procedure, respectively. Zero-field-cooled and field-cooled curves reveal a dramatic shift in the blocking temperature of the coated nanoparticles, and a significant change in their anisotropy. The hydrophobic nanoparticles were able to form stable ferrofluids in a range of organic solvents and show good heating rates in a 400 kHz alternating magnetic field. - Highlights: ► Hydrophobic iron oxide nanoparticles synthesized by a new microemulsion approach. ► Strong influence of oleic acid coating on blocking temperature observed. ► Stable non-aqueous ferrofluids prepared. ► Favorable heating rates under alternating magnetic field

Stability of anti-reflection coatings via the self-assembly encapsulation of silica nanoparticles by diazo-resins

Science.gov (United States)

Metzman, Jonathan S.; Ridley, Jason I.; Khalifa, Moataz B.; Heflin, James R.

2015-12-01

A modified silica nanoparticle (MSNP) solution was formed by the encapsulation of negatively charged silica nanoparticles by the UV-crosslinkable polycation oligomer diazo-resin (DAR). Appropriate DAR encapsulation concentrations were determined by use of zeta-potential and dynamic light scattering measurements. The MSNPs were used in conjunction with poly(styrene sulfonate) (PSS) to grow homogenous ionic self-assembled multilayer anti-reflection coatings. Stability was induced within the films by the exposure of UV-irradiation that allowed for crosslinking of the DAR and PSS. The films were characterized by UV/vis/IR spectroscopy and field emission scanning electron microscopy. The transmission and reflection levels were >98.5% and <0.05%, respectively. The refractive indices resided in the 1.25-1.26 range. The solvent stability was tested by sonication of the films in a ternary solvent (H2O/DMF/ZnCl2 3:5:2 w/w/w).

Functionalization of magnetic nanoparticles with 3-aminopropyl silane

International Nuclear Information System (INIS)

Campelj, Stanislav; Makovec, Darko; Drofenik, Miha

2009-01-01

Superparamagnetic maghemite nanoparticles were functionalized with 3-aminopropyl triethoxy silane (APS). The influence of the different experimental parameters (temperature, pH, and reactant concentration) on the efficiency of the APS bonding directly to the maghemite nanoparticles or after their coating with a thin layer of silica was systematically studied. The functionalization was followed with measurements of the ζ-potential and direct measurements of the surface APS concentration on the nanoparticles. The surface concentration of the APS was much higher in the case when the APS was bonded to the silica-coated nanoparticles compared to bonding directly to the surfaces of the iron-oxide nanoparticles.

Polymer-Silica nanoparticles composite films as protective coatings for stone-based monuments

Energy Technology Data Exchange (ETDEWEB)

Manoudis, P [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Papadopoulou, S [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Karapanagiotis, I [' Ormylia' Art Diagnosis Centre, Ormylia, Chalkidiki, 63071 (Greece); Tsakalof, A [Medical Department, University of Thessaly, Larissa, 41222 (Greece); Zuburtikudis, I [Department of Industrial Design Engineering, TEI of Western Macedonia, Kozani, 50100 (Greece); Panayiotou, C [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece)

2007-04-15

The decrease of surface energy of mineral substrates similar to those used in many stone monuments of cultural heritage by the application of protective polymer coatings along with the simultaneous increase of their surface roughness can increase their ability to repel water substantially. In this work, the effect of artificially induced roughness on the water repellency of mineral substrates coated with protective polymer films was investigated. Natural marble samples or home made calcium carbonate blocks were tried as the mineral substrates. The roughness increase was achieved by mineral chemical etching or by creation of nanoscale binary composition film on the substrate surface. PMMA and PFPE were the polymers used, while different-sized silica nanoparticles were employed for the production of the nanocomposite films. Examination of the coated and uncoated surfaces with profilometry and AFM and measurements of water contact angles reveal a pronounced effect of the surface roughness on water repellency. Especially in the case of nanocomposite coatings, the surfaces become super-hydrophobic. This result indicates that the nanoscale binary composition film scheme, which is characterized by its simplicity and low cost, is a suitable candidate for the water protection of stone-based monuments on large scale.

Polymer-Silica nanoparticles composite films as protective coatings for stone-based monuments

International Nuclear Information System (INIS)

Manoudis, P; Papadopoulou, S; Karapanagiotis, I; Tsakalof, A; Zuburtikudis, I; Panayiotou, C

2007-01-01

The decrease of surface energy of mineral substrates similar to those used in many stone monuments of cultural heritage by the application of protective polymer coatings along with the simultaneous increase of their surface roughness can increase their ability to repel water substantially. In this work, the effect of artificially induced roughness on the water repellency of mineral substrates coated with protective polymer films was investigated. Natural marble samples or home made calcium carbonate blocks were tried as the mineral substrates. The roughness increase was achieved by mineral chemical etching or by creation of nanoscale binary composition film on the substrate surface. PMMA and PFPE were the polymers used, while different-sized silica nanoparticles were employed for the production of the nanocomposite films. Examination of the coated and uncoated surfaces with profilometry and AFM and measurements of water contact angles reveal a pronounced effect of the surface roughness on water repellency. Especially in the case of nanocomposite coatings, the surfaces become super-hydrophobic. This result indicates that the nanoscale binary composition film scheme, which is characterized by its simplicity and low cost, is a suitable candidate for the water protection of stone-based monuments on large scale

Reduced bacteria adhesion on octenidine loaded mesoporous silica nanoparticles coating on titanium substrates.

Science.gov (United States)

Xu, Gaoqiang; Shen, Xinkun; Dai, Liangliang; Ran, Qichun; Ma, Pingping; Cai, Kaiyong

2017-01-01

Bacterial infection is one of the most severe postoperative complications leading to implantation failure. The early bacterial stage (4-6h) was proved to be the "decisive period" for long-term bacteria-related infection. Thus, to endow potential early antibacterial capacity for a titanium (Ti) based implant, an effective antiseptic agent of octenidine dihydrochloride (OCT) was effectively loaded on the mesoporous silica nanoparticles (MSNs)-incorporated titania coating which was fabricated by an electrophoretic-enhanced micro-arc oxidation technique. The surface characteristic of the coatings were characterized by various methods (SEM, AFM, XPS, XRD, etc.), and its corrosion resistance was also examined by the potentiodynamic polarization curves. The composite coating without OCT loading not only displayed good cytocompatibility but also exhibited certain anti-bacterial property. After loading with OCT, its antibacterial efficiency of the titanium substrates with composite coating was greatly enhanced without compromising their cytocompatibility. The study provides an approach for the fabrication of anti-bacterial Ti implant for potential orthopedic application. Copyright © 2016 Elsevier B.V. All rights reserved.

Liposome-coated mesoporous silica nanoparticles loaded with L-cysteine for photoelectrochemical immunoassay of aflatoxin B1.

Science.gov (United States)

Lin, Youxiu; Zhou, Qian; Zeng, Yongyi; Tang, Dianping

2018-06-02

The authors describe a photoelectrochemical (PEC) immunoassay for determination of aflatoxin B 1 (AFB 1 ) in foodstuff. The competitive immunoreaction is carried out on a microplate coated with a capture antibody against AFB 1 using AFB 1 -bovine serum albumin (BSA)-liposome-coated mesoporous silica nanoparticles (MSN) loaded with L-cysteine as a support. The photocurrent is produced by a photoactive material consisting of cerium-doped Bi 2 MoO 6 . Initially, L-cysteine acting as the electron donor is gated in the pores by interaction between mesoporous silica and liposome. Thereafter, AFB 1 -BSA conjugates are covalently bound to the liposomes. Upon introduction of the analyte (AFB 1 ), the labeled AFB 1 -BSA complex competes with the analyte for the antibody deposited on the microplate. Accompanying with the immunocomplex, the liposomes on the MSNs are lysed upon addition of Triton X-100. This results in the opening of the pores and in a release of L-cysteine. Free cysteine then induces the electron-hole scavenger of the photoactive nanosheets to increase the photocurrent. The photocurrent (relative to background signal) increases with increasing AFB 1 concentration. Under optimum conditions, the photoactive nanosheets display good photoelectrochemical responses, and allow the detection of AFB 1 at a concentration as low as 0.1 pg·mL -1 within a linear response in the 0.3 pg·mL -1 to 10 ng·mL -1 concentration range. Accuracy was evaluated by analyzing naturally contaminated and spiked peanut samples by using a commercial AFB 1 ELISA kit as the reference, and well-matching results were obtained. Graphical abstract Schematic presentation of a photoelectrochemical immunoassay for AFB 1 . It is based on the use of Ce-doped Bi 2 MoO 6 nanosheets and of liposome-coated mesoporous silica nanoparticles loaded with L-cysteine.

Engineering and characterization of mesoporous silica-coated magnetic particles for mercury removal from industrial effluents

International Nuclear Information System (INIS)

Dong Jie; Xu Zhenghe; Wang Feng

2008-01-01

Mesoporous silica coatings were synthesized on dense liquid silica-coated magnetite particles using cetyl-trimethyl-ammonium chloride (CTAC) as molecular templates, followed by sol-gel process. A specific surface area of the synthesized particles as high as 150 m 2 /g was obtained. After functionalization with mercapto-propyl-trimethoxy-silane (MPTS) through silanation reaction, the particles exhibited high affinity of mercury in aqueous solutions. Atomic force microscopy (AFM), zeta potential measurement, thermal gravimetric analysis (TGA), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS) were used to characterize the synthesis processes, surface functionalization, and mercury adsorption on the synthesized magnetite particles. The loading capacity of the particles for mercury was determined to be as high as 14 mg/g at pH 2. A unique feature of strong magnetism of the synthesized nanocomposite particles makes the subsequent separation of the magnetic sorbents from complex multiphase suspensions convenient and effective

Engineering and characterization of mesoporous silica-coated magnetic particles for mercury removal from industrial effluents

Science.gov (United States)

Dong, Jie; Xu, Zhenghe; Wang, Feng

2008-03-01

Mesoporous silica coatings were synthesized on dense liquid silica-coated magnetite particles using cetyl-trimethyl-ammonium chloride (CTAC) as molecular templates, followed by sol-gel process. A specific surface area of the synthesized particles as high as 150 m 2/g was obtained. After functionalization with mercapto-propyl-trimethoxy-silane (MPTS) through silanation reaction, the particles exhibited high affinity of mercury in aqueous solutions. Atomic force microscopy (AFM), zeta potential measurement, thermal gravimetric analysis (TGA), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS) were used to characterize the synthesis processes, surface functionalization, and mercury adsorption on the synthesized magnetite particles. The loading capacity of the particles for mercury was determined to be as high as 14 mg/g at pH 2. A unique feature of strong magnetism of the synthesized nanocomposite particles makes the subsequent separation of the magnetic sorbents from complex multiphase suspensions convenient and effective.

Synthesis, Characterization, and Applications of Magnetic Nanoparticles Featuring Polyzwitterionic Coatings

Directory of Open Access Journals (Sweden)

Philip Biehl

2018-01-01

Full Text Available Throughout the last decades, magnetic nanoparticles (MNP have gained tremendous interest in different fields of applications like biomedicine (e.g., magnetic resonance imaging (MRI, drug delivery, hyperthermia, but also more technical applications (e.g., catalysis, waste water treatment have been pursued. Different surfactants and polymers are extensively used for surface coating of MNP to passivate the surface and avoid or decrease agglomeration, decrease or modulate biomolecule absorption, and in most cases increase dispersion stability. For this purpose, electrostatic or steric repulsion can be exploited and, in that regard, surface charge is the most important (hybrid particle property. Therefore, polyelectrolytes are of great interest for nanoparticle coating, as they are able to stabilize the particles in dispersion by electrostatic repulsion due to their high charge densities. In this review article, we focus on polyzwitterions as a subclass of polyelectrolytes and their use as coating materials for MNP. In the context of biomedical applications, polyzwitterions are widely used as they exhibit antifouling properties and thus can lead to minimized protein adsorption and also long circulation times.

Studies on Preparation of Photosensitizer Loaded Magnetic Silica Nanoparticles and Their Anti-Tumor Effects for Targeting Photodynamic Therapy

Directory of Open Access Journals (Sweden)

Chen Zhi-Long

2009-01-01

Full Text Available Abstract As a fast developing alternative of traditional therapeutics, photodynamic therapy (PDT is an effective, noninvasive, nontoxic therapeutics for cancer, senile macular degeneration, and so on. But the efficacy of PDT was compromised by insufficient selectivity and low solubility. In this study, novel multifunctional silica-based magnetic nanoparticles (SMNPs were strategically designed and prepared as targeting drug delivery system to achieve higher specificity and better solubility. 2,7,12,18-Tetramethyl-3,8-di-(1-propoxyethyl-13,17-bis-(3-hydroxypropyl porphyrin, shorted as PHPP, was used as photosensitizer, which was first synthesized by our lab with good PDT effects. Magnetite nanoparticles (Fe3O4 and PHPP were incorporated into silica nanoparticles by microemulsion and sol–gel methods. The prepared nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The nanoparticles were approximately spherical with 20–30 nm diameter. Intense fluorescence of PHPP was monitored in the cytoplasm of SW480 cells. The nanoparticles possessed good biocompatibility and could generate singlet oxygen to cause remarkable photodynamic anti-tumor effects. These suggested that PHPP-SMNPs had great potential as effective drug delivery system in targeting photodynamic therapy, diagnostic magnetic resonance imaging and magnetic hyperthermia therapy.

Deposition of GdVO4:Eu3+ nanoparticles on silica nanospheres by a simple sol gel method

Science.gov (United States)

Liu, Guixia; Hong, Guangyan; Wang, Jinxian; Dong, Xiangting

2006-07-01

The deposition and coating of GdVO4:Eu3+ nanoparticles on spherical silica was carried out using a simple sol-gel method at low temperature. The GdVO4:Eu3+-coated silica composites obtained were characterized by differential thermal analysis (DTA), thermogravimetric (TG) analysis, x-ray diffraction (XRD), Fourier-transform IR spectroscopy (FT-IR), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), photoluminescence spectra, and kinetic decay. It is found that the ~5 nm GdVO4:Eu3+ nanoparticles coating the silica spheres are crystal in the as-prepared samples and the crystallinity increases with increasing annealing temperature. The composites obtained are spherical in shape with an average size of 100 nm. The GdVO4:Eu3+ nanoparticles are linked with silica cores by a chemical bond. The photoluminescence spectra of the obtained GdVO4:Eu3+-coated silica composites are similar to those of the bulk GdVO4:Eu3+ phosphors. The strongest peak is near 617 nm, which indicates that Eu3+ is located in the low symmetry site with non-inversion centre.

Gold-coated nanoparticles for use in biotechnology applications

Science.gov (United States)

Berning, Douglas E [Los Alamos, NM; Kraus, Jr., Robert H.; Atcher, Robert W [Los Alamos, NM; Schmidt, Jurgen G [Los Alamos, NM

2009-07-07

A process of preparing gold-coated magnetic nanoparticles is disclosed and includes forming a suspension of magnetic nanoparticles within a suitable liquid, adding an amount of a reducible gold compound and a reducing agent to the suspension, and, maintaining the suspension for time sufficient to form gold-coated magnetic nanoparticles.

A novel thermal decomposition approach for the synthesis of silica-iron oxide core–shell nanoparticles

International Nuclear Information System (INIS)

Kishore, P.N.R.; Jeevanandam, P.

2012-01-01

Highlights: ► Silica-iron oxide core–shell nanoparticles have been synthesized by a novel thermal decomposition approach. ► The silica-iron oxide core–shell nanoparticles are superparamagnetic at room temperature. ► The silica-iron oxide core–shell nanoparticles serve as good photocatalyst for the degradation of Rhodamine B. - Abstract: A simple thermal decomposition approach for the synthesis of magnetic nanoparticles consisting of silica as core and iron oxide nanoparticles as shell has been reported. The iron oxide nanoparticles were deposited on the silica spheres (mean diameter = 244 ± 13 nm) by the thermal decomposition of iron (III) acetylacetonate, in diphenyl ether, in the presence of SiO 2 . The core–shell nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, field emission-scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, diffuse reflectance spectroscopy, and magnetic measurements. The results confirm the presence of iron oxide nanoparticles on the silica core. The core–shell nanoparticles are superparamagnetic at room temperature indicating the presence of iron oxide nanoparticles on silica. The core–shell nanoparticles have been demonstrated as good photocatalyst for the degradation of Rhodamine B.

Chitosan-coated nickel-ferrite nanoparticles as contrast agents in magnetic resonance imaging

International Nuclear Information System (INIS)

Ahmad, Tanveer; Bae, Hongsub; Iqbal, Yousaf; Rhee, Ilsu; Hong, Sungwook; Chang, Yongmin; Lee, Jaejun; Sohn, Derac

2015-01-01

We report evidence for the possible application of chitosan-coated nickel-ferrite (NiFe 2 O 4 ) nanoparticles as both T 1 and T 2 contrast agents in magnetic resonance imaging (MRI). The coating of nickel-ferrite nanoparticles with chitosan was performed simultaneously with the synthesis of the nickel-ferrite nanoparticles by a chemical co-precipitation method. The coated nanoparticles were cylindrical in shape with an average length of 17 nm and an average width of 4.4 nm. The bonding of chitosan onto the ferrite nanoparticles was confirmed by Fourier transform infrared spectroscopy. The T 1 and T 2 relaxivities were 0.858±0.04 and 1.71±0.03 mM −1 s −1 , respectively. In animal experimentation, both a 25% signal enhancement in the T 1 -weighted mage and a 71% signal loss in the T 2 -weighted image were observed. This demonstrated that chitosan-coated nickel-ferrite nanoparticles are suitable as both T 1 and T 2 contrast agents in MRI. We note that the applicability of our nanoparticles as both T 1 and T 2 contrast agents is due to their cylindrical shape, which gives rise to both inner and outer sphere processes of nanoparticles. - Highlights: • Chitosan-coated nickel-ferrite (Ni-Fe 2 O 4 ) nanoparticles were synthesized in an aqueous system by chemical co-precipitation. • The characterization of bare and chitosan-coated nanoparticles were performed using various analytical tools, such as TEM, FTIR, XRD, and VMS. • We evaluated the coated particles as potential T 1 and T 2 contrast agents for MRI by measuring T 1 and T 2 relaxation times as a function of iron concentration. • Both T 1 and T 2 effects were also observed in animal experimentation

Stability of magnetite nanoparticles with different coatings in a simulated blood plasma

Energy Technology Data Exchange (ETDEWEB)

Favela-Camacho, Sarai E.; Pérez-Robles, J. Francisco [Center for Research and Advanced Studies of National Polytechnic Institute, CINVESTAV-Querétaro Unit (Mexico); García-Casillas, Perla E. [Autonomous University of Juarez, Department of Materials Science, Institute of Engineering and Technology (Mexico); Godinez-Garcia, Andrés, E-mail: andgodinez@xanum.uam.mx [Universidad Autónoma Metropolitana, Departamento de Ingeniería de Procesos e Hidráulica (Mexico)

2016-07-15

Magnetite nanoparticles (MNPs) have demonstrated to be a potential platform for simultaneous anticancer drug delivery and magnetic resonance imaging (MRI). However, magnetite is unstable at the blood plasma conditions. Therefore, to study their stability in a broad range of particle size, the MNPs were synthesized using two methods, the fast injection co-precipitation method (FIC) and the reflux co-precipitation method (RC). The MNPs obtained by the RC and the FIC methods have an average size of agglomerates of 200 and 45 nm respectively. They were dispersed using sodium citrate as surfactant and were coated with silica and chitosan. A total of four kind of coated MNPs were synthesized: magnetite/sodium citrate, magnetite/silica, magnetite/sodium citrate/silica and magnetite/sodium citrate/silica/chitosan. Different samples of the coated MNPs were immersed in a simulated blood plasma solution (Phosphate-Buffered Saline, PBS, Gibco{sup ®}), for periods of 24, 48 and 72 h. Inductively coupled plasma (ICP) technique was used to analyze the composition of the simulated plasma after those periods of time. The obtained results suggest that the uncoated samples showed an appreciable weight loss, and the iron composition in the simulated plasma increased. This last means that the used coatings avoid iron dissolution from the MNPs.Graphical abstract.

Adherence of paclitaxel drug in magnetite chitosan nanoparticles

International Nuclear Information System (INIS)

Escobar Zapata, Edna V.; Martínez Pérez, Carlos A.; Rodríguez González, Claudia A.; Castro Carmona, Javier S.; Quevedo Lopez, Manuel A.; García-Casillas, Perla E.

2012-01-01

Highlights: ► Chitosan silica magnetite adsorbs antineoplastic drug. ► Silica coating improve the drug adherence. - Abstract: Cancer treatment is a big challenge in medicine where chemotherapies and radiotherapies are aggressive and poorly effective having side effects as delirium, fatigue, insomnia, nausea and vomiting which are common problems for cancer patients. For this reason, during the last two decades, many researchers have developed several techniques to improve the current therapies; one of them is the functionalization of magnetic nanoparticles for drug delivery. In this work, magnetic nanoparticles with an average crystallite size 21.8 nm were covered in a core/shell type; magnetite/silica, magnetite/chitosan, and a double shell magnetite/silica/chitosan were developed for attaching an antineoplastic drug. The mechanism for the functionalization of the nanoparticles with a single and double shell was studied with Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adherence of an antineoplastic drug, paclitaxel, onto functionalized nanoparticles was analyzed with a UV–Visible spectroscopy at a wavelength of 253 nm. It was found that the adherence of the drug is improved up to 18% when magnetite nanoparticles are coated with a single chitosan shell, and when the nanoparticles are coated with a silica/chitosan shell the adherence increases up to 29%.

o-Vanillin functionalized mesoporous silica – coated magnetite nanoparticles for efficient removal of Pb(II) from water

Energy Technology Data Exchange (ETDEWEB)

Culita, Daniela C., E-mail: danaculita@yahoo.co.uk [“Ilie Murgulescu” Institute of Physical Chemistry, Splaiul Independentei 202, Bucharest (Romania); Simonescu, Claudia Maria; Patescu, Rodica-Elena [Politehnica University, Faculty of Applied Chemistry and Materials Science, Bucharest (Romania); Dragne, Mioara [S.C. KEMCRISTAL S.R.L., Muncii Str., No. 51, Fundulea, Călăraşi (Romania); Stanica, Nicolae [“Ilie Murgulescu” Institute of Physical Chemistry, Splaiul Independentei 202, Bucharest (Romania); Oprea, Ovidiu [Politehnica University, Faculty of Applied Chemistry and Materials Science, Bucharest (Romania)

2016-06-15

o-Vanillin functionalized mesoporous silica – coated magnetite (Fe{sub 3}O{sub 4}@MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N{sub 2} adsorption–desorption technique and magnetic measurements. The capacity of Fe{sub 3}O{sub 4}@MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica – coated magnetite (Fe{sub 3}O{sub 4}@MCM-41) and amino – modified mesoporous silica coated magnetite (Fe{sub 3}O{sub 4}@MCM-41-NH{sub 2}). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH=4.4 and T=298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80–90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe{sub 3}O{sub 4}@MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water. - Graphical abstract: A novel magnetic adsorbent based on o-vanillin functionalized mesoporous silica – coated magnetite was synthesized and fully characterized and its adsorption capacity for Pb(II) ions in aqueous solutions was evaluated. The maximum adsorption capacity for Pb(II) ions was determined to be 155.71 mg g{sup −1}. The adsorption rate was very high at the beginning of the adsorption process, 90% of the total amount of Pb(II) being removed within the first 60 min. Display Omitted.

o-Vanillin functionalized mesoporous silica – coated magnetite nanoparticles for efficient removal of Pb(II) from water

International Nuclear Information System (INIS)

Culita, Daniela C.; Simonescu, Claudia Maria; Patescu, Rodica-Elena; Dragne, Mioara; Stanica, Nicolae; Oprea, Ovidiu

2016-01-01

o-Vanillin functionalized mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N 2 adsorption–desorption technique and magnetic measurements. The capacity of Fe 3 O 4 @MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41) and amino – modified mesoporous silica coated magnetite (Fe 3 O 4 @MCM-41-NH 2 ). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH=4.4 and T=298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80–90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe 3 O 4 @MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water. - Graphical abstract: A novel magnetic adsorbent based on o-vanillin functionalized mesoporous silica – coated magnetite was synthesized and fully characterized and its adsorption capacity for Pb(II) ions in aqueous solutions was evaluated. The maximum adsorption capacity for Pb(II) ions was determined to be 155.71 mg g −1 . The adsorption rate was very high at the beginning of the adsorption process, 90% of the total amount of Pb(II) being removed within the first 60 min. Display Omitted

Magnetic nanoparticles for power absorption: Optimizing size, shape and magnetic properties

International Nuclear Information System (INIS)

Gonzalez-Fernandez, M.A.; Torres, T.E.; Andres-Verges, M.; Costo, R.; Presa, P. de la; Serna, C.J.; Morales, M.P.; Marquina, C.; Ibarra, M.R.; Goya, G.F.

2009-01-01

We present a study on the magnetic properties of naked and silica-coated Fe 3 O 4 nanoparticles with sizes between 5 and 110 nm. Their efficiency as heating agents was assessed through specific power absorption (SPA) measurements as a function of particle size and shape. The results show a strong dependence of the SPA with the particle size, with a maximum around 30 nm, as expected for a Neel relaxation mechanism in single-domain particles. The SiO 2 shell thickness was found to play an important role in the SPA mechanism by hindering the heat outflow, thus decreasing the heating efficiency. It is concluded that a compromise between good heating efficiency and surface functionality for biomedical purposes can be attained by making the SiO 2 functional coating as thin as possible. - Graphical Abstract: The magnetic properties of Fe 3 O 4 nanoparticles from 5 to 110 nm are presented, and their efficiency as heating agents discussed as a function of particle size, shape and surface functionalization.

Surface Modification of Silica Nanoparticles with Titanium Tetraisopropoxide and Evaluation of their Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Leila Mazaheri

2012-12-01

Full Text Available Silica nanoparticles were modified with titanium tetraisopropoxide (TTIP via atwo-step sol-gel route. The modified silica nanoparticles were characterized using FTIR spectroscopy, thermal gravimetric analysis (TGA and EDAX elemental analysis. Photocatalytic activity of the modified nanocomposites was evaluated by photo-activated degradation of Rhodamine B (Rh.B dyestuff, as a colorant model, in distilled water. Reduction in Rh.B concentration in aqueous solution was evaluated by UV-visible spectroscopy and with the aid of visual observations. The FTIR spectroscopy results confirmed the formation of Ti-O-Si chemical bond on the surfaceof silica nanoparticles. TGA test results showed that the weight loss of the modified sample is due to deterioration of the alkoxy groups of the SiO2 surface. According to the results of EDAX elemental analysis, the presence of carbon and titanium in the structure of the modified samples and also reduction in oxygen levels are attributed to the chemical interactions due to surface chemical modification. Carbon detection in the composition can be attributed to the presence of isopropoxide in titanium tetraisopropoxide compound. The results also revealed that, with TiO2 grafting on the silica nanoparticles surface, absorption in UV region is increased and that the silica nanoparticles modified with titanate compound show photocatalytic characteristics and degradation ability of Rh.B dyestuff under UV light irradiation. It became also evident that the photocatalytic activity of the modified nanoparticles is less than TiO2 nanoparticles. However, by inclusion of modified silica nanoparticles into the polymeric coating, the photocatalytic properties of the coating can be established. Although modified silica nanoparticles have less photocatalytic activity compared to TiO2 nanoparticles, but they cause less damage to the polymer matrix.

Silica coatings on clarithromycin.

Science.gov (United States)

Bele, Marjan; Dmitrasinovic, Dorde; Planinsek, Odon; Salobir, Mateja; Srcic, Stane; Gaberscek, Miran; Jamnik, Janko

2005-03-03

Pre-crystallized clarithromycin (6-O-methylerythromycin A) particles were coated with silica from the tetraethyl orthosilicate (TEOS)-ethanol-aqueous ammonia system. The coatings had a typical thickness of 100-150 nm and presented about 15 wt.% of the silica-drug composite material. The properties of the coatings depended on reactant concentration, temperature and mixing rate and, in particular, on the presence of a cationic surfactant (cetylpyridinium chloride). In the presence of cetylpyridinium chloride the silica coatings slightly decreased the rate of pure clarithromycin dissolution.

Dual imaging probes for magnetic resonance imaging and fluorescence microscopy based on perovskite manganite nanoparticles

Czech Academy of Sciences Publication Activity Database

Kačenka, M.; Kaman, Ondřej; Kotek, J.; Falteisek, L.; Černý, J.; Jirák, D.; Herynek, V.; Zacharovová, K.; Berková, A.; Jendelová, Pavla; Kupčík, Jaroslav; Pollert, Emil; Veverka, Pavel; Lukeš, I.

2011-01-01

Roč. 21, č. 1 (2011), s. 157-164 ISSN 0959-9428 R&D Projects: GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z50390703; CEZ:AV0Z40720504 Keywords : cellular labelling * dual probe * magnetic nanoparticles * MRI * silica coating Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.968, year: 2011

One-pot synthesis and characterization of rhodamine derivative-loaded magnetic core-shell nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhang Jin, E-mail: jzhang@eng.uwo.ca; Li Jiaxin [University of Western Ontario, Department of Chemical and Biochemical Engineering (Canada); Razavi, Fereidoon S. [Brock University, Department of Physics (Canada); Mumin, Abdul Md. [University of Western Ontario, Department of Chemical and Biochemical Engineering (Canada)

2011-05-15

A new method to produce elaborate nanostructure with magnetic and fluorescent properties in one entity is reported in this article. Magnetite (Fe{sub 3}O{sub 4}) coated with fluorescent silica (SiO{sub 2}) shell was produced through the one-pot reaction, in which one reactor was utilized to realize the synthesis of superparamagnetic core of Fe{sub 3}O{sub 4}, the formation of SiO{sub 2} coating through the condensation and polymerization of tetraethylorthosilicate (TEOS), and the encapsulation of tetramethyl rhodamine isothiocyanate-dextran (TRITC-dextran) within silica shell. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD) were carried out to investigate the core-shell structure. The magnetic core of the core-shell nanoparticles is 60 {+-} 10 nm in diameter. The thickness of the fluorescent SiO{sub 2} shell is estimated at 15 {+-} 5 nm. In addition, the fluorescent signal of the SiO{sub 2} shell has been detected by the laser confocal scanning microscopy (LCSM) with emission wavelength ({lambda}{sub em}) at 566 nm. In addition, the magnetic properties of TRITC-dextran loaded silica-coating iron oxide nanoparticles (Fe{sub 3}O{sub 4}-SiO{sub 2} NPs) were studied. The hysteresis loop of the core-shell NPs measured at room temperature shows that the saturation magnetization (M{sub s}) is not reached even at the field of 70 kOe (7T). Meanwhile, the very low coercivity (H{sub c}) and remanent magnetization (M{sub r}) are 0.375 kOe and 6.6 emu/g, respectively, at room temperature. It indicates that the core-shell particles have the superparamagnetic properties. The measured blocking temperature (T{sub B}) of the TRITC-dextran loaded Fe{sub 3}O{sub 4}-SiO{sub 2} NPs is about 122.5 K. It is expected that the multifunctional core-shell nanoparticles can be used in bio-imaging.

Size-dependent magnetic anisotropy of PEG coated Fe3O4 nanoparticles; comparing two magnetization methods

Science.gov (United States)

Nayek, C.; Manna, K.; Imam, A. A.; Alqasrawi, A. Y.; Obaidat, I. M.

2018-02-01

Understanding the size dependent magnetic anisotropy of iron oxide nanoparticles is essential for the successful application of these nanoparticles in several technological and medical fields. PEG-coated iron oxide (Fe3O4) nanoparticles with core diameters of 12 nm, 15 nm, and 16 nm were synthesized by the usual co-precipitation method. The morphology and structure of the nanoparticles were investigated using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD). Magnetic measurements were conducted using a SQUID. The effective magnetic anisotropy was calculated using two methods from the magnetization measurements. In the first method the zero-field-cooled magnetization versus temperature measurements were used at several applied magnetic fields. In the second method we used the temperature-dependent coercivity curves obtained from the zero-field-cooled magnetization versus magnetic field hysteresis loops. The role of the applied magnetic field on the effective magnetic anisotropy, calculated form the zero-field-cooled magnetization versus temperature measurements, was revealed. The size dependence of the effective magnetic anisotropy constant Keff obtained by the two methods are compared and discussed.

Synthesis and application of luminescent single CdS quantum dot encapsulated silica nanoparticles directed for precision optical bioimaging

Directory of Open Access Journals (Sweden)

Veeranarayanan S

2012-07-01

Full Text Available Srivani Veeranarayanan, Aby Cheruvathoor Poulose, M Sheikh Mohamed, Yutaka Nagaoka, Seiki Iwai, Yuya Nakagame, Shosaku Kashiwada, Yasuhiko Yoshida, Toru Maekawa, D Sakthi KumarBio Nano Electronics Research Centre, Graduate School of Interdisciplinary New Science, Toyo University, Kawagoe, JapanAbstract: This paper presents the synthesis of aqueous cadmium sulfide (CdS quantum dots (QDs and silica-encapsulated CdS QDs by reverse microemulsion method and utilized as targeted bio-optical probes. We report the role of CdS as an efficient cell tag with fluorescence on par with previously documented cadmium telluride and cadmium selenide QDs, which have been considered to impart high levels of toxicity. In this study, the toxicity of bare QDs was efficiently quenched by encapsulating them in a biocompatible coat of silica. The toxicity profile and uptake of bare CdS QDs and silica-coated QDs, along with the CD31-labeled, silica-coated CdS QDs on human umbilical vein endothelial cells and glioma cells, were investigated. The effect of size, along with the time-dependent cellular uptake of the nanomaterials, has also been emphasized. Enhanced, high-specificity imaging toward endothelial cell lines in comparison with glioma cells was achieved with CD31 antibody-conjugated nanoparticles. The silica-coated nanomaterials exhibited excellent biocompatibility and greater photostability inside live cells, in addition to possessing an extended shelf life. In vivo biocompatibility and localization study of silica-coated CdS QDs in medaka fish embryos, following direct nanoparticle exposure for 24 hours, authenticated the nanomaterials' high potential for in vivo imaging, augmented with superior biocompatibility. As expected, CdS QD-treated embryos showed 100% mortality, whereas the silica-coated QD-treated embryos stayed viable and healthy throughout and after the experiments, devoid of any deformities. We provide highly cogent and convincing evidence for such

Chitosan-coated nickel-ferrite nanoparticles as contrast agents in magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Tanveer [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Department of Physics, Abdul Wali Khan University, Mardan (Pakistan); Bae, Hongsub; Iqbal, Yousaf [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Rhee, Ilsu, E-mail: ilrhee@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Hong, Sungwook [Division of Science Education, Daegu University, Gyeongsan 712-714 (Korea, Republic of); Chang, Yongmin; Lee, Jaejun [Department of Diagnostic Radiology, College of Medicine, Kyungpook National University and Hospital, Daegu 700-721 (Korea, Republic of); Sohn, Derac [Department of Physics, Hannam University, Daejon (Korea, Republic of)

2015-05-01

We report evidence for the possible application of chitosan-coated nickel-ferrite (NiFe{sub 2}O{sub 4}) nanoparticles as both T{sub 1} and T{sub 2} contrast agents in magnetic resonance imaging (MRI). The coating of nickel-ferrite nanoparticles with chitosan was performed simultaneously with the synthesis of the nickel-ferrite nanoparticles by a chemical co-precipitation method. The coated nanoparticles were cylindrical in shape with an average length of 17 nm and an average width of 4.4 nm. The bonding of chitosan onto the ferrite nanoparticles was confirmed by Fourier transform infrared spectroscopy. The T{sub 1} and T{sub 2} relaxivities were 0.858±0.04 and 1.71±0.03 mM{sup −1} s{sup −1}, respectively. In animal experimentation, both a 25% signal enhancement in the T{sub 1}-weighted mage and a 71% signal loss in the T{sub 2}-weighted image were observed. This demonstrated that chitosan-coated nickel-ferrite nanoparticles are suitable as both T{sub 1} and T{sub 2} contrast agents in MRI. We note that the applicability of our nanoparticles as both T{sub 1} and T{sub 2} contrast agents is due to their cylindrical shape, which gives rise to both inner and outer sphere processes of nanoparticles. - Highlights: • Chitosan-coated nickel-ferrite (Ni-Fe{sub 2}O{sub 4}) nanoparticles were synthesized in an aqueous system by chemical co-precipitation. • The characterization of bare and chitosan-coated nanoparticles were performed using various analytical tools, such as TEM, FTIR, XRD, and VMS. • We evaluated the coated particles as potential T{sub 1} and T{sub 2} contrast agents for MRI by measuring T{sub 1} and T{sub 2} relaxation times as a function of iron concentration. • Both T{sub 1} and T{sub 2} effects were also observed in animal experimentation.

Casein-Coated Fe5C2 Nanoparticles with Superior r2 Relaxivity for Liver-Specific Magnetic Resonance Imaging.

Science.gov (United States)

Cowger, Taku A; Tang, Wei; Zhen, Zipeng; Hu, Kai; Rink, David E; Todd, Trever J; Wang, Geoffrey D; Zhang, Weizhong; Chen, Hongmin; Xie, Jin

2015-01-01

Iron oxide nanoparticles have been extensively used as T2 contrast agents for liver-specific magnetic resonance imaging (MRI). The applications, however, have been limited by their mediocre magnetism and r2 relaxivity. Recent studies show that Fe5C2 nanoparticles can be prepared by high temperature thermal decomposition. The resulting nanoparticles possess strong and air stable magnetism, suggesting their potential as a novel type of T2 contrast agent. To this end, we improve the synthetic and surface modification methods of Fe5C2 nanoparticles, and investigated the impact of size and coating on their performances for liver MRI. Specifically, we prepared 5, 14, and 22 nm Fe5C2 nanoparticles and engineered their surface by: 1) ligand addition with phospholipids, 2) ligand exchange with zwitterion-dopamine-sulfonate (ZDS), and 3) protein adsorption with casein. It was found that the size and surface coating have varied levels of impact on the particles' hydrodynamic size, viability, uptake by macrophages, and r2 relaxivity. Interestingly, while phospholipid- and ZDS-coated Fe5C2 nanoparticles showed comparable r2, the casein coating led to an r2 enhancement by more than 2 fold. In particular, casein coated 22 nm Fe5C2 nanoparticle show a striking r2 of 973 mM(-1)s(-1), which is one of the highest among all of the T2 contrast agents reported to date. Small animal studies confirmed the advantage of Fe5C2 nanoparticles over iron oxide nanoparticles in inducing hypointensities on T2-weighted MR images, and the particles caused little toxicity to the host. The improvements are important for transforming Fe5C2 nanoparticles into a new class of MRI contrast agents. The observations also shed light on protein-based surface modification as a means to modulate contrast ability of magnetic nanoparticles.

Improvement of slip property of magnetic tape by wet silica surface treatment on cobalt-coating type {gamma}-Fe{sub 2}O{sub 3} magnetic particles; Kobaruto hichakugata {gamma}-Fe{sub 2}O{sub 3} jiseibiryushi no shisshiki shirika hyomenshori niyoru jikitepu no suberi tokusei no kaizen

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Kazuyuki; Iwasaki, Keisuke; Tanaka, Yasuyuki; Morii, Hiroko

1999-02-05

During the running of a magnetic taper coated with magnetic particles, sometimes troubles of the slip property between the magnetic tape and a magnetic head occur. In this research, silica coating onto the surfaces of magnetic iron oxide particles in water slurry was carried out, and a magnetic tape coated with these surface-modified particles was prepared so as to investigate the effect of the silica coating on the slip property of the magnetic tape. It was found that, for needle cobalt-coating type {gamma}- Fe{sub 2}O{sub 3}, the dynamic friction coefficient of the magnetic tape can be reduced from about 0.4 to abut 0.2 by coating silica at nm order. This was estimated that the adsorption amount of myristic acid as a lubricator component existing in the magnetic tape to the magnetic particles are reduced by the silica coating so that the amount of myristic acid effectively acting on the slip property of the magnetic tape surface is increased. Further, within the investigation scope of the present research, it has been clarified that the magnetic characteristics of the magnetic particles and coating dispersion property are not deteriorated by the surface treatment with silica, and a preferable magnetic recording medium retaining both magnetic characteristic and slip property can be obtained. (translated by NEDO)

Adherence of paclitaxel drug in magnetite chitosan nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Escobar Zapata, Edna V.; Martinez Perez, Carlos A.; Rodriguez Gonzalez, Claudia A.; Castro Carmona, Javier S. [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Ciudad Juarez, Ave. Del Charro 610 norte, Col. Partido Romero, C.P. 32320, Cd. Juarez Chihuahua (Mexico); Quevedo Lopez, Manuel A. [Departamento de Polimeros y Materiales, Universidad de Sonora, Blvd. Luis Encinas y Rosales, Hermosillo, Sonora (Mexico); Garcia-Casillas, Perla E., E-mail: pegarcia@uacj.mx [Instituto de Ingenieria y Tecnologia, Universidad Autonoma de Ciudad Juarez, Ave. Del Charro 610 norte, Col. Partido Romero, C.P. 32320, Cd. Juarez Chihuahua (Mexico)

2012-09-25

Highlights: Black-Right-Pointing-Pointer Chitosan silica magnetite adsorbs antineoplastic drug. Black-Right-Pointing-Pointer Silica coating improve the drug adherence. - Abstract: Cancer treatment is a big challenge in medicine where chemotherapies and radiotherapies are aggressive and poorly effective having side effects as delirium, fatigue, insomnia, nausea and vomiting which are common problems for cancer patients. For this reason, during the last two decades, many researchers have developed several techniques to improve the current therapies; one of them is the functionalization of magnetic nanoparticles for drug delivery. In this work, magnetic nanoparticles with an average crystallite size 21.8 nm were covered in a core/shell type; magnetite/silica, magnetite/chitosan, and a double shell magnetite/silica/chitosan were developed for attaching an antineoplastic drug. The mechanism for the functionalization of the nanoparticles with a single and double shell was studied with Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adherence of an antineoplastic drug, paclitaxel, onto functionalized nanoparticles was analyzed with a UV-Visible spectroscopy at a wavelength of 253 nm. It was found that the adherence of the drug is improved up to 18% when magnetite nanoparticles are coated with a single chitosan shell, and when the nanoparticles are coated with a silica/chitosan shell the adherence increases up to 29%.

o-Vanillin functionalized mesoporous silica - coated magnetite nanoparticles for efficient removal of Pb(II) from water

Science.gov (United States)

Culita, Daniela C.; Simonescu, Claudia Maria; Patescu, Rodica-Elena; Dragne, Mioara; Stanica, Nicolae; Oprea, Ovidiu

2016-06-01

o-Vanillin functionalized mesoporous silica - coated magnetite (Fe3O4@MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption-desorption technique and magnetic measurements. The capacity of Fe3O4@MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica - coated magnetite (Fe3O4@MCM-41) and amino - modified mesoporous silica coated magnetite (Fe3O4@MCM-41-NH2). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH=4.4 and T=298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80-90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe3O4@MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water.

Chitosan-Coated Magnetic Nanoparticles with Low Chitosan Content Prepared in One-Step

Directory of Open Access Journals (Sweden)

Yolanda Osuna

2012-01-01

Full Text Available Chitosan-coated magnetic nanoparticles (CMNP were obtained at 50°C in a one-step method comprising coprecipitation in the presence of low chitosan content. CMNP showed high magnetization and superparamagnetism. They were composed of a core of 9.5 nm in average diameter and a very thin chitosan layer in accordance with electron microscopy measurements. The results from Fourier transform infrared spectrometry demonstrated that CMNP were obtained and those from thermogravimetric analysis allowed to determine that they were composed of 95 wt% of magnetic nanoparticles and 5 wt% of chitosan. 67% efficacy in the Pb+2 removal test indicated that only 60% of amino groups on CMNP surface bound to Pb, probably due to some degree of nanoparticle flocculation during the redispersion. The very low weight ratio chitosan to magnetic nanoparticles obtained in this study, 0.053, and the high yield of the precipitation reactions (≈97% are noticeable.

Influence of Surface Coating of Magnetic Nanoparticles on Mechanical Properties of Polymer Nanocomposites

Science.gov (United States)

Yarar, Ecem; Karakas, Gizem; Rende, Deniz; Ozisik, Rahmi; Malta, Seyda

Polymer nanocomposites have emerged as promising materials due to improved properties when compared with conventional bulk polymers. Nanofillers are natural or synthetic organic/inorganic particles that are less than 100 nm in at least one dimension. Even the addition of trace amounts of nanofillers to polymers may lad to unique combinations of properties. Among variety of inorganic nanofillers, iron oxide magnetic nanoparticles are of great interest due to their unique physical and chemical properties, such as low toxicity, biocompatibility, large magnetization and conductivity, owing to their extremely small size and large specific surface area. In this study, approximately 8-10 nm magnetic nanoparticles coated with either citric acid or oleic acid are synthesized and blended with poly(methyl methacrylate) (PMMA) or poly(ethylene oxide) (PEO). The hydrophobicity/hydrophillicity of the polymer and the surface coating on the iron oxide nanoparticles are exploited to control the dispersion state of nanoparticles, and the effect of dispersion on mechanical and thermal properties of the nanocomposite are investigated via experimental methods such as dynamic mechanical analysis and differential scanning calorimetry. This material is based upon work partially supported by the National Science Foundation under Grant No. CMMI-1538730 and TUBITAK 112M666.

Elaboration of colloidal silica sols in aqueous medium: functionalities, optical properties and chemical detection of coating

International Nuclear Information System (INIS)

Le Guevel, X.

2006-03-01

The aim of this work was to study surface reactivity of silica nanoparticles through physical and chemical properties of sols and coatings. Applications are numerous and they are illustrated in this work by optical coating preparation for laser components and chemical gas sensor development for nitroaromatics detection. On one hand, protocol synthesis of colloidal silica sols has been developed in water medium using sol-gel process (0 to 100 w%). These sols, so-called BLUESIL, are time-stable during at least one year. Homogeneous coatings having thickness fixed to 200 nm, have been prepared on silica substrate and show high porosity and high transparence. Original films have been developed using catalytic curing in gas atmosphere (ammonia curing) conferring good abrasive resistance to the coating without significant properties modification. In order to reduce film sensitivity to molecular adsorption (water, polluting agents... ), specific BLUESIL coatings have been prepared showing hydrophobic property due to apolar species grafting onto silica nanoparticles. Using this route, coatings having several functional properties such as transparence, hydrophobicity, high porosity and good abrasive resistance have been elaborated. On the other hand, we show that colloidal silica is a material specifically adapted to the detection of nitro aromatic vapors (NAC). Indeed, the use of colloidal silica as chemical gas sensor reveals very high sensitivity, selectivity to NAC compared to Volatile Organic Compound (V.O.C) and good detection performances during one year. Moreover, chemical sensors using functionalized colloidal silica have exhibited good results of detection, even in high humidity medium (≥70 %RH). (author)

Facile and high-efficient immobilization of histidine-tagged multimeric protein G on magnetic nanoparticles

Science.gov (United States)

Lee, Jiho; Chang, Jeong Ho

2014-12-01

This work reports the high-efficient and one-step immobilization of multimeric protein G on magnetic nanoparticles. The histidine-tagged (His-tag) recombinant multimeric protein G was overexpressed in Escherichia coli BL21 by the repeated linking of protein G monomers with a flexible linker. High-efficient immobilization on magnetic nanoparticles was demonstrated by two different preparation methods through the amino-silane and chloro-silane functionalization on silica-coated magnetic nanoparticles. Three kinds of multimeric protein G such as His-tag monomer, dimer, and trimer were tested for immobilization efficiency. For these tests, bicinchoninic acid (BCA) assay was employed to determine the amount of immobilized His-tag multimeric protein G. The result showed that the immobilization efficiency of the His-tag multimeric protein G of the monomer, dimer, and trimer was increased with the use of chloro-silane-functionalized magnetic nanoparticles in the range of 98% to 99%, rather than the use of amino-silane-functionalized magnetic nanoparticles in the range of 55% to 77%, respectively.

High impact of in situ dextran coating on biocompatibility, stability and magnetic properties of iron oxide nanoparticles.

Science.gov (United States)

Shaterabadi, Zhila; Nabiyouni, Gholamreza; Soleymani, Meysam

2017-06-01

Biocompatible ferrofluids based on dextran coated iron oxide nanoparticles were fabricated by conventional co-precipitation method. The experimental results show that the presence of dextran in reaction medium not only causes to the appearance of superparamagnetic behavior but also results in significant suppression in saturation magnetization of dextran coated samples. These results can be attributed to size reduction originated from the role of dextran as a surfactant. Moreover, weight ratio of dextran to magnetic nanoparticles has a remarkable influence on size and magnetic properties of nanoparticles, so that the sample prepared with a higher weight ratio of dextran to nanoparticles has the smaller size and saturation magnetization compare with the other samples. In addition, the ferrofluids containing such nanoparticles have an excellent stability at physiological pH for several months. Furthermore, the biocompatibility studies reveal that surface modification of nanoparticles by dextran dramatically decreases the cytotoxicity of bare nanoparticles and consequently improves their potential application for diagnostic and therapeutic purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

International Nuclear Information System (INIS)

Shen, Shou-Cang; Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai; Tan, Reginald B.H.

2011-01-01

Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: → Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. → Strong positive charge was created by aminopropyl-modification. → Capability for immobilization of negatively charged protein was enhanced. → Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by 13 C and 29 Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

Energy Technology Data Exchange (ETDEWEB)

Shen, Shou-Cang, E-mail: shen_shoucang@ices.a-star.edu.sg [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Tan, Reginald B.H., E-mail: reginald_tan@ices.a-star.edu.sg [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Department of Chemical and Biomolecular Engineering, The National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore)

2011-10-15

Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: {yields} Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. {yields} Strong positive charge was created by aminopropyl-modification. {yields} Capability for immobilization of negatively charged protein was enhanced. {yields} Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by {sup 13}C and {sup 29}Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

Photocatalytic degradation of methyl red dye by silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Badr, Y. [National Institute of Laser Enhanced Science, Cairo University, Cairo (Egypt); Abd El-Wahed, M.G. [Chemistry Department, Faculty of Science, Zagazig University, Zagazig (Egypt); Mahmoud, M.A. [Chemistry Department, Faculty of Science, Zagazig University, Zagazig (Egypt)], E-mail: mahmoudchem@yahoo.com

2008-06-15

Silica nanoparticles (SiO{sub 2} NPs) were found to be photocatalytically active for degradation of methyl red dye (MR). The SiO{sub 2} NPs and SiO{sub 2} NPs doped with silver (and or) gold nanoparticles were prepared. From the transmission electron microscopy (TEM) images the particle size and particle morphology of catalysts were monitored. Moreover, SiO{sub 2} NPs doped with silver and gold ions were used as a photocatalyst for degradation of MR. The rate of photocatalytic degradation of MR was found to be increased in the order of SiO{sub 2} NPs, SiO{sub 2} NPs coated with gold nanoparticles (Au NPs) and silver nanoparticles (Ag NPs), SiO{sub 2} NPs coated with Ag NPs, SiO{sub 2} NPs coated with Au NPs, Ag{sup +}-doped SiO{sub 2} NPs, and Au{sup 3+}-doped SiO{sub 2} NPs. The kinetic and mechanism of photocatalytic reaction were studied and accorded well with experimental results.

Nanosilver-penetrated polyion graphene complex membrane for mediator-free amperometric immunoassay of alpha-fetoprotein using nanosilver-coated silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tang Juan [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108 (China); Tang Dianping, E-mail: dianping.tang@fzu.edu.c [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108 (China); Su Biling; Li Qunfang; Qiu Bin [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108 (China); Chen Guonan, E-mail: gnchen@fzu.edu.c [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108 (China)

2011-04-15

Research highlights: {yields} We fabricate a polyion graphene complex membrane-based immunosensing platform for sensitive electrochemical immunoassay of alpha-fetoprotein. {yields} Nanosilver-coated silica nanocomposites as bionanolabels. {yields} Graphene nanosheets, single-stranded DNA and silver nanoparticles as matrices. {yields} Direct electron transfer without electron mediator. {yields} Analysis of real samples and method comparison. - Abstract: A facile and sensitive mediator-free electrochemical immunosensor for detection of alpha-fetoprotein (AFP) was designed by using nanosilver-coated silica nanoparticles (Ag-SiO{sub 2}) as bionanolabels. To construct such an electrochemical immunosensor, silver ions/single-stranded DNA/graphene nanosheets were initially immobilized on a gold electrode in turn, then silver ions were in situ reduced to silver nanoparticles with the aid of NaBH{sub 4}, and anti-AFP antibodies conjugated to silver nanoparticles were used. In the presence of AFP analyte, the sandwiched immunocomplex was formed on the electrode surface by using horseradish peroxidase-anti-AFP conjugate-labeled Ag-SiO{sub 2} (HRP-anti-AFP-Ag-SiO{sub 2}) as secondary antibodies. Compared with pure silver nanoparticles, Ag-SiO{sub 2} nanocomposites could provide a large room for the immobilization of HRP-anti-AFP, and improve the electrochemical responses of the immunosensor. Meanwhile, the presence of highly conductive graphene nanosheets and silver nanoparticles provided a good pathway for electron transfer. Under optimal conditions, the immunosensor exhibited good electrochemical responses toward AFP ranging from 0.3 to 200 ng/mL with a detection limit (LOD) of 0.05 ng/mL (at 3{sigma}) in pH 6.0 PBS-H{sub 2}O{sub 2} system. Intra- and inter-assay displayed good precisions with coefficient of variation below 9.5%. In addition, the method was evaluated with 23 clinical serum samples, receiving good correlation with results from commercially available

Nanosilver-penetrated polyion graphene complex membrane for mediator-free amperometric immunoassay of alpha-fetoprotein using nanosilver-coated silica nanoparticles

International Nuclear Information System (INIS)

Tang Juan; Tang Dianping; Su Biling; Li Qunfang; Qiu Bin; Chen Guonan

2011-01-01

Research highlights: → We fabricate a polyion graphene complex membrane-based immunosensing platform for sensitive electrochemical immunoassay of alpha-fetoprotein. → Nanosilver-coated silica nanocomposites as bionanolabels. → Graphene nanosheets, single-stranded DNA and silver nanoparticles as matrices. → Direct electron transfer without electron mediator. → Analysis of real samples and method comparison. - Abstract: A facile and sensitive mediator-free electrochemical immunosensor for detection of alpha-fetoprotein (AFP) was designed by using nanosilver-coated silica nanoparticles (Ag-SiO 2 ) as bionanolabels. To construct such an electrochemical immunosensor, silver ions/single-stranded DNA/graphene nanosheets were initially immobilized on a gold electrode in turn, then silver ions were in situ reduced to silver nanoparticles with the aid of NaBH 4 , and anti-AFP antibodies conjugated to silver nanoparticles were used. In the presence of AFP analyte, the sandwiched immunocomplex was formed on the electrode surface by using horseradish peroxidase-anti-AFP conjugate-labeled Ag-SiO 2 (HRP-anti-AFP-Ag-SiO 2 ) as secondary antibodies. Compared with pure silver nanoparticles, Ag-SiO 2 nanocomposites could provide a large room for the immobilization of HRP-anti-AFP, and improve the electrochemical responses of the immunosensor. Meanwhile, the presence of highly conductive graphene nanosheets and silver nanoparticles provided a good pathway for electron transfer. Under optimal conditions, the immunosensor exhibited good electrochemical responses toward AFP ranging from 0.3 to 200 ng/mL with a detection limit (LOD) of 0.05 ng/mL (at 3σ) in pH 6.0 PBS-H 2 O 2 system. Intra- and inter-assay displayed good precisions with coefficient of variation below 9.5%. In addition, the method was evaluated with 23 clinical serum samples, receiving good correlation with results from commercially available electrochemiluminescent analyzer.

Synthesis and Characterization of Cobalt Ferrite Nanoparticles ...

African Journals Online (AJOL)

prepared material. It was observed that surface modification such as with silica coating on the cobalt ferrite will have significant effect on the structural and magnetic properties. It is also observed that, silica coated nanoparticles could be used in biomedical applications (Hong et al., 2013). In this work we have chosen sol-gel ...

Evaluation of oxidative response and tissular damage in rat lungs exposed to silica-coated gold nanoparticles under static magnetic fields

Directory of Open Access Journals (Sweden)

Ferchichi S

2016-06-01

Full Text Available Soumaya Ferchichi,1 Hamdi Trabelsi,1 Inès Azzouz,1 Amel Hanini,2 Ahmed Rejeb,3 Olfa Tebourbi,1 Mohsen Sakly,1 Hafedh Abdelmelek1 1Laboratory of Integrative Physiology, Faculty Of Sciences of Bizerte, 2Laboratory of Vascular Pathology, Carthage University, Carthage 3Laboratory of Pathological Anatomy, National School of Veterinary Medicine of Sidi Thabet, Manouba Univeristy, Manouba, Tunisia Abstract: The purpose of our study was the evaluation of toxicological effects of silica-coated gold nanoparticles (GNPs and static magnetic fields (SMFs; 128 mT exposure in rat lungs. Animals received a single injection of GNPs (1,100 µg/kg, 100 nm, intraperitoneally and were exposed to SMFs, over 14 days (1 h/day. Results showed that GNPs treatment induced a hyperplasia of bronchus-associated lymphoid tissue. Fluorescence microscopy images showed that red fluorescence signal was detected in rat lungs after 2 weeks from the single injection of GNPs. Oxidative response study showed that GNPs exposure increased malondialdehyde level and decreased CuZn-superoxide dismutase, catalase, and glutathione peroxidase activities in rat lungs. Furthermore, the histopathological study showed that combined effects of GNPs and SMFs led to more tissular damages in rat lungs in comparison with GNPs-treated rats. Interestingly, intensity of red fluorescence signal was enhanced after exposure to SMFs indicating a higher accumulation of GNPs in rat lungs under magnetic environment. Moreover, rats coexposed to GNPs and SMFs showed an increased malondialdehyde level, a fall of CuZn-superoxide dismutase, catalase, and glutathione peroxidase activities in comparison with GNPs-treated group. Hence, SMFs exposure increased the accumulation of GNPs in rat lungs and led to more toxic effects of these nanocomplexes. Keywords: malondialdehyde, catalase, superoxide dismutase, glutathione peroxidase, bronchus-associated lymphoid tissue, nanotoxicity, histopathological study

Toxicity of silica nanoparticles and the effect of protein corona

DEFF Research Database (Denmark)

Foldbjerg, Rasmus; Jespersen, Lars Vesterby; Wang, Jing

2010-01-01

  The cytotoxicity of silica nanoparticles (NPs) was investigated in the human lung cell line, A549. Silica NPs of different sizes (DLS size; 16-42 nm) were used to determine appropriate dose metrics whereas the effect of the NP corona was tested by coating the NPs with bovine serum albumin (BSA......). The NPs were characterized by TEM and DLS as monodisperse and non-aggregated in solution and the NP suspensions were free of metal and endotoxin impurities as tested by ICP-MS and the LAL test. Cellular uptake and binding of the silica NPs was indirectly assessed by flow cytometry side scatter and SEM...... upon silica NP exposure. The silica NP surface area was found to be the best dose metric for predicting cytotoxicity and IL-8 release. Generally, the NPs were only cytotoxic at high concentrations and BSA-coating of the NPs significantly decreased the cytotoxicity and cellular IL-8 secretion. All...

Inorganic Nanocrystals Functionalized Mesoporous Silica Nanoparticles: Fabrication and Enhanced Bio-applications

Directory of Open Access Journals (Sweden)

Tiancong Zhao

2017-12-01

Full Text Available Mesoporous SiO2 nanoparticles (MSNs are one of the most promising materials for bio-related applications due to advantages such as good biocompatibility, tunable mesopores, and large pore volume. However, unlike the inorganic nanocrystals with abundant physical properties, MSNs alone lack functional features. Thus, they are not sufficiently suitable for bio-applications that require special functions. Consequently, MSNs are often functionalized by incorporating inorganic nanocrystals, which provide a wide range of intriguing properties. This review focuses on inorganic nanocrystals functionalized MSNs, both their fabrication and bio-applications. Some of the most utilized methods for coating mesoporous silica (mSiO2 on nanoparticles were summarized. Magnetic, fluorescence and photothermal inorganic nanocrystals functionalized MSNs were taken as examples to demonstrate the bio-applications. Furthermore, asymmetry of MSNs and their effects on functions were also highlighted.

Magnetic hyperthermia studies on water-soluble polyacrylic acid-coated cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Krishna Surendra, M. [Indian Institute of Technology Madras, Department of Physics, Nano Functional Materials Technology Centre, Materials Research Centre (India); Annapoorani, S. [Anna University of Technology, Department of Nanotechnology (India); Ansar, Ereath Beeran; Harikrishna Varma, P. R. [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Bioceramics Laboratory (India); Ramachandra Rao, M. S., E-mail: msrrao@iitm.ac.in [Indian Institute of Technology Madras, Department of Physics, Nano Functional Materials Technology Centre, Materials Research Centre (India)

2014-12-15

We report on synthesis and hyperthermia studies in the water-soluble ferrofluid made of polyacrylic acid-coated cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with different particle sizes. Magnetic nanoparticles were synthesized using co-precipitation method and particle size was varied as 6, 10, and 14 nm by varying the precursor to surfactant concentration. PAA surfactant bonding and surfactant thickness were studied by FTIR and thermogravimetric analysis. At room temperature, nanoparticles show superparamagnetism and saturation magnetization was found to vary from 33 to 44 emu/g with increase in the particle size from 6 to 14 nm, and this increase was attributed to the presence of a magnetic inert layer of 4 Å thick. Effect of particle size, concentration, and alternating magnetic field strength at 275 kHz on specific absorption rate were studied by preparing ferrofluids in deionized water at different concentrations. Ferrofluids at a concentration of 1.25 g/L, with 10 min of AMF exposure of strength ∼15.7 kA/m show stable temperatures ∼48, 58, and 68 °C with increase in the particle sizes 6, 10, and 14 nm. A maximum specific absorption rate of 251 W/g for ferrofluid with a particle size of 10 nm at 1.25 g/L, 15.7 kA/m, and 275 kHz was observed. Viability of L929 fibroblasts is measured by MTT assay cytotoxicity studies using the polyacrylic acid-coated CoFe{sub 2}O{sub 4} nanoparticles.

Silica-Coated Liposomes for Insulin Delivery

Directory of Open Access Journals (Sweden)

Neelam Dwivedi

2010-01-01

Full Text Available Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evident from Confocal Micro-Raman spectroscopy. Silica coat enhances the stability of insulin-loaded delivery vehicles. In vivo study shows that these silica coated formulations were biologically active in reducing glucose levels.

Benefits of Silica Core-Shell Structures on the Temperature Sensing Properties of Er,Yb:GdVO4 Up-Conversion Nanoparticles.

Science.gov (United States)

Savchuk, Oleksandr A; Carvajal, Joan J; Cascales, C; Aguiló, M; Díaz, F

2016-03-23

We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 mol %) and determined their thermal sensing properties through the fluorescence intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core-shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298-343 K). The absolute sensitivity for temperature determination calculated for the core-shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications.

Core/Shell Structured Magnetic Nanoparticles for Biological Applications

International Nuclear Information System (INIS)

Park, Jeong Chan; Jung, Myung Hwan

2013-01-01

Magnetic nanoparticles have been widely used for biomedical applications, such as magnetic resonance imaging (MRI), hyperthermia, drug delivery and cell signaling. The surface modification of the nanomaterials is required for biomedical use to give physiogical stability, surface reactivity and targeting properties. Among many approaches for the surface modification with materials, such as polymers, organic ligands and metals, one of the most attractive ways is using metals. The fabrication of metal-based, monolayer-coated magnetic nanoparticles has been intensively studied. However, the synthesis of metal-capped magnetic nanoparticles with monodispersities and controllable sizes is still challenged. Recently, gold-capped magnetic nanoparticles have been reported to increase stability and to provide biocompatibility. Magnetic nanoparticle with gold coating is an attractive system, which can be stabilized in biological conditions and readily functionalized in biological conditions and readily functionalized through well-established surface modification (Au-S) chemistry. The Au coating offers plasmonic properties to magnetic nanoparticles. This makes the magnetic/Au core/shell combinations interesting for magnetic and optical applications. Herein, the synthesis and characterization of gold capped-magnetic core structured nanomaterials with different gold sources, such as gold acetate and chloroauric acid have been reported. The core/shell nanoparticles were transferred from organic to aqueous solutions for biomedical applications. Magnetic core/shell structured nanoparticles have been prepared and transferred from organic phase to aqueous solutions. The resulting Au-coated magnetic core nanoparticles might be an attractive system for biomedical applications, which are needed both magnetic resonance imaging and optical imaging

Fabrication of Superhydrophobic Surface on Polydopamine-coated Al Plate by Using Modified SiO{sub 2} Nanoparticles/Polystyrene Nano-Composite Coating

Energy Technology Data Exchange (ETDEWEB)

Moon, Songho; Lee, Woohee; Ahn, Yonghyun [Dankook University, Yongin (Korea, Republic of)

2016-04-15

A superhydrophobic Al surface has been fabricated by coating with polydopamine, followed by coating with a modified silica nanoparticles/PS composite solution. The role of polydopamine layer is to improve the adhesion of the modified silica nanoparticles. This platform is an ideal structure for attaching various nano/micro particles. Aluminum is an important industrial metal, and the superhydrophobic surface of Al plates has potential applications in various fields. Aluminum is a relatively lightweight, soft, and durable metal with good thermal conductivity and excellent corrosion resistance.

Highly Efficient Fumed Silica Nanoparticles for Peptide Bond Formation: Converting Alanine to Alanine Anhydride.

Science.gov (United States)

Guo, Chengchen; Jordan, Jacob S; Yarger, Jeffery L; Holland, Gregory P

2017-05-24

In this work, thermal condensation of alanine adsorbed on fumed silica nanoparticles is investigated using thermal analysis and multiple spectroscopic techniques, including infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectroscopies. Thermal analysis shows that adsorbed alanine can undergo thermal condensation, forming peptide bonds within a short time period and at a lower temperature (∼170 °C) on fumed silica nanoparticle surfaces than that in bulk (∼210 °C). Spectroscopic results further show that alanine is converted to alanine anhydride with a yield of 98.8% during thermal condensation. After comparing peptide formation on solution-derived colloidal silica nanoparticles, it is found that fumed silica nanoparticles show much better efficiency and selectivity than solution-derived colloidal silica nanoparticles for synthesizing alanine anhydride. Furthermore, Raman spectroscopy provides evidence that the high efficiency for fumed silica nanoparticles is likely related to their unique surface features: the intrinsic high population of strained ring structures present at the surface. This work indicates the great potential of fumed silica nanoparticles in synthesizing peptides with high efficiency and selectivity.

Synthesis of functionalized magnetite nanoparticles to use as liver targeting MRI contrast agent

International Nuclear Information System (INIS)

Yazdani, Farshad; Fattahi, Bahare; Azizi, Najmodin

2016-01-01

The aim of this research was the preparation of functionalized magnetite nanoparticles to use as a liver targeting contrast agent in magnetic resonance imaging (MRI). For this purpose, Fe_3O_4 nanoparticles were synthesized via the co-precipitation method. The synthesized nanoparticles were coated with silica via the Stober method and finally the coated nanoparticles were functionalized with mebrofenin. Formation of crystalline magnetite particles was confirmed by X-ray diffraction (XRD) analysis. The Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray analyzer (EDX) of the final product showed that silica had been effectively bonded onto the surface of the magnetite nanoparticles and the coated nanoparticles functionalized with mebrofenin. The magnetic resonance imaging of the functional nanoparticles showed that the Fe_3O_4–SiO_2-mebrofenin composite is an effective MRI contrast agent for liver targeting. - Highlights: • Superparamagnetic magnetite nanoparticles have been synthesized by simple and economical method. • Preperation of functional MNPs as a MRI contrast agent for liver targeting. • Gaining a good r_2 relaxivity of the coated functional nanoparticles.

Cellular membrane trafficking of mesoporous silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Fang, I-Ju [Iowa State Univ., Ames, IA (United States)

2012-01-01

This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

Chitosan-Coated Magnetic Nanoparticles Prepared in One Step by Reverse Microemulsion Precipitation

OpenAIRE

Hened Saade; Salvador Fernández; Ramón Díaz de León; Gilberto Hurtado; María G. Pineda; Raúl G. López; Darío Bueno

2013-01-01

Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 ?C and 80 ?C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ?4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle si...

Determination of Organophosphorous Pesticides in Environmental Water Samples Using Surface-Engineered C18 Functionalized Silica-Coated Core-Shell Magnetic Nanoparticles-Based Extraction Coupled with GC-MS/MS Analysis.

Science.gov (United States)

Srivastava, Neha; Kumari, Supriya; Nair, Kishore; Alam, Samsul; Raza, Syed K

2017-05-01

The present paper depicts a novel method based on magnetic SPE (MSPE) for the determination of organophosphorus pesticides (OPs) such as phorate, malathion, and chlorpyrifos in environmental water samples. In this study, C18 functionalized silica-coated core-shell iron oxide magnetic nanoparticles (MNPs) were used as a surface-engineered magnetic sorbent for the selective extraction of pesticides from aqueous samples, followed by GC-MS and GC-tandem MS analysis for confirmative determination of the analytes. Various important method parameters, including quantity of MNP adsorbent, volume of sample, effective time for extraction, nature of the desorbing solvent, and pH of the aqueous sample, were investigated and optimized to obtain maximum method performance. Under the optimized instrumental analysis conditions, good linearity (r2 value ≥0.994) was achieved at the concentration range of 0.5-500 μg/L. Recoveries were in the range of 79.2-96.3 and 80.4-97.5% in selective-ion monitoring and multiple reaction monitoring (MRM) modes, respectively, at the spiking concentrations of 1, 5, and 10 μg/L. MRM mode showed better sensitivity, selectivity, and low-level detection (0.5 μg/L) of analytes. The novel MSPE method is a simple, cheap, rapid, and eco-friendly method for the determination of OPs in environmental water samples.

Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

Science.gov (United States)

Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

2016-02-01

The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol-gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

Magnetoliposomes based on nickel/silica core/shell nanoparticles: Synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Ana Rita O.; Gomes, I.T.; Almeida, Bernardo G. [Centro de Física (CFUM), Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Araújo, J.P. [IFIMUP/IN – Instituto de Nanociência e Nanotecnologia, R. Campo Alegre, 4169-007 Porto (Portugal); Castanheira, Elisabete M.S. [Centro de Física (CFUM), Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Coutinho, Paulo J.G., E-mail: pcoutinho@fisica.uminho.pt [Centro de Física (CFUM), Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

2014-12-15

In the present work, nickel magnetic nanoparticles with diameters lower than 100 nm, with and without silica shell, were synthesized by microheterogeneous templating. The magnetic properties of the nanoparticles show a typical ferromagnetic behavior with a coercive field of 80 Oe. Dry magnetoliposomes (DMLs) with diameter between 58 nm and 76 nm were obtained from the synthesis of nanoparticles in the presence of a lipid or surfactant layer, and aqueous magnetoliposomes (AMLs) were obtained by encapsulation of the nanoparticles in liposomes. FRET (Förster resonance energy transfer) experiments were performed to study the non-specific interactions between aqueous magnetoliposomes and giant unilamellar vesicles (GUVs), as models of cell membranes. It was possible to detect membrane fusion between GUVs and AMLs containing both NBD-C{sub 6}-HPC (donor) and the dye Nile Red (acceptor). - Highlights: • Magnetic nickel nanoparticles were synthesized in microheterogeneous media. • The nanoparticles were covered with a silica shell to improve biocompatibility. • Aqueous and dry magnetoliposomes were prepared, the latter with diameter around 70 nm. • Membrane fusion between magnetoliposomes and models of cell membranes was detected by FRET.

Magnetoliposomes based on nickel/silica core/shell nanoparticles: Synthesis and characterization

International Nuclear Information System (INIS)

Rodrigues, Ana Rita O.; Gomes, I.T.; Almeida, Bernardo G.; Araújo, J.P.; Castanheira, Elisabete M.S.; Coutinho, Paulo J.G.

2014-01-01

In the present work, nickel magnetic nanoparticles with diameters lower than 100 nm, with and without silica shell, were synthesized by microheterogeneous templating. The magnetic properties of the nanoparticles show a typical ferromagnetic behavior with a coercive field of 80 Oe. Dry magnetoliposomes (DMLs) with diameter between 58 nm and 76 nm were obtained from the synthesis of nanoparticles in the presence of a lipid or surfactant layer, and aqueous magnetoliposomes (AMLs) were obtained by encapsulation of the nanoparticles in liposomes. FRET (Förster resonance energy transfer) experiments were performed to study the non-specific interactions between aqueous magnetoliposomes and giant unilamellar vesicles (GUVs), as models of cell membranes. It was possible to detect membrane fusion between GUVs and AMLs containing both NBD-C 6 -HPC (donor) and the dye Nile Red (acceptor). - Highlights: • Magnetic nickel nanoparticles were synthesized in microheterogeneous media. • The nanoparticles were covered with a silica shell to improve biocompatibility. • Aqueous and dry magnetoliposomes were prepared, the latter with diameter around 70 nm. • Membrane fusion between magnetoliposomes and models of cell membranes was detected by FRET

Synthesis, characterization and magnetic property of maghemite (γ-Fe2O3) nanoparticles and their protective coating with pepsin for bio-functionalization

International Nuclear Information System (INIS)

Bandhu, A.; Sutradhar, S.; Mukherjee, S.; Greneche, J.M.; Chakrabarti, P.K.

2015-01-01

Highlights: • Maghemite nanoparticles were prepared by a modified co-precipitation method. • Nanoparticles were then successfully coated with pepsin for bio-functionlization. • XRD and Mössbauer spectra confirmed the maghemite phase of the nanoparticles. • Magnetic data were analysed to evaluate particle size, anisotropy etc. - Abstract: Maghemite nanoparticles (γ-Fe 2 O 3 ) are prepared by co-precipitation method. To obtain bio-functionalized magnetic nanoparticles for magnetically controlled drug delivery, the prepared nanoparticles are successfully coated with pepsin, a bio-compatible polymer and digestive enzyme. Crystallographic phase of the nanoparticles is confirmed by X-ray diffractograms (XRD), high resolution transmission electron microscopy (HRTEM) and 57 Fe Mössbauer spectrometry. The average size of nanoparticles/nanocrystallites is estimated from the (3 1 1) peak of the XRD pattern using Debye–Scherrer formula. Results of HRTEM of coated and bare samples are in good agreement with those extracted from the XRD analysis. The dynamic magnetic properties are observed and different quantities viz., coercive field, magnetization, remanence, hysteresis losses etc., are estimated, which confirmed the presence of superparamagnetic relaxation of nanoparticles. Mössbauer spectra of the samples recorded at both 300 and 77 K, confirmed that the majority of particles are maghemite together with a very small fraction of magnetite nanoparticles

PEGylated Lipid bilayer coated mesoporous silica nanoparticles for co-delivery of paclitaxel and curcumin: Design, characterization and its cytotoxic effect.

Science.gov (United States)

Lin, Jiahao; Cai, Qiang; Tang, Yinian; Xu, Yanjun; Wang, Qian; Li, Tingting; Xu, Huihao; Wang, Shuaiyu; Fan, Kai; Liu, Zhongjie; Jin, Yipeng; Lin, Degui

2018-01-30

Highly ordered mesoporous silica nanoparticles (MSNs) with pore diameter of 2.754nm and particle size of 115±15nm were prepared with etching method. Homogeneous PEGylated lipid bilayer with 10-15nm thickness was coated around the surface of MSNs using film hydration method. Systematic optimization and characterization of co-encapsulation process of paclitaxel (Tax) and curcumin (Cur) into PEGylated lipid bilayer coated mesoporous silica nanoparticles (PLMSNs) were performed carrying out single factor test, associated with Box-Behnken Design. The concentration of encapsulated drugs was measured by reversed phase high performance liquid chromatography (RP-HPLC) method. Optimal factor settings were as follows: 50mg MSNs, ratio of MSNs to lipid (w/w)=1:1.11, and ratio of lipid to CHO (w/w)=3.93:1. The average experimental EE Tax , EE Cur and stability score value were (77.48±2.73) %, (30.70±3.56) % and 4 point respectively based on the conditions mentioned above. Morphology determination of Tax-Cur-PLMSNs revealed that the composite nanoparticles were spherical particals with uniform dispersion. In vitro release experiment indicated that PLMSNs improved dissolution of Tax compared to Tax powder suspension and exhibited sustained release property. Tax-Cur-PLMSNs manifested definite and persistently promoted cytotoxic effect against canine breast cancer cells. This prolonged and enhanced activity of Tax-Cur-PLMSNs might contribute to its sustained release effect. Copyright © 2017. Published by Elsevier B.V.

The effect of coating on heat generation properties of Iron oxide nanoparticles

Science.gov (United States)

Yuan, Yuan

Magnetic nanoparticles have attracted more and more attention for their potential application as heating agents in cancer hyperthermia. The effectiveness of cancer hyperthermia can be increased by using particles that have a higher heat generation rate, quantified by specific absorption rate (SAR), at a smaller applied field. In order to optimize the functionality of nanoparticles as heating agents, it is essential to have a comprehensive understanding of factors that may influence SAR including coating and aggregation. In all biomedical applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration and add functionality. Coatings may profoundly influence particles' clustering behavior and magnetic properties. Yet its effect on the heat generation rate of the nanoparticles has been scarcely investigated. In this context, a systematic investigation was carried out in this dissertation in order to understand the impact of the surface coating of magnetic nanoparticles on their heat generation rate. The study also includes investigation of normal nerve cell viability in presence of biofunctionalized magnetic nanoparticles with and without exposure to magnetic heating. Commercially available suspensions of iron oxide nanoparticles with a diameter of approximately 10 nm and different coatings relevant to biomedical applications such as aminosilane, carboxymethyl-dextran, protein A, biotin were extensively characterized. First of all, magnetic phase reduction of magnetite nanoparticles was examined by studying the discrepancy between the volume fraction of magnetic phase calculated from magnetization curve and the magnetic core concentration obtained from Tiron chelation test. The findings indicated that coatings might interact with the surface atoms of the magnetic core and form a magnetically disordered layer reducing the total amount of the magnetic phase. Secondly, the impact of coating and aggregation

Functionalization of silica nanoparticles for polypropylene nanocomposites applications

International Nuclear Information System (INIS)

Bracho, Diego; Palza, Humberto; Quijada, Raul; Dougnac, Vivianne

2011-01-01

Synthetic silica nanospheres of different diameters produced via the sol-gel method were used in order to enhance the barrier properties of the polypropylene-silica nanocomposites. Modification of the silica surface by reaction with organic chlorosilanes was performed in order to improve the particles interaction with the polypropylene matrix and its dispersion. Unmodified and modified silica nanoparticles were characterized using electronic microscopy (TEM), elemental analysis, thermo gravimetric analysis (TGA), and solid state nuclear magnetic resonance (NMR) spectroscopy. Preliminary permeability tests of the polymer-silica nanocomposite films showed no significant change at low particles load (3 wt%) regardless its size or surface functionality, mainly because of the low aspect ratio of the silica nanospheres. However, it is expected that at a higher concentration of silica particles differences will be observed. (author)

Multifunctional magnetic core–shell dendritic mesoporous silica nanospheres decorated with tiny Ag nanoparticles as a highly active heterogeneous catalyst

International Nuclear Information System (INIS)

Sun, Zebin; Li, Haizhen; Cui, Guijia; Tian, Yaxi; Yan, Shiqiang

2016-01-01

Graphical abstract: - Highlights: • A multifunctional magnetic core–shell dendritic silica nanocatalyst was successfully fabricated by an oil–water biphase stratification coating strategy. • The magnetic core–shell dendritic silica nanomaterials Fe_3O_4@SiO_2@Dendritic-SiO_2 were chosen as the catalyst's support for the first time. • The as-synthesized nanocatalyst exhibited excellent catalytic activity and reusability due to easy accessibility of active sites and superparamagnetism. • The novel catalyst could be conveniently recovered by magnetic separation from the reaction system. - Abstract: In present work, a multifunctional magnetic core–shell dendritic silica nanocatalyst Fe_3O_4@SiO_2@Dendritic-SiO_2-NH_2-Ag with easy accessibility of active sites and convenient recovery was successfully fabricated by an oil–water biphase stratification coating strategy, and characterized by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N_2 adsorption–desorption, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The as-synthesized nanocatalyst Fe_3O_4@SiO_2@Dendritic-SiO_2-NH_2-Ag displayed excellent catalytic activity for the catalytic reduction of 4-nitrophenol and 2-nitroaniline using sodium borohydride in aqueous solution at room temperature due to easy accessibility of active sites. Interestingly, the novel catalyst could be conveniently recovered by magnetic separation from the reaction system and recycled for at least five times without significant loss in activity. These results indicate that the above mentioned approach based on magnetic core–shell dendritic silica Fe_3O_4@SiO_2@Dendritic-SiO_2 provided a useful platform for the preparation of noble metal nanocatalysts with easy accessibility, excellent catalytic activity and convenient recovery.

Synthesis of Various Silica Nanoparticles for Foam Stability

International Nuclear Information System (INIS)

Yoon, Suk Bon; Yoon, Inho; Jung, Chonghun; Kim, Chorong; Choi, Wangkyu; Moon, Jeikwon

2013-01-01

The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles

Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell.

Science.gov (United States)

Nagao, Daisuke; Yokoyama, Mikio; Yamauchi, Noriko; Matsumoto, Hideki; Kobayashi, Yoshio; Konno, Mikio

2008-09-02

Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride was added just after coprecipitation of Fe (2+) and Fe (3+). The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores, an amphoteric initiator of 2,2'-azobis[ N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.

Impact of the Excitation Source and Plasmonic Material on Cylindrical Active Coated Nano-Particles

Directory of Open Access Journals (Sweden)

Richard W. Ziolkowski

2011-09-01

Full Text Available Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles, as well as to their far-field radiation characteristics, in the presence of an electric or a magnetic line source. A constant frequency canonical gain model is used to account for the gain introduced in the dielectric part of the nano-particle, whereas three different plasmonic materials (silver, gold, and copper are employed and compared for the nano-shell layers.

Synthesis and characterization of Fe3O4 nanoparticles coated with fucan polysaccharides

International Nuclear Information System (INIS)

Silva, V.A.J.; Andrade, P.L.; Silva, M.P.C.; Bustamante D, A.; De Los Santos Valladares, Luis; Albino Aguiar, J.

2013-01-01

In this work we report the preparation of fucan-coated magnetite (Fe 3 O 4 ) nanoparticles by the co-precipitation method. These nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Mössbauer spectroscopy and magnetic measurements. The nanoparticles showed quasi-spherical morphology with mean sizes around 10 nm. XRD and FT-IR confirmed the functionalization of the Fe 3 O 4 nanoparticles with the fucan polysaccharide. Room temperature magnetization measurements and Mössbauer spectroscopy showed that the nanoparticles exhibited superparamagnetic behavior at 300 K and the magnetic properties of the Fe 3 O 4 are partly screened by the coating preventing aggregation. - Highlights: • Syntheses of fucan-coated Fe 3 O 4 nanoparticles were made by co-precipitation method. • The efficiency of polysaccharide coated was analyzed by XRD and FT-IR. • The magnetic nanoparticles mean size was 10–20 nm. • The fucan-coated magnetite nanoparticles showed superparamagnetic behavior

Using silicon-coated gold nanoparticles to enhance the fluorescence of CdTe quantum dot and improve the sensing ability of mercury (II)

Science.gov (United States)

Zhu, Jian; Chang, Hui; Li, Jian-Jun; Li, Xin; Zhao, Jun-Wu

2018-01-01

The effect of silicon-coated gold nanoparticles with different gold core diameter and silica shell thickness on the fluorescence emission of CdTe quantum dots (QDs) was investigated. For gold nanoparticles with a diameter of 15 nm, silica coating can only results in fluorescence recover of the bare gold nanoparticle-induced quenching of QDs. However, when the size of gold nanoparticle is increased to 60 nm, fluorescence enhancement of the QDs could be obtained by silica coating. Because of the isolation of the silica shell-reduced quenching effect and local electric field effect, the fluorescence of QDs gets intense firstly and then decreases. The maximum fluorescence enhancement takes place as the silica shell has a thickness of 30 nm. This enhanced fluorescence from silicon-coated gold nanoparticles is demonstrated for sensing of Hg2 +. Under optimal conditions, the enhanced fluorescence intensity decreases linearly with the concentration of Hg2 + ranging from 0 to 200 ng/mL. The limit of detection for Hg2 + is 1.25 ng/mL. Interference test and real samples detection indicate that the influence from other metal ions could be neglected, and the Hg2 + could be specifically detected.

Structural characterization of copolymer embedded magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Nedelcu, G.G., E-mail: ggnedelcu@yahoo.com [Faculty of Physics, University “Alexandru Ioan Cuza”, Carol I Bulevard, Nr.11, 700506 Iasi (Romania); Nastro, A.; Filippelli, L. [Department of Chemistry and Chemical Technology, University of Calabria, Via P. Bucci, 87036 Arcavacata di Rende, Cosenza (Italy); Cazacu, M.; Iacob, M. [Institute of Macromolecular Chemistry “Petru Poni”, Aleea Grigore Ghica Voda, nr. 41A, 700487 Iasi (Romania); Rossi, C. Oliviero [Department of Chemistry and Chemical Technology, University of Calabria, Via P. Bucci, 87036 Arcavacata di Rende, Cosenza (Italy); Popa, A.; Toloman, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca 5 (Romania); Dobromir, M.; Iacomi, F. [Faculty of Physics, University “Alexandru Ioan Cuza”, Carol I Bulevard, Nr.11, 700506 Iasi (Romania)

2015-10-15

Highlights: • The emulsion polymerization method was used to synthesize three samples of poly(methyl methacrylate-co-acrylic acid) coated magnetite obtained before through co-precipitation technique. • Poly(methyl methacrylate-co-acrylic acid) coated magnetite nanoparticles were prepared having spherical shape and dimensions between 13 and 16 nm without agglomerations. • Fourier transform infrared spectra have found that the magnetite was pure and spectral characteristics of PMMA-co-AAc were present. • The electron spin resonance spectra revealed that interactions between nanoparticles are very weak due to the fact that the nanoparticles have been individually embedded in polymer. • The resonance field values as function of temperature demonstrate that the presence of polymer has not modified essentially its magnetic properties, except that at temperatures below 140 K there was a change due to decreasing of the magnetic anisotropy. - Abstract: Small magnetic nanoparticles (Fe{sub 3}O{sub 4}) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

Stability of polyelectrolyte-coated iron nanoparticles for T2-weighted magnetic resonance imaging

Science.gov (United States)

McGrath, Andrew J.; Dolan, Ciaran; Cheong, Soshan; Herman, David A. J.; Naysmith, Briar; Zong, Fangrong; Galvosas, Petrik; Farrand, Kathryn J.; Hermans, Ian F.; Brimble, Margaret; Williams, David E.; Jin, Jianyong; Tilley, Richard D.

2017-10-01

Iron nanoparticles are highly-effective magnetic nanoparticles for T2 magnetic resonance imaging (MRI). However, the stability of their magnetic properties is dependent on good protection of the iron core from oxidation in aqueous media. Here we report the synthesis of custom-synthesized phosphonate-grafted polyelectrolytes (PolyM3) of various chain lengths, for efficient coating of iron nanoparticles with a native iron oxide shell. The size of the nanoparticle-polyelectrolyte assemblies was investigated by transmission electron microscopy and dynamic light scattering, while surface attachment was confirmed by Fourier transform infrared spectroscopy. Low cytotoxicity was observed for each of the nanoparticle-polyelectrolyte ("Fe-PolyM3") assemblies, with good cell viability (>80%) remaining up to 100 μg mL-1 Fe in HeLa cells. When applied in T2-weighted MRI, corresponding T2 relaxivities (r2) of the Fe-PolyM3 assemblies were found to be dependent on the chain length of the polyelectrolyte. A significant increase in contrast was observed when polyelectrolyte chain length was increased from 6 to 65 repeating units, implying a critical chain length required for stabilization of the α-Fe nanoparticle core.

Generation of drugs coated iron nanoparticles through high energy ball milling

Energy Technology Data Exchange (ETDEWEB)

Radhika Devi, A.; Murty, B. S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Chelvane, J. A. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036 (India)

2014-03-28

The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

Toxicity assessment of silica coated iron oxide nanoparticles and biocompatibility improvement by surface engineering.

Directory of Open Access Journals (Sweden)

Maria Ada Malvindi

Full Text Available We have studied in vitro toxicity of iron oxide nanoparticles (NPs coated with a thin silica shell (Fe3O4/SiO2 NPs on A549 and HeLa cells. We compared bare and surface passivated Fe3O4/SiO2 NPs to evaluate the effects of the coating on the particle stability and toxicity. NPs cytotoxicity was investigated by cell viability, membrane integrity, mitochondrial membrane potential (MMP, reactive oxygen species (ROS assays, and their genotoxicity by comet assay. Our results show that NPs surface passivation reduces the oxidative stress and alteration of iron homeostasis and, consequently, the overall toxicity, despite bare and passivated NPs show similar cell internalization efficiency. We found that the higher toxicity of bare NPs is due to their stronger in-situ degradation, with larger intracellular release of iron ions, as compared to surface passivated NPs. Our results indicate that surface engineering of Fe3O4/SiO2 NPs plays a key role in improving particles stability in biological environments reducing both cytotoxic and genotoxic effects.

Silica-modified Fe-doped calcium sulfide nanoparticles for in vitro and in vivo cancer hyperthermia

International Nuclear Information System (INIS)

Wu, Steven Yueh-Hsiu; Yang, Kai-Chiang; Tseng, Ching-Li; Chen, Jung-Chih; Lin, Feng-Huei

2011-01-01

In this study, sulfide-based magnetic Fe-doped CaS nanoparticles modified with a silica layer were investigated for cancer hyperthermia. A polyvinyl pyrrolidone polymer was used as the coupling agent. The developed nanoparticles contained 11.6 wt% iron concentration, and their X-ray diffraction pattern was similar to those of CaS and Fe–CaS nanoparticles. The average particle size was approximately 47.5 nm and homogeneously dispersed in aqueous solutions. The major absorption bands of silica were observed from the FTIR spectrum. The magnetic properties and heating efficiency were also examined. The specific absorption ratio of nanoparticles at a concentration of 10 mg/mL at 37 °C in an ethanol carrier fluid was 37.92 W/g, and the nanoparticles would raise the temperature to over 45 °C within 15 min. A cytotoxicity analysis revealed that the nanoparticles had good biocompatibility, which indicated that the nanoparticles did not affect cell viability. The therapeutic effects of the nanoparticles were investigated using in vitro and animal studies. Cells seeded with nanoparticles and treated under an AC magnetic field revealed a percentage of cytotoxicity (60%) that was significantly higher from that in other groups. In the animal study, during a hyperthermia period of 15 days, tumor-bearing Balb/c mice that were subcutaneously injected with nanoparticles and exposed to an AC magnetic field manifested a reduction in tumor volume. The newly developed silica-modified Fe–CaS nanoparticles can thus be considered a promising and attractive hyperthermia thermoseed.

Superparamagnetism and coercivity in HCP-Co nanoparticles dispersed in silica matrix

Energy Technology Data Exchange (ETDEWEB)

Julian Fernandez, C. de E-mail: dejulian@padova.infm.it; Mattei, G.; Sangregorio, C.; Battaglin, C.; Gatteschi, D.; Mazzoldi, P

2004-05-01

The magnetic properties of Co HCP nanoparticles dispersed in a silica matrix with sizes between 2{+-}0.7 and 5{+-}2.2 nm were investigated. The temperature dependence of zero-field cooled and field cooled magnetizations and of the coercive field were analyzed considering the thermal activated demagnetization process. Enhanced anisotropy was observed for the 2 nm nanoparticles, while the demagnetization process of the larger ones is dominated by interparticle interactions.

Preparation of Mn-Zn ferrite nanoparticles and their silica-coated clusters: magnetic properties and transverse relaxivity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kuličková, Jarmila; Herynek, Vít; Koktan, Jakub; Maryško, Miroslav; Dědourková, T.; Knížek, Karel; Jirák, Zdeněk

2017-01-01

Roč. 427, Apr (2017), s. 251-257 ISSN 0304-8853 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : magnetic nanoparticles * Mn-Zn ferrite * hydrothermal synthesis * magnetic resonance imaging * transverse relaxivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

Synthesis, characterization and magnetic property of maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles and their protective coating with pepsin for bio-functionalization

Energy Technology Data Exchange (ETDEWEB)

Bandhu, A.; Sutradhar, S.; Mukherjee, S. [Solid State Research Laboratory, Department of Physics, Burdwan University, Burdwan 713104, West Bengal (India); Greneche, J.M. [Laboratoire de Physique de l’Etat Condensé – UMR CNRS 6087, Université du Maine, 72085, Le Mans Cedex 9 (France); Chakrabarti, P.K., E-mail: pabitra_c@hotmail.com [Solid State Research Laboratory, Department of Physics, Burdwan University, Burdwan 713104, West Bengal (India)

2015-10-15

Highlights: • Maghemite nanoparticles were prepared by a modified co-precipitation method. • Nanoparticles were then successfully coated with pepsin for bio-functionlization. • XRD and Mössbauer spectra confirmed the maghemite phase of the nanoparticles. • Magnetic data were analysed to evaluate particle size, anisotropy etc. - Abstract: Maghemite nanoparticles (γ-Fe{sub 2}O{sub 3}) are prepared by co-precipitation method. To obtain bio-functionalized magnetic nanoparticles for magnetically controlled drug delivery, the prepared nanoparticles are successfully coated with pepsin, a bio-compatible polymer and digestive enzyme. Crystallographic phase of the nanoparticles is confirmed by X-ray diffractograms (XRD), high resolution transmission electron microscopy (HRTEM) and {sup 57}Fe Mössbauer spectrometry. The average size of nanoparticles/nanocrystallites is estimated from the (3 1 1) peak of the XRD pattern using Debye–Scherrer formula. Results of HRTEM of coated and bare samples are in good agreement with those extracted from the XRD analysis. The dynamic magnetic properties are observed and different quantities viz., coercive field, magnetization, remanence, hysteresis losses etc., are estimated, which confirmed the presence of superparamagnetic relaxation of nanoparticles. Mössbauer spectra of the samples recorded at both 300 and 77 K, confirmed that the majority of particles are maghemite together with a very small fraction of magnetite nanoparticles.

Fluorine Based Superhydrophobic Coatings

Directory of Open Access Journals (Sweden)

Jean-Denis Brassard

2012-05-01

Full Text Available Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been realized via Stöber process and further functionalized using fluoroalkylsilane (FAS-17 molecules to incorporate the fluorinated groups with the silica nanoparticles in an ethanolic solution. The synthesized fluorinated silica nanoparticles have been spin coated on flat aluminum alloy, silicon and glass substrates. Functionalization of silica nanoparticles with fluorinated groups has been confirmed by Fourier Transform Infrared spectroscopy (FTIR by showing the presence of C-F and Si-O-Si bonds. The water contact angles and surface roughness increase with the number of spin-coated thin films layers. The critical size of ~119 nm renders aluminum surface superhydrophobic with three layers of coating using as-prepared nanoparticle suspended solution. On the other hand, seven layers are required for a 50 vol.% diluted solution to achieve superhydrophobicity. In both the cases, water contact angles were more than 150°, contact angle hysteresis was less than 2° having a critical roughness value of ~0.700 µm. The fluorinated silica nanoparticle coated surfaces are also transparent and can be used as paint additives to obtain transparent coatings.

Preparation of Fe3O4 magnetic nanoparticles coated with gallic acid for drug delivery

Science.gov (United States)

Dorniani, Dena; Hussein, Mohd Zobir Bin; Kura, Aminu Umar; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

2012-01-01

Background and methods Magnetic iron oxide nanoparticles were prepared using a sonochemical method under atmospheric conditions at a Fe2+ to Fe3+ molar ratio of 1:2. The iron oxide nanoparticles were subsequently coated with chitosan and gallic acid to produce a core-shell structure. Results X-ray diffraction demonstrated that the magnetic nanoparticles were pure Fe3O4 with a cubic inverse spinel structure. Transmission electron microscopy showed that the Fe3O4 nanoparticles were of spherical shape with a mean diameter of 11 nm, compared with 13 nm for the iron oxide-chitosan-gallic acid (FCG) nanocarriers. Conclusion The magnetic nanocarrier enhanced the thermal stability of the drug, gallic acid. Release of the active drug from the FCG nanocarrier was found to occur in a controlled manner. The gallic acid and FCG nanoparticles were not toxic in a normal human fibroblast (3T3) line, and anticancer activity was higher in HT29 than MCF7 cell lines. PMID:23166439

Fluorescein isothiocyanate labeled, magnetic nanoparticles conjugated D-penicillamine-anti-metadherin and in vitro evaluation on breast cancer cells

International Nuclear Information System (INIS)

Akca, Ozlet; Unak, Perihan; Medine, E. Ylker; Sakarya, Serhan; Ozdemir, Caglar; Timur, Suna

2011-01-01

Silane modified magnetic nanoparticles were prepared after capped with silica generated from the hydrolyzation of tetraethyl orthosilicate (TEOS). Amino silane (SG-Si900) was added to this solution for surface modification of silica coated magnetic particles. Finally, D-penicillamine (D-PA)-antimetadherin (anti-MTDH) was covalently linked to the amine group using glutaraldehyde as cross-linker. Magnetic nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and atomic force microscopy (AFM). AFM results showed that particles are nearly monodisperse, and the average size of particles was 40 to 50 nm. An amino acid derivative D-PA was conjugated anti-MTDH, which results the increase of uptaking potential of a conjugated agent, labelled fluorescein isothiocyanate (FITC) and then conjugated to the magnetic nanoparticles. In vitro evaluation of the conjugated D-PA-anti-MTDH-FITC to magnetic nanoparticle was studied on MCF-7 breast cancer cell lines. Fluorescence microscopy images of cells after incubation of the sample were obtained to monitor the interaction of the sample with the cancerous cells. Incorporation on cells of FITC labeled and magnetic nanoparticles conjugated D-PA-anti-MTDH was found higher than FITC labeled D-PA-anti-MTDH. The results show that magnetic properties and application of magnetic field increased incorporation rates. The obtained D-PA-anti-MTDH-magnetic nanoparticles-FITC complex has been used for in vitro imaging of breast cancer cells. FITC labeled and magnetic nanoparticles conjugated D-PA-anti-MTDH may be useful as a new class of scintigraphic agents. Results of this study are sufficiently encouraging to bring about further evaluation of this and related compounds for ultraviolet magnetic resonance (UV-MR) dual imaging. (author)

The effect of two novel amino acid-coated magnetic nanoparticles on survival in vascular endothelial cells, bone marrow stromal cells, and macrophages

Science.gov (United States)

Wu, Qinghua; Meng, Ning; Zhang, Yanru; Han, Lei; Su, Le; Zhao, Jing; Zhang, Shangli; Zhang, Yun; Zhao, Baoxiang; Miao, Junying

2014-09-01

Magnetic nanoparticles (MNPs) have been popularly used in many fields. Recently, many kinds of MNPs are modified as new absorbents, which have attracted considerable attention and are promising to be applied in waste water. In our previous study, we synthesized two novel MNPs surface-coated with glycine or lysine, which could efficiently remove many anionic and cationic dyes under severe conditions. It should be considered that MNP residues in water may exert some side effects on human health. In the present study, we evaluated the potential nanotoxicity of MNPs in human endothelial cells, macrophages, and rat bone marrow stromal cells. The results showed that the two kinds of nanoparticles were consistently absorbed into the cell cytoplasm. The concentration of MNPs@Gly that could distinctly decrease survival was 15 μg/ml in human umbilical vascular endothelial cells (HUVECs) or bone marrow stromal cells (BMSCs) and 10 μg/ml in macrophages. While the concentration of MNPs@Lys that obviously reduced viability was 15 μg/ml in HUVECs or macrophages and 50 μg/ml in BMSCs. Furthermore, cell nucleus staining and cell integrity assay indicated that the nanoparticles induced cell apoptosis, but not necrosis even at a high concentration. Altogether, these data suggest that the amino acid-coated magnetic nanoparticles exert relatively high cytotoxicity. By contrast, lysine-coated magnetic nanoparticles are more secure than glycine-coated magnetic nanoparticles.

Superparamagnetism and coercivity in HCP-Co nanoparticles dispersed in silica matrix

International Nuclear Information System (INIS)

Julian Fernandez, C. de; Mattei, G.; Sangregorio, C.; Battaglin, C.; Gatteschi, D.; Mazzoldi, P.

2004-01-01

The magnetic properties of Co HCP nanoparticles dispersed in a silica matrix with sizes between 2±0.7 and 5±2.2 nm were investigated. The temperature dependence of zero-field cooled and field cooled magnetizations and of the coercive field were analyzed considering the thermal activated demagnetization process. Enhanced anisotropy was observed for the 2 nm nanoparticles, while the demagnetization process of the larger ones is dominated by interparticle interactions

Stabilisation effects of superparamagnetic nanoparticles on clustering in nanocomposite microparticles and on magnetic behaviour

Energy Technology Data Exchange (ETDEWEB)

Mandel, K., E-mail: karl-sebastian.mandel@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany); Hutter, F., E-mail: frank.hutter@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Gellermann, C., E-mail: carsten.gellermann@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Sextl, G., E-mail: gerhard.sextl@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany)

2013-04-15

Superparamagnetic nanoparticles of magnetite were coprecipitated from iron salts, dispersed with nitric acid and stabilised either by lactic acid (LA) or by a polycarboxylate-ether polymer (MELPERS4343, MP). The differently stabilised nanoparticles were incorporated into a silica matrix to form nanocomposite microparticles. The silica matrix was prepared either from tetraethylorthosilicate (TEOS) or from an aqueous sodium silicate (water glass) solution. Stabilisation of nanoparticles had a crucial influence on microparticle texture and nanoparticle distribution in the silica matrix. Magnetic measurements in combination with transmission electron microscopy (TEM) investigations suggest a uniform magnetic interaction of nanoparticles in case of LA stabilisation and magnetically interacting nanoparticle clusters of different sizes in case of MP stabilisation. Splitting of blocking temperature (T{sub B}) and irreversible temperature (T{sub ir}) in zero field cooled (ZFC) and field cooled (FC) measurements is discussed in terms of nanoparticle clustering. -- Highlights: ► Superparamagnetic nanoparticles were synthesised, dispersed and stabilised. ► Stabilisation is either via a polycarboxylate ether polymer or lactic acid. ► Stabilised nanoparticles were incorporated into silica to form composite particles. ► Depending on the stabilisation, nanoparticle clustering in the composites differed. ► Clustering influences zero field cooled/field cooled magnetic measurements.

Antibacterial silver nanocluster/silica composite coatings on stainless steel

Energy Technology Data Exchange (ETDEWEB)

Ferraris, M.; Perero, S. [Politecnico di Torino, Department of Applied Science and Technology, Torino, C.so Duca degli Abruzzi 24, I-10129 (Italy); Ferraris, S., E-mail: sara.ferraris@polito.it [Politecnico di Torino, Department of Applied Science and Technology, Torino, C.so Duca degli Abruzzi 24, I-10129 (Italy); Miola, M.; Vernè, E. [Politecnico di Torino, Department of Applied Science and Technology, Torino, C.so Duca degli Abruzzi 24, I-10129 (Italy); Skoglund, S. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Dr. Kristinas v. 51, SE-100 44 (Sweden); Blomberg, E. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Dr. Kristinas v. 51, SE-100 44 (Sweden); SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, P.O. Box 5607, SE-114 86 Stockholm (Sweden); Odnevall Wallinder, I. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Dr. Kristinas v. 51, SE-100 44 (Sweden)

2017-02-28

Highlights: • A silver nanocluster-silica composite coating sputter-deposited onto stainless steel. • Good adhesion and resistance upon cleaning with NaOH, H{sub 2}SO{sub 4} and detergents. • Low release of silver ions and no release as silver nanoparticles. • Good antibacterial activity against S. aureus even after heating to 450 °C. • Good antibacterial activity shown during cheese production. - Abstract: A coating made of silver nanocluster/silica composites has been deposited, via a radio frequency (RF) co-sputtering technique, for the first time onto stainless steel (AISI 304L) with the aim to improve its antibacterial properties. Different thermal treatments after coating deposition have been applied in order to optimize the coating adhesion, cohesion and its antibacterial properties. Its applicability has been investigated at realistic conditions in a cheese production plant. The physico-chemical characteristics of the coatings have been analyzed by means of different bulk and surface analytical techniques. Field emission scanning electron microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM) were employed to assess coating morphology, composition, surface roughness, wetting properties, size and local distribution of the nanoparticles within the coating. Tape tests were used to determine the adhesion/cohesion properties of the coating. The amount and time-dependence of released silver in solutions of acetic acid, artificial water, artificial tap water and artificial milk were determined by means of Atomic Absorption Spectroscopy (AAS). The antibacterial effect of the coating was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus in compliance with National Committee for Clinical Laboratory Standards (NCCLS) and AATCC 147 standards. The Ahearn test was performed to measure the adhesion of bacteria to the coated stainless steel

Antibacterial silver nanocluster/silica composite coatings on stainless steel

International Nuclear Information System (INIS)

Ferraris, M.; Perero, S.; Ferraris, S.; Miola, M.; Vernè, E.; Skoglund, S.; Blomberg, E.; Odnevall Wallinder, I.

2017-01-01

Highlights: • A silver nanocluster-silica composite coating sputter-deposited onto stainless steel. • Good adhesion and resistance upon cleaning with NaOH, H_2SO_4 and detergents. • Low release of silver ions and no release as silver nanoparticles. • Good antibacterial activity against S. aureus even after heating to 450 °C. • Good antibacterial activity shown during cheese production. - Abstract: A coating made of silver nanocluster/silica composites has been deposited, via a radio frequency (RF) co-sputtering technique, for the first time onto stainless steel (AISI 304L) with the aim to improve its antibacterial properties. Different thermal treatments after coating deposition have been applied in order to optimize the coating adhesion, cohesion and its antibacterial properties. Its applicability has been investigated at realistic conditions in a cheese production plant. The physico-chemical characteristics of the coatings have been analyzed by means of different bulk and surface analytical techniques. Field emission scanning electron microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM) were employed to assess coating morphology, composition, surface roughness, wetting properties, size and local distribution of the nanoparticles within the coating. Tape tests were used to determine the adhesion/cohesion properties of the coating. The amount and time-dependence of released silver in solutions of acetic acid, artificial water, artificial tap water and artificial milk were determined by means of Atomic Absorption Spectroscopy (AAS). The antibacterial effect of the coating was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus in compliance with National Committee for Clinical Laboratory Standards (NCCLS) and AATCC 147 standards. The Ahearn test was performed to measure the adhesion of bacteria to the coated stainless steel surface

Synthesize and characterization of a novel anticorrosive cobalt ferrite nanoparticles dispersed in silica matrix (CoFe2O4-SiO2) to improve the corrosion protection performance of epoxy coating

International Nuclear Information System (INIS)

Gharagozlou, M.; Ramezanzadeh, B.; Baradaran, Z.

2016-01-01

Highlights: • An anticorrosive cobalt ferrite nanopigment dispersed in silica matrix was synthesized. • The nanopigment showed proper inhibition performance in solution study. • The nanopigment significantly improved the corrosion resistance of the epoxy coating. - Abstract: This study aimed at studying the effect of an anticorrosive nickel ferrite nanoparticle dispersed in silica matrix (NiFe 2 O 4 -SiO 2 ) on the corrosion protection properties of steel substrate. NiFe 2 O 4 and NiFe 2 O 4 -SiO 2 nanopigments were synthesized and then characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Then, 1 wt.% of nanopigments was dispersed in an epoxy coating and the resultant nanocomposites were applied on the steel substrates. The corrosion inhibition effects of nanopigments were tested by an electrochemical impedance spectroscopy (EIS) and salt spray test. Results revealed that dispersing nickel ferrite nanoparticles in a silica matrix (NiFe 2 O 4 -SiO 2 ) resulted in the enhancement of the nanopigment dispersion in the epoxy coating matrix. Inclusion of 1 wt.% of NiFe 2 O 4 -SiO 2 nanopigment into the epoxy coating enhanced its corrosion protection properties before and after scratching.

Nanostructure and magnetic properties of CoNi-alloy-based nanoparticles dispersed in a silica matrix

International Nuclear Information System (INIS)

De Julian, C.; Sangregorio, C.; Mattei, G.; Battaglin, G.; Cattaruzza, E.; Gonella, F.; Lo Russo, S.; D'Orazio, F.; Lucari, F.; De, G.; Gatteschi, D.; Mazzoldi, P.

2001-01-01

A comparative study of the magnetic behavior of FCC alloy CoNi (1:1) nanoparticles, embedded in a silica matrix and prepared by the ion implantation and sol-gel techniques, is presented. The blocking temperature is related to the size distribution, and, at least for the ion-implanted samples, only an enhanced effective anisotropy explains the experimental results. The hysteretic behavior is explained in terms of the temperature dependence of the anisotropy and of the particle volume fraction that determines the dipolar interactions

Nanostructure and magnetic properties of CoNi-alloy-based nanoparticles dispersed in a silica matrix

Energy Technology Data Exchange (ETDEWEB)

De Julian, C. E-mail: dejulian@padova.infm.it; Sangregorio, C.; Mattei, G.; Battaglin, G.; Cattaruzza, E.; Gonella, F.; Lo Russo, S.; D' Orazio, F.; Lucari, F.; De, G.; Gatteschi, D.; Mazzoldi, P

2001-05-01

A comparative study of the magnetic behavior of FCC alloy CoNi (1:1) nanoparticles, embedded in a silica matrix and prepared by the ion implantation and sol-gel techniques, is presented. The blocking temperature is related to the size distribution, and, at least for the ion-implanted samples, only an enhanced effective anisotropy explains the experimental results. The hysteretic behavior is explained in terms of the temperature dependence of the anisotropy and of the particle volume fraction that determines the dipolar interactions.

Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging

International Nuclear Information System (INIS)

Osborne, Elizabeth A; Atkins, Tonya M; Kauzlarich, Susan M; Gilbert, Dustin A; Liu Kai; Louie, Angelique Y

2012-01-01

Currently, magnetic iron oxide nanoparticles are the only nanosized magnetic resonance imaging (MRI) contrast agents approved for clinical use, yet commercial manufacturing of these agents has been limited or discontinued. Though there is still widespread demand for these particles both for clinical use and research, they are difficult to obtain commercially, and complicated syntheses make in-house preparation unfeasible for most biological research labs or clinics. To make commercial production viable and increase accessibility of these products, it is crucial to develop simple, rapid and reproducible preparations of biocompatible iron oxide nanoparticles. Here, we report a rapid, straightforward microwave-assisted synthesis of superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic method as either a two-step or single-step process. A striking benefit of these methods is the ability to obtain swift and consistent results without the necessity for air-, pH- or temperature-sensitive techniques; therefore, reaction times and complex manufacturing processes are greatly reduced as compared to conventional synthetic methods. This is a great benefit for cost-effective translation to commercial production. The nanoparticles are found to be superparamagnetic and exhibit properties consistent for use in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization. (paper)

Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging.

Science.gov (United States)

Osborne, Elizabeth A; Atkins, Tonya M; Gilbert, Dustin A; Kauzlarich, Susan M; Liu, Kai; Louie, Angelique Y

2012-06-01

Currently, magnetic iron oxide nanoparticles are the only nanosized magnetic resonance imaging (MRI) contrast agents approved for clinical use, yet commercial manufacturing of these agents has been limited or discontinued. Though there is still widespread demand for these particles both for clinical use and research, they are difficult to obtain commercially, and complicated syntheses make in-house preparation unfeasible for most biological research labs or clinics. To make commercial production viable and increase accessibility of these products, it is crucial to develop simple, rapid and reproducible preparations of biocompatible iron oxide nanoparticles. Here, we report a rapid, straightforward microwave-assisted synthesis of superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic method as either a two-step or single-step process. A striking benefit of these methods is the ability to obtain swift and consistent results without the necessity for air-, pH- or temperature-sensitive techniques; therefore, reaction times and complex manufacturing processes are greatly reduced as compared to conventional synthetic methods. This is a great benefit for cost-effective translation to commercial production. The nanoparticles are found to be superparamagnetic and exhibit properties consistent for use in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization.

Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

Science.gov (United States)

Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

2015-10-01

Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

Effects of coating molecules on the magnetic heating properties of Au-Fe3O4 heterodimer nanoparticles

Science.gov (United States)

Yamamoto, Y.; Ogasawara, J.; Himukai, H.; Itoh, T.

2016-10-01

In this paper, we report the heating properties of gold-magnetite (Au-Fe3O4) heterodimer nanoparticles (NPs) subjected to an alternating magnetic field. The Au-Fe3O4 NPs coated with oleic acid and oleylamine (OA) were synthesized through a method that combines seed mediation and high-temperature decomposition. The coating was replaced with dimercaptosuccinic acid (DMSA) by the ligand-exchange method. The specific absorption rates (SARs) for the OA- and DMSA-coated Au-Fe3O4 NPs coated with OA and DMSA at room temperature were determined through the calorimetric and magnetometric methods. SAR depended on the square of the magnetic field H up to an H value of 4 kA/m. The absolute value of the SAR for DMSA-coated NPs is about fivefold higher than that of the OA-coated NPs. The AC magnetic hysteresis measurements showed the recovery of the magnetic volume and the decrease in the magnetic anisotropy of the DMSA-coated NPs relative to those of the OA-coated NPs. These results suggest that the protective agent influences the magnetic properties of magnetite NPs via gold NPs.

Mesoporous silica nanoparticles for treating spinal cord injury

Science.gov (United States)

White-Schenk, Désirée.; Shi, Riyi; Leary, James F.

2013-02-01

An estimated 12,000 new cases of spinal cord injury (SCI) occur every year in the United States. A small oxidative molecule responsible for secondary injury, acrolein, is an important target in SCI. Acrolein attacks essential proteins and lipids, creating a feed-forward loop of oxidative stress in both the primary injury area and the surrounding areas. A small molecule used and FDA-approved for hypertension, hydralazine, has been found to "scavenge" acrolein after injury, but its delivery and short half-life, as well as its hypertension effects, hinder its application for SCI. Nanomedical systems broaden the range of therapeutic availability and efficacy over conventional medicine. They allow for targeted delivery of therapeutic molecules to tissues of interest, reducing side effects of untargeted therapies in unwanted areas. Nanoparticles made from silica form porous networks that can carry therapeutic molecules throughout the body. To attenuate the acrolein cascade and improve therapeutic availability, we have used a one-step, modified Stober method to synthesize two types of silica nanoparticles. Both particles are "stealth-coated" with poly(ethylene) glycol (PEG) (to minimize interactions with the immune system and to increase circulation time), which is also a therapeutic agent for SCI by facilitating membrane repair. One nanoparticle type contains an amine-terminal PEG (SiNP-mPEG-Am) and the other possesses a terminal hydrazide group (SiNP-mPEG-Hz). The former allows for exploration of hydralazine delivery, loading, and controlled release. The latter group has the ability to react with acrolein, allowing the nanoparticle to scavenge directly. The nanoparticles have been characterized and are being explored using neuronal PC-12 cells in vitro, demonstrating the potential of novel silica nanoparticles for use in attenuating secondary injury after SCI.

Optimal size for heating efficiency of superparamagnetic dextran-coated magnetite nanoparticles for application in magnetic fluid hyperthermia

Science.gov (United States)

Shaterabadi, Zhila; Nabiyouni, Gholamreza; Soleymani, Meysam

2018-06-01

Dextran-coated magnetite (Fe3O4) nanoparticles with average particle sizes of 4 and 19 nm were synthesized through in situ and semi-two-step co-precipitation methods, respectively. The experimental results confirm the formation of pure phase of magnetite as well as the presence of dextran layer on the surface of modified magnetite nanoparticles. The results also reveal that both samples have the superparamagnetic behavior. Furthermore, calorimetric measurements show that the dextran-coated Fe3O4 nanoparticles with an average size of 4 nm cannot produce any appreciable heat under a biologically safe alternating magnetic field used in hyperthermia therapy; whereas, the larger ones (average size of 19 nm) are able to increase the temperature of their surrounding medium up to above therapeutic range. In addition, measured specific absorption rate (SAR) values confirm that magnetite nanoparticles with an average size of 19 nm are very excellent candidates for application in magnetic hyperthermia therapy.

Silver deposited carboxymethyl chitosan-grafted magnetic nanoparticles as dual action deliverable antimicrobial materials.

Science.gov (United States)

Vo, Duc-Thang; Sabrina, Sabrina; Lee, Cheng-Kang

2017-04-01

Carboxymethyl chitosan (CMCS) was known to have a much better antimicrobial activity than chitosan due to the increased cationic -NH 3 + groups resulted from the intra- and intermolecular interactions between the carboxyl and amino groups. CMCS was grafted onto the surface of silica coated magnetic nanoparticles (MNPs) to obtain magnetically retrievable and deliverable antimicrobial nanoparticles (MNPs@CMCS). The presence of carboxylate groups in CMCS not only enhanced antimicrobial activity but also enabled Ag ions chelating ability to induce the in situ formation of Ag nanoparticles (AgNPs). The deposition of AgNPs on the surface of MNPs@CMCS could significantly increase its antimicrobial activity against planktonic cells due to the dual action of CMCS and AgNPs. Due to its high magnetism, the as-prepared MNPs@CMCS-Ag could be efficiently delivered into an existing biofilm under the guidance of an applied magnetic field. Without direct contact, the Ag ions and/or radical oxygen species (ROS) released from the deposited Ag nanoparticles could effectively kill the bacteria embedded in the extracellular polymeric substances (EPS) matrix of biofilm. Copyright © 2016 Elsevier B.V. All rights reserved.

Short and long term biosorption of silica-coated iron oxide nanoparticles in heterotrophic biofilms

International Nuclear Information System (INIS)

Herrling, Maria P.; Lackner, Susanne; Tatti, Oleg; Guthausen, Gisela; Delay, Markus; Franzreb, Matthias; Horn, Harald

2016-01-01

The increased application of engineered nanoparticles (ENP) in industrial processes and consumer products has raised concerns about their impact on health and environmental safety. When ENP enter the global water cycle by e.g. wastewater streams, wastewater treatment plants (WWTP) represent potential sinks for ENP. During biological WWT, the attachment of ENP to biofilms is responsible for the desired removal of ENP from the water phase avoiding their release into the aquatic environment. However, the fundamental mechanisms guiding the interactions between ENP and biofilms are not yet fully understood. Therefore, this study investigates the behavior and biosorption of inorganic ENP, here magnetic iron oxide nanoparticles coated with silica (scFe_3O_4-NP), with heterotrophic biofilms at different time scales. Their magnetic properties enable to follow scFe_3O_4-NP in the biofilm system by a magnetic susceptibility balance and magnetic resonance imaging. Biofilms were exposed to scFe_3O_4-NP at short contact times (5 min) in flow cells and complementary, scFe_3O_4-NP were introduced into a moving bed biofilm reactor (MBBR) to be observed for 27 d. Mass balances revealed that scFe_3O_4-NP sorbed to the biofilm within a few minutes, but that the total biosorption was rather low (3.2 μg Fe/mg TSS). scFe_3O_4-NP mainly sorbed to the biofilm surface inducing the detachment of outer biofilm parts starting after an exposure time of 3 h in the MBBR. The biosorption depended on the exposure concentration of scFe_3O_4-NP, but less on the contact time. Most scFe_3O_4-NP exited the flow cell (up to 65%) and the MBBR (57%) via the effluent. This effect was favored by the stabilization of scFe_3O_4-NP in the bulk liquid by organic matter leading to a low retention capacity of the MBBR system. The results contribute to improve our understanding about the fate of ENP in environmental and in technical biofilm systems and give indications for future investigations needed

A novel approach to fabrication of superparamagnetite hollow silica/magnetic composite spheres

Energy Technology Data Exchange (ETDEWEB)

Yuan Junjie, E-mail: yuanjunjie@tongji.edu.c [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433 (China); Zhang Xiong; Qian He [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China)

2010-08-15

We described a method for synthesizing hollow silica/magnetic composite spheres using sulfonic acid functionalized hollow silica spheres (SAFHSS) as templates. The Fe{sub 3}O{sub 4} nanoparticles were deposited on or imbedded in the hollow silica shell by a precipitation reaction. The morphologies, composition and properties of the hollow composite spheres were characterized by transmission electron microscopy, Fourier transform infrared analysis, X-ray diffraction measurement and vibrating-sample magnetometry measurement. The results indicated crystal sizes and amount of the Fe{sub 3}O{sub 4} nanoparticles on the SAFHSS. The magnetic properties of the hollow composite spheres were controlled by adjusting the proportion between Fe{sup 2+} and Fe{sup 3+} and iron ion total concentration. When appropriate loading species were added into the system, superparamagnetite hollow composite spheres were obtained. The method also could be applicable to prepare other superparamagnetite hollow silica/ferrite composite spheres.

Cell viability and MRI performance of highly efficient polyol-coated magnetic nanoparticles

International Nuclear Information System (INIS)

Arteaga-Cardona, Fernando; Gutiérrez-García, Eric; Hidalgo-Tobón, Silvia; López-Vasquez, Ciro; Brito-Barrera, Yazmín A.; Flores-Tochihuitl, Julia; Angulo-Molina, Aracely; Reyes-Leyva, Julio R.; González-Rodríguez, Roberto; Coffer, Jeffery L.; Pal, Umapada

2016-01-01

This work aimed at determining conditions that would allow us to control the size of the NPs and create a system with characteristics apt for biomedical applications. We describe a comprehensive study on the synthesis and physical characterization of two highly sensitive sets of triethylene glycol (TREG) and polyethylene glycol (PEG)-coated superparamagnetic iron oxide nanoparticles (SPIONs) to be evaluated for use as magnetic resonance (MR) contrast agents. The ferrofluids demonstrated excellent colloidal stability in deionized water at pH 7.0 as indicated by dynamic light scattering (DLS) data. The magnetic relaxivities, r_2, were measured on a 1.5 T clinical MRI instrument. Values in the range from 205 to 257 mM"−"1 s"−"1 were obtained, varying proportionally to the SPIONs’ sizes and coating nature. Further in vitro cell viability tests and in vivo biodistribution analyses of the intravenously administered nanoparticles showed that the prepared systems have good biocompatibility and migrate to several organs, mainly the meninges, spleen, and liver. Based on these results, our findings demonstrated the potential utility of these nanosystems as clinical contrast agents for MR imaging.

Cell viability and MRI performance of highly efficient polyol-coated magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Arteaga-Cardona, Fernando [Universidad de las Américas de Puebla, Departamento de Ciencias Químico-Biológicas (Mexico); Gutiérrez-García, Eric [Instituto Literario, Universidad Autónoma del Estado de México (Mexico); Hidalgo-Tobón, Silvia, E-mail: shid@xanum.uam.mx [Universidad Autónoma Metropolitana, Departamento de Física (Mexico); López-Vasquez, Ciro; Brito-Barrera, Yazmín A. [Universidad de las Américas de Puebla, Departamento de Ciencias Químico-Biológicas (Mexico); Flores-Tochihuitl, Julia [Benemérita Universidad Autónoma de Puebla, Facultad de Estomatología (Mexico); Angulo-Molina, Aracely [Universidad de Sonora, Departamento de Ciencias Químico-Biológicas (Mexico); Reyes-Leyva, Julio R. [Instituto Mexicano del Seguro Social, Centro de Investigación Biomédica de Oriente (CIBIOR) (Mexico); González-Rodríguez, Roberto; Coffer, Jeffery L. [Texas Christian University, Department of Chemistry (United States); Pal, Umapada [Benemérita Universidad Autónoma de Puebla, Apdo, Instituto de Física (Mexico); and others

2016-11-15

This work aimed at determining conditions that would allow us to control the size of the NPs and create a system with characteristics apt for biomedical applications. We describe a comprehensive study on the synthesis and physical characterization of two highly sensitive sets of triethylene glycol (TREG) and polyethylene glycol (PEG)-coated superparamagnetic iron oxide nanoparticles (SPIONs) to be evaluated for use as magnetic resonance (MR) contrast agents. The ferrofluids demonstrated excellent colloidal stability in deionized water at pH 7.0 as indicated by dynamic light scattering (DLS) data. The magnetic relaxivities, r{sub 2}, were measured on a 1.5 T clinical MRI instrument. Values in the range from 205 to 257 mM{sup −1} s{sup −1} were obtained, varying proportionally to the SPIONs’ sizes and coating nature. Further in vitro cell viability tests and in vivo biodistribution analyses of the intravenously administered nanoparticles showed that the prepared systems have good biocompatibility and migrate to several organs, mainly the meninges, spleen, and liver. Based on these results, our findings demonstrated the potential utility of these nanosystems as clinical contrast agents for MR imaging.

Simultaneous hyperthermia and doxorubicin delivery from polymer-coated magnetite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Iglesias, G.R., E-mail: iglesias@ugr.es [Department of Applied Physics, University of Granada, Granada 18071 (Spain); Delgado, A.V.; González-Caballero, F. [Department of Applied Physics, University of Granada, Granada 18071 (Spain); Ramos-Tejada, M.M. [Department of Physics, University of Jaén, Linares 23700 (Spain)

2017-06-01

In this work, the hyperthermia response, (i.e., heating induced by an externally applied alternating magnetic field) and the simultaneous release of an anti-cancer drug (doxorubicin) by polymer-coated magnetite nanoparticles have been investigated. After describing the setup for hyperthermia measurements in suspensions of magnetic nanoparticles, the hyperthermia (represented by the rate of suspension heating and, ultimately, by the specific absorption rate or SAR) of magnetite nanoparticles (both bare and polymer-coated as drug nanocarriers) is discussed. The effect of the applied ac magnetic field on doxorubicin release is also studied, and it is concluded that the field does not interfere with the release process, demonstrating the double functionality of the investigated particles. - Highlights: • Magnetite NPs coated with polymers are used for drug delivery and hyperthermia. • The SAR of polyelectrolyte-coated NPs is larger because of their improved stability. • The antitumor drug doxorubicin is adsorbed on the coated particles. • The release rate of the drug is not affected by the ac magnetic field used in hyperthermia.

Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

International Nuclear Information System (INIS)

Kayal, S.; Ramanujan, R.V.

2010-01-01

Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe 3 O 4 ), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.

Silica-Coated Liposomes for Insulin Delivery

OpenAIRE

Neelam Dwivedi; M. A. Arunagirinathan; Somesh Sharma; Jayesh Bellare

2010-01-01

Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evid...

Synthesis and Characterization of Hollow Magnetic Alloy (GdNi2, Co5Gd Nanospheres Coated with Gd2O3

Directory of Open Access Journals (Sweden)

Wang Li

2014-01-01

Full Text Available Uniform magnetic hollow nanospheres (GdNi2, Co5Gd coated with Gd2O3 have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO2 spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniform nanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.

Silica nanoparticle-based dual imaging colloidal hybrids: cancer cell imaging and biodistribution

Directory of Open Access Journals (Sweden)

Lee H

2015-08-01

Full Text Available Haisung Lee,1 Dongkyung Sung,2 Jinhoon Kim,3 Byung-Tae Kim,3 Tuntun Wang,4 Seong Soo A An,5 Soo-Won Seo,6 Dong Kee Yi4 1Molecular Diagnostics, In Vitro Diagnostics Unit, New Business Division, SK Telecom, 2Department of Life Sciences, Graduate School of Korea University, 3Interdisciplinary Graduate Program of Biomedical Engineering, School of Medicine, Sungkyunkwan University, Samsung Medical Center, 4Department of Chemistry, Myongji University, Seoul, 5Department of Bionanotechnology, Gachon Medical Research Institute, Gachon University, Seongnam, 6Medical Device Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, Daegu, Republic of Korea Abstract: In this study, fluorescent dye-conjugated magnetic resonance (MR imaging agents were investigated in T mode. Gadolinium-conjugated silica nanoparticles were successfully synthesized for both MR imaging and fluorescence diagnostics. Polyamine and polycarboxyl functional groups were modified chemically on the surface of the silica nanoparticles for efficient conjugation of gadolinium ions. The derived gadolinium-conjugated silica nanoparticles were investigated by zeta potential analysis, transmission electron microscopy, inductively coupled plasma mass spectrometry, and energy dispersive x-ray spectroscopy. MR equipment was used to investigate their use as contrast-enhancing agents in T1 mode under a 9.4 T magnetic field. In addition, we tracked the distribution of the gadolinium-conjugated nanoparticles in both lung cancer cells and organs in mice. Keywords: dual bioimaging, MR imaging, silica colloid, T1 contrast imaging, nanohybrid

The effect of polymer coatings on proton transverse relaxivities of aqueous suspensions of magnetic nanoparticles

International Nuclear Information System (INIS)

Carroll, Matthew R J; House, Michael J; Woodward, Robert C; St Pierre, Timothy G; Huffstetler, Phillip P; Miles, William C; Goff, Jonathon D; Davis, Richey M; Riffle, Judy S

2011-01-01

Iron oxide magnetic nanoparticles are good candidates for magnetic resonance imaging (MRI) contrast agents due to their high magnetic susceptibilities. Here we investigate 19 polyether-coated magnetite nanoparticle systems comprising three series. All systems were synthesized from the same batch of magnetite nanoparticles. A different polyether was used for each series. Each series comprised systems with systematically varied polyether loadings per particle. A highly significant (p < 0.0001) linear correlation (r = 0.956) was found between the proton relaxivity and the intensity-weighted average diameter measured by dynamic light scattering in the 19 particle systems studied. The intensity-weighted average diameter measured by dynamic light scattering is sensitive to small number fractions of larger particles/aggregates. We conclude that the primary effect leading to differences in proton relaxivity between systems arises from the small degree of aggregation within the samples, which appears to be determined by the nature of the polymer and, for one system, the degree of polymer loading of the particles. For the polyether coatings used in this study, any changes in relaxivity from differences in water exclusion or diffusion rates caused by the polymer are minor in comparison with the changes in relaxivity resulting from variations in the degree of aggregation.

The effect of polymer coatings on proton transverse relaxivities of aqueous suspensions of magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Carroll, Matthew R J; House, Michael J; Woodward, Robert C; St Pierre, Timothy G [School of Physics, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009 (Australia); Huffstetler, Phillip P; Miles, William C; Goff, Jonathon D; Davis, Richey M; Riffle, Judy S, E-mail: stpierre@physics.uwa.edu.au [Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States)

2011-08-12

Iron oxide magnetic nanoparticles are good candidates for magnetic resonance imaging (MRI) contrast agents due to their high magnetic susceptibilities. Here we investigate 19 polyether-coated magnetite nanoparticle systems comprising three series. All systems were synthesized from the same batch of magnetite nanoparticles. A different polyether was used for each series. Each series comprised systems with systematically varied polyether loadings per particle. A highly significant (p < 0.0001) linear correlation (r = 0.956) was found between the proton relaxivity and the intensity-weighted average diameter measured by dynamic light scattering in the 19 particle systems studied. The intensity-weighted average diameter measured by dynamic light scattering is sensitive to small number fractions of larger particles/aggregates. We conclude that the primary effect leading to differences in proton relaxivity between systems arises from the small degree of aggregation within the samples, which appears to be determined by the nature of the polymer and, for one system, the degree of polymer loading of the particles. For the polyether coatings used in this study, any changes in relaxivity from differences in water exclusion or diffusion rates caused by the polymer are minor in comparison with the changes in relaxivity resulting from variations in the degree of aggregation.

Investigating unexpected magnetism of mesoporous silica-supported Pd and PdO nanoparticles

KAUST Repository

Song, Hyon Min

2015-01-13

The synthesis and magnetic behavior of matrix-supported Pd and PdO nanoparticles (NPs) are described. Mesoporous silica with hexagonal columnal packing is selected as a template, and the impregnation method with thermal annealing is used to obtain supported Pd and PdO NPs. The heating rate and the annealing conditions determine the particle size and the phase of the NPs, with a fast heating rate of 30 °C/min producing the largest supported Pd NPs. Unusual magnetic behaviors are observed. (1) Contrary to the general belief that smaller Pd NPs or cluster size particles have higher magnetization, matrix-supported Pd NPs in this study maintain the highest magnetization with room temperature ferromagnetism when the size is the largest. (2) Twin boundaries along with stacking faults are more pronounced in these large Pd NPs and are believed to be the reason for this high magnetization. Similarly, supported PdO NPs were prepared under air conditions with different heating rates. Their phase is tetragonal (P42/mmc) with cell parameters of a = 3.050 Å and c = 5.344 Å, which are slightly larger than in the bulk phase (a = 3.03 Å, c = 5.33 Å). Faster heating rate of 30 °C/min also produces larger particles and larger magnetic hysteresis loop, although magnetization is smaller and few twin boundaries are observed compared to the supported metallic Pd NPs.

Synthesis, characterization, and in vitro evaluation of novel polymer-coated magnetic nanoparticles for controlled delivery of doxorubicin

Directory of Open Access Journals (Sweden)

Akbarzadeh A

2012-02-01

Full Text Available Abolfazl Akbarzadeh1, Nosratollah Zarghami2, Haleh Mikaeili3, Davoud Asgari4, Amir Mohammad Goganian5, Hanie Khaksar Khiabani5, Mohammad Samiei6, Soodabeh Davaran31Department of Medicinal Chemistry, Tabriz University of Medical Sciences, 2Department of Clinical Biochemistry and Laboratory Medicine, Division of Medical Biotechnology, Faculty of Medicine, Tabriz University of Medical Sciences, 3Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, 4Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, 5Department of Organic Chemistry, Faculty of Chemistry, University of Tabriz, 6Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, IranAbstract: Poly (N-isopropylacrylamide-methyl methacrylic acid, PNIPAAm-MAA-grafted magnetic nanoparticles were synthesized using silane-coated magnetic nanoparticles as a template for radical polymerization of N-isopropylacrylamide and methacrylic acid. Properties of these nanoparticles, such as size, drug-loading efficiency, and drug release kinetics, were evaluated in vitro for targeted and controlled drug delivery. The resulting nanoparticles had a diameter of 100 nm and a doxorubicin-loading efficiency of 75%, significantly higher doxorubicin release at 40°C compared with 37°C, and pH 5.8 compared with pH 7.4, demonstrating their temperature and pH sensitivity, respectively. In addition, the particles were characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. In vitro cytotoxicity testing showed that the PNIPAAm-MAA-coated magnetic nanoparticles had no cytotoxicity and were biocompatible, indicating their potential for biomedical application.Keywords: magnetic nanoparticles, drug loading, doxorubicin release, biocompatibility

Synthesis and characterization of Fe{sub 3}O{sub 4} nanoparticles coated with fucan polysaccharides

Energy Technology Data Exchange (ETDEWEB)

Silva, V.A.J.; Andrade, P.L. [Programa de Pós-Graduação em Ciências de Materiais, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, 50670-901 Recife-PE (Brazil); Laboratório de Imunopatologia Keizo Asami (LIKA), Universidade Federal de Pernambuco, 50670-901 Recife-PE (Brazil); Silva, M.P.C. [Laboratório de Imunopatologia Keizo Asami (LIKA), Universidade Federal de Pernambuco, 50670-901 Recife-PE (Brazil); Departamento de Bioquímica, Universidade Federal de Pernambuco, 50670-420 Recife-PE (Brazil); Bustamante D, A. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149 Lima (Peru); De Los Santos Valladares, Luis [Laboratório de Imunopatologia Keizo Asami (LIKA), Universidade Federal de Pernambuco, 50670-901 Recife-PE (Brazil); Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Albino Aguiar, J., E-mail: albino@df.ufpe.br [Programa de Pós-Graduação em Ciências de Materiais, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, 50670-901 Recife-PE (Brazil); Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife-PE (Brazil)

2013-10-15

In this work we report the preparation of fucan-coated magnetite (Fe{sub 3}O{sub 4}) nanoparticles by the co-precipitation method. These nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Mössbauer spectroscopy and magnetic measurements. The nanoparticles showed quasi-spherical morphology with mean sizes around 10 nm. XRD and FT-IR confirmed the functionalization of the Fe{sub 3}O{sub 4} nanoparticles with the fucan polysaccharide. Room temperature magnetization measurements and Mössbauer spectroscopy showed that the nanoparticles exhibited superparamagnetic behavior at 300 K and the magnetic properties of the Fe{sub 3}O{sub 4} are partly screened by the coating preventing aggregation. - Highlights: • Syntheses of fucan-coated Fe{sub 3}O{sub 4} nanoparticles were made by co-precipitation method. • The efficiency of polysaccharide coated was analyzed by XRD and FT-IR. • The magnetic nanoparticles mean size was 10–20 nm. • The fucan-coated magnetite nanoparticles showed superparamagnetic behavior.

Chitosan-coated magnetic nanoparticles prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion.

Science.gov (United States)

Pineda, María Guadalupe; Torres, Silvia; López, Luis Valencia; Enríquez-Medrano, Francisco Javier; de León, Ramón Díaz; Fernández, Salvador; Saade, Hened; López, Raúl Guillermo

2014-07-02

Chitosan-coated magnetic nanoparticles (CMNP) were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

Chitosan-Coated Magnetic Nanoparticles Prepared in One-Step by Precipitation in a High-Aqueous Phase Content Reverse Microemulsion

Directory of Open Access Journals (Sweden)

María Guadalupe Pineda

2014-07-01

Full Text Available Chitosan-coated magnetic nanoparticles (CMNP were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles

Digital Repository Service at National Institute of Oceanography (India)

Narayanan, T.N.; Mary, A.P.R.; Swalih, P.K.A.; Kumar, D.S.; Makarov, D.; Albrecht, M.; Puthumana, J.; Anas, A.; Anantharaman, A.

-interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a...

Fabrication of Coatings on the Surface of Magnesium Alloy by Plasma Electrolytic Oxidation Using ZrO2 and SiO2 Nanoparticles

Directory of Open Access Journals (Sweden)

S. V. Gnedenkov

2015-01-01

Full Text Available Results of investigation of the incorporation of zirconia and silica nanoparticles into the coatings formed on magnesium alloy by plasma electrolytic oxidation are presented. Comprehensive research of electrochemical and mechanical properties of obtained coatings was carried out. It was established that the polarization resistance of the samples with a coating containing zirconia nanoparticles is two times higher than that for the sample with base PEO layer. One of the important reasons for improving the protective properties of coatings formed in electrolytes containing nanoparticles consists in enhanced morphological characteristics, in particular, the porosity decrease and increase of thickness and resistivity (up to two orders of magnitude for ZrO2-containing coating of porousless sublayer in comparison with base PEO layer. Incorporation of silica and zirconia particles into the coating increases the mechanical performances. The layers containing nanoparticles have greater hardness and are more wear resistant in comparison with the coatings formed in the base electrolyte.

Laser-ablative fabrication of nanoparticle inks for 3D inkjetprinting of multifunctional coatings

Science.gov (United States)

Ionin, A. A.; Ivanova, A. K.; Khmel'nitskii, R. A.; Klevkov, Yu V.; Kudryashov, S. I.; Mel'nik, N. N.; Nastulyavichus, A. A.; Rudenko, A. A.; Saraeva, I. N.; Smirnov, N. A.; Zayarny, D. A.

2017-12-01

We report the fabrication of multifunctional coatings via inkjet printing using water-based nanoinks in the form of selenium (Se) and gold (Au) nanoparticle (NP) colloids, prepared by laser ablation of solid targets in deionized water or 50%-isopropyl alcohol solution. Nanoparticles and NP-based coatings were deposited onto silver films, magnetronsputtered to silica-glass substrates, and characterized by means of scanning and transmission electron microscopy (SEM, TEM), UV-vis-IR, Raman and energy-dispersive X-ray spectroscopies.

Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

Synthesis and characterization of magnetite nanoparticles coated with lauric acid

Energy Technology Data Exchange (ETDEWEB)

Mamani, J.B., E-mail: javierbm@einstein.br [Instituto do Cérebro-InCe, Hospital Israelita Albert Einstein-HIAE, 05651-901 São Paulo (Brazil); Costa-Filho, A.J. [Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (Brazil); Cornejo, D.R. [Instituto de Física Universidade de São Paulo, USP, São Paulo (Brazil); Vieira, E.D. [Instituto de Física, Universidade Federal de Goiás, Goiânia (Brazil); Gamarra, L.F. [Instituto do Cérebro-InCe, Hospital Israelita Albert Einstein-HIAE, 05651-901 São Paulo (Brazil)

2013-07-15

Understanding the process of synthesis of magnetic nanoparticles is important for its implementation in in vitro and in vivo studies. In this work we report the synthesis of magnetic nanoparticles made from ferrous oxide through coprecipitation chemical process. The nanostructured material was coated with lauric acid and dispersed in aqueous medium containing surfactant that yielded a stable colloidal suspension. The characterization of magnetic nanoparticles with distinct physico-chemical configurations is fundamental for biomedical applications. Therefore magnetic nanoparticles were characterized in terms of their morphology by means of TEM and DLS, which showed a polydispersed set of spherical nanoparticles (average diameter of ca. 9 nm) as a result of the protocol. The structural properties were characterized by using X-ray diffraction (XRD). XRD pattern showed the presence of peaks corresponding to the spinel phase of magnetite (Fe{sub 3}O{sub 4}). The relaxivities r{sub 2} and r{sub 2}* values were determined from the transverse relaxation times T{sub 2} and T{sub 2}* at 3 T. Magnetic characterization was performed using SQUID and FMR, which evidenced the superparamagnetic properties of the nanoparticles. Thermal characterization using DSC showed exothermic events associated with the oxidation of magnetite to maghemite. - Highlights: • Synthesis of magnetic nanoparticles coated with lauric acid • Characterization of magnetic nanoparticles • Morphological, structural, magnetic, calorimetric and relaxometric characterization.

Silica artificial opal incorporated with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

2009-07-15

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Silica artificial opal incorporated with silver nanoparticles

International Nuclear Information System (INIS)

Li Wenjiang; Sun Tan

2009-01-01

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Staphylococcus aureus detection in blood samples by silica nanoparticle-oligonucleotides conjugates.

Science.gov (United States)

Borsa, Baris A; Tuna, Bilge G; Hernandez, Frank J; Hernandez, Luiza I; Bayramoglu, Gulay; Arica, M Yakup; Ozalp, V Cengiz

2016-12-15

A fast, specific and sensitive homogeneous assay for Staphylococcus aureus detection was developed by measuring the activity of secreted nuclease from the bacteria via a modified DNA oligonucleotide. As biosensor format, an effective system, Nanokeepers as previously reported, were used for triggered release of confined fluorophores, and hence specific detection of S. aureus on nuclease activity was obtained. The interference from blood components for fluorescent quantification was eliminated by a pre-purification by aptamer-functionalized silica magnetic nanoparticles. The reported assay system was exclusively formed by nucleic acid oligos and magnetic or mesoporous silica nanoparticles, that can be used on blood samples in a stepwise manner. The assay was successfully used as a sensing platform for the specific detection of S. aureus cells as low as 682 CFU in whole blood. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis Characterization and Photocatalytic Studies of Cobalt Ferrite-Silica-Titania Nanocomposites

Directory of Open Access Journals (Sweden)

David Greene

2014-04-01

Full Text Available In this work, CoFe2O4@SiO2@TiO2 core-shell magnetic nanostructures have been prepared by coating of cobalt ferrite nanoparticles with the double SiO2/TiO2 layer using metallorganic precursors. The Transmission Electron Microscopy (TEM, Energy Dispersive X-Ray Analysis (EDX, Vibrational Sample Magnetometer (VSM measurements and Raman spectroscopy results confirm the presence both of the silica and very thin TiO2 layers. The core-shell nanoparticles have been sintered at 600 °C and used as a catalyst in photo-oxidation reactions of methylene blue under UV light. Despite the additional non-magnetic coatings result in a lower value of the magnetic moment, the particles can still easily be retrieved from reaction mixtures by magnetic separation. This retention of magnetism was of particular importance allowing magnetic recovery and re-use of the catalyst.

Synthesis of streptavidin-conjugated magnetic nanoparticles for DNA detection

International Nuclear Information System (INIS)

Gong Peijun; Peng Zheyang; Wang Yao; Qiao Ru; Mao Weixing; Qian Haisheng; Zhang Mengya; Li Congcong; Shi Shenyuan

2013-01-01

In this paper, we report a fabrication of streptavidin-coated magnetic nanoparticles used for DNA detection. Initially, amino-functionalized Fe 3 O 4 nanoparticles with high saturation magnetization are prepared by a photopolymerization method using allylamine as monomer. It is followed by covalent immobilization of streptavidin onto the particle surface via a two-step reaction using glutaraldehyde as coupling agent. Streptavidin-coated magnetic nanoparticles are characterized and further tested for their ability to capture DNA target after binding biotinylated oligonucleotide probes. The results show that the products (∼27.2 nm) have a maximum biotin-binding capacity of 0.71 nmol mg −1 when the immobilization reaction is conducted with a mass ratio of streptavidin to magnetic carriers above 0.2 in phosphate buffered saline (pH 7.4) for 24 h. In addition, highly negative ζ-potential and good magnetic susceptibility of the nanocomposites make them applicable for DNA collection and detection, which is verified by the results from the preliminary application of streptavidin-coated magnetic nanoparticles in DNA detection. Therefore, the magnetic nanoparticles provide a promising approach for rapid collection and detection of gene.

Mesoporous silica coatings for cephalosporin active release at the bone-implant interface

Energy Technology Data Exchange (ETDEWEB)

Rădulescu, Dragoş [Bucharest University Hospital, Department of Orthopedics and Traumatology, 169 Splaiul Independentei, 050098 Bucharest (Romania); Voicu, Georgeta; Oprea, Alexandra Elena; Andronescu, Ecaterina [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Grumezescu, Valentina [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Lasers Department, National Institute for Lasers, Plasma & Radiation Physics, PO Box MG-36, Măgurele, Bucharest (Romania); Holban, Alina Maria [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, 1-3 Portocalelor Lane, Bucharest (Romania); Research Institute of the University of Bucharest, Bd. Mihail Kogălniceanu 36-46, 050107 Bucharest (Romania); Vasile, Bogdan Stefan; Surdu, Adrian Vasile [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Grumezescu, Alexandru Mihai, E-mail: grumezescu@yahoo.com [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); and others

2016-06-30

Graphical abstract: - Highlights: • Silica/Zinforo thin coatings by matrix assisted pulsed laser evaporation. • Anti-adherent coating on medical surfaces against E. coli. • Thin coatings show a great biocompatibility in vitro and in vivo. - Abstract: In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanoparticles (MSNs) to release Zinforo (ceftarolinum fosmil) in biologically active form. The MSNs were prepared by using a classic procedure with cetyltrimethylammonium bromide as sacrificial template and tetraethylorthosilicate as the monomer. The Brunauer–Emmett–Teller (BET) and transmission electron microscopy (TEM) analyses revealed network-forming granules with diameters under 100 nm and an average pore diameter of 2.33 nm. The deposited films were characterized by SEM, TEM, XRD and IR. Microbiological analyses performed on ceftaroline-loaded films demonstrated that the antibiotic was released in an active form, decreasing the microbial adherence rate and colonization of the surface. Moreover, the in vitro and in vivo assays proved the excellent biodistribution and biocompatibility of the prepared systems. Our results suggest that the obtained bioactive coatings possess a significant potential for the design of drug delivery systems and antibacterial medical-use surfaces, with great applications in bone implantology.

Advanced Nanocomposite Coatings of Fusion Bonded Epoxy Reinforced with Amino-Functionalized Nanoparticles for Applications in Underwater Oil Pipelines

OpenAIRE

Patricia A. Saliba; Alexandra A. P. Mansur; Herman S. Mansur

2016-01-01

The performance of fusion-bonded epoxy coatings can be improved through advanced composite coatings reinforced with nanomaterials. Hence, in this study a novel organic-inorganic nanocomposite finish was designed, synthesized, and characterized, achieved by adding γ-aminopropyltriethoxysilane modified silica nanoparticles produced via sol-gel process in epoxy-based powder. After the curing process of the coating reinforced with nanoparticles, the formation of a homogenous novel nanocomposite w...

Nano-magnetic particles used in biomedicine: core and coating materials.

Science.gov (United States)

Karimi, Z; Karimi, L; Shokrollahi, H

2013-07-01

Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. Copyright © 2013 Elsevier B.V. All rights reserved.

Short and long term biosorption of silica-coated iron oxide nanoparticles in heterotrophic biofilms

Energy Technology Data Exchange (ETDEWEB)

Herrling, Maria P. [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Lackner, Susanne [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Urban Bioengineering for Resource Recovery, Bauhaus-Institute for Infrastructure Solutions, Bauhaus-Universität Weimar, Coudraystraße 7, 99423 Weimar (Germany); Tatti, Oleg [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Guthausen, Gisela [Pro" 2NMR, Institute for Biological Interfaces 4 and Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Adenauerring 20b, 76131 Karlsruhe (Germany); Delay, Markus [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Franzreb, Matthias [Institute of Functional Interfaces, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Horn, Harald, E-mail: harald.horn@kit.edu [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); DVGW Research Laboratories for Water Chemistry and Water Technology, Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany)

2016-02-15

The increased application of engineered nanoparticles (ENP) in industrial processes and consumer products has raised concerns about their impact on health and environmental safety. When ENP enter the global water cycle by e.g. wastewater streams, wastewater treatment plants (WWTP) represent potential sinks for ENP. During biological WWT, the attachment of ENP to biofilms is responsible for the desired removal of ENP from the water phase avoiding their release into the aquatic environment. However, the fundamental mechanisms guiding the interactions between ENP and biofilms are not yet fully understood. Therefore, this study investigates the behavior and biosorption of inorganic ENP, here magnetic iron oxide nanoparticles coated with silica (scFe{sub 3}O{sub 4}-NP), with heterotrophic biofilms at different time scales. Their magnetic properties enable to follow scFe{sub 3}O{sub 4}-NP in the biofilm system by a magnetic susceptibility balance and magnetic resonance imaging. Biofilms were exposed to scFe{sub 3}O{sub 4}-NP at short contact times (5 min) in flow cells and complementary, scFe{sub 3}O{sub 4}-NP were introduced into a moving bed biofilm reactor (MBBR) to be observed for 27 d. Mass balances revealed that scFe{sub 3}O{sub 4}-NP sorbed to the biofilm within a few minutes, but that the total biosorption was rather low (3.2 μg Fe/mg TSS). scFe{sub 3}O{sub 4}-NP mainly sorbed to the biofilm surface inducing the detachment of outer biofilm parts starting after an exposure time of 3 h in the MBBR. The biosorption depended on the exposure concentration of scFe{sub 3}O{sub 4}-NP, but less on the contact time. Most scFe{sub 3}O{sub 4}-NP exited the flow cell (up to 65%) and the MBBR (57%) via the effluent. This effect was favored by the stabilization of scFe{sub 3}O{sub 4}-NP in the bulk liquid by organic matter leading to a low retention capacity of the MBBR system. The results contribute to improve our understanding about the fate of ENP in environmental and in

Super magnetic nanoparticles NiFe2O4, coated with aluminum-nickel oxide sol-gel lattices to safe, sensitive and selective purification of his-tagged proteins.

Science.gov (United States)

Mirahmadi-Zare, Seyede Zohreh; Allafchian, Alireza; Aboutalebi, Fatemeh; Shojaei, Pendar; Khazaie, Yahya; Dormiani, Kianoush; Lachinani, Liana; Nasr-Esfahani, Mohammad-Hossein

2016-05-01

Super magnetic nanoparticle NiFe2O4 with high magnetization, physical and chemical stability was introduced as a core particle which exhibits high thermal stability (>97%) during the harsh coating process. Instead of multi-stage process for coating, the magnetic nanoparticles was mineralized via one step coating by a cheap, safe, stable and recyclable alumina sol-gel lattice (from bohemite source) saturated by nickel ions. The TEM, SEM, VSM and XRD imaging and BET analysis confirmed the structural potential of NiFe2O4@NiAl2O4 core-shell magnetic nanoparticles for selective and sensitive purification of His-tagged protein, in one step. The functionality and validity of the nickel magnetic nanoparticles were attested by purification of three different bioactive His-tagged recombinant fusion proteins including hIGF-1, GM-CSF and bFGF. The bonding capacity of the nickel magnetics nanoparticles was studied by Bradford assay and was equal to 250 ± 84 μg Protein/mg MNP base on protein size. Since the metal ion leakage is the most toxicity source for purification by nickel magnetic nanoparticles, therefor the nickel leakage in purified final protein was determined by atomic absorption spectroscopy and biological activity of final purified protein was confirmed in comparison with reference. Also, in vitro cytotoxicity of nickel magnetic nanoparticles and trace metal ions were investigated by MTS assay analysis. The results confirmed that the synthesized nickel magnetic nanoparticles did not show metal ion toxicity and not affected on protein folding. Copyright © 2016 Elsevier Inc. All rights reserved.

Chemical synthesis and characterization of hollow dopamine coated, pentagonal and flower shaped magnetic iron oxide nanoparticles

Science.gov (United States)

Riasat, Rabia; Kaynat, Sumbal

2018-04-01

Iron oxide nanoparticles have gained attention recently in the field of nanoscience and technology due to their unique physicochemical properties. We hereby chemically synthesized novel pentagonal flower shaped iron oxide nanoparticles by thermal decomposition of iron penta-carbonyl in a two way annealing process. Controlled oxidation by acid etching was performed for these nanoparticles. At first 13 nm core shell nanoparticles of iron oxide (Fe/Fe3O4) were synthesized at 120°C annealing temperature that act as template material. The core shell nanoparticles then converted into porous hollow core shell nanoparticles (PH Fe/ Fe3O4) in a two way annealing process of heating, first at 100°C then at 250°C and heating rate of 5°C was kept constant throughout the reaction time. X-Ray diffraction (XRD) was done for the phase confirmation of as synthesized nanoparticles. Transmission electron microscopy (TEM) and higher resolution transmission electron microscopy (HRTEM) clearly shows the flower like nanoparticles that are approx. 16 nm-18 nm in size having the 4-5 nm core of Fe and 1-2 nm of the pores in the shell while the cavity between the shell and core is about 2 nm and the shell is 4-5 nm in diameter according to the TEM micrographs. The as prepared nanoparticles were then surface functionalized by dopamine polymer to make them water dispersible. Fourier transform Infrared spectroscopy confirmed the dopamine coating on the nanoparticles and the magnetic saturation of 38 emu/g of nanoparticles was analyzed by vibrating sample magnetometer (VSM). Magnetic saturation persists in the dopamine coated nanoparticles. These nanoparticles were surface functionalized with dopamine and show dispersity in the aqueous media and can further be exploited in many nano-biotechnological applications including target specific therapeutic applications for several diseases.

Carbon dots based dual-emission silica nanoparticles as ratiometric fluorescent probe for nitrite determination in food samples.

Science.gov (United States)

Xiang, Guoqiang; Wang, Yule; Zhang, Heng; Fan, Huanhuan; Fan, Lu; He, Lijun; Jiang, Xiuming; Zhao, Wenjie

2018-09-15

In this work, a simple and effective strategy for designing a ratiometric fluorescent nanosensor was described. A carbon dots (CDs) based dual-emission nanosensor for nitrite was prepared by coating the CDs on to dye-doped silica nanoparticles. Dual-emission silica nanoparticles fluorescence was quenched in sulfuric acid using potassium bromate (KBrO 3 ). The nitrite present catalyzed the KBrO 3 oxidation, resulting in ratiometric fluorescence response of the dual-emission silica nanoparticles. Several important parameters affecting the performance of the nanosensor were investigated. Under optimized conditions, the limit of detection was 1.0 ng mL -1 and the linear range 10-160 ng mL -1 . Furthermore, the sensor was suitable for nitrite determination in different food samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biocompatibility of chitosan-coated iron oxide nanoparticles with osteoblast cells

Directory of Open Access Journals (Sweden)

Shi S

2012-10-01

Full Text Available Si-Feng Shi,1 Jing-Fu Jia,2 Xiao-Kui Guo,3 Ya-Ping Zhao,2 De-Sheng Chen,1 Yong-Yuan Guo,1 Tao Cheng,1 Xian-Long Zhang11Department of Orthopedic Surgery, Shanghai Sixth People’s Hospital, School of Medicine, 2School of Chemistry and Chemical Technology, 3Department of Medical Microbiology and Parasitology, School of Medicine, Shanghai Jiao Tong University Shanghai, ChinaBackground: Bone disorders (including osteoporosis, loosening of a prosthesis, and bone infections are of great concern to the medical community and are difficult to cure. Therapies are available to treat such diseases, but all have drawbacks and are not specifically targeted to the site of disease. Chitosan is widely used in the biomedical community, including for orthopedic applications. The aim of the present study was to coat chitosan onto iron oxide nanoparticles and to determine its effect on the proliferation and differentiation of osteoblasts.Methods: Nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, x-ray diffraction, zeta potential, and vibrating sample magnetometry. Uptake of nanoparticles by osteoblasts was studied by transmission electron microscopy and Prussian blue staining. Viability and proliferation of osteoblasts were measured in the presence of uncoated iron oxide magnetic nanoparticles or those coated with chitosan. Lactate dehydrogenase, alkaline phosphatase, total protein synthesis, and extracellular calcium deposition was studied in the presence of the nanoparticles.Results: Chitosan-coated iron oxide nanoparticles enhanced osteoblast proliferation, decreased cell membrane damage, and promoted cell differentiation, as indicated by an increase in alkaline phosphatase and extracellular calcium deposition. Chitosan-coated iron oxide nanoparticles showed good compatibility with osteoblasts.Conclusion: Further research is necessary to optimize magnetic nanoparticles for the treatment of bone disease

Investigation of the interaction between magnetic nanoparticles surface-coated with carboxymethyldextran and blood cells using Raman spectroscopy

International Nuclear Information System (INIS)

Santana, J.F.B.; Soler, M.A.G.; Silva, S.W. da; Guedes, M.H.; Lacava, Z.G.M.; Azevedo, R.B.; Morais, P.C.

2005-01-01

This study reports on in vitro biological tests performed with a biocompatible magnetic fluid based on carboxymethyldextran-coated magnetite nanoparticles (CMDM). Micro Raman spectroscopy was used to investigate the effect of dispersing (CMDM) nanoparticles in mice blood. We focused our investigation in the use of the Raman spectroscopy for monitoring the hemoglobin structural changes, which may be associated with the oxygen-binding process

Synthesis of magnetic hollow silica using polystyrene bead as a template

International Nuclear Information System (INIS)

Wu, W.; Caruntu, D.; Martin, A.; Yu, M.H.; O'Connor, C.J.; Zhou, W.L.; Chen, J.-F.

2007-01-01

In this paper, we report a new route to synthesize novel magnetic hollow silica nanospheres (MHSNs) using polystyrene particles as sacrificial templates, and TEOS and Fe 3 O 4 as precursors. TEM, EDS, XRD, and SQUID were applied to characterize MHSNs. TEM and EDS results show that the MHSNs consist of about 200 nm of hollow cores and ∼35 nm shells with ∼10 nm of Fe 3 O 4 nanoparticles embedded. The polystyrene beads were successfully removed by immersing the as-prepared silica nanocomposite in a toluene solution. XRD results demonstrate that the Fe 3 O 4 magnetic nanoparticles still keep spinel structure even heated at low temperature. The surface status of the polystyrene beads and Fe 3 O 4 nanoparticles has an important effect on the formation of the MHSNs. The MHSNs present a superparamagnetism at room temperature by SQUID measurement. The MHSNs have potential applications in biosystem and nanomedicine

Multifunctional nanomedicine with silica: Role of silica in nanoparticles for theranostic, imaging, and drug monitoring.

Science.gov (United States)

Chen, Fang; Hableel, Ghanim; Zhao, Eric Ruike; Jokerst, Jesse V

2018-07-01

The idea of multifunctional nanomedicine that enters the human body to diagnose and treat disease without major surgery is a long-standing dream of nanomaterials scientists. Nanomaterials show incredible properties that are not found in bulk materials, but achieving multi-functionality on a single material remains challenging. Integrating several types of materials at the nano-scale is critical to the success of multifunctional nanomedicine device. Here, we describe the advantages of silica nanoparticles as a tool for multifunctional nano-devices. Silica nanoparticles have been intensively studied in drug delivery due to their biocompatibility, degradability, tunable morphology, and ease of modification. Moreover, silica nanoparticles can be integrated with other materials to obtain more features and achieve theranostic capabilities and multimodality for imaging applications. In this review, we will first compare the properties of silica nanoparticles with other well-known nanomaterials for bio-applications and describe typical routes to synthesize and integrate silica nanoparticles. We will then highlight theranostic and multimodal imaging application that use silica-based nanoparticles with a particular interest in real-time monitoring of therapeutic molecules. Finally, we will present the challenges and perspective on future work with silica-based nanoparticles in medicine. Copyright © 2018 Elsevier Inc. All rights reserved.

Synthesis, characterisation and functionalisation of luminescent silica nanoparticles

International Nuclear Information System (INIS)

Labéguerie-Egéa, Jessica; McEvoy, Helen M.; McDonagh, Colette

2011-01-01

The synthesis of highly monodispersed, homogeneous and stable luminescent silica nanoparticles, synthesized using a process based on the Stöber method is reported here. These particles have been functionalised with the ruthenium and europium complexes: bis (2,2′-bipyridine)-(5-aminophenanthroline) Ru bis (hexafluorophosphate), abbreviated to (Ru(bpy) 2 (phen-5-NH 2 )(PF 6 )), and tris (dibenzoylmethane)-mono (5-aminophenanthroline) europium(III), abbreviated to (Eu:TDMAP). Both dyes have a free amino group available, facilitating the covalent conjugation of the dyes inside the silica matrix. Due to the covalent bond between the dyes and the silica, no dye leaching or nanoparticle diameter modification was observed. The generic and versatile nature of the synthesis process was demonstrated via the synthesis of both europium and ruthenium-functionalised nanoparticles. Following this, the main emphasis of the study was the characterisation of the luminescence of the ruthenium-functionalised silica nanoparticles, in particular, as a function of surface carboxyl or amino group functionalisation. It was demonstrated that the luminescence of the ruthenium dye is highly affected by the ionic environment at the surface of the nanoparticle, and that these effects can be counteracted by encapsulating the ruthenium-functionalised nanoparticles in a plain 15 nm silica layer. Moreover, the ruthenium-functionalised silica nanoparticles showed high relative brightness compared to the free dye in solution and efficient functionalisation with amino or carboxyl groups. Due to their ease of fabrication and attractive characteristics, the ruthenium-functionalised silica nanoparticles described here have the potential to be highly desirable fluorescent labels, particularly, for biological applications.

Magnetic solid-phase extraction of tetracyclines using ferrous oxide coated magnetic silica microspheres from water samples.

Science.gov (United States)

Lian, Lili; Lv, Jinyi; Wang, Xiyue; Lou, Dawei

2018-01-26

A novel magnetic solid-phase extraction approach was proposed for extraction of potential residues of tetracyclines (TCs) in tap and river water samples, based on Fe 3 O 4 @SiO 2 @FeO magnetic nanocomposite. Characterized results showed that the received Fe 3 O 4 @SiO 2 @FeO had distinguished magnetism and core-shell structure. Modified FeO nanoparticles with an ∼5 nm size distribution were homogeneously dispersed on the surface of the silica shell. Owing to the strong surface affinity of Fe (II) toward TCs, the magnetic nanocomposite could be applied to efficiently extract three TCs antibiotics, namely, oxytetracycline, tetracycline and chlortetracycline from water samples. Several factors, such as sorbent amount, pH condition, adsorption and desorption time, desorption solvent, selectivity and sample volume, influencing the extraction performance of TCs were investigated and optimized. The developed method showed excellent linearity (R > 0.9992) in the range of 0.133-333 μg L -1 , under optimized conditions. The limits of detection were between 0.027 and 0.107 μg L -1 for oxytetracycline, tetracycline and chlortetracycline, respectively. The feasibility of this method was evaluated by analysis of tap and river water samples. The recoveries at the spiked concentration levels ranged from 91.0% to 104.6% with favorable reproducibility (RSD < 4%). Copyright © 2017 Elsevier B.V. All rights reserved.

Susceptibility investigation of the nanoparticle coating-layer effect on the particle interaction in biocompatible magnetic fluids

International Nuclear Information System (INIS)

Morais, P.C.; Santos, J.G.; Silveira, L.B.; Gansau, C.; Buske, N.; Nunes, W.C.; Sinnecker, J.P.

2004-01-01

AC susceptibility was used to investigate the effect of the surface-coating layer in two biocompatible, magnetite-based, magnetic fluid samples. Dextran and dimercaptosuccinic acid (DMSA) were the surface coating species. The temperature and frequency dependence of the peak susceptibility was discussed using the Vogel-Fulcher relation, from which the typical energy barrier (temperature correction) values of 1340±20 K (70±3 K) and 1230±30 K (86±5 K) were obtained for the dextran- and DMSA-coated nanoparticles, respectively

Tailoring magnetic nanoparticle for transformers application.

Science.gov (United States)

Morais, P C; Silva, A S; Leite, E S; Garg, V K; Oliveira, A C; Viali, W R; Sartoratto, P P C

2010-02-01

In this study photoacoustic spectroscopy was used to investigate the effect of dilution of an oil-based magnetic fluid sample on the magnetic nanoparticle surface-coating. Changes of the photoacoustic signal intensity on the band-L region (640 to 830 nm) upon dilution of the stock magnetic fluid sample were discussed in terms of molecular surface desorption. The model proposed here assumes that the driving force taking the molecules out from the nanoparticle surface into the bulk solvent is the gradient of osmotic pressure. This gradient of osmotic pressure is established between the nanoparticle surface and the bulk suspension. It is further assumed that the photoacoustic signal intensity (area under the photoacoustic spectra) scales linearly with the number of coating molecules (surface grafting) at the nanoparticle surface. This model picture provides a non-linear analytical description for the reduction of the surface grafting coefficient upon dilution, which was successfully-used to curve-fit the photoacoustic experimental data.

Size-Dependent Accumulation of PEGylated Silane-Coated Magnetic Iron Oxide Nanoparticles in Murine Tumors

DEFF Research Database (Denmark)

Larsen, Esben Kjær Unmack; Nielsen, T.; Wittenborn, T.

2009-01-01

following intravenous injection. Biocompatible iron oxide MNPs coated with PEG were prepared by replacing oleic acid with a biocompatible and commercially available silane-PEG to provide an easy and effective method for chemical coating. The colloidal stable PEGylated MNPs were magnetically separated...... into two distinct size subpopulations of 20 and 40 nm mean diameters with increased phagocytic uptake observed for the 40 nm size range in vitro. MRI detection revealed greater iron accumulation in murine tumors for 40 nm nanoparticles after intravenous injection. The enhanced MRI contrast of the larger...

Modified silica sol coatings for surface enhancement of leather.

Science.gov (United States)

Mahltig, Boris; Vossebein, Lutz; Ehrmann, Andrea; Cheval, Nicolas; Fahmi, Amir

2012-06-01

The presented study reports on differently modified silica sols for coating applications on leather. Silica sols are prepared by acidic hydrolysis of tetraethoxysilane and modified by silane compounds with fluorinated and non-fluorinated alkylgroups. In contrast to many earlier investigations regarding sol-gel applications on leather, no acrylic resin is used together with the silica sols when applying on leather. The modified silica particles are supposed to aggregate after application, forming thus a modified silica coating on the leather substrate. Scanning electron microscopy investigation shows that the applied silica coatings do not fill up or close the pores of the leather substrate. However, even if the pores of the leather are not sealed by this sol-gel coating, an improvement of the water repellent and oil repellent properties of the leather substrates are observed. These improved properties of leather by application of modified silica sols can provide the opportunity to develop sol-gel products for leather materials present in daily life.

Silane-coated magnetic nanoparticles with surface thiol functions for conjugation with gold nanostars

KAUST Repository

Pallavicini, Piersandro

2015-11-10

Small (d ∼ 8 nm) magnetite nanoparticles, FeONP, are prepared and coated with mercaptopropyl trimethoxysilane (MPTS) to form FeONP@MPTS. In the coating step controlled MPTS/FeONP molar ratios are used, ranging from 1 to 7.8 × 10. The total quantity of MPTS per FeONP is determined by SEM-EDS analysis and the average number of free, reactive -SH groups per FeONP is calculated by a colorimetric method. At very low molar ratios MPTS forms a submonolayer on the FeONP surface with all -SH free to react, while on increasing the MPTS/FeONP molar ratio the (CHO)Si- groups of MPTS polymerize, forming a progressively thicker shell, in which only a small fraction of the -SH groups, positioned on the shell surface, is available for further reaction. The MPTS shell reduces the magnetic interactions occurring between the magnetite cores, lowering the occurrence and strength of collective magnetic states, with FeONP@MPTS showing the typical behaviour expected for a sample with a mono-modal size distribution of superparamagnetic nanoparticles. Interaction of FeONP@MPTS with gold nanostars (GNS) was tested, using both FeONP@MPTS with a MPTS submonolayer and with increasing shell thickness. Provided that a good balance is used between the number of available -SH and the overall size of FeONP@MPTS, the free thiols of such nanoparticles bind GNS decorating their surface, as shown by UV-Vis spectroscopy and TEM imaging.

Breast cancer cells synchronous labeling and separation based on aptamer and fluorescence-magnetic silica nanoparticles

Science.gov (United States)

Wang, Qiu-Yue; Huang, Wei; Jiang, Xing-Lin; Kang, Yan-Jun

2018-01-01

In this work, an efficient method based on biotin-labeled aptamer and streptavidin-conjugated fluorescence-magnetic silica nanoprobes (FITC@Fe3O4@SiNPs-SA) has been established for human breast carcinoma MCF-7 cells synchronous labeling and separation. Carboxyl-modified fluorescence-magnetic silica nanoparticles (FITC@Fe3O4@SiNPs-COOH) were first synthesized using the Stöber method. Streptavidin (SA) was then conjugated to the surface of FITC@Fe3O4@SiNPs-COOH. The MCF-7 cell suspension was incubated with biotin-labeled MUC-1 aptamer. After centrifugation and washing, the cells were then treated with FITC@Fe3O4@SiNPs-SA. Afterwards, the mixtures were separated by a magnet. The cell-probe conjugates were then imaged using fluorescent microscopy. The results show that the MUC-1 aptamer could recognize and bind to the targeted cells with high affinity and specificity, indicating the prepared FITC@Fe3O4@SiNPs-SA with great photostability and superparamagnetism could be applied effectively in labeling and separation for MCF-7 cell in suspension synchronously. In addition, the feasibility of MCF-7 cells detection in peripheral blood was assessed. The results indicate that the method above is also applicable for cancer cells synchronous labeling and separation in complex biological system.

Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method

International Nuclear Information System (INIS)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-01-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability. - Highlights: ► Uniformly coated Mn–Zn ferrite powder increased the operating frequency of SMCs. ► Compared with epoxy coated, the permeability of SMCs increased by 33.5% at 10 kHz. ► 400 °C is the optimum annealing temperature to attain the desired permeability.

Studies on polyethylene glycol coating on NiFe2O4 nanoparticles for biomedical applications

International Nuclear Information System (INIS)

Phadatare, M.R.; Khot, V.M.; Salunkhe, A.B.; Thorat, N.D.; Pawar, S.H.

2012-01-01

The NiFe 2 O 4 nanoparticles were prepared by the combustion method and these nanoparticles were successfully coated with polyethylene glycol (PEG) for the possible biomedical applications such as magnetic resonance imaging, drug delivery, tissue repair, magnetic fluid hyperthermia etc. The structural and magnetic characterizations of NiFe 2 O 4 nanoparticles were carried out by x-ray diffraction and vibrating sample magnetometry techniques, respectively. The morphology of the uncoated and coated nanoparticles was studied by scanning electron microscopy. The existence of PEG layer on NiFe 2 O 4 nanoparticles was confirmed by fourier transform infrared spectroscopy technique. - Highlights: ► Synthesis of nanocrystalline NiFe 2 O 4 by the combustion method. ► Magnetic properties of the NiFe 2 O 4 nanoparticles at room temperature. ► Coating of NiFe 2 O 4 nanoparticles by Polyethylene glycol (PEG).

A Highly Stable and Magnetically Recyclable Nanocatalyst System: Mesoporous Silica Spheres Embedded with FeCo/Graphitic Shell Magnetic Nanoparticles and Pt Nanocatalysts.

Science.gov (United States)

Kim, Da Jeong; Li, Yan; Kim, Yun Jin; Hur, Nam Hwi; Seo, Won Seok

2015-12-01

We have developed a highly stable and magnetically recyclable nanocatalyst system for alkene hydrogenation. The materials are composed of mesoporous silica spheres (MSS) embedded with FeCo/graphitic shell (FeCo/GC) magnetic nanoparticles and Pt nanocatalysts (Pt-FeCo/GC@MSS). The Pt-FeCo/GC@MSS have superparamagnetism at room temperature and show type IV isotherm typical for mesoporous silica, thereby ensuring a large enough inner space (surface area of 235.3 m(2)  g(-1), pore volume of 0.165 cm(3)  g(-1), and pore diameter of 2.8 nm) to undergo catalytic reactions. We have shown that the Pt-FeCo/GC@MSS system readily converts cyclohexene into cyclohexane, which is the only product isolated and Pt-FeCo/GC@MSS can be seperated very quickly by an external magnetic field after the catalytic reaction is finished. We have demonstrated that the recycled Pt-FeCo/GC@MSS can be reused further for the same hydrogenation reaction at least four times without loss in the initial catalytic activity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Amperometric glucose sensor based on enhanced catalytic reduction of oxygen using glucose oxidase adsorbed onto core-shell Fe3O4-silica-Au magnetic nanoparticles

International Nuclear Information System (INIS)

Wang Aijun; Li Yongfang; Li Zhonghua; Feng Jiuju; Sun Yanli; Chen Jianrong

2012-01-01

Monodisperse Fe 3 O 4 magnetic nanoparticles (NPs) were prepared under facile solvothermal conditions and successively functionalized with silica and Au to form core/shell Fe 3 O 4 -silica-Au NPs. Furthermore, the samples were used as matrix to construct a glucose sensor based on glucose oxidase (GOD). The immobilized GOD retained its bioactivity with high protein load of 3.92 × 10 −9 mol·cm −2 , and exhibited a surface-controlled quasi-reversible redox reaction, with a fast heterogeneous electron transfer rate of 7.98 ± 0.6 s −1 . The glucose biosensor showed a broad linear range up to 3.97 mM with high sensitivity of 62.45 μA·mM −1 cm −2 and fast response (less than 5 s). - Graphical abstract: Core-shell structured Fe 3 O 4 -silica-Au nanoparticles were prepared and used as matrix to construct an amperometric glucose sensor based on glucose oxidase, which showed broad linear range, high sensitivity, and fast response. Highlights: ► Synthesis of monodispersed Fe 3 O 4 nanoparticles. ► Fabrication of core/shell Fe 3 O 4 -silica-Au nanoparticles. ► Construction of a novel glucose sensor with wide linear range, high sensitivity and fast response.

Effects of AC magnetic field and carboxymethyldextran-coated magnetite nanoparticles on mice peritoneal cells

International Nuclear Information System (INIS)

Araujo Guedes, Maria Helena; Sadeghiani, Neda; Lima Guedes Peixoto, Danielle; Poubel Coelho, Julia; Santos Barbosa, Luzirlane; Bentes Azevedo, Ricardo; Kueckelhaus, Selma; Silva, Maria de Fatima da; Morais, Paulo Cesar; Guerrero Marques Lacava, Zulmira

2005-01-01

A portable apparatus was developed to perform magnetohyperthermia (MHT) assays. In order to investigate its efficiency on cell lysis, biological effects of the AC magnetic field exposure after carboxymethyldextran-coated magnetite-nanoparticles (CMDC) treatment were investigated. Phagocyte capacity, cell viability, and morphology data evidenced that the CMDC sample and the apparatus are useful to further investigate MHT in cancer therapy

Plasmonic and silicon spherical nanoparticle antireflective coatings

Science.gov (United States)

Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

2016-03-01

Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

Preparation of silica nanoparticles through microwave-assisted acid-catalysis.

Science.gov (United States)

Lovingood, Derek D; Owens, Jeffrey R; Seeber, Michael; Kornev, Konstantin G; Luzinov, Igor

2013-12-16

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber's methods, which have smooth surfaces.

Size-dependent cytotoxicity and inflammatory responses of PEGylated silica-iron oxide nanocomposite size series

Energy Technology Data Exchange (ETDEWEB)

Injumpa, Wishulada [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Ritprajak, Patcharee [Department of Microbiology, and RU in Oral Microbiology and Immunology, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330 (Thailand); Insin, Numpon, E-mail: Numpon.I@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

2017-04-01

Iron oxides nanoparticles have been utilized in biological systems and biomedical applications for many years because they are relatively safe and stable comparing to other magnetic nanomaterials. In some applications, iron oxide nanoparticles were modified with silica in order to be more stable in biological systems and able to be functionalized with various functional groups. Moreover, poly(ethylene glycol) (PEG) was one on the most used polymer to graft onto the nanoparticles in order to increase their biocompatibility, dispersibility and stability in aqueous solutions. Therefore, the nanocomposites comprising iron oxide nanoparticles, silica, and PEG could become multifunctional carriers combining superparamagnetic character, multi-functionality and high stability in biological environments. Herein, we reported the preparation of the nanocomposites and effects of their sizes on cytotoxicity and inflammatory responses. The PEGylated silica-iron oxide nanocomposites were prepared by coating of poly(poly(ethylene glycol) monomethyl ether methacrylate) (PPEGMA) on magnetic nanoparticle-silica nanocomposites via Atom Transfer Radical Polymerization (ATRP). The iron oxide nanoparticles were synthesized using a thermal decomposition method. The silica shells were then coated on iron oxides nanoparticles using reverse microemulsion and sol-gel methods. The size series of the nanocomposites with the diameter of 24.86±4.38, 45.24±5.00, 98.10±8.88 and 202.22±6.70 nm as measured using TEM were obtained. Thermogravimetric analysis (TGA) was used for the determination of % weight of PPEGMA on the nanocomposites showing the weight loss of ranging from 65% for smallest particles to 30% for largest particles. The various sizes (20, 40, 100, 200 nm) and concentrations (10, 100, 1000 μg/mL) of the nanocomposites were tested for their cytotoxicity in fibroblast and macrophage cell lines using MTT assay. The different sizes did not affect cell viability of fibroblast, albeit

A facile method for emulsified oil-water separation by using polyethylenimine-coated magnetic nanoparticles

Science.gov (United States)

Lü, Ting; Qi, Dongming; Zhang, Dong; Lü, Yulan; Zhao, Hongting

2018-04-01

Oil spills and oily wastewater discharges from ships and industrial activities have serious impacts on the environment and human health. In this study, a class of easy-to-synthesize polyethylenimine (PEI)-coated Fe3O4 magnetic nanoparticles (MNPs) was successfully synthesized via a one-step coprecipitation method. The synthesized PEI-coated Fe3O4 MNPs were characterized by using multiple technologies and applied in emulsified oil-water separation for the first time. It was found that the PEI effectively tuned the surface charge and wettability of MNPs. As a result, the PEI-coated MNPs could successfully assemble at the oil-water interface and promote the coalescence of oil droplets, thereby facilitating the subsequent magnetic separation. Results showed that the oil-water separation performance was superior and enhanced with the increase of ionic strength. Recycling experiment indicated that the PEI-coated MNPs could be reused up to six times without showing a significant decrease in separation efficiency. All of these results suggested that the PEI-coated MNP could potentially be used as a class of promising nanomaterials for emulsified oil-water separation. [Figure not available: see fulltext.

Doxorubicin loaded PEG-b-poly(4-vinylbenzylphosphonate) coated magnetic iron oxide nanoparticles for targeted drug delivery

Energy Technology Data Exchange (ETDEWEB)

Hałupka-Bryl, Magdalena, E-mail: magdalenahalupka@op.pl [The NanoBioMedical Centre, Adam Mickiewicz University, Poznań (Poland); Division of Medical Physics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Department of Materials Sciences, Graduate School of Pure and Applied Sciences, University of Tsukuba (Japan); Bednarowicz, Magdalena [The NanoBioMedical Centre, Adam Mickiewicz University, Poznań (Poland); Division of Medical Physics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Department of Materials Sciences, Graduate School of Pure and Applied Sciences, University of Tsukuba (Japan); Dobosz, Bernadeta; Krzyminiewski, Ryszard [The NanoBioMedical Centre, Adam Mickiewicz University, Poznań (Poland); Division of Medical Physics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Zalewski, Tomasz [The NanoBioMedical Centre, Adam Mickiewicz University, Poznań (Poland); Wereszczyńska, Beata [Department of Macromolecular Physics, Adam Mickiewicz University, Poznań (Poland); Nowaczyk, Grzegorz; Jarek, Marcin [The NanoBioMedical Centre, Adam Mickiewicz University, Poznań (Poland); Nagasaki, Yukio [Department of Materials Sciences, Graduate School of Pure and Applied Sciences, University of Tsukuba (Japan); Master’s School of Medicinal Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba (Japan); International Centre for Materials Nanoarchitectonics Satellite (WPI-MANA), National Institute For Materials Sciences (NIMS) and University of Tsukuba (Japan)

2015-06-15

Due to their unique physical properties, superparamagnetic iron oxide nanoparticles are increasingly used in medical applications. They are very useful carriers for delivering antitumor drugs in targeted cancer treatment. Magnetic nanoparticles with chemiotherapeutic were synthesized by coprecipitation method followed by coating with biocompatible polymer. The aim of this work is to characterize physical and magnetic properties of synthesized nanoparicles. Characterization was carried out using EPR, HRTEM, X-ray diffraction, SQUID and NMR methods. The present findings show that synthesized nanosystem is promising tool for potential magnetic drug delivery. - Highlights: • Synthesized PEG-PIONs/DOX have excellent physical properties. • PEG-PIONs/DOX have a potential to in vivo application. • PEG-PIONs/DOX could be used as drug delivery system as well as contrast agents.

Electromagnetics of active coated nano-particles

DEFF Research Database (Denmark)

Arslanagic, Samel

2013-01-01

This work reviews the fundamental properties of several spherical and cylindrical active coated nano-particles excited by their respective single and/or multiple sources of radiation at optical frequencies. Particular attention is devoted to the influence of the source location and orientation, t......, the optical gain constant and the nano-particle material composition on the electric and magnetic near fields, the power flow density, the radiated power as well as the directivities. Resonant as well as quasi-transparent states will be emphasized in the discussion.......This work reviews the fundamental properties of several spherical and cylindrical active coated nano-particles excited by their respective single and/or multiple sources of radiation at optical frequencies. Particular attention is devoted to the influence of the source location and orientation...

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids

Directory of Open Access Journals (Sweden)

Joachim Allouche

2014-07-01

Full Text Available The design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms.

Formulation of novel lipid-coated magnetic nanoparticles as the probe for in vivo imaging

Directory of Open Access Journals (Sweden)

Mou Chung-Yuan

2009-09-01

Full Text Available Abstract Background Application of superparamagnetic iron oxide nanoparticles (SPIOs as the contrast agent has improved the quality of magnetic resonance (MR imaging. Low efficiency of loading the commercially available iron oxide nanoparticles into cells and the cytotoxicity of previously formulated complexes limit their usage as the image probe. Here, we formulated new cationic lipid nanoparticles containing SPIOs feasible for in vivo imaging. Methods Hydrophobic SPIOs were incorporated into cationic lipid 1,2-dioleoyl-3-(trimethylammonium propane (DOTAP and polyethylene-glycol-2000-1,2-distearyl-3-sn-phosphatidylethanolamine (PEG-DSPE based micelles by self-assembly procedure to form lipid-coated SPIOs (L-SPIOs. Trace amount of Rhodamine-dioleoyl-phosphatidylethanolamine (Rhodamine-DOPE was added as a fluorescent indicator. Particle size and zeta potential of L-SPIOs were determined by Dynamic Light Scattering (DLS and Laser Doppler Velocimetry (LDV, respectively. HeLa, PC-3 and Neuro-2a cells were tested for loading efficiency and cytotoxicity of L-SPIOs using fluorescent microscopy, Prussian blue staining and flow cytometry. L-SPIO-loaded CT-26 cells were tested for in vivo MR imaging. Results The novel formulation generates L-SPIOs particle with the average size of 46 nm. We showed efficient cellular uptake of these L-SPIOs with cationic surface charge into HeLa, PC-3 and Neuro-2a cells. The L-SPIO-loaded cells exhibited similar growth potential as compared to unloaded cells, and could be sorted by a magnet stand over ten-day duration. Furthermore, when SPIO-loaded CT-26 tumor cells were injected into Balb/c mice, the growth status of these tumor cells could be monitored using optical and MR images. Conclusion We have developed a novel cationic lipid-based nanoparticle of SPIOs with high loading efficiency, low cytotoxicity and long-term imaging signals. The results suggested these newly formulated non-toxic lipid-coated magnetic

A decomposable silica-based antibacterial coating for percutaneous titanium implant

Directory of Open Access Journals (Sweden)

Wang J

2017-01-01

antibacterial titanium coating continuously released gentamycin and inhibited S. aureus growth. In vitro investigation showed that the obtained nanodelivery system has good biocompatibility. Therefore, this design can be further investigated as a method to prevent infection around percutaneous implants. Keywords: silica nanoparticles, microarc oxidation, gentamycin, control release, fibroblasts

Polyinosinic:polycytidylic acid loading onto different generations of PAMAM dendrimer-coated magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Khodadust, Rouhollah, E-mail: raoul.1357@gmail.com [Middle East Technical University, Department of Biotechnology (Turkey); Mutlu, Pelin [Middle East Technical University, Central Laboratory, Molecular Biology and Biotechnology R and D Center (Turkey); Yalc Latin-Small-Letter-Dotless-I n, Serap [Ahi Evran University, Department of Food Engineering (Turkey); Unsoy, Gozde; Gunduz, Ufuk, E-mail: ufukg@metu.edu.tr [Middle East Technical University, Department of Biotechnology (Turkey)

2013-08-15

Poly (I:C), which is a synthetic double-stranded RNA, have significant toxicity on tumor cells. The immobilization of Poly (I:C) onto nanoparticles is important for the fabrication of targeted delivery systems. In this study, different generations of newly synthesized PAMAM dendron-coated magnetic nanoparticles (DcMNP) which can be targeted to the tumor site under magnetic field were efficiently loaded for the first time with Poly (I:C). Different generations of DcMNPs (G{sub 2}, G{sub 3}, G{sub 4}, G{sub 5}, G{sub 6}, and G{sub 7}) were synthesized. Poly (I:C) activation was achieved in the presence of EDC and 1-methylimidazole. Loading of Poly (I:C) onto DcMNPs was followed by agarose gel electrophoresis. Acidic reaction conditions were found as superior to basic and neutral for binding of Poly (I:C). In addition, having more functional groups at the surface, higher generations (G{sub 7}, G{sub 6}, and G{sub 5}) of PAMAM DcMNPs were found more suitable as a delivery system for Poly (I:C). Further in vitro and in vivo analyses of Poly (I:C)/PAMAM magnetic nanoparticles may provide new opportunities for the selective targeting and killing of tumor cells.

Polyphosphoric acid supported on Ni0.5Zn0.5Fe2O4 nanoparticles as a magnetically-recoverable green catalyst for the synthesis of pyranopyrazoles

Directory of Open Access Journals (Sweden)

Farid Moeinpour

2017-05-01

Full Text Available Polyphosphoric acid supported on silica coated Ni0.5Zn0.5Fe2O4 nanoparticles was found to be magnetically separable, highly efficient, eco-friendly, green and recyclable heterogeneous catalyst. This new catalyst at first was fully characterized by TEM, SEM, FTIR and XRD techniques and then catalytic activity of this catalyst was investigated in the synthesis of 5-cyano-1,4-dihydropyrano[2,3-c]pyrazoles. Also the Ni0.5Zn0.5Fe2O4 magnetic nanoparticle-supported polyphosphoric acid could be reused at least six times without significant loss of activity. It could be recovered easily by applying an external magnet.

Chitosan–Collagen Coated Magnetic Nanoparticles for Lipase Immobilization—New Type of “Enzyme Friendly” Polymer Shell Crosslinking with Squaric Acid

Directory of Open Access Journals (Sweden)

Marta Ziegler-Borowska

2017-01-01

Full Text Available This article presents a novel route for crosslinking a polysaccharide and polysaccharide/protein shell coated on magnetic nanoparticles (MNPs surface via condensation reaction with squaric acid (SqA. The syntheses of four new types of collagen-, chitosan-, and chitosan–collagen coated magnetic nanoparticles as supports for enzyme immobilization have been done. Structure and morphology of prepared new materials were characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR, XRD, and TEM analysis. Next, the immobilization of lipase from Candida rugosa was performed on the nanoparticles surface via N-(3-dimethylaminopropyl-N′-ethylcarbodiimide hydrochloride (EDC/N-hydroxy-succinimide (NHS mechanism. The best results of lipase activity recovery and specific activities were observed for nanoparticles with polymer shell crosslinked via a novel procedure with squaric acid. The specific activity for lipase immobilized on materials crosslinked with SqA (52 U/mg lipase was about 2-fold higher than for enzyme immobilized on MNPs with glutaraldehyde addition (26 U/mg lipase. Moreover, a little hyperactivation of lipase immobilized on nanoparticles with SqA was observed (104% and 112%.

Biological Fate of Fe3O4 Core-Shell Mesoporous Silica Nanoparticles Depending on Particle Surface Chemistry

Science.gov (United States)

Rascol, Estelle; Daurat, Morgane; Da Silva, Afitz; Maynadier, Marie; Dorandeu, Christophe; Charnay, Clarence; Garcia, Marcel; Lai-Kee-Him, Joséphine; Bron, Patrick; Auffan, Mélanie; Angeletti, Bernard; Devoisselle, Jean-Marie; Guari, Yannick; Gary-Bobo, Magali; Chopineau, Joël

2017-01-01

The biological fate of nanoparticles (NPs) for biomedical applications is highly dependent of their size and charge, their aggregation state and their surface chemistry. The chemical composition of the NPs surface influences their stability in biological fluids, their interaction with proteins, and their attraction to the cell membranes. In this work, core-shell magnetic mesoporous silica nanoparticles (Fe3O4@MSN), that are considered as potential theranostic candidates, are coated with polyethylene glycol (PEG) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayer. Their biological fate is studied in comparison to the native NPs. The physicochemical properties of these three types of NPs and their suspension behavior in different media are investigated. The attraction to a membrane model is also evaluated using a supported lipid bilayer. The surface composition of NPs strongly influences their dispersion in biological fluids mimics, protein binding and their interaction with cell membrane. While none of these types of NPs is found to be toxic on mice four days after intravenous injection of a dose of 40 mg kg−1 of NPs, their surface coating nature influences the in vivo biodistribution. Importantly, NP coated with DMPC exhibit a strong accumulation in liver and a very low accumulation in lung in comparison with nude or PEG ones. PMID:28665317

Synchrotron macro ATR-FTIR microspectroscopic analysis of silica nanoparticle-embedded polyester coated steel surfaces subjected to prolonged UV and humidity exposure.

Science.gov (United States)

Vongsvivut, Jitraporn; Truong, Vi Khanh; Al Kobaisi, Mohammad; Maclaughlin, Shane; Tobin, Mark J; Crawford, Russell J; Ivanova, Elena P

2017-01-01

Surface modification of polymers and paints is a popular and effective way to enhance the properties of these materials. This can be achieved by introducing a thin coating that preserves the bulk properties of the material, while protecting it from environmental exposure. Suitable materials for such coating technologies are inorganic oxides, such as alumina, titania and silica; however, the fate of these materials during long-term environmental exposure is an open question. In this study, polymer coatings that had been enhanced with the addition of silica nanoparticles (SiO2NPs) and subsequently subjected to environmental exposure, were characterized both before and after the exposure to determine any structural changes resulting from the exposure. High-resolution synchrotron macro ATR-FTIR microspectroscopy and surface topographic techniques, including optical profilometry and atomic force microscopy (AFM), were used to determine the long-term effect of the environment on these dual protection layers after 3 years of exposure to tropical and sub-tropical climates in Singapore and Queensland (Australia). Principal component analysis (PCA) based on the synchrotron macro ATR-FTIR spectral data revealed that, for the 9% (w/w) SiO2NP/polymer coating, a clear discrimination was observed between the control group (no environmental exposure) and those samples subjected to three years of environmental exposure in both Singapore and Queensland. The PCA loading plots indicated that, over the three year exposure period, a major change occurred in the triazine ring vibration in the melamine resins. This can be attributed to the triazine ring being very sensitive to hydrolysis under the high humidity conditions in tropical/sub-tropical environments. This work provides the first direct molecular evidence, acquired using a high-resolution mapping technique, of the climate-induced chemical evolution of a polyester coating. The observed changes in the surface topography of the

Improvement of tribological properties of magnetic tape by silica coating onto the Co-{gamma}-Fe{sub 2}O{sub 3} fine particles; Kobaruto hichakugata {gamma}-Fe{sub 2}O{sub 3} jisei biryushi no shisshiki shirika hyomen shori ni yoru jikitepu no suberi tokusei no kaizen

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Kazuyuki; Iwasaki, Keisuke; Tanaka, Yasuyuki; Morii, Hiroko [Toda Kogyo Corporation, Hiroshima (Japan). R and D Center

1999-01-10

In order to improve the tribological properties of magnetic tape with Co-{gamma}-Fe{sub 2}O{sub 3} fine particles against a magnetic head, the silica coating onto the surface of Co-{gamma}-Fe{sub 2}O{sub 3} particles in aqueous slurry is investigated experimentally, and the kinetic friction coefficient of magnetic tapes prepared using the coated particles is measured. By this silica coating, the amount of myristic acid absorbed on the Co-{gamma}-Fe{sub 2}O{sub 3} particles tends to decrease and the kinetic friction coefficient of the magnetic tapes can be reduced from 0.4 to 0.2 because of the increase of the effective amount of myristic acid working as the lubricant when the magnetic tape is moving. Since the magnetic properties and the dispersibility of Co-{gamma}-Fe{sub 2}O{sub 3} pigment in the magnetic lacquer are not degraded by the silica coating, this coating method is expected to result in magnetic recording media with both good magnetic and low friction properties. (author)

Rapid and Efficient Protein Digestion using Trypsin Coated Magnetic Nanoparticles under Pressure Cycles

Energy Technology Data Exchange (ETDEWEB)

Lee, Byoungsoo; Lopez-Ferrer, Daniel; Kim, Byoung Chan; Na, Hyon Bin; Park, Yong Il; Weitz, Karl K.; Warner, Marvin G.; Hyeon, Taeghwan; Lee, Sang-Won; Smith, Richard D.; Kim, Jungbae

2011-01-01

Trypsin-coated magnetic nanoparticles (EC-TR/NPs), prepared via a simple crosslinking of the enzyme to magnetic nanoparticles, were highly stable and could be easily captured using a magnet after the digestion was complete. EC-TR/NPs showed a negligible loss of trypsin activity after multiple uses and continuous shaking, while a control sample of covalently-attached trypsin on NPs resulted in a rapid inactivation under the same conditions due to the denaturation and autolysis of trypsin. Digestions were carried out on a single model protein, a five protein mixture, and a whole mouse brain proteome, and also compared for digestion at atmospheric pressure and 37 ºC for 12 h, and in combination with pressure cycling technology (PCT) at room temperature for 1 min. In all cases, the EC-TR/NPs performed equally as well or better than free trypsin in terms of the number of peptide/protein identifications and reproducibility across technical replicates. However, the concomitant use of EC-TR/NPs and PCT resulted in very fast (~1 min) and more reproducible digestions.

Magnetite Nanoparticles Coated with Rifampicin and Chlortetracycline for Drug Delivery Applications

International Nuclear Information System (INIS)

Nadejde, Claudia; Ciurlica, Ecaterina Foca-nici; Creanga, Dorina; Carlescu, Aurelian; Badescu, Vasile

2010-01-01

Four types of biocompatible magnetic fluids based on superparamagnetic nanoparticles with Fe 3 O 4 cores were functionalized with antibiotics (rifampicin or chlortetracycline) as potential candidates for in vivo biomedical applications, such as magnetically controlled drug delivery. The synthesis consisted in coprecipitation of iron oxide in basic, as well as in acid medium, followed by the dispersion of the resulted magnetite nanoparticles in aqueous solution containing the antibiotic. The chosen method to prepare the magnetite-core/drug-shell systems avoided intermediate organic coating of the magnetic nanoparticles. Comparative analysis of the rheological features of the aqueous magnetic fluid samples was performed. The structural features of the coated magnetic particles were investigated by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). Good crystallinity and adequate stability in time were evidenced. Drug delivery curves were spectrophotometrically provided.

Fluorescent Silica Nanoparticles in the Detection and Control of the Growth of Pathogen

International Nuclear Information System (INIS)

Chitra, K.; Annadurai, G.

2013-01-01

In this present study the bio conjugated fluorescent silica nanoparticles give an efficient fluorescent-based immunoassay for the detection of pathogen. The synthesized silica nanoparticles were poly dispersed and the size of the silica nanoparticles was in the range of 114-164 nm. The energy dispersive X-ray spectrophotometer showed the presence of silica at 1.8 keV and the selected area diffractometer showed amorphous nature of silica nanoparticles. The FTIR spectrum confirmed the attachment of dye and carboxyl group onto the silica nanoparticles surface. The fluorescent silica nanoparticles showed highly efficient fluorescence and the fluorescent emission of silica nanoparticles occurred at 536 nm. The SEM image showed the aggregation of nanoparticles and bacteria. The growth of the pathogenic E. coli was controlled using silica nanoparticles; therefore silica nanoparticles could be used in food packaging material, biomedical material, and so forth. This work provides a rapid, simple, and accurate method for the detection of pathogen using fluorescent-based immunoassay.

Magnetic stents retain nanoparticle-bound antirestenotic drugs transported by lipid microbubbles.

Science.gov (United States)

Räthel, T; Mannell, H; Pircher, J; Gleich, B; Pohl, U; Krötz, F

2012-05-01

Coating coronary stents with antirestenotic drugs revolutionized interventional cardiology. We developed a system for post-hoc drug delivery to uncoated stents. We coupled rapamycin or a chemically similar fluorescent dye to superparamagnetic nanoparticles. The antiproliferative activity of rapamycin coupled to nanoparticles was confirmed in vitro in primary porcine vascular cells. The particles were then incorporated into lipid based microbubbles. Commercially available stents were made magnetizable by nickel plating and used to induce strong field gradients in order to capture magnetic microbubbles from flowing liquids when placed in an external magnetic field. Nanoparticle bound Rapamycin dose dependently inhibited cell proliferation in vitro. Magnetic microcbubbles carrying coated nanoparticles were caught by magnets placed external to a flow-through tube. Plating commercial stents with nickel resulted in increased deposition at stent struts and allowed for widely increased distance of external magnets. Deposition depended on circulation time and velocity and distance of magnets. Deposited microbubbles were destroyed by ultrasound and delivered their cargo to targeted sites. Drugs can be incorporated into nanoparticle loaded microbubbles and thus be delivered to magnetizable stents from circulating fluids by applying external magnetic fields. This technology could allow for post-hoc drug coating of already implanted vascular stents.

Multifunctional Silica Nanoparticles Modified via Silylated-Decaborate Precursors

Directory of Open Access Journals (Sweden)

Fatima Abi-Ghaida

2015-01-01

Full Text Available A new class of multifunctional silica nanoparticles carrying boron clusters (10-vertex closo-decaborate and incorporating luminescent centers (fluorescein has been developed as potential probes/carriers for potential application in boron neutron capture therapy (BNCT. These silica nanoparticles were charged in situ with silylated-fluorescein fluorophores via the Stöber method and their surface was further functionalized with decaborate-triethoxysilane precursors. The resulting decaborate dye-doped silica nanoparticles were characterized by TEM, solid state NMR, DLS, nitrogen sorption, elemental analysis, and fluorescence spectroscopy.

High-coercivity FePt nanoparticle assemblies embedded in silica thin films

International Nuclear Information System (INIS)

Yan, Q; Purkayastha, A; Singh, A P; Li, H; Ramanath, G; Li, A; Ramanujan, R V

2009-01-01

The ability to process assemblies using thin film techniques in a scalable fashion would be a key to transmuting the assemblies into manufacturable devices. Here, we embed FePt nanoparticle assemblies into a silica thin film by sol-gel processing. Annealing the thin film composite at 650 deg. C transforms the chemically disordered fcc FePt phase into the fct phase, yielding magnetic coercivity values H c >630 mT. The positional order of the particles is retained due to the protection offered by the silica host. Such films with assemblies of high-coercivity magnetic particles are attractive for realizing new types of ultra-high-density data storage devices and magneto-composites.

Tuning the magnetism of ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Viñas, S. Liébana [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Departamento de Física Aplicada, Universidade de Vigo, Vigo 36310 (Spain); Simeonidis, K. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Li, Z.-A.; Ma, Z. [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Myrovali, E.; Makridis, A.; Sakellari, D. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Angelakeris, M., E-mail: agelaker@auth.gr [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Wiedwald, U.; Spasova, M. [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Farle, M., E-mail: michael.farle@uni-due.de [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany)

2016-10-01

The importance of magnetic interactions within an individual nanoparticle or between adjacent ones is crucial not only for the macroscopic collective magnetic behavior but for the AC magnetic heating efficiency as well. On this concept, single-(MFe{sub 2}O{sub 4} where M=Fe, Co, Mn) and core–shell ferrite nanoparticles consisting of a magnetically softer (MnFe{sub 2}O{sub 4}) or magnetically harder (CoFe{sub 2}O{sub 4}) core and a magnetite (Fe{sub 3}O{sub 4}) shell with an overall size in the 10 nm range were synthesized and studied for their magnetic particle hyperthermia efficiency. Magnetic measurements indicate that the coating of the hard magnetic phase (CoFe{sub 2}O{sub 4}) by Fe{sub 3}O{sub 4} provides a significant enhancement of hysteresis losses over the corresponding single-phase counterpart response, and thus results in a multiplication of the magnetic hyperthermia efficiency opening a novel pathway for high-performance, magnetic hyperthermia agents. At the same time, the existence of a biocompatible Fe{sub 3}O{sub 4} outer shell, toxicologically renders these systems similar to iron-oxide ones with significantly milder side-effects. - Highlights: • Magnetic hyperthermia is studied for 10 nm single and core/shell ferrite nanoparticles. • Maximum heating rate is observed for Fe{sub 3}O{sub 4}-coated CoFe{sub 2}O{sub 4} nanoparticles. • The increase is attributed to the interaction of phases with different anisotropy. • The presence of biocompatible Fe{sub 3}O{sub 4} shell potentially minimizes toxic side-effects.

Functionalization of Silica Nanoparticles for Polypropylene Nanocomposite Applications

Directory of Open Access Journals (Sweden)

Diego Bracho

2012-01-01

Full Text Available Synthetic silica nanospheres of 20 and 100 nm diameter were produced via the sol-gel method to be used as filler in polypropylene (PP composites. Modification of the silica surface was further performed by reaction with organic chlorosilanes in order to improve the particles interaction with the hydrophobic polyolefin matrix. These nanoparticles were characterized using transmission electronic microscopy (TEM, elemental analysis, thermogravimetric analysis (TGA, and solid-state nuclear magnetic resonance (NMR spectroscopy. For unmodified silica, it was found that the 20 nm particles have a greater effect on both mechanical and barrier properties of the polymeric composite. In particular, at 30 wt%, Young's modulus increases by 70%, whereas water vapor permeability (WVP increases by a factor of 6. Surface modification of the 100 nm particles doubles the value of the composite breaking strain compared to unmodified particles without affecting Young's modulus, while 20 nm modified particles presented a slight increase on both Young's modulus and breaking strain. Modified 100 nm particles showed a higher WVP compared to the unmodified particles, probably due to interparticle condensation during the modification step. Our results show that the addition of nanoparticles on the composite properties depends on both particle size and surface modifications.

Synthesis and nonlinear optical properties of zirconia-protected gold nanoparticles embedded in sol-gel derived silica glass

Science.gov (United States)

Le Rouge, A.; El Hamzaoui, H.; Capoen, B.; Bernard, R.; Cristini-Robbe, O.; Martinelli, G.; Cassagne, C.; Boudebs, G.; Bouazaoui, M.; Bigot, L.

2015-05-01

A new approach to dope a silica glass with gold nanoparticles (GNPs) is presented. It consisted in embedding zirconia-coated GNPs in a silica sol to form a doped silica gel. Then, the sol-doped nanoporous silica xerogel is densified leading to the formation of a glass monolith. The spectral position and shape of the surface plasmon resonance (SPR) reported around 520 nm remain compatible with small spherical GNPs in a silica matrix. The saturable absorption behavior of this gold/zirconia-doped silica glass has been evidenced by Z-scan technique. A second-order nonlinear absorption coefficient β of about -13.7 cm GW-1 has been obtained at a wavelength near the SPR of the GNPs.

Functional Magnetic Nanoparticles

Science.gov (United States)

Gass, James

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Silica nanoparticle stability in biological media revisited.

Science.gov (United States)

Yang, Seon-Ah; Choi, Sungmoon; Jeon, Seon Mi; Yu, Junhua

2018-01-09

The stability of silica nanostructure in the core-silica shell nanomaterials is critical to understanding the activity of these nanomaterials since the exposure of core materials due to the poor stability of silica may cause misinterpretation of experiments, but unfortunately reports on the stability of silica have been inconsistent. Here, we show that luminescent silver nanodots (AgNDs) can be used to monitor the stability of silica nanostructures. Though relatively stable in water and phosphate buffered saline, silica nanoparticles are eroded by biological media, leading to the exposure of AgNDs from AgND@SiO 2 nanoparticles and the quenching of nanodot luminescence. Our results reveal that a synergistic effect of organic compounds, particularly the amino groups, accelerates the erosion. Our work indicates that silica nanostructures are vulnerable to cellular medium and it may be possible to tune the release of drug molecules from silica-based drug delivery vehicles through controlled erosion.

Molecular Simulations of Gold Nanoparticles Coated With Self-Assembled Alkanethiolate Monolayers

National Research Council Canada - National Science Library

Henz, Brian J; Fischer, James W; Zachariah, Michael R

2006-01-01

In order to utilize the novel electrical, magnetic, optical, and physical properties of coated metal nanoparticles, one must be able to efficiently predict the nanoparticle size-dependent properties...

Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

Science.gov (United States)

López, A. J.; Rico, A.; Rodríguez, J.; Rams, J.

2010-08-01

Silica coatings reinforced with carbon nanotubes were produced via sol-gel route using two mixing techniques of the sol-gel precursors, mechanical and ultrasonic mixing, and dip-coating as deposition process on magnesium alloy substrates. Effective incorporation and distribution of 0.1 wt.% of carbon nanotubes in the amorphous silica matrix of the coatings were achieved using both techniques. Fabrication procedure determines the morphological aspects of the coating. Only mechanical mixing process produced coatings dense and free of defects. Nanoindentation technique was used to examine the influence of the fabrication process in the mechanical features of the final coatings, i.e. indentation fracture toughness, Young's modulus and hardness. A maximum toughening effect of about 24% was achieved in silica coatings reinforced with carbon nanotubes produced by the mechanical mixing route. Scanning electron microscopy investigation revealed that the toughening of these reinforced coatings was mainly due to bridging effect of the reinforcement.

Photochemical oxygen reduction by zinc phthalocyanine and silver/gold nanoparticle incorporated silica thin films

Energy Technology Data Exchange (ETDEWEB)

Pal, Manas; Ganesan, Vellaichamy, E-mail: velganesh@yahoo.com; Azad, Uday Pratap

2012-12-15

Silver or gold nanoparticles are synthesized using a borohydride reduction method and are anchored simultaneously into/onto the mercaptopropyl functionalized silica. Later, zinc phthalocyanine is adsorbed onto the above materials. Thin films of these materials are prepared by coating an aqueous colloidal suspension of the respective material onto glass plates. Visible light irradiation of these films in oxygen saturated, stirred aqueous solutions effectively reduces oxygen to hydrogen peroxide. The photocatalytic reduction of oxygen is explained on the basis of the semiconducting properties of the silica films. The back electron transfer reaction is largely prevented by means of a sacrificial electron donor, triethanolamine. - Highlights: Black-Right-Pointing-Pointer Zinc phthalocyanine adsorbed silica materials were prepared. Black-Right-Pointing-Pointer Thin films of these materials photocatalytically reduce oxygen. Black-Right-Pointing-Pointer The photocatalysis is explained based on semiconductor properties of the materials. Black-Right-Pointing-Pointer Metal nanoparticles increase the photocatalytic efficiency of the materials.

Molecular Organization Induced Anisotropic Properties of Perylene - Silica Hybrid Nanoparticles.

Science.gov (United States)

Sriramulu, Deepa; Turaga, Shuvan Prashant; Bettiol, Andrew Anthony; Valiyaveettil, Suresh

2017-08-10

Optically active silica nanoparticles are interesting owing to high stability and easy accessibility. Unlike previous reports on dye loaded silica particles, here we address an important question on how optical properties are dependent on the aggregation-induced segregation of perylene molecules inside and outside the silica nanoparticles. Three differentially functionalized fluorescent perylene - silica hybrid nanoparticles are prepared from appropriate ratios of perylene derivatives and tetraethyl orthosilicate (TEOS) and investigated the structure property correlation (P-ST, P-NP and P-SF). The particles differ from each other on the distribution, organization and intermolecular interaction of perylene inside or outside the silica matrix. Structure and morphology of all hybrid nanoparticles were characterized using a range of techniques such as electron microscope, optical spectroscopic measurements and thermal analysis. The organizations of perylene in three different silica nanoparticles were explored using steady-state fluorescence, fluorescence anisotropy, lifetime measurements and solid state polarized spectroscopic studies. The interactions and changes in optical properties of the silica nanoparticles in presence of different amines were tested and quantified both in solution and in vapor phase using fluorescence quenching studies. The synthesized materials can be regenerated after washing with water and reused for sensing of amines.

Fe{sub 3}O{sub 4} magnetic core coated by silver and functionalized with N-acetyl cysteine as novel nanoparticles in ferritin adsorption

Energy Technology Data Exchange (ETDEWEB)

Akduman, Beguem [Faculty of Science and Arts, Adnan Menderes University, Department of Chemistry (Turkey); Uygun, Murat [Kocarl Latin-Small-Letter-Dotless-I Vocational and Training School, Adnan Menderes University (Turkey); Uygun, Deniz Aktas, E-mail: daktas@adu.edu.tr [Faculty of Science and Arts, Adnan Menderes University, Department of Chemistry (Turkey); Antalik, Marian [Institute of Experimental Physics, Slovak Academy of Science, Department of Biophysics (Slovakia)

2013-04-15

A novel metal-chelate affinity matrix utilizing N-acetyl cysteine as a metal chelating agent was synthesized. For this, magnetic Fe{sub 3}O{sub 4} core was coated with silver by chemical reduction. Then, these magnetic silver nanoparticles were covered with N-acetyl cysteine, and Fe{sup 3+} was chelated to this modified magnetic silver nanoparticle. These magnetic nanoparticles were characterized by SEM, AFM, EDX, and ESR analysis. Synthesized nanoparticles were spherical and average size is found to be 69 nm. Fe{sup 3+} chelated magnetic silver nanoparticles were used for the adsorption of ferritin from its aqueous solution. Optimum conditions for the ferritin adsorption experiments were performed at pH 6.0 phosphate buffer and 25 Degree-Sign C of medium temperature and the maximum ferritin adsorption capacity is found to be 89.57 mg/g nanoparticle. Ferritin adsorption onto magnetic silver nanoparticles was increased with increasing ferritin concentration while adsorption capacity was decreased with increasing ionic strength. Affinity of the magnetic silver nanoparticles to the ferritin molecule was shown with SPR analysis. It was also observed that the adsorption capacity of the magnetic silver nanoparticles was not significantly changed after the five adsorption/desorption cycles.

Silica nanoparticles on front glass for efficiency enhancement in superstrate-type amorphous silicon solar cells

Science.gov (United States)

Das, Sonali; Banerjee, Chandan; Kundu, Avra; Dey, Prasenjit; Saha, Hiranmay; Datta, Swapan K.

2013-10-01

Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar cells (SCs) has been applied using highly monodispersed and stable silica nanoparticles (NPs). The silica NPs having 300 nm diameter were synthesized by Stober technique where the size of the NPs was controlled by varying the alcohol medium. The synthesized silica NPs were analysed by dynamic light scattering technique and Fourier transform infrared spectroscopy. The NPs were spin coated on glass side of fluorinated tin oxide (SnO2: F) coated glass superstrate and optimization of the concentration of the colloidal solution, spin speed and number of coated layers was done to achieve minimum reflection characteristics. An estimation of the distribution of the NPs for different optimization parameters has been done using field-emission scanning electron microscopy. Subsequently, the transparent conducting oxide coated glass with the layer having the minimum reflectance is used for fabrication of amorphous silicon SC. Electrical analysis of the fabricated cell indicates an improvement of 6.5% in short-circuit current density from a reference of 12.40 mA cm-2 while the open circuit voltage and the fill factor remains unaltered. A realistic optical model has also been proposed to gain an insight into the system.

Silica nanoparticles on front glass for efficiency enhancement in superstrate-type amorphous silicon solar cells

International Nuclear Information System (INIS)

Das, Sonali; Kundu, Avra; Dey, Prasenjit; Saha, Hiranmay; Datta, Swapan K; Banerjee, Chandan

2013-01-01

Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar cells (SCs) has been applied using highly monodispersed and stable silica nanoparticles (NPs). The silica NPs having 300 nm diameter were synthesized by Stober technique where the size of the NPs was controlled by varying the alcohol medium. The synthesized silica NPs were analysed by dynamic light scattering technique and Fourier transform infrared spectroscopy. The NPs were spin coated on glass side of fluorinated tin oxide (SnO 2 : F) coated glass superstrate and optimization of the concentration of the colloidal solution, spin speed and number of coated layers was done to achieve minimum reflection characteristics. An estimation of the distribution of the NPs for different optimization parameters has been done using field-emission scanning electron microscopy. Subsequently, the transparent conducting oxide coated glass with the layer having the minimum reflectance is used for fabrication of amorphous silicon SC. Electrical analysis of the fabricated cell indicates an improvement of 6.5% in short-circuit current density from a reference of 12.40 mA cm −2 while the open circuit voltage and the fill factor remains unaltered. A realistic optical model has also been proposed to gain an insight into the system. (paper)

Superparamagnetic nanoparticles for enhanced magnetic resonance and multimodal imaging

Science.gov (United States)

Sikma, Elise Ann Schultz

Magnetic resonance imaging (MRI) is a powerful tool for noninvasive tomographic imaging of biological systems with high spatial and temporal resolution. Superparamagnetic (SPM) nanoparticles have emerged as highly effective MR contrast agents due to their biocompatibility, ease of surface modification and magnetic properties. Conventional nanoparticle contrast agents suffer from difficult synthetic reproducibility, polydisperse sizes and weak magnetism. Numerous synthetic techniques and nanoparticle formulations have been developed to overcome these barriers. However, there are still major limitations in the development of new nanoparticle-based probes for MR and multimodal imaging including low signal amplification and absence of biochemical reporters. To address these issues, a set of multimodal (T2/optical) and dual contrast (T1/T2) nanoparticle probes has been developed. Their unique magnetic properties and imaging capabilities were thoroughly explored. An enzyme-activatable contrast agent is currently being developed as an innovative means for early in vivo detection of cancer at the cellular level. Multimodal probes function by combining the strengths of multiple imaging techniques into a single agent. Co-registration of data obtained by multiple imaging modalities validates the data, enhancing its quality and reliability. A series of T2/optical probes were successfully synthesized by attachment of a fluorescent dye to the surface of different types of nanoparticles. The multimodal nanoparticles generated sufficient MR and fluorescence signal to image transplanted islets in vivo. Dual contrast T1/T2 imaging probes were designed to overcome disadvantages inherent in the individual T1 and T2 components. A class of T1/T2 agents was developed consisting of a gadolinium (III) complex (DTPA chelate or DO3A macrocycle) conjugated to a biocompatible silica-coated metal oxide nanoparticle through a disulfide linker. The disulfide linker has the ability to be reduced

Mesoporous Silica and Organosilica Nanoparticles: Physical Chemistry, Biosafety, Delivery Strategies, and Biomedical Applications

KAUST Repository

Croissant, Jonas G.

2017-11-30

Predetermining the physico-chemical properties, biosafety, and stimuli-responsiveness of nanomaterials in biological environments is essential for safe and effective biomedical applications. At the forefront of biomedical research, mesoporous silica nanoparticles and mesoporous organosilica nanoparticles are increasingly investigated to predict their biological outcome by materials design. In this review, it is first chronicled that how the nanomaterial design of pure silica, partially hybridized organosilica, and fully hybridized organosilica (periodic mesoporous organosilicas) governs not only the physico-chemical properties but also the biosafety of the nanoparticles. The impact of the hybridization on the biocompatibility, protein corona, biodistribution, biodegradability, and clearance of the silica-based particles is described. Then, the influence of the surface engineering, the framework hybridization, as well as the morphology of the particles, on the ability to load and controllably deliver drugs under internal biological stimuli (e.g., pH, redox, enzymes) and external noninvasive stimuli (e.g., light, magnetic, ultrasound) are presented. To conclude, trends in the biomedical applications of silica and organosilica nanovectors are delineated, such as unconventional bioimaging techniques, large cargo delivery, combination therapy, gaseous molecule delivery, antimicrobial protection, and Alzheimer\\'s disease therapy.

The toxicity of silver and silica nanoparticles in comparable human and mouse cell lines

DEFF Research Database (Denmark)

Foldbjerg, Rasmus; Beer, Christiane; Sutherland, Duncan S

The toxicity of silica (SiO2) and PVP-coated silver (Ag) nanoparticles (NPs) was investigated in two pairs of human or mouse cell lines originating from lung epithelium (A549 and ASB-XIV) and macrophages (THP-1 and J744A.1). Both NPs were characterized in H2O and cell media and demonstrated to be...

Surface functionalization of chitosan-coated magnetic nanoparticles for covalent immobilization of yeast alcohol dehydrogenase from Saccharomyces cerevisiae

Science.gov (United States)

Li, Gui-yin; Zhou, Zhi-de; Li, Yuan-jian; Huang, Ke-long; Zhong, Ming

2010-12-01

A novel and efficient immobilization of yeast alcohol dehydrogenase (YADH, EC1.1.1.1) from Saccharomyces cerevisiae has been developed by using the surface functionalization of chitosan-coated magnetic nanoparticles (Fe 3O 4/KCTS) as support. The magnetic Fe 3O 4/KCTS nanoparticles were prepared by binding chitosan alpha-ketoglutaric acid (KCTS) onto the surface of magnetic Fe 3O 4 nanoparticles. Later, covalent immobilization of YADH was attempted onto the Fe 3O 4/KCTS nanoparticles. The effect of various preparation conditions on the immobilized YADH process such as immobilization time, enzyme concentration and pH was investigated. The influence of pH and temperature on the activity of the free and immobilized YADH using phenylglyoxylic acid as substrate has also been studied. The optimum reaction temperature and pH value for the enzymatic conversion catalyzed by the immobilized YADH were 30 °C and 7.4, respectively. Compared to the free enzyme, the immobilized YADH retained 65% of its original activity and exhibited significant thermal stability and good durability.

Preparation and characterization of (3-aminopropyl)triethoxysilane-coated magnetite nanoparticles

International Nuclear Information System (INIS)

Yamaura, M.; Camilo, R.L.; Sampaio, L.C.; Macedo, M.A.; Nakamura, M.; Toma, H.E.

2004-01-01

Magnetite nanoparticles coated with (3-aminopropyl)triethoxysilane, NH 2 (CH 2 ) 3 Si(OC 2 H 5 ) 3 , were prepared by silanization reaction and characterized by X-ray diffractometry, transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy and magnetization measurements. Both uncoated and organosilane-coated magnetite exhibited superparamagnetic behavior and strong magnetization at room temperature. Basic groups anchored on the external surface of the coated magnetite were observed. The superparamagnetic particles of coated magnetite are able to bind to biological molecules, drugs and metals and in this way remove them from medium by magnetic separation procedures

Incorporation and release of drug into/from superparamagnetic iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Maver, Uros; Bele, Marjan [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia); Makovec, Darko; Campelj, Stanislav [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Jamnik, Janko [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia); Gaberscek, Miran [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia)], E-mail: miran.gaberscek@ki.si

2009-10-15

The aim of this study was to attach a model drug (naproxen) onto superparamagnetic iron oxide nanoparticles (SPION). First, SPION were coated with thin layer of silica that contained micropores. We demonstrated that such surface functionalization could be optimized by the use of citric acid which prevented SPION agglomeration during the procedure. HRTEM investigation showed a uniform 1-2-nm-thick silica coating around SPION. This coating did not affect significantly the magnetic properties of the SPION. Into the coated SPION we successfully incorporated about 30 wt% of naproxen. The latter was readily released after immersion into a testing solution. The composites could be interesting for potential use in diagnostics.

Incorporation and release of drug into/from superparamagnetic iron oxide nanoparticles

International Nuclear Information System (INIS)

Maver, Uros; Bele, Marjan; Makovec, Darko; Campelj, Stanislav; Jamnik, Janko; Gaberscek, Miran

2009-01-01

The aim of this study was to attach a model drug (naproxen) onto superparamagnetic iron oxide nanoparticles (SPION). First, SPION were coated with thin layer of silica that contained micropores. We demonstrated that such surface functionalization could be optimized by the use of citric acid which prevented SPION agglomeration during the procedure. HRTEM investigation showed a uniform 1-2-nm-thick silica coating around SPION. This coating did not affect significantly the magnetic properties of the SPION. Into the coated SPION we successfully incorporated about 30 wt% of naproxen. The latter was readily released after immersion into a testing solution. The composites could be interesting for potential use in diagnostics.

Impact of the Excitation Source and Plasmonic Material on Cylindrical Active Coated Nano-Particles

DEFF Research Database (Denmark)

Arslanagic, Samel; Liu, Yan; Malureanu, Radu

2011-01-01

Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles...

Dielectrophoresis-magnetophoresis force driven magnetic nanoparticle movement in transformer oil based magnetic fluids.

Science.gov (United States)

Lee, Jong-Chul; Lee, Sangyoup

2013-09-01

Magnetic fluid is a stable colloidal mixture contained magnetic nanoparticles coated with a surfactant. Recently, it was found that the fluid has properties to increase heat transfer and dielectric characteristics due to the added magnetic nanoparticles in transformer oils. The magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength when the electric field is applied. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field. The behaviors of magnetic nanoparticles in both the fields must play an important role in changing the heat transfer and dielectric characteristics of the fluids. In this study, we visualized the movement of magnetic nanoparticles influenced by both the fields applied in-situ. It was found that the magnetic nanoparticles travel in the region near the electrode by the electric field and form long chains along the field direction by the magnetic field. It can be inferred that the movement of magnetic nanoparticles appears by both the fields, and the breakdown voltage of transformer oil based magnetic fluids might be influenced according to the dispersion of magnetic nanoparticles.

Fabrication of silica-coated gold nanorods and investigation of their property of photothermal conversion

International Nuclear Information System (INIS)

Inose, Tomoya; Oikawa, Takahiro; Shibuya, Kyosuke; Tokunaga, Masayuki; Hatoyama, Keiichiro; Nakashima, Kouichi; Kamei, Takashi; Gonda, Kohsuke; Kobayashi, Yoshio

2017-01-01

This study described the preparation of silica-coated Au nanorods (AuNR/SiO 2 ) in a colloidal solution, assessed their property of photothermal conversion, and investigated their ability to kill cancer cells using photothermal conversion. Au-seed nanoparticles were produced by reducing hydrogen tetrachloroaurate (HAuCl 4 ) with sodium borohydride (NaBH 4 ) in aqueous n-hexadecyltrimethylammonium bromide (CTAB) solution. AuNRs were then fabricated by reducing HAuCl 4 and silver nitrate (AgNO 3 ) with L-ascorbic acid in the aqueous CTAB solution in the presence of Au-seed nanoparticles. The as-prepared AuNRs were washed by a process composed mainly of centrifugation to remove the CTAB. The washed AuNRs were coated with silica by mixing the AuNR colloidal solution, an aqueous solution of (3-aminopropyl)trimethoxysilane, and tetraethylorthosilicate/ethanol solution with a water/ethanol solution. We found that the addition of AuNR/SiO 2 in water, in mice, and in a culture medium with cancer cells, followed by irradiation with a laser, cause an increase in temperature, demonstrating that AuNR/SiO 2 have the ability of photothermal conversion. In addition, the cancer cells in the culture medium were found to be killed due to the increase in temperature caused by the photothermal conversion. - Highlights: • This study described the preparation of silica-coated Au nanorods (AuNR/SiO 2 ) colloidal solution. • The AuNR/SiO 2 had the ability of photothermal conversion. • The AuNR/SiO 2 also had the ability to kill cancer cells using the photothermal conversion.

Quantification of the aggregation of magnetic nanoparticles with different polymeric coatings in cell culture medium

International Nuclear Information System (INIS)

Eberbeck, D; Zirpel, P; Trahms, L; Kettering, M; Hilger, I; Bergemann, C

2010-01-01

The knowledge of the physico-chemical characteristics of magnetic nanoparticles (MNPs) is essential to enhance the efficacy of MNP-based therapeutic treatments (e.g. magnetic heating, magnetic drug targeting). According to the literature, the MNP uptake by cells may depend on the coating of MNPs, the surrounding medium as well as on the aggregation behaviour of the MNPs. Therefore, in this study, the aggregation behaviour of MNPs in various media was investigated. MNPs with different coatings were suspended in cell culture medium (CCM) containing fetal calf serum (FCS) and the distribution of the hydrodynamic sizes was measured by magnetorelaxometry (MRX). FCS as well as bovine serum albumin (BSA) buffer (phosphate buffered saline with 0.1% bovine serum albumin) may induce MNP aggregation. Its strength depends crucially on the type of coating. The degree of aggregation in CCM depends on its FCS content showing a clear, local maximum at FCS concentrations, where the IgG concentration (part of FCS) is of the order of the MNP number concentration. Thus, we attribute the observed aggregation behaviour to the mechanism of agglutination of MNPs by serum compartments as for example IgG. No aggregation was induced for MNPs coated with dextran, polyarabic acid or sodium phosphate, respectively, which were colloidally stable in CCM.

Perhydropolysilazane derived silica coating protecting Kapton from atomic oxygen attack

Energy Technology Data Exchange (ETDEWEB)

Hu Longfei [China Academy of Aerospace Aerodynamics, Beijing 100074 (China); Li Meishuan, E-mail: mshli@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xu Caihong; Luo Yongming [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

2011-11-30

By using surface sol-gel method with perhydropolysilazane (PHPS) as a precursor, a silica coating was prepared on a Kapton substrate as an atomic oxygen (AO) protective coating. The AO exposure tests were conducted in a ground-based simulator. It is found that the erosion yield of Kapton decreases by about three orders of magnitude after the superficial application of the coating. After AO exposure, the surface of the coating is smooth and uniform, no surface shrinkage induced cracks or undercutting erosion are observed. This is because that during AO exposure the PHPS is oxidized directly to form SiO{sub 2} without through intermediate reaction processes, the surface shrinkage and cracking tendency are prohibited. Meanwhile, this PHPS derived silica coating also presents self-healing effect due to the oxidation of free Si. Compared with other kinds of silica or organic polymer coatings, this PHPS derived silica coating exhibits a superior AO erosion resistance.

Perhydropolysilazane derived silica coating protecting Kapton from atomic oxygen attack

International Nuclear Information System (INIS)

Hu Longfei; Li Meishuan; Xu Caihong; Luo Yongming

2011-01-01

By using surface sol–gel method with perhydropolysilazane (PHPS) as a precursor, a silica coating was prepared on a Kapton substrate as an atomic oxygen (AO) protective coating. The AO exposure tests were conducted in a ground-based simulator. It is found that the erosion yield of Kapton decreases by about three orders of magnitude after the superficial application of the coating. After AO exposure, the surface of the coating is smooth and uniform, no surface shrinkage induced cracks or undercutting erosion are observed. This is because that during AO exposure the PHPS is oxidized directly to form SiO 2 without through intermediate reaction processes, the surface shrinkage and cracking tendency are prohibited. Meanwhile, this PHPS derived silica coating also presents self-healing effect due to the oxidation of free Si. Compared with other kinds of silica or organic polymer coatings, this PHPS derived silica coating exhibits a superior AO erosion resistance.

Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles.

Science.gov (United States)

Alzahrani, Eman

2015-01-01

The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs) using a coprecipitation method, followed by coating with silver (Ag) in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX) spectroscopy, and X-ray diffraction (XRD) analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48 nm, and the average particle size changed to 55 nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln⁡(C o /C) and the irradiation time was found to be linear. Ag-Fe3O4 nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step.

Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles

Directory of Open Access Journals (Sweden)

Eman Alzahrani

2015-01-01

Full Text Available The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs using a coprecipitation method, followed by coating with silver (Ag in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM, transmission electron microscopy (TEM, energy-dispersive X-ray (EDAX spectroscopy, and X-ray diffraction (XRD analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48 nm, and the average particle size changed to 55 nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln⁡(Co/C and the irradiation time was found to be linear. Ag-Fe3O4 nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step.

PAMAM dendrimer-coated iron oxide nanoparticles: synthesis and characterization of different generations

International Nuclear Information System (INIS)

Khodadust, Rouhollah; Unsoy, Gozde; Yalcın, Serap; Gunduz, Gungor; Gunduz, Ufuk

2013-01-01

This study focuses on the synthesis and characterization of different generations (G 0 –G 7 ) of polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles (DcMNPs). In this study, superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method. The synthesized nanoparticles were modified with aminopropyltrimethoxysilane for dendrimer coating. Aminosilane-modified MNPs were coated with PAMAM dendrimer. The characterization of synthesized nanoparticles was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering, and vibrating sample magnetometry (VSM) analyses. TEM images demonstrated that the DcMNPs have monodisperse size distribution with an average particle diameter of 16 ± 5 nm. DcMNPs were found to be superparamagnetic through VSM analysis. The synthesis, aminosilane modification, and dendrimer coating of iron oxide nanoparticles were validated by FTIR and XPS analyses. Cellular internalization of nanoparticles was studied by inverted light scattering microscopy, and cytotoxicity was determined by XTT analysis. Results demonstrated that the synthesized DcMNPs, with their functional groups, symmetry perfection, size distribution, improved magnetic properties, and nontoxic characteristics could be suitable nanocarriers for targeted cancer therapy upon loading with various anticancer agents.