Enhancing production and cytotoxic activity of polymeric soluble FasL-based chimeric proteins by concomitant expression of soluble FasL.

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Aurore Morello

Full Text Available Membrane FasL is the natural trigger of Fas-mediated apoptosis. A soluble homotrimeric counterpart (sFasL also exists which is very weakly active, and needs oligomerization beyond its trimeric state to induce apoptosis. We recently generated a soluble FasL chimera by fusing the immunoglobulin-like domain of the leukemia inhibitory factor receptor gp190 to the extracellular region of human FasL, which enabled spontaneous dodecameric homotypic polymerization of FasL. This polymeric soluble human FasL (pFasL displayed anti-tumoral activity in vitro and in vivo without systemic cytotoxicity in mouse. In the present work, we focused on the improvement of pFasL, with two complementary objectives. First, we developed more complex pFasL-based chimeras that contained a cell-targeting module. Secondly, we attempted to improve the production and/or the specific activity of pFasL and of the cell-targeting chimeras. We designed two chimeras by fusing to pFasL the extracellular portions of the HLA-A2 molecule or of a human gamma-delta TCR, and analyzed the consequences of co-expressing these molecules or pFasL together with sFasL on their heterotopic cell production. This strategy significantly enhanced the production of pFasL and of the two chimeras, as well as the cytotoxic activity of the two chimeras but not of pFasL. These results provide the proof of concept for an optimization of FasL-based chimeric proteins for a therapeutic use.

pH-sensitive polymeric nanoparticles to improve oral bioavailability of peptide/protein drugs and poorly water-soluble drugs.

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Wang, Xue-Qing; Zhang, Qiang

2012-10-01

pH-sensitive polymeric nanoparticles are promising for oral drug delivery, especially for peptide/protein drugs and poorly water-soluble medicines. This review describes current status of pH-sensitive polymeric nanoparticles for oral drug delivery and introduces the mechanisms of drug release from them as well as possible reasons for absorption improvement, with emphasis on our contribution to this field. pH-sensitive polymeric nanoparticles are prepared mainly with polyanions, polycations, their mixtures or cross-linked polymers. The mechanisms of drug release are the result of carriers' dissolution, swelling or both of them at specific pH. The possible reasons for improvement of oral bioavailability include the following: improve drug stability, enhance mucoadhesion, prolong resident time in GI tract, ameliorate intestinal permeability and increase saturation solubility and dissolution rate for poorly water-soluble drugs. As for the advantages of pH-sensitive nanoparticles over conventional nanoparticles, we conclude that (1) most carriers used are enteric-coating materials and their safety has been approved. (2) The rapid dissolution or swelling of carriers at specific pH results in quick drug release and high drug concentration gradient, which is helpful for absorption. (3) At the specific pH carriers dissolve or swell, and the bioadhesion of carriers to mucosa becomes high because nanoparticles turn from solid to gel, which can facilitate drug absorption. Copyright © 2012 Elsevier B.V. All rights reserved.

Pentosan-derived water-soluble carbon nano dots with substantial fluorescence: Properties and application as a photosensitizer

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Wu, Qiong; Li, Wei; Wu, Yanjiao; Huang, Zhanhua; Liu, Shouxin

2014-10-01

The hydrothermal carbonization of monosaccharides and polysaccharides is widely used in the production of carbonaceous material with a desired structure. However, the liquid products are regarded as waste and discarded. Here, we report a facile approach for the synthesis of water-soluble carbon nano dots (CNDs) with substantial fluorescence from the liquid by-products of the hydrothermal carbonization of pentosan, thus the by-products of pulp refining. The synthesized CNDs are monodispersed spheres with abundant oxygen-containing groups and they have an average size of 30 nm. Quantum yield measurements revealed CNDs with substantial green photoluminescence (PL) without passivation. Additionally, excitation was independent, pH-sensitive and stable. The use of CNDs as a photosensitizer in the CNDs/TiO2 system for methylene blue (MB) degradation under visible light irradiation is attractive. The spectral response range of the CNDs/TiO2 system can be widened from the UV region to a part of the visible light region (400-550 nm).

Ring-opening polymerization of 19-electron [2]cobaltocenophanes: a route to high-molecular-weight, water-soluble polycobaltocenium polyelectrolytes.

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Mayer, Ulrich F J; Gilroy, Joe B; O'Hare, Dermot; Manners, Ian

2009-08-05

Water-soluble, high-molecular-weight polycobaltocenium polyelectrolytes have been prepared by ring-opening polymerization (ROP) techniques. Anionic polymerization of a strained 19-electron dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium chloride resulted in the formation of oligomers with up to nine repeat units. Thermal ROP of dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium nitrate resulted in the formation of high-molecular-weight polycobaltocenium nitrate, a redox-active cobalt-containing polyelectrolyte.

Newly Synthesized Water Soluble Cholinium-Purpurin Photosensitizers and Their Stabilized Gold Nanoparticles as Promising Anticancer Agents

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Young Key Shim

2008-05-01

Full Text Available For possible future use in Photodynamic Therapy (PDT and/or Photothermal Therapy (PTT of cancer and screening of cancer cells a new type of ionic liquid photosensitizer –Cholinium-Purpurin-18 (Chol-Pu-18 – was synthesized and small gold (Au nanoparticles, stabilized by this photosensitizer were prepared without adding any particular reducing agents and CTAB. UV-Vis spectroscopy and Transmission Electron Microscopy (TEM were used for characterization of the nanoparticles and FAB-MS and NMR of the ionic liquid choline hydroxide, purpurin carboxylate and their ionic liquid type of photosensitizer were obtained.

Amphiphilic polymeric micelles as the nanocarrier for peroral delivery of poorly soluble anticancer drugs.

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Tian, Ye; Mao, Shirui

2012-06-01

Many amphiphilic copolymers have recently been synthesized as novel promising micellar carriers for the delivery of poorly water-soluble anticancer drugs. Studies on the formulation and oral delivery of such micelles have demonstrated their efficacy in enhancing drug uptake and absorption, and exhibit prolonged circulation time in vitro and in vivo. In this review, literature on hydrophobic modifications of several hydrophilic polymers, including polyethylene glycol, chitosan, hyaluronic acid, pluronic and tocopheryl polyethylene glycol succinate, is summarized. Parameters influencing the properties of polymeric micelles for oral chemotherapy are discussed and strategies to overcome main barriers for polymeric micelles peroral absorption are proposed. During the design of polymeric micelles for peroral chemotherapy, selecting or synthesizing copolymers with good compatibility with the drug is an effective strategy to increase drug loading and encapsulation efficiency. Stability of the micelles can be improved in different ways. It is recommended to take permeability, mucoadhesion, sustained release, and P-glycoprotein inhibition into consideration during copolymer preparation or to consider adding some excipients in the formulation. Furthermore, both the copolymer structure and drug loading methods should be controlled in order to get micelles with appropriate particle size for better absorption.

Encapsulation of curcumin in polymeric nanoparticles for antimicrobial Photodynamic Therapy.

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Jeffersson Krishan Trigo Gutierrez

Full Text Available Curcumin (CUR has been used as photosensitizer in antimicrobial Photodynamic Therapy (aPDT. However its poor water solubility, instability, and scarce bioavalibility hinder its in vivo application. The aim of this study was to synthesize curcumin in polymeric nanoparticles (NP and to evaluate their antimicrobial photodynamic effect and cytoxicity. CUR in anionic and cationic NP was synthesized using polylactic acid and dextran sulfate by the nanoprecipitation method. For cationic NP, cetyltrimethylammonium bromide was added. CUR-NP were characterized by physicochemical properties, photodegradation, encapsulation efficiency and release of curcumin from nanoparticles. CUR-NP was compared with free CUR in 10% dimethyl sulfoxide (DMSO as a photosensitizer for aPDT against planktonic and biofilms (mono-, dual- and triple-species cultures of Streptococcus mutans, Candida albicans and Methicillin-Resistant Staphylococcus aureus. The cytotoxicity effect of formulations was evaluated on keratinocytes. Data were analysed by parametric (ANOVA and non-parametric (Kruskal-Wallis tests (α = 0.05. CUR-NP showed alteration in the physicochemical properties along time, photodegradation similar to free curcumin, encapsulation efficiency up to 67%, and 96% of release after 48h. After aPDT planktonic cultures showed reductions from 0.78 log10 to complete eradication, while biofilms showed no antimicrobial effect or reductions up to 4.44 log10. Anionic CUR-NP showed reduced photoinactivation of biofilms. Cationic CUR-NP showed microbicidal effect even in absence of light. Anionic formulations showed no cytotoxic effect compared with free CUR and cationic CUR-NP and NP. The synthesized formulations improved the water solubility of CUR, showed higher antimicrobial photodynamic effect for planktonic cultures than for biofilms, and the encapsulation of CUR in anionic NP reduced the cytotoxicity of 10% DMSO used for free CUR.

Encapsulation of curcumin in polymeric nanoparticles for antimicrobial Photodynamic Therapy

Science.gov (United States)

Trigo Gutierrez, Jeffersson Krishan; Zanatta, Gabriela Cristina; Ortega, Ana Laura Mira; Balastegui, Maria Isabella Cuba; Sanitá, Paula Volpato; Pavarina, Ana Cláudia; Barbugli, Paula Aboud

2017-01-01

Curcumin (CUR) has been used as photosensitizer in antimicrobial Photodynamic Therapy (aPDT). However its poor water solubility, instability, and scarce bioavalibility hinder its in vivo application. The aim of this study was to synthesize curcumin in polymeric nanoparticles (NP) and to evaluate their antimicrobial photodynamic effect and cytoxicity. CUR in anionic and cationic NP was synthesized using polylactic acid and dextran sulfate by the nanoprecipitation method. For cationic NP, cetyltrimethylammonium bromide was added. CUR-NP were characterized by physicochemical properties, photodegradation, encapsulation efficiency and release of curcumin from nanoparticles. CUR-NP was compared with free CUR in 10% dimethyl sulfoxide (DMSO) as a photosensitizer for aPDT against planktonic and biofilms (mono-, dual- and triple-species) cultures of Streptococcus mutans, Candida albicans and Methicillin-Resistant Staphylococcus aureus. The cytotoxicity effect of formulations was evaluated on keratinocytes. Data were analysed by parametric (ANOVA) and non-parametric (Kruskal-Wallis) tests (α = 0.05). CUR-NP showed alteration in the physicochemical properties along time, photodegradation similar to free curcumin, encapsulation efficiency up to 67%, and 96% of release after 48h. After aPDT planktonic cultures showed reductions from 0.78 log10 to complete eradication, while biofilms showed no antimicrobial effect or reductions up to 4.44 log10. Anionic CUR-NP showed reduced photoinactivation of biofilms. Cationic CUR-NP showed microbicidal effect even in absence of light. Anionic formulations showed no cytotoxic effect compared with free CUR and cationic CUR-NP and NP. The synthesized formulations improved the water solubility of CUR, showed higher antimicrobial photodynamic effect for planktonic cultures than for biofilms, and the encapsulation of CUR in anionic NP reduced the cytotoxicity of 10% DMSO used for free CUR. PMID:29107978

Novel one-component polymeric benzophenone photoinitiator containing poly (ethylene glycol) as hydrogen donor

Energy Technology Data Exchange (ETDEWEB)

Wang, Kemin, E-mail: wangkm61@gmail.com; Lu, Yuhui; Chen, Penghui; Shi, Jingsong; Wang, Hongning; Yu, Qiang, E-mail: yuqiang@cczu.edu.cn

2014-02-14

Benzophenone (BP) is a common initiator which is often used in the UV-curing production and related fields. However, the shortcomings such as toxicity, odor, and migration always limit the development of the traditional BP photoinitiator. Polymeric benzophenone photoinitiator (PEG-BP) was synthesized basing on polyethylene glycol (PEG), succinic anhydride, 4-hydroxybenzophenone and epichlorohydrin. The structure of PEG-BP was characterized by IR and {sup 1}H NMR. The radiation absorption of PEG-BP was detected by UV spectrophotometer with the maximum absorption wavelength at 283 nm in acetonitrile solvent, undergone significant redshift corresponding to small molecule photoinitiator BP, thus enhanced the photosensitive efficiency of UV-curing system in the long wavelength region. Besides, PEG-BP has better water solubility than BP, thus could be used in both oil and aqueous solution. The obvious advantage of this initiator was the elimination of amine based hydrogen donors and to provide alternative hydrogen donors with easily availability and non-toxicity. The effects of molecular weights of PEG-BP, photoinitiator concentration, UV-radiation intensity and different monomers on photopolymerization kinetics were investigated in detail. The synthesized polymeric photoinitiators are attractive to be used as type II photoinitiators. - Highlights: • Novel one-component polymeric benzophenone photoinitiator was synthesized. • This photoinitiator contained poly (ethylene glycol) as hydrogen donor. • This photoinitiator was the elimination of amine based hydrogen donors.

Solvent-Free Polymerization of L-Aspartic Acid in the Presence of D-Sorbitol to Obtain Water Soluble or Network Copolymers

Science.gov (United States)

L-aspartic acid was thermally polymerized in the presence of D-sorbitol with the goal of synthesizing new, higher molecular weight water soluble and absorbent copolymers. No reaction occurred when aspartic acid alone was heated at 170 or 200 degrees C. In contrast, heating sorbitol and aspartic ac...

Trifluoromethyl Boron Dipyrromethene Derivatives as Potential Photosensitizers for Photodynamic Therapy

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Jian-Yong Liu

2018-02-01

Full Text Available In this study, two novel boron dipyrromethene-based photosensitizers (BDP3 and BDP6 substituted with three or six trifluoromethyl groups have been synthesized and characterized with various spectroscopic methods, and their photo-physical, photo-chemical, and photo-biological properties have also been explored. The two photosensitizers are highly soluble and remain nonaggregated in N,N-dimethylformamide as shown by the intense and sharp Q-band absorption. Under red light irradiation (λ = 660 nm, 1.5 J/cm2, both photosensitizers show high and comparable cytotoxicity towards HepG2 human hepatocarcinoma and HeLa human cervical carcinoma cells with IC50 values of 0.42–0.49 μM. The high photocytotoxicity of BDP3 and BDP6 can be due to their high cellular uptake and low aggregation tendency in biological media, which result in a high efficiency to generate reactive oxygen species inside the cells. Confocal laser fluorescence microscopic studies indicate that they have superior selective affinities to the mitochondria and lysosomes of HepG2 and HeLa cells. The results show that these two trifluoromethyl boron dipyrromethene derivatives are potential anticancer agents for photodynamic therapy.

Study of photosensitization reaction progress in a 96 well plate with photosensitizer rich condition using Talaporfin sodium

Science.gov (United States)

Ogawa, Emiyu; Takahashi, Mei; Arai, Tsunenori

2013-02-01

To quantitatively investigate photosensitization reaction in vitro against myocardial cells with photosensitizer rich condition in solution using Talaporfin sodium in the well of a 96 well plate, we studied photosensitization reaction progress in this well. We have proposed non-thermal conduction block of myocardium tissue using the photosensitization reaction with laser irradiation shortly after Talaporfin sodium injection. In above situation, the photosensitizer is located outside the myocardial cells in high concentration. To understand interaction of the photosensitization reaction in which the photosensitizer distributes outside cells, the photosensitization reaction progress in the well was studied. Talaporfin sodium (799.69 MW) solution and a 663 nm diode laser were used. The photosensitizer solution concentrations of 12.5-37.5 μM were employed. The photosensitizer fluorescence with 0.29 W/cm2 in irradiance, which was optimized in previous cell death study, was measured during the laser irradiation until 40 J/cm2. The photosensitizer solution absorbance and dissolved oxygen pressure after the laser irradiation were also measured. We found that the photosensitization reaction progress had 2 distinctive phases of different reaction rate: rapid photosensitization reaction consuming dissolved oxygen and gentle photosensitization reaction with oxygen diffusion from the solution-air boundary. The dissolved oxygen pressure and photosensitizer solution absorbance were 30% and 80% of the initial values after the laser irradiation, respectively. Therefore, oxygen was rate-controlling factor of the photosensitization reaction in the well with the photosensitizer rich condition. In the oxygen diffusion phase, the oxygen pressure was maintained around 40 mmHg until the laser irradiation of 40 J/cm2 and it is similar to that of myocardium tissue in vivo. We think that our 96 well plate in vitro system may simulate PDT in myocardial tissue with photosensitization reaction

RAFT Aqueous Dispersion Polymerization of N-(2-(Methacryloyloxy)ethyl)pyrrolidone: A Convenient Low Viscosity Route to High Molecular Weight Water-Soluble Copolymers.

Science.gov (United States)

Cunningham, Victoria J; Derry, Matthew J; Fielding, Lee A; Musa, Osama M; Armes, Steven P

2016-06-28

RAFT solution polymerization of N -(2-(methacryoyloxy)ethyl)pyrrolidone (NMEP) in ethanol at 70 °C was conducted to produce a series of PNMEP homopolymers with mean degrees of polymerization (DP) varying from 31 to 467. Turbidimetry was used to assess their inverse temperature solubility behavior in dilute aqueous solution, with an LCST of approximately 55 °C being observed in the high molecular weight limit. Then a poly(glycerol monomethacylate) (PGMA) macro-CTA with a mean DP of 63 was chain-extended with NMEP using a RAFT aqueous dispersion polymerization formulation at 70 °C. The target PNMEP DP was systematically varied from 100 up to 6000 to generate a series of PGMA 63 -PNMEP x diblock copolymers. High conversions (≥92%) could be achieved when targeting up to x = 5000. GPC analysis confirmed high blocking efficiencies and a linear evolution in M n with increasing PNMEP DP. A gradual increase in M w / M n was also observed when targeting higher DPs. However, this problem could be minimized ( M w / M n RAFT aqueous dispersion polymerization of NMEP was approximately four times faster than the RAFT solution polymerization of NMEP in ethanol when targeting the same DP in each case. This is perhaps surprising because both 1 H NMR and SAXS studies indicate that the core-forming PNMEP chains remain relatively solvated at 70 °C in the latter formulation. Moreover, dissolution of the initial PGMA 63 -PNMEP x particles occurs on cooling from 70 to 20 °C as the PNMEP block passes through its LCST. Hence this RAFT aqueous dispersion polymerization formulation offers an efficient route to a high molecular weight water-soluble polymer in a rather convenient low-viscosity form. Finally, the relatively expensive PGMA macro-CTA was replaced with a poly(methacrylic acid) (PMAA) macro-CTA. High conversions were also achieved for PMAA 85 -PNMEP x diblock copolymers prepared via RAFT aqueous dispersion polymerization for x ≤ 4000. Again, better control was achieved when

Method of polymerizing ethylenically unsaturated materials by irradiation and composition for use therein

International Nuclear Information System (INIS)

Nemcek, J.; Heap, N.

1976-01-01

This patent concerns photopolymerizable compositions consisting essentially of at least one polymerizable ethylenically unsaturated material and a photosensitive catalyst comprising (a) from 0.5 to 5 percent based on the ethylenically unsaturated material of at least one photosensitizer having the structure Ph(CO)C 2 A(CO)Ph, where Ph is phenyl, halogen-substituted phenyl, phenylene or halogen-substituted phenylene and A is a cyclic hydrocarbyl group, a halogen-substituted cyclic hydrocarbyl group, or a group of the formula X(NR)COCONRY, where X and Y each is hydrogen, a hydrocarbyl, or a halogen-substituted hydrocarbyl group, and (b) from 1 to 5 percent by weight based on the ethylenically unsaturated material of a reducing agent capable of reducing the photosensitizer when the photosensitizer is in an excited state. Also described is a process of preparing polymeric materials by irradiating the foregoing polymerizable composition at a wavelength capable of exciting the photosensitizer to an excited state

Advanced smart-photosensitizers for more effective cancer treatment.

Science.gov (United States)

Park, Wooram; Cho, Soojeong; Han, Jieun; Shin, Heejun; Na, Kun; Lee, Byeongdu; Kim, Dong-Hyun

2017-12-19

Photodynamic therapy (PDT) based upon the use of light and photosensitizers (PSs) has been used as a novel treatment approach for a variety of tumors. It, however, has several major limitations in the clinic: poor water solubility, long-term phototoxicity, low tumor targeting efficacy, and limited light penetration. With advances in nanotechnology, materials science, and clinical interventional imaging procedures, various smart-PSs have been developed for improving their cancer-therapeutic efficacy while reducing the adverse effects. Here, we briefly review state-of-the-art smart-PSs and discuss the future directions of PDT technology.

The application of PS printing plate with Biimidazole photosensitive initiating systems

International Nuclear Information System (INIS)

Li Lidong; Xu Jinqi; Gao Fang; Yang Yongyuan

1999-01-01

The ultraviolet photosensitive initiating system is composed of 4,4'-bis(N,N'-dimethyl-amino)benzophenone(MK), 2-chlorohexaarylbiimidazole(o-C1-HABI) and a hydrogen donor co-initiator n-dodecyl mercaptan(SH). Under the irradiation by high pressure mercury lamp, the relationship between the photo-polymerization rate of MMA and the concentration of each component of the system, including MK, o-C1-HABI and SH, was studied. The excellent results have been obtained through studying the system's application on PS lithographic printing plate

Effect of Pluronic F127 on the photosensitizing properties of dimegine in the presence of nanoparticles

Science.gov (United States)

Aksenova, N. A.; Kardumyan, V. V.; Glagolev, N. N.; Shashkova, V. T.; Matveeva, I. A.; Timashev, P. S.; Solov'eva, A. B.

2015-08-01

It is shown that the activity of the water-soluble porphyrin photosensitizer dimegine (DMG) in the oxidation reaction of tryptophan, a test reaction for photodynamic therapy (PDT), can be enhanced by introducing silver, gold, and hydroxyapatite nanoparticles (NP) into the reaction medium if an amphiphilic polymer (AP) with the properties of a SAS is introduced into this mixture. It is concluded that the effect of enhancing the photosensitizing activity of dimegine is due to the formation of nanoparticle-Pluronic-porphyrin triple systems in which Pluronic (PL) plays the role of a bridge, forming complex and adsorption bonds with porphyrin and nanoparticles.

Water sorption and solubility of bulk-fill composites polymerized with a third generation LED LCU

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Tuğba MİSİLLİ

2017-10-01

Full Text Available Abstract The aim of this study was to compare the degree of water sorption and solubility in bulk-fills after curing with a polywave light source. A total of 120 disc-shaped specimens (8 mm diameter; 4 mm depth were prepared from three regular bulk-fill materials (X-tra Fil, Tetric N-Ceram Bulk Fill, SonicFill, and a control material (Filtek Z250, cured in 3 different modes (standard: 1000 mW/cm2-20 s; high power: 1400 mW/cm2-12 s; xtra power: 3200 mW/cm2-6 s using a third generation light-emitting diode light curing unit. Water sorption and solubility levels of the specimens were measured according to the ISO 4049:2009 specification after storing in distilled water for 30 days. Data were analyzed using two-way ANOVA and Tukey’s post-hoc test (p < 0.05. The Z250 sample exposed to high power presented a higher sorption compared to the X-tra Fil and SonicFill samples. In xtra power mode, the values of Z250 and SonicFill were similar to each other and higher compared to those of X-tra Fil. Only SonicFill exhibited significantly different sorption values depending on the curing mode, the highest of which was achieved when using the xtra power mode. The highest solubility values were obtained for SonicFill. No statistically significant differences were found among other groups. No significant correlation was detected between water sorption and solubility. The traditional composite group exhibited a higher water sorption values than the bulk-fills. The reduction in polymerization time significantly increased the sorption of SonicFill. SonicFill showed the highest water solubility value among the composites tested.

Fabrication of self-written waveguide in photosensitive polyimide resin by controlling photochemical reaction of photosensitizer

International Nuclear Information System (INIS)

Yamashita, K.; Kuro, T.; Oe, K.; Mune, K.; Tagawa, K.; Naitou, R.; Mochizuki, A.

2004-01-01

We have investigated optical properties of photosensitive polyimide appropriating for long self-written waveguide fabrication. From systematic measurements of absorption properties, it was found that photochemical reaction of photosensitizer dissolved in the photosensitive polyimide resins relates to transparency after the exposure, which limits the length of the fabricated self-written waveguide. By controlling the photochemical reaction, in which the photosensitive polyimide resin has sufficient transparency during exposure, four times longer self-written waveguide core was fabricated

Photoreactivity of biologically active compounds. VIII. Photosensitized polymerization of lens proteins by antimalarial drugs in vitro.

Science.gov (United States)

Kristensen, S; Wang, R H; Tønnesen, H H; Dillon, J; Roberts, J E

1995-02-01

The drugs commonly used in the treatment of malaria are photochemically unstable. Several of these compounds cause dermal and ocular toxic reactions that may be light induced. The in vitro photopolymerization of calf lens proteins in the presence of antimalarial drugs was studied as part of a screening of the photochemical properties and phototoxic capabilities of these compounds. The pseudo-first-order rate constant for the reaction was calculated, and related to the amount of light absorbed by the compounds in order to determine the relative photosensitizing effect of each drug. The reaction mechanisms were evaluated by adding a variety of quenchers to the reaction medium during irradiation. Based on the results obtained in this study and previous knowledge about the pharmacokinetic behavior of these compounds, several of the drugs investigated have to be considered as potential photosensitizers in the human lens, the retina and the skin.

Polymer-lipid-PEG hybrid nanoparticles as photosensitizer carrier for photodynamic therapy.

Science.gov (United States)

Pramual, Sasivimon; Lirdprapamongkol, Kriengsak; Svasti, Jisnuson; Bergkvist, Magnus; Jouan-Hureaux, Valérie; Arnoux, Philippe; Frochot, Céline; Barberi-Heyob, Muriel; Niamsiri, Nuttawee

2017-08-01

Polymer-lipid-PEG hybrid nanoparticles were investigated as carriers for the photosensitizer (PS), 5,10,15,20-Tetrakis(4-hydroxy-phenyl)-21H,23H-porphine (pTHPP) for use in photodynamic therapy (PDT). A self-assembled nanoprecipitation technique was used for preparing two types of core polymers poly(d,l-lactide-co-glycolide) (PLGA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with lipid-PEG as stabilizer. The resulting nanoparticles had an average particle size of 88.5±3.4nm for PLGA and 215.0±6.3nm for PHBV. Both nanoparticles exhibited a core-shell structure under TEM with high zeta potential and loading efficiency. X-ray powder diffraction analysis showed that the encapsulated pTHPP molecules in polymeric nanoparticles no longer had peaks of free pTHPP in the crystalline state. The pTHPP molecules encapsulated inside the polymeric core demonstrated improved photophysical properties in terms of singlet oxygen generation and cellular uptake rate in a FTC-133 human thyroid carcinoma cell line, compared to non-encapsulated pTHPP. The pTHPP-loaded polymer-lipid-PEG nanoparticles showed better in vitro phototoxicity compared to free pTHPP, in both time- and concentration-dependent manners. Overall, this study provides detailed analysis of the photophysical properties of pTHPP molecules when entrapped within either PLGA or PHBV nanoparticle cores, and demonstrates the effectiveness of these systems for delivery of photosensitizers. The two polymeric systems may have different potential benefits, when used with cancer cells. For instance, the pTHPP-loaded PLGA system requires only a short time to show a PDT effect and may be suitable for topical PDT, while the delayed photo-induced cytotoxic effect of the pTHPP-loaded PHBV system may be more suitable for cancer solid tumors. Hence, both pTHPP-encapsulated polymer-lipid-PEG nanoparticles can be considered promising delivery systems for PDT cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Polymeric Cantilever Arrays for Biosensing Applications

DEFF Research Database (Denmark)

Calleja, M.; Tamayo, J.; Johansson, Alicia

2003-01-01

We report the fabrication of arrays of polymeric cantilevers for biochemistry applications. The cantilevers are fabricated in the polymer SU-8. The use of a polymer as the component material for the cantilevers provides the sensors with very high sensitivity due to convenient mechanical material...... properties. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. The method allows obtaining well-controlled and uniform mechanical properties of the cantilevers. The elastic constant of the cantilevers was measured, and their dynamic response...

Polyaniline - Carrageenan - Polyvinyl Alcohol Composite Material Synthesized Via Interfacial Polymerization, its Morphological Characteristics and Enhanced Solubility in Water

Science.gov (United States)

Montalbo, R. C. K.; Marquez, M. C.

2017-09-01

In recent years, conducting polyaniline (PAni) has been a popular interest of research in the field of conducting polymers due to its relatively low cost, ease of production, good conductivity, and environmental stability. Many studies however, have focused on improving its short-comings such as its limited processability and solubility in common solvents. In this study, PAni, soluble in water was produced via interfacial polymerization with chloroform as the organic solvent. Poly(vinyl alcohol) (PVA) and kappa(κ), iota(ι) and lambda(λ) - carrageenan (κCGN, ιCGN, λCGN) were added to the aqueous layer to stabilize PAni in the medium. FTIR and UV-Vis absorption spectra of the solutions as well as the fabricated film confirmed the existence of PAni emeraldine salt (PAni-ES). FTIR spectrum also confirmed the peaks corresponding to the interaction of PAni with the CGNs. Moreover, PVA-CGN played a very large role on the stability of the PAni nanofibers integrated on the PVA-CGN matrix. The morphologies of the products were further investigated using SEM and TEM. Polymer electrolyte for supercapacitor or an interfacial layer for organic solar cell is being targeted as potential application of the synthesized water soluble PAni.

A Photosensitizer-Loaded DNA Origami Nanosystem for Photodynamic Therapy.

Science.gov (United States)

Zhuang, Xiaoxi; Ma, Xiaowei; Xue, Xiangdong; Jiang, Qiao; Song, Linlin; Dai, Luru; Zhang, Chunqiu; Jin, Shubin; Yang, Keni; Ding, Baoquan; Wang, Paul C; Liang, Xing-Jie

2016-03-22

Photodynamic therapy (PDT) offers an alternative for cancer treatment by using ultraviolet or visible light in the presence of a photosensitizer and molecular oxygen, which can produce highly reactive oxygen species that ultimately leading to the ablation of tumor cells by multifactorial mechanisms. However, this technique is limited by the penetration depth of incident light, the hypoxic environment of solid tumors, and the vulnerability of photobleaching reduces the efficiency of many imaging agents. In this work, we reported a cellular level dual-functional imaging and PDT nanosystem BMEPC-loaded DNA origami for photodynamic therapy with high efficiency and stable photoreactive property. The carbazole derivative BMEPC is a one- and two-photon imaging agent and photosensitizer with large two-photon absorption cross section, which can be fully excited by near-infrared light, and is also capable of destroying targets under anaerobic condition by generating reactive intermediates of Type I photodynamic reactions. However, the application of BMEPC was restricted by its poor solubility in aqueous environment and its aggregation caused quenching. We observed BMEPC-loaded DNA origami effectively reduced the photobleaching of BMEPC within cells. Upon binding to DNA origami, the intramolecular rotation of BMEPC became proper restricted, which intensify fluorescence emission and radicals production when being excited. After the BMEPC-loaded DNA origami are taken up by tumor cells, upon irradiation, BMEPC could generate free radicals and be released due to DNA photocleavage as well as the following partially degradation. Apoptosis was then induced by the generation of free radicals. This functional nanosystem provides an insight into the design of photosensitizer-loaded DNA origami for effective intracellular imaging and photodynamic therapy.

Photosensitization of liposomes by porphyrins

Energy Technology Data Exchange (ETDEWEB)

Grossweiner, L I; Goyal, G C

1984-01-01

Lipid peroxidation was photosensitized in egg phosphatidylcholine (EPC) liposomes by hematoporphyrin (HP), hematoporphyrin derivative (HpD) and uroporphyrin I (Uro-I). Photosensitization by HP was type II via singlet oxygen (/sup 1/O/sub 2/) for the monomeric and dimeric states and type I for aggregated HP. Uro-I was an efficient type II /sup 1/O/sub 2/ photosensitizer. The HpD fraction enriched in the active biological component (HpD-A) was a type II /sup 1/O/sub 2/ photosensitizer at high and low concentrations. The spectral differences between HpD-A in buffer and solubilized in small EPC liposomes are attributed to a conformation change of a key dimer constituent from a folded to a planar geometry. The implications of the results for the action mechanism in photoradiation therapy of tumors with these porphyrins are discussed. 73 references, 1 figure, 5 tables.

Photosensitizers for radiation-curable coatings

International Nuclear Information System (INIS)

Cordes, W.F. III.

1977-01-01

2-Alkoxy-1,3-diphenyl-1,3-propanedione compounds have been found useful as photosensitizers in radiation-curable coating compositions. The novel photosensitizers of this invention have the structural formula in which R is an alkyl radical of from one eight carbon atoms. 11 claims

Properties of halogenated and sulfonated porphyrins relevant for the selection of photosensitizers in anticancer and antimicrobial therapies.

Directory of Open Access Journals (Sweden)

Barbara Pucelik

Full Text Available The impact of substituents on the photochemical and biological properties of tetraphenylporphyrin-based photosensitizers for photodynamic therapy of cancer (PDT as well as photodynamic inactivation of microorganisms (PDI was examined. Spectroscopic and physicochemical properties were related with therapeutic efficacy in PDT of cancer and PDI of microbial cells in vitro. Less polar halogenated, sulfonamide porphyrins were most readily taken up by cells compared to hydrophilic and anionic porphyrins. The uptake and PDT of a hydrophilic porphyrin was significantly enhanced with incorporation in polymeric micelles (Pluronic L121. Photodynamic inactivation studies were performed against Gram-positive (S. aureus, E. faecalis, Gram-negative bacteria (E. coli, P. aeruginosa, S. marcescens and fungal yeast (C. albicans. We observed a 6 logs reduction of S. aureus after irradiation (10 J/cm2 in the presence of 20 μM of hydrophilic porphyrin, but this was not improved with incorporation in Pluronic L121. A 2-3 logs reduction was obtained for E. coli using similar doses, and a decrease of 3-4 logs was achieved for C. albicans. Rational substitution of tetraphenylporphyrins improves their photodynamic properties and informs on strategies to obtain photosensitizers for efficient PDT and PDI. However, the design of the photosensitizers must be accompanied by the development of tailored drug formulations.

Probing Photosensitization by Functionalized Carbon Nanotubes

Science.gov (United States)

Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

Zero-order release of poorly water-soluble drug from polymeric films made via aqueous slurry casting.

Science.gov (United States)

Zhang, Lu; Alfano, Joy; Race, Doran; Davé, Rajesh N

2018-05-30

In spite of significant recent interest in polymeric films containing poorly water-soluble drugs, dissolution mechanism of thicker films has not been investigated. Consequently, release mechanisms of poorly water-soluble drugs from thicker hydroxypropyl methylcellulose (HPMC) films are investigated, including assessing thickness above which they exhibit zero-order drug release. Micronized, surface modified particles of griseofulvin, a model drug of BSC class II, were incorporated into aqueous slurry-cast films of different thicknesses (100, 500, 1000, 1500 and 2000 μm). Films 1000 μm and thicker were formed by either stacking two or more layers of ~500 μm, or forming a monolithic thick film. Compared to monolithic thick films, stacked films required simpler manufacturing process (easier casting, short drying time) and resulted in better critical quality attributes (appearance, uniformity of thickness and drug per unit area). Both the film forming approaches exhibited similar release profiles and followed the semi-empirical power law. As thickness increased from 100 μm to 2000 μm, the release mechanism changed from Fickian diffusion to zero-order release for films ≥1000 μm. The diffusional power law exponent, n, achieved value of 1, confirming zero-order release, whereas the percentage drug release varied linearly with sample surface area, and sample thickness due to fixed sample diameter. Thus, multi-layer hydrophilic polymer aqueous slurry-cast thick films containing poorly water-soluble drug particles provide a convenient dosage form capable of zero-order drug release with release time modulated through number of layers. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanoparticles with high payloads of pipemidic acid, a poorly soluble crystalline drug: drug-initiated polymerization and self-assembly approach

Directory of Open Access Journals (Sweden)

Elisabetta Pancani

2018-05-01

Full Text Available Nowadays, biodegradable polymers such as poly(lactic acid (PLA, poly(D,L-lactic-co-glycolic acid (PLGA and poly(ε-caprolactone (PCL remain the most common biomaterials to produce drug-loaded nanoparticles (NPs. Pipemidic acid (PIP is a poorly soluble antibiotic with a strong tendency to crystallize. PIP incorporation in PLA/PLGA NPs was challenging because of PIP crystals formation and burst release. As PIP had a poor affinity for the NPs, an alternative approach to encapsulation was used, consisting in coupling PIP to PCL. Thus, a PCL–PIP conjugate was successfully synthesized by an original drug-initiated polymerization in a single step without the need of catalyst. PCL–PIP was characterized by NMR, IR, SEC and mass spectrometry. PCL–PIP was used to prepare self-assembled NPs with PIP contents as high as 27% (w/w. The NPs were characterized by microscopy, DLS, NTA and TRPS. This study paves the way towards the production of NPs with high antibiotic payloads by drug-initiated polymerization. Further studies will deal with the synthesis of novel polymer–PIP conjugates with ester bonds between the drug and PCL. PIP can be considered as a model drug and the strategy developed here could be extended to other challenging antibiotics or anticancer drugs and employed to efficiently incorporate them in NPs. KEY WORDS: Pipemidic acid, Nanoparticle, Antibiotic, Nanoprecipitation, Crystalline drug, Drug-initiated   polymerization

New Photosensitizers for Photodynamic Therapy in Gastroenterology

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SG Bown

1999-01-01

Full Text Available Most applications of photodynamic therapy (PDT in gastroenterology to date have used porfimer sodium as the photosensitizing agent. For destroying small lesions in the wall of the gastrointestinal tract in inoperable patients, it has proved to be most effective, but attempts to achieve circumferential mucosal ablation, as in the treatment of Barrett’s esophagus, have led to a high incidence of strictures, and all patients have cutaneous photosensitivity, which can last up to three months. Two new photosensitizers are of particular interest to gastroenterologists. PDT with metatetrahydroxyphenyl chlorin produces a similar biological effect as PDT with porfimer sodium, but the light doses required are much smaller, and cutaneous photosensitivity lasts only two to three weeks. Further, it can be used with percutaneous light delivery to destroy localized pancreatic cancers. The photosensitizing agent 5-amino levulinic acid, converted in vivo into the photoactive derivative protoporphyrin IX, sensitizes the mucosa much more than the underlying layers. This makes it feasible to destroy areas of abnormal mucosa without damaging the underlying muscle and is, therefore, better for treating Barrett’s esophagus. Detailed clinical studies are required to establish the real role of PDT with the use of these and other new photosensitizers.

Soluble polymer conjugates for drug delivery.

Science.gov (United States)

Minko, Tamara

2005-01-01

The use of water-soluble polymeric conjugates as drug carriers offers several possible advantages. These advantages include: (1) improved drug pharmacokinetics; (2) decreased toxicity to healthy organs; (3) possible facilitation of accumulation and preferential uptake by targeted cells; (4) programmed profile of drug release. In this review, we will consider the main types of useful polymeric conjugates and their role and effectiveness as carriers in drug delivery systems.: © 2005 Elsevier Ltd . All rights reserved.

Adult-onset photosensitivity: clinical significance and epilepsy syndromes including idiopathic (possibly genetic) photosensitive occipital epilepsy.

Science.gov (United States)

Koutroumanidis, Michalis; Tsirka, Vasiliki; Panayiotopoulos, Chrysostomos

2015-09-01

To evaluate the clinical associations of adult-onset photosensitivity, we studied the clinical and EEG data of patients who were referred due to a possible first seizure and who had a photoparoxysmal response on their EEG. Patients with clinical evidence of photosensitivity before the age of 20 were excluded. Of a total of 30 patients, four had acute symptomatic seizures, two had vasovagal syncope, and 24 were diagnosed with epilepsy. Nine of the 24 patients had idiopathic (genetic) generalized epilepsies and predominantly generalized photoparoxysmal response, but also rare photically-induced seizures, while 15 had exclusively, or almost exclusively, reflex photically-induced occipital seizures with frequent secondary generalization and posterior photoparoxysmal response. Other important differences included a significantly older age at seizure onset and paucity of spontaneous interictal epileptic discharges in patients with photically-induced occipital seizures; only a quarter of these had occasional occipital spikes, in contrast to the idiopathic (genetic) generalized epilepsy patients with typically generalized epileptic discharges. On the other hand, both groups shared a positive family history of epilepsy, common seizure threshold modulators (such as tiredness and sleep deprivation), normal neurological examination and MRI, a generally benign course, and good response to valproic acid. We demonstrated that photosensitivity can first occur in adult life and manifest, either as idiopathic (possibly genetic) photosensitive occipital epilepsy with secondary generalization or as an EEG, and less often, a clinical/EEG feature of idiopathic (genetic) generalized epilepsies. Identification of idiopathic photosensitive occipital epilepsy fills a diagnostic gap in adult first-seizure epileptology and is clinically important because of its good response to antiepileptic drug treatment and fair prognosis.

Mechanism to preserve phrenic nerve function during photosensitization reaction: drug uptake and photosensitization reaction effect on electric propagation

Science.gov (United States)

Takahashi, Haruka; Hamada, Risa; Ogawa, Emiyu; Arai, Tsunenori

2018-02-01

To study a mechanism of phrenic nerve preservation phenomena during a photosensitization reaction, we investigated an uptake of talaporfin sodium and photosensitization reaction effect on an electric propagation. Right phrenic nerve was completely preserved after superior vena cava isolations using the photosensitization reaction in canine animal experiments, in spite of adjacent myocardium was electrically blocked. We predicted that low drug uptake and/or low photosensitization reaction effect on the nerve might be a mechanism of that phenomena. To investigate uptake to various nerve tissue, a healthy extracted crayfish ventral nerve cord and an extracted porcine phrenic nerve were immersed in 20 μg/ml talaporfin sodium solution for 0-240 min. The mean talaporfin sodium fluorescence brightness increased depending on the immersion time. This brightness saturated around the immersion time of 120 min. We found that talaporfin sodium uptake inside the perineurium which directly related to the electric propagation function was lower than that of outside in the porcine phrenic nerve. To investigate photosensitization reaction effect on electric propagation, the crayfish nerve was immersed into the same solution for 15 min and irradiated by a 663 nm laser light with 120 mW/cm2. Since we found the action potential disappeared when the irradiation time was 25-65 s, we consider that the crayfish nerve does not tolerant to the photosensitization reaction on electric propagation function at atmospheric pressure. From these results, we think that the low uptake of talaporfin sodium inside the perineurium and low oxygen partial pressure of nerve might be the possible mechanism to preserve phrenic nerve in vivo.

Photosensitized oxidation of DNA and its components

International Nuclear Information System (INIS)

Decarroz, Chantal.

1982-09-01

Chemical changes in DNA components during the photodynamic effect are responsible for Mutagenic and carcinogenic phenomena. Basically two competitive mechanisns involving respectively a charge transfer (type I) and singlet oxygen (type II) are implicated in reactions photo-sensitized by different agents (acridines, phenothiazines, porphyrins, flavins, psoralenes...). A study of the photosensitized oxidation of DNA itself was approached through characterization of the main final products in the case of purine nucleosides. Methyl-2 naphthoquinone - 1,4 (vitamin K 3 ) displays a special photosensitization mechanism involving a cation radical type of intermediary [fr

Nanobody-photosensitizer conjugates for targeted photodynamic therapy

NARCIS (Netherlands)

Heukers, Raimond; van Bergen en Henegouwen, P; Oliveira, Sabrina

2014-01-01

Photodynamic therapy (PDT) induces cell death through light activation of a photosensitizer (PS). Targeted delivery of PS via monoclonal antibodies has improved tumor selectivity. However, these conjugates have long half-lives, leading to relatively long photosensitivity in patients. In an attempt

Water-Insoluble Photosensitizer Nanocolloids Stabilized by Supramolecular Interfacial Assembly towards Photodynamic Therapy

Science.gov (United States)

Liu, Yamei; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Shen, Guizhi; Yan, Xuehai

2017-02-01

Nanoengineering of hydrophobic photosensitizers (PSs) is a promising approach for improved tumor delivery and enhanced photodynamic therapy (PDT) efficiency. A variety of delivery carriers have been developed for tumor delivery of PSs through the enhanced permeation and retention (EPR) effect. However, a high-performance PS delivery system with minimum use of carrier materials with excellent biocompatibility is highly appreciated. In this work, we utilized the spatiotemporal interfacial adhesion and assembly of supramolecular coordination to achieve the nanoengineering of water-insoluble photosensitizer Chlorin e6 (Ce6). The hydrophobic Ce6 nanoparticles are well stabilized in a aqueous medium by the interfacially-assembled film due to the coordination polymerization of tannic acid (TA) and ferric iron (Fe(III)). The resulting Ce6@TA-Fe(III) complex nanoparticles (referenced as Ce6@TA-Fe(III) NPs) significantly improves the drug loading content (~65%) and have an average size of 60 nm. The Ce6@TA-Fe(III) NPs are almost non-emissive as the aggregated states, but they can light up after intracellular internalization, which thus realizes low dark toxicity and excellent phototoxicity under laser irradiation. The Ce6@TA-Fe(III) NPs prolong blood circulation, promote tumor-selective accumulation of PSs, and enhanced antitumor efficacy in comparison to the free-carrier Ce6 in vivo evaluation.

HPMA-based polymeric micelles for curcumin solubilization and inhibition of cancer cell growth.

Science.gov (United States)

Naksuriya, Ornchuma; Shi, Yang; van Nostrum, Cornelus F; Anuchapreeda, Songyot; Hennink, Wim E; Okonogi, Siriporn

2015-08-01

Curcumin (CM) has been reported as a potential anticancer agent. However, its pharmaceutical applications as therapeutic agent are hampered because of its poor aqueous solubility. The present study explores the advantages of polymeric micelles composed of block copolymers of methoxypoly(ethylene glycol) (mPEG) and N-(2-hydroxypropyl) methacrylamide (HPMA) modified with monolactate, dilactate and benzoyl side groups to enhance CM solubility and inhibitory activity against cancer cells. Amphiphilic block copolymers, ω-methoxypoly(ethylene glycol)-b-(N-(2-benzoyloxypropyl) methacrylamide) (PEG-HPMA-Bz) were synthesized and characterized by (1)H NMR and GPC. One polymer with a molecular weight of 28,000Da was used to formulate CM and compared with other aromatic substituted polymers. CM was loaded by a fast heating method (PEG-HPMA-DL and PEG-HPMA-Bz-L) and a nanoprecipitation method (PEG-HPMA-Bz). Physicochemical characteristics and cytotoxicity/cytocompatibility of the CM loaded polymeric micelles were evaluated. It was found that HPMA-based polymeric micelles significantly enhanced the solubility of CM. The PEG-HPMA-Bz micelles showed the best solubilization properties. CM loaded polymeric micelles showed sustained release of the loading CM for more than 20days. All of CM loaded polymeric micelles formulations showed a significantly potent cytotoxic effect against three cancer cell lines. HPMA-based polymeric micelles are therefore promising nanodelivery systems of CM for cancer therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

[Pharmaceutical chemistry of drug-initiated photosensitivity].

Science.gov (United States)

Rácz, Ákos; Tóth, Lívia

2015-01-01

The photosensitivity originated from drugs is a common problem in medical and pharmaceutical practice. It is of prominent importance in drug development and in regulatory issues. The photosensitizer effect of drug substances is determined by their chemical structures, and it mainly originates from aromatic chromophore systems and photo-dissociable bonds forming free radicals. The photodegradation may happen in many different types of chemical reaction pathways. Our aim is to demonstrate in this review the interrelations between structure and photodegradation. We show examples for the different reaction types, with drugs from different pharmacologic therapeutic classes. The in vivo chemical reactivity of photodegradates of pharmaceutical substances, the in vitro methods of investigation for testing photoreactivity and phototoxicity, and briefly the clinical tests for photosensitivity disorders are also discussed.

Polymeric Micelles, a Promising Drug Delivery System to Enhance Bioavailability of Poorly Water-Soluble Drugs

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Wei Xu

2013-01-01

Full Text Available Oral administration is the most commonly used and readily accepted form of drug delivery; however, it is find that many drugs are difficult to attain enough bioavailability when administered via this route. Polymeric micelles (PMs can overcome some limitations of the oral delivery acting as carriers able to enhance drug absorption, by providing (1 protection of the loaded drug from the harsh environment of the GI tract, (2 release of the drug in a controlled manner at target sites, (3 prolongation of the residence time in the gut by mucoadhesion, and (4 inhibition of efflux pumps to improve the drug accumulation. To explain the mechanisms for enhancement of oral bioavailability, we discussed the special stability of PMs, the controlled release properties of pH-sensitive PMs, the prolongation of residence time with mucoadhesive PMs, and the P-gp inhibitors commonly used in PMs, respectively. The primary purpose of this paper is to illustrate the potential of PMs for delivery of poorly water-soluble drugs with bioavailability being well maintained.

Wetting, Solubility and Chemical Characteristics of Plasma-Polymerized 1-Isopropyl-4-Methyl-1,4-Cyclohexadiene Thin Films

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Jakaria Ahmad

2014-07-01

Full Text Available Investigations on the wetting, solubility and chemical composition of plasma polymer thin films provide an insight into the feasibility of implementing these polymeric materials in organic electronics, particularly where wet solution processing is involved. In this study, thin films were prepared from 1-isopropyl-4-methyl-1,4-cyclohexadiene (γ-Terpinene using radio frequency (RF plasma polymerization. FTIR showed the polymers to be structurally dissimilar to the original monomer and highly cross-linked, where the loss of original functional groups and the degree of cross-linking increased with deposition power. The polymer surfaces were hydrocarbon-rich, with oxygen present in the form of O–H and C=O functional groups. The oxygen content decreased with deposition power, with films becoming more hydrophobic and, thus, less wettable. The advancing and receding contact angles were investigated, and the water advancing contact angle was found to increase from 63.14° to 73.53° for thin films prepared with an RF power of 10 W to 75 W. The wetting envelopes for the surfaces were constructed to enable the prediction of the surfaces’ wettability for other solvents. The effect of roughness on the wetting behaviour of the films was insignificant. The polymers were determined to resist solubilization in solvents commonly used in the deposition of organic semiconducting layers, including chloroform and chlorobenzene, with higher stability observed in films fabricated at higher RF power.

Interfacial electron transfer dynamics of photosensitized zinc oxide nanoclusters

Energy Technology Data Exchange (ETDEWEB)

Murakoshi, Kei; Yanagida, Shozo [Osaka Univ. (Japan). Graduate School of Engineering; Capel, M. [Brookhaven National Lab., Upton, NY (United States)] [and others

1997-06-01

The authors have prepared and characterized photosensitized zinc oxide (ZnO) nanoclusters, dispersed in methanol, using carboxylated coumarin dyes for surface adsorption. Femtosecond time-resolved emission spectroscopy allows the authors to measure the photo-induced charge carrier injection rate constant from the adsorbed photosensitizer to the n-type semiconductor nanocluster. These results are compared with other photosensitized semiconductors.

Liposomal photosensitizers: potential platforms for anticancer photodynamic therapy

Directory of Open Access Journals (Sweden)

L.A. Muehlmann

2011-08-01

Full Text Available Photodynamic therapy is a well-established and clinically approved treatment for several types of cancer. Antineoplastic photodynamic therapy is based on photosensitizers, i.e., drugs that absorb photons translating light energy into a chemical potential that damages tumor tissues. Despite the encouraging clinical results with the approved photosensitizers available today, the prolonged skin phototoxicity, poor selectivity for diseased tissues, hydrophobic nature, and extended retention in the host organism shown by these drugs have stimulated researchers to develop new formulations for photodynamic therapy. In this context, due to their amphiphilic characteristic (compatibility with both hydrophobic and hydrophilic substances, liposomes have proven to be suitable carriers for photosensitizers, improving the photophysical properties of the photosensitizers. Moreover, as nanostructured drug delivery systems, liposomes improve the efficiency and safety of antineoplastic photodynamic therapy, mainly by the classical phenomenon of extended permeation and retention. Therefore, the association of photosensitizers with liposomes has been extensively studied. In this review, both current knowledge and future perspectives on liposomal carriers for antineoplastic photodynamic therapy are critically discussed.

Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products.

Science.gov (United States)

Duan, Liang; Tian, Zhiyong; Song, Yonghui; Jiang, Wei; Tian, Yuan; Li, Shan

2015-01-01

The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.

The characteristics of extracellular polymeric substances and soluble microbial products in moving bed biofilm reactor-membrane bioreactor.

Science.gov (United States)

Duan, Liang; Jiang, Wei; Song, Yonghui; Xia, Siqing; Hermanowicz, Slawomir W

2013-11-01

The characteristics of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in conventional membrane bioreactor (MBR) and in moving bed biofilm reactor-membrane bioreactors (MBBR-MBR) were investigated in long-term (170 days) experiments. The results showed that all reactors had high removal efficiency of ammonium and COD, despite very different fouling conditions. The MBBR-MBR with media fill ratio of 26.7% had much lower total membrane resistance and no obvious fouling were detected during the whole operation. In contrast, MBR and MBBR-MBR with lower and higher media fill experienced more significant fouling. Low fouling at optimum fill ratio may be due to the higher percentage of small molecular size (100 kDa) of EPS and SMP in the reactor. The composition of EPS and SMP affected fouling due to different O-H bonds in hydroxyl functional groups, and less polysaccharides and lipids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Photosensitive Strip RETHGEM

CERN Document Server

Peskov, Vladimir; Nappi, E.; Oliveira, R.; Paic, G.; Pietropaolo, F.; Picchi, P.

2008-01-01

An innovative photosensitive gaseous detector, consisting of a GEM like amplification structure with double layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen printing technology on the top of the metallic strips grid The inner metallic grid is used for 2D position measurements whereas the resistive layer provides an efficient spark protected operation at high gains - close to the breakdown limit. Detectors with active areas of 10cm x10cm and 10cm x20cm were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large area detectors for UV visualization, as for example, in Cherenkov imaging devices.

Interaction of acetamiprid with extracellular polymeric substances ...

African Journals Online (AJOL)

Extracellular polymeric substances (EPS) are important components of activated sludge and it plays an important role in removing pollutants. The interaction between EPS and organic pollutants is still little known. In the present study, the interaction of soluble/bound EPS with acetamiprid, a neonicotinoid insecticide, was ...

Photosensitivity: a current biological overview.

Science.gov (United States)

Elkeeb, Dena; Elkeeb, Laila; Maibach, Howard

2012-12-01

The level of interest in photoirritation (phototoxicity) has increased because of the awareness among the scientific community of the increase in the UV portion of the solar spectrum reaching the earth. The need of new chemicals and drugs puts pressure on pre-test methods for side effects, especially interactive adverse effects with UV light. So pre-marketing clinical trials conducted before a new drug is licensed are essential, as such, at the early phases of the discovery process of the drug/chemical, developing an efficacious photosensitivity testing system is prudent to avoid such potential side effects. To review published literature and provide an overview on exogenous photosensitivity and assays used to evaluate the photosensitivity potential of drugs/chemicals. As well as testing considerations by the Regulatory bodies (namely, the Organization for Economic Cooperation and Development, the U.S Food and Drug Administration and the European Union regulatory agencies). We searched medical and scientific search engines as well as websites of the EU and US Regulatory agencies and used keywords such as cutaneous phototoxicity, phototoxicity in vitro assays, phototoxicity in vivo assays and other related terms.

Development of Smart Phthalocyanine-based Photosensitizers for Photodynamic Therapy

Science.gov (United States)

Chow, Yun Sang

Phthalocyanines are versatile functional dyes that have shown great potential in cancer theranostics, especially in photodynamic therapy (PDT). This research work aims to develop "smart" phthalocyanine-based photosensitizers for targeted PDT. This thesis describes the synthesis, spectroscopic characterization, photophysical properties, and in vitro photodynamic activities of several series of carefully designed phthalocyanine-based photosensitizers. Chapter 1 presents an overview of PDT, including its historical development, photophysical mechanisms, and biological mechanisms. Various classes of photosensitizers are introduced with emphasis putting on phthalocyanines, which exhibit ideal characteristics of photosensitizers for PDT. In recent years, several approaches have been used to develop photosensitizers with higher tumor selectivity and minimal skin photosensitivity after PDT. Activatable photosensitizers can provide a "turn on" mechanism to offer an additional control of the specificity of treatment. Photosensitizers can also work cooperatively with the tumor-targeting groups or anticancer drugs so as to achieve targeted or dual therapy, which can enhance the efficacy of PDT. The novel approaches mentioned above have been widely used and combined to form multi-functional photosensitizing agents. These novel concepts and development of PDT are discussed and illustrated with relevant examples at the end of this chapter. To minimize the prolonged skin photosensitivity, photosensitizers that can only be activated by tumor-associated stimuli have been developed. Due to the abnormal metabolism in tumor tissues, their surface usually exhibits a lower pH compared to that of the normal tissues. Also, the pH difference between the intracellular and the physiological environment provides a pH-activation mechanism. Chapter 2 presents the synthesis and spectroscopic characterization of a pH-responsive zinc(II) phthalocyanine tetramer, in which the phthalocyanine units

Light-induced antibacterial activity of electrospun chitosan-based material containing photosensitizer

Energy Technology Data Exchange (ETDEWEB)

Severyukhina, A.N., E-mail: severyuhina_alexandra@mail.ru [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Petrova, N.V.; Yashchenok, A.M. [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Bratashov, D.N. [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Department of Nano- and Biomedical Technologies, Saratov State University, 410012 Saratov (Russian Federation); Smuda, K. [Institute of Transfusion Medicine, Charité-Universitätsmedizin, 10117 Berlin (Germany); Mamonova, I.A. [Institute of Traumatology and Orthopedics, 410002 Saratov (Russian Federation); Yurasov, N.A. [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Puchinyan, D.M. [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Institute of Traumatology and Orthopedics, 410002 Saratov (Russian Federation); Georgieva, R. [Institute of Transfusion Medicine, Charité-Universitätsmedizin, 10117 Berlin (Germany); Department of Medical Physics, Biophysics and Radiology, Medical Faculty, Trakia University, 6000 Stara Zagora (Bulgaria); Bäumler, H. [Institute of Transfusion Medicine, Charité-Universitätsmedizin, 10117 Berlin (Germany); Lapanje, A. [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Josef Stefan Institute, 1000 Ljubljana (Slovenia); Gorin, D.A. [Institute of Nanostructures and Biosystems, Saratov State University, 410012 Saratov (Russian Federation); Department of Nano- and Biomedical Technologies, Saratov State University, 410012 Saratov (Russian Federation)

2017-01-01

Increasing antimicrobial resistance requires the development of novel materials and approaches for treatment of various infections. Utilization of photodynamic therapy represents an advanced alternative to antibiotics and metal-based agents. Here, we report the fabrication of electrospun material that possesses benefits of both topical antimicrobial and photodynamic therapies. This material combines chitosan, as a biocompatible polymer, and a second generation photosensitizer. The incorporation of photosensitizer doesn't affect the material morphology and its nearly uniform distribution in fibers structure was observed by confocal Raman microscopy. Owing to photosensitizer the prepared material exhibits the light-induced and spatially limited antimicrobial activity that was demonstrated against Staphylococcus aureus, an important etiological infectious agent. Such material can be potentially used in antibacterial therapy of chronic wounds, infections of diabetic ulcers, and burns, as well as rapidly spreading and intractable soft-tissue infections caused by resistant bacteria. - Highlights: • Chitosan with a phthalocyanine photosensitizer was electrospun into fibers. • Photosensitizer was uniformly distributed in the electrospun material. • The incorporation of photosensitizer does not affect the fiber morphology. • Chitosan/photosensitizer composites possess light-induced antibacterial activity. • The antibacterial activity of the material is limited to the area of irradiation.

Acidolysis small molecular phenolic ether used as accelerator in photosensitive diazonaphthaquinone systems

Science.gov (United States)

Zhou, Haihua; Zou, Yingquan

2006-03-01

The photosensitive compounds in the photosensitive coatings of positive PS plates are the diazonaphthaquinone derivatives. Some acidolysis small molecular phenolic ethers, which were synthesized by some special polyhydroxyl phenols with vinyl ethyl ether, are added in the positive diazonaphthaquinone photosensitive composition to improve its sensitivity, composed with photo-acid-generators. The effects to the photosensitivity, anti-alkali property, anti-isopropyl alcohol property, dot resolution and line resolution of the coatings are studied with different additive percent of the special phenolic ethers. In the conventional photosensitive diazonaphthaquinone systems for positive PS plates, the photosensitivity is improved without negative effects to resolution, anti-alkali and anti-isopropyl alcohol properties when added about 5% of the special acidolysis phenolic ethers, EAAE or DPHE, composed with photo-acid-generators.

Polymeric micelles as a drug carrier for tumor targeting

Directory of Open Access Journals (Sweden)

Neha M Dand

2013-01-01

Full Text Available Polymeric micelle can be targeted to tumor site by passive and active mechanism. Some inherent properties of polymeric micelle such as size in nanorange, stability in plasma, longevity in vivo, and pathological characteristics of tumor make polymeric micelles to be targeted at the tumor site by passive mechanism called enhanced permeability and retention effect. Polymeric micelle formed from the amphiphilic block copolymer is suitable for encapsulation of poorly water soluble, hydrophobic anticancer drugs. Other characteristics of polymeric micelles such as separated functionality at the outer shell are useful for targeting the anticancer drug to tumor by active mechanisms. Polymeric micelles can be conjugated with many ligands such as antibodies fragments, epidermal growth factors, α2 -glycoprotein, transferrine, and folate to target micelles to cancer cells. Application of heat and ultrasound are the alternative methods to enhance drug accumulation in tumoral cells. Targeting using micelles can also be done to tumor angiogenesis which is the potentially promising target for anticancer drugs. This review summarizes about recently available information regarding targeting the anticancer drug to the tumor site using polymeric micelles.

Nanonization strategies for poorly water-soluble drugs.

Science.gov (United States)

Chen, Huabing; Khemtong, Chalermchai; Yang, Xiangliang; Chang, Xueling; Gao, Jinming

2011-04-01

Poor water solubility for many drugs and drug candidates remains a major obstacle to their development and clinical application. Conventional formulations to improve solubility suffer from low bioavailability and poor pharmacokinetics, with some carriers rendering systemic toxicities (e.g. Cremophor(®) EL). In this review, several major nanonization techniques that seek to overcome these limitations for drug solubilization are presented. Strategies including drug nanocrystals, nanoemulsions and polymeric micelles are reviewed. Finally, perspectives on existing challenges and future opportunities are highlighted. Published by Elsevier Ltd.

Catalytic olefin polymerization with early transition metal compounds

NARCIS (Netherlands)

Eshuis, Johan Jan Willem

1991-01-01

The catalysis of organic reactions by soluble metal complexes has become a major tool in synthesis, both in the laboratory and in the chemical industry. Processes catalyzed by transition metal complexes include carbonylation, olefin polymerization, olefin addition, olefin oxidation and alkane and

Microbial control of food-related surfaces: Na-Chlorophyllin-based photosensitization.

Science.gov (United States)

Luksiene, Zivile; Paskeviciute, Egle

2011-10-05

The aim of this study was to evaluate efficiency of photosensitization as surface sanitation alternative using model systems when food pathogens, their spores and biofilms were attached to the food-related surface (polyolefine). In addition it was important to compare antibacterial efficiency of Na-Chlorophyllin (Na-Chl)-based photosensitization with conventional sanitizers. Obtained results indicate that Bacilluscereus ATCC 12826 and Listeriamonocytogenes ATCC 7644 as well as their thermoresistant strains B.cereus SV90 and L.monocytogenes 56LY were effectively inactivated (7 log) by Na-Chl-based photosensitization in vitro. Inactivation rate of thermoresistant strains was slower. The number of attached to the surface B.cereus ATCC 12826 and L.monocytogenes ATCC 7644 was reduced from 4-4.5 log to 0 log after photosensitization treatment. To achieve adequate inactivation of thermoresistant strains the higher Na-Chl concentration and longer illumination times had to be used. Comparison of different surface decontamination treatments reveal that photosensitization is much more effective against all surface-attached B.cereus and L.monocytogenes strains than washing with water or 200 ppm Na-hypochlorite. It is important to note, that surface-attached B.cereus spores and L.monocytogenes biofilms can be eliminated from it by photosensitization as well. Our data support the idea that Na-Chlorophyllin-based photosensitization has high antibacterial potential which may serve in the future for the development of human and environment friendly, non-thermal surface decontamination technique. Copyright © 2011 Elsevier B.V. All rights reserved.

Prospects for photosensitive dopants in liquid argon

International Nuclear Information System (INIS)

Anderson, D.F.

1990-12-01

Evidence is presented that the addition of a few ppM of a photosensitive dopant to a U/liquid argon or Pb/liquid argon calorimeter will make a substantial reduction in the e/π ratio. Previous results indicating high voltage problems and no change in the e/π ratio in tests of photosensitive dopants with the Fermilab D0 experiment's U/liquid argon tests calorimeter are also explained. 13 refs., 3 figs

Polymerized soluble venom--human serum albumin

International Nuclear Information System (INIS)

Patterson, R.; Suszko, I.M.; Grammer, L.C.

1985-01-01

Extensive previous studies have demonstrated that attempts to produce polymers of Hymenoptera venoms for human immunotherapy resulted in insoluble precipitates that could be injected with safety but with very limited immunogenicity in allergic patients. We now report soluble polymers prepared by conjugating bee venom with human serum albumin with glutaraldehyde. The bee venom-albumin polymer (BVAP) preparation was fractionated on Sephacryl S-300 to have a molecular weight range higher than catalase. 125 I-labeled bee venom phospholipase A was almost completely incorporated into BVAP. Rabbit antibody responses to bee venom and bee venom phospholipase A were induced by BVAP. Human antisera against bee venom were absorbed by BVAP. No new antigenic determinants on BVAP were present as evidenced by absorption of antisera against BVAP by bee venom and albumin. BVAP has potential immunotherapeutic value in patients with anaphylactic sensitivity to bee venom

Two-photon polymerization of an epoxy-acrylate resin material system

International Nuclear Information System (INIS)

Winfield, R.J.; O'Brien, S.

2011-01-01

Improved material systems are of great interest in the development of two-photon polymerization techniques for the fabrication of three dimensional micro- and nano-structures. The properties of the photosensitive resin are important in the realisation of structures with submicron dimensions. In this study investigation of a custom organic resin, cross-linked by a two-photon induced process, using a femtosecond Ti:sapphire laser, is described. A structural, optical and mechanical analysis of the optimised material is presented. The influence of both material system and laser processing parameters on achievable micro-structure and size is presented as are representative structures. Parameters include: laser power, photo-initiator concentration and material composition.

Applications of polymeric micelles with tumor targeted in chemotherapy

International Nuclear Information System (INIS)

Ding Hui; Wang Xiaojun; Zhang Song; Liu Xinli

2012-01-01

Polymeric micelles (PMs) have gained more progress as a carrier system with the quick development of biological and nanoparticle techniques. In particular, PMs with smart targeting can deliver anti-cancer drugs directly into tumor cells at a sustained rate. PMs with core–shell structure (with diameters of 10 ∼ 100 nm) have been prepared by a variety of biodegradable and biocompatible polymers via a self-assembly process. The preparation of polymeric micelles with stimuli-responsive block copolymers or modification of target molecules on polymeric micelles’ surface are able to significantly improve the efficiency of drug delivery. Polymeric micelles, which have been considered as a novel promising drug carrier for cancer therapeutics, are rapidly evolving and being introduced in an attempt to overcome several limitations of traditional chemotherapeutics, including water solubility, tumor-specific accumulation, anti-tumor efficacy, and non-specific toxicity. This review describes the preparation of polymeric micelles and the targeted modification which greatly enhance the effects of chemotherapeutic agents.

Polymerized soluble venom--human serum albumin

Energy Technology Data Exchange (ETDEWEB)

Patterson, R.; Suszko, I.M.; Grammer, L.C.

1985-03-01

Extensive previous studies have demonstrated that attempts to produce polymers of Hymenoptera venoms for human immunotherapy resulted in insoluble precipitates that could be injected with safety but with very limited immunogenicity in allergic patients. We now report soluble polymers prepared by conjugating bee venom with human serum albumin with glutaraldehyde. The bee venom-albumin polymer (BVAP) preparation was fractionated on Sephacryl S-300 to have a molecular weight range higher than catalase. /sup 125/I-labeled bee venom phospholipase A was almost completely incorporated into BVAP. Rabbit antibody responses to bee venom and bee venom phospholipase A were induced by BVAP. Human antisera against bee venom were absorbed by BVAP. No new antigenic determinants on BVAP were present as evidenced by absorption of antisera against BVAP by bee venom and albumin. BVAP has potential immunotherapeutic value in patients with anaphylactic sensitivity to bee venom.

Novel approach to control Salmonella enterica by modern biophotonic technology: photosensitization.

Science.gov (United States)

Buchovec, I; Vaitonis, Z; Luksiene, Z

2009-03-01

Salmonellosis is one of the most common foodborne diseases in the world. The aim of this study was to evaluate the antibacterial efficiency of 5-aminolevulinic acid (ALA) based photosensitization against one of food pathogens Salmonella enterica. Salmonella enterica was incubated with ALA (7.5 mmol l(-1)) for 1-4 h and afterwards illuminated with visible light. The light source used for illumination of S. enterica emitted light lambda = 400 nm with energy density 20 mW cm(-2). The illumination time varied from 0 to 20 min and subsequently a total energy dose reached 0-24 J cm(-2). The data obtained indicate that S. enterica is able to produce endogenous photosensitizer PpIX when incubated with ALA. Remarkable inactivation of micro-organisms can be achieved (6 log) after photosensitization. It is obvious that photosensitization-based inactivation of S. enterica depends on illumination as well as incubation with ALA time. ALA-based photosensitization can be an effective tool against multi-drug resistant Gram-negative bacteria S. enterica serovar Typhimurium. Experimental data and mathematical evaluations support the idea that ALA-based photosensitization can be a useful tool for the development of nonthermal food preservation technology in future.

Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch.

Science.gov (United States)

Say, R; Şenay, R Hilal; Biçen, Özlem; Ersöz, Arzu; Şişman Yılmaz, Filiz; Akgöl, Sinan; Denizli, Adil

2013-05-01

α-Amylase (EC 3.2.1.1; α-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. Km values were 0.26 and 0.87 mM and Vmax values were 0.36 IU mg(-1) and 22.32 IU mg(-1) for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70-80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. Copyright © 2012 Elsevier B.V. All rights reserved.

Micelles from lipid derivatives of water-soluble polymers as delivery systems for poorly soluble drugs.

Science.gov (United States)

Lukyanov, Anatoly N; Torchilin, Vladimir P

2004-05-07

Polymeric micelles have a whole set of unique characteristics, which make them very promising drug carriers, in particular, for poorly soluble drugs. Our review article focuses on micelles prepared from conjugates of water-soluble polymers, such as polyethylene glycol (PEG) or polyvinyl pyrrolidone (PVP), with phospholipids or long-chain fatty acids. The preparation of micelles from certain polymer-lipid conjugates and the loading of these micelles with various poorly soluble anticancer agents are discussed. The data on the characterization of micellar preparations in terms of their morphology, stability, longevity in circulation, and ability to spontaneously accumulate in experimental tumors via the enhanced permeability and retention (EPR) effect are presented. The review also considers the preparation of targeted immunomicelles with specific antibodies attached to their surface. Available in vivo results on the efficiency of anticancer drugs incorporated into plain micelles and immunomicelles in animal models are also discussed.

A microtitre-based method for measuring the haem polymerization inhibitory activity (HPIA) of antimalarial drugs.

Science.gov (United States)

Basilico, N; Pagani, E; Monti, D; Olliaro, P; Taramelli, D

1998-07-01

The malaria parasite metabolizes haemoglobin and detoxifies the resulting haem by polymerizing it to form haemozoin (malaria pigment). A polymer identical to haemozoin, beta-haematin, can be obtained in vitro from haematin at acidic pH. Quinoline-containing anti-malarials (e.g. chloroquine) inhibit the formation of either polymer. Haem polymerization is an essential and unique pharmacological target. To identify molecules with haem polymerization inhibitory activity (HPIA) and quantify their potency, we developed a simple, inexpensive, quantitative in-vitro spectrophotometric microassay of haem polymerization. The assay uses 96-well U-bottomed polystyrene microplates and requires 24 h and a microplate reader. The relative amounts of polymerized and unpolymerized haematin are determined, based on solubility in DMSO, by measuring absorbance at 405 nm in the presence of test compounds as compared with untreated controls. The final product (a solid precipitate of polymerized haematin) was validated using infrared spectroscopy and the assay proved reproducible; in this assay, activity could be partly predicted based on the compound's chemical structure. Both water-soluble and water-insoluble compounds can be quantified by this method. Although the throughput of this assay is lower than that of radiometric methods, the assay is easier to set up and cheaper, and avoids the problems related to radioactive waste disposal.

Synthesis of a series of soluble main-chain chiral nonracemic poly(alkyl-aryl ketone

Directory of Open Access Journals (Sweden)

2008-06-01

Full Text Available A series of main-chain chiral polyketones have been synthesized through condensation polymerization of a dihalide and a diketone with optically pure binaphthyl moiety as linkage in the polymer backbone. The solubility of the polymers can be easily enhanced by substituents at the alpha position next to the carbonyl groups. Reducing the steric hindrance of the substituents in the monomers increases the reactivity of the polymerization. The chiral polymers exhibit large optical rotations. Circular Dichroism (CD spectra of the polymers are similar to those of the corresponding monomers. The novel synthetic strategy may have great impact on future development of palladium catalyzed condensation polymerizations. The highly soluble chiral polymers synthesized allow for preparation of materials in the form of thin films and have potentials applications in various areas such as chiral separation and recognition.

Photosensitive Gaseous Detectors for Cryogenic Temperature Applications

CERN Document Server

Periale, L; Iacobaeus, C; Lund-Jensen, B; Picchi, P; Pietropaolo, F

2007-01-01

There are several proposals and projects today for building LXe Time Projection Chambers (TPCs) for dark matter search. An important element of these TPCs are the photomultipliers operating either inside LXe or in vapors above the liquid. We have recently demonstrated that photosensitive gaseous detectors (wire type and hole-type) can operate perfectly well until temperatures of LN2. In this paper results of systematic studies of operation of the photosensitive version of these detectors (combined with reflective or semi-transparent CsI photocathodes) in the temperature interval of 300-150 K are presented. In particular, it was demonstrated that both sealed and flushed by a gas detectors could operate at a quite stable fashion in a year/time scale. Obtained results, in particular the long-term stability of photosensitive gaseous detectors, strongly indicate that they can be cheap and simple alternatives to photomultipliers or avalanche solid-state detectors in LXe TPC applications.

Photosensitizers and radiosensitizers in dermatology and oncology

International Nuclear Information System (INIS)

Bruckner, V.

1979-01-01

Two therapeutic modalities are currently of great interest, namely photo- and radiosensitization. Whereas photosensitizers only function in combination with ultraviolet (UV) light, radiosensitizers act only in combination with ionizing radiation. Because of the small UV penetration, up to a maximum of 0,5 mm, photosensitization can take place only at the surface of the body, i.e. the skin. Photosensitizers are applied in dermatology in order to optimize and improve the UV therapy of certain diseases (mainly psoriasis, mycosis fungoides and vitiligo). Radiosensitizers lead to an increase in sensitivity of the hypoxic and therefore radioresistant parts of tumours against X- and gamma-radiation. With sufficient concentration within the tumour, they can act where the radiation can reach, even in the deeper parts of the body. They represent a modern and useful aid to radiation oncology. Because of neurotoxic effects, however, their practical use is limited. A short review of the history, mechanisms of action, application and side-effects of these photo- and radiosensitizers is presented

Photosensitizers and radiosensitizers in dermatology and oncology

Energy Technology Data Exchange (ETDEWEB)

Bruckner, V [Stellenbosch University, Parowvallei (South Africa). Departments of Medical Physics and Radiology

1979-09-22

Two therapeutic modalities are currently of great interest, namely photo- and radiosensitization. Whereas photosensitizers only function in combination with ultraviolet (UV) light, radiosensitizers act only in combination with ionizing radiation. Because of the small UV penetration, up to a maximum of 0,5 mm, photosensitization can take place only at the surface of the body, i.e. the skin. Photosensitizers are applied in dermatology in order to optimize and improve the UV therapy of certain diseases (mainly psoriasis, mycosis fungoides and vitiligo). Radiosensitizers lead to an increase in sensitivity of the hypoxic and therefore radioresistant parts of tumours against X- and gamma-radiation. With sufficient concentration within the tumour, they can act where the radiation can reach, even in the deeper parts of the body. They represent a modern and useful aid to radiation oncology. Because of neurotoxic effects, however, their practical use is limited. A short review of the history, mechanisms of action, application and side-effects of these photo- and radiosensitizers is presented.

Poly(3-hydroxybutyrate) and Eudragit E microparticles: a release system to enhance the aqueous solubility of felodipine and simvastatin

International Nuclear Information System (INIS)

Bazzo, Giovana C.; Pezzini, Bianca R.; Zetola, Melissa; Wagner, Theodoro M.; Caetano, Daniela B.; Boch, Maura; Schmucker, Iara C.; Schucko, Sacha K.

2009-01-01

Poor water-soluble drugs are a problem for the development of oral solid dosage forms, since it has great potential for low bioavailability. Thus, release systems that promote the increase of aqueous solubility of these drugs are advantageous. This study aimed to evaluate the feasibility of incorporation of felodipine and simvastatin in polymeric microparticles, to improve the aqueous solubility of the drugs. Microparticles of poly(3-hydroxybutyrate) [PHB] and Eudragit E was prepared by emulsion - solvent evaporation technique and characterized as to morphology and encapsulation efficiency of the drugs. Particles with spherical shapes and high levels of drug encapsulated were obtained. There was a significant increase in aqueous solubility of felodipine and simvastatin after its incorporation into the polymeric microparticles. X-ray diffraction analysis showed the conversion of both drugs to amorphous form, which may have contributed to increased the solubility. (author)

Solid state photosensitive devices which employ isolated photosynthetic complexes

Science.gov (United States)

Peumans, Peter; Forrest, Stephen R.

2009-09-22

Solid state photosensitive devices including photovoltaic devices are provided which comprise a first electrode and a second electrode in superposed relation; and at least one isolated Light Harvesting Complex (LHC) between the electrodes. Preferred photosensitive devices comprise an electron transport layer formed of a first photoconductive organic semiconductor material, adjacent to the LHC, disposed between the first electrode and the LHC; and a hole transport layer formed of a second photoconductive organic semiconductor material, adjacent to the LHC, disposed between the second electrode and the LHC. Solid state photosensitive devices of the present invention may comprise at least one additional layer of photoconductive organic semiconductor material disposed between the first electrode and the electron transport layer; and at least one additional layer of photoconductive organic semiconductor material, disposed between the second electrode and the hole transport layer. Methods of generating photocurrent are provided which comprise exposing a photovoltaic device of the present invention to light. Electronic devices are provided which comprise a solid state photosensitive device of the present invention.

Photosensitivity to selsun shampoo

Directory of Open Access Journals (Sweden)

Mani M

1994-01-01

Full Text Available A case of photosensitive dermatitis, occurring after the second application of 2.5% selenium sulphide (Selsun shampoo, Abbot, is reported. The shampoo was diluted to half strength with water, before use. The patient had pityriasis versicolor, with extensive lesions on the covered as well as exposed areas.

Application of various water soluble polymers in gas hydrate inhibition

DEFF Research Database (Denmark)

Kamal, Muhammad Shahzad; Hussein, Ibnelwaleed A.; Sultan, Abdullah S.

2016-01-01

. This review presents the various types of water soluble polymers used for hydrate inhibition, including conventional and novel polymeric inhibitors along with their limitations. The review covers the relevant properties of vinyl lactam, amide, dendrimeric, fluorinated, and natural biodegradable polymers....... The factors affecting the performance of these polymers and the structure-property relationships are reviewed. A comprehensive review of the techniques used to evaluate the performance of the polymeric inhibitors is given. This review also addresses recent developments, current and future challenges...

Solubility and IR studies of gamma-irradiated arabinoxylan

International Nuclear Information System (INIS)

Ebringerova, A.; Kacurakova, M.; Hromadkova, Z.; Pruzinec, J.

1989-01-01

The structural and solubility changes of a water-insoluble arabinoxylan with a low degree of branching was studied after γ-irradiation by IR spectroscopy and chemical analysis of the polysaccharide and its polymeric fractions. New functional groups like hydroperoxidic, carbonylic and endiolic ones were found after irradiation. The IR spectra shows that the structural changes involved by radiolytic treatment are reflected in the shape of the IR spectra of both polymeric fractions. The ratio of absorbance of the peaks at 1725 and 2920 cm -1 increased with radiation dose. (author) 17 refs.; 2 figs.; 2 tabs

Fluorescent proteins as singlet oxygen photosensitizers: mechanistic studies in photodynamic inactivation of bacteria

Science.gov (United States)

Ruiz-González, Rubén.; White, John H.; Cortajarena, Aitziber L.; Agut, Montserrat; Nonell, Santi; Flors, Cristina

2013-02-01

Antimicrobial photodynamic therapy (aPDT) combines a photosensitizer, light and oxygen to produce reactive oxygen species (ROS), mainly singlet oxygen (1O2), to photo-oxidize important biomolecules and induce cell death. aPDT is a promising alternative to standard antimicrobial strategies, but its mechanisms of action are not well understood. One of the reasons for that is the lack of control of the photosensitizing drugs location. Here we report the use of geneticallyencoded fluorescent proteins that are also 1O2 photosensitizers to address the latter issue. First, we have chosen the red fluorescent protein TagRFP as a photosensitizer, which unlike other fluorescent proteins such as KillerRed, is able to produce 1O2 but not other ROS. TagRFP photosensitizes 1O2 with a small, but not negligible, quantum yield. In addition, we have used miniSOG, a more efficient 1O2 photosensitizing fluorescent flavoprotein that has been recently engineered from phototropin 2. We have genetically incorporated these two photosensitizers into the cytosol of E. coli and demonstrated that intracellular 1O2 is sufficient to kill bacteria. Additional assays have provided further insight into the mechanism of cell death. Photodamage seems to occur primarily in the inner membrane, and extends to the outer membrane if the photosensitizer's efficiency is high enough. These observations are markedly different to those reported for external photosensitizers, suggesting that the site where 1O2 is primarily generated proves crucial for inflicting different types of cell damage.

Photosensitizing medication use and risk of skin cancer

DEFF Research Database (Denmark)

Kaae, Jeanette; Boyd, Heather A; Hansen, Anne

2010-01-01

Many commonly used medications, including both medications for long-term (daily) use and short-term use (treatment courses of finite duration), have photosensitizing properties. Whether use of these medications affects skin cancer risk, however, is unclear.......Many commonly used medications, including both medications for long-term (daily) use and short-term use (treatment courses of finite duration), have photosensitizing properties. Whether use of these medications affects skin cancer risk, however, is unclear....

Photobleaching-induced changes in photosensitizing properties of dissolved organic matter

KAUST Repository

Niu, Xi-Zhi; Liu, Chao; Gutié rrez, Leonardo A.; Croue, Jean-Philippe

2014-01-01

Photosensitizing properties of different dissolved organic matter (DOM) were investigated according to their performance in singlet oxygen (1O2), triplet state of DOM (3DOM*), and hydroxyl radical (·OH) productions. The photobleaching of DOM solutions after irradiation was characterized by fluorescence excitation-emission matrix and UV-Vis spectroscopy. The photosensitizing properties of pre-irradiated DOM solutions were changed in a sunlight simulator. The performance of DOMs in photosensitized degradation of several contaminants was investigated. For a 20h exposure, the observed degradation rate constant (kobs) of some contaminants decreased as a function of exposure time, and highly depended on the properties of both DOM and contaminant. Degradation of contaminants with lower kobs was more susceptible to DOM photobleaching-induced decrease in kobs. Under the current experimental conditions, the photobleaching-induced decrease of DOM photo-reactivity in contaminant degradation was mainly attributed to indirect phototransformation of DOM caused by the interactions between photo-inductive DOM moieties and photochemically-produced reactive species. Reactive contaminants can inhibit DOM indirect photobleaching by scavenging reactive species, photosensitized degradation of these contaminants exhibited a stable kobs as a result. This is the first study to report DOM photobleaching-induced changes in the simultaneous DOM photosensitized degradation of contaminants and the inhibitory effect of reactive contaminants on DOM photobleaching.

Photobleaching-induced changes in photosensitizing properties of dissolved organic matter

KAUST Repository

Niu, Xi-Zhi

2014-12-01

Photosensitizing properties of different dissolved organic matter (DOM) were investigated according to their performance in singlet oxygen (1O2), triplet state of DOM (3DOM*), and hydroxyl radical (·OH) productions. The photobleaching of DOM solutions after irradiation was characterized by fluorescence excitation-emission matrix and UV-Vis spectroscopy. The photosensitizing properties of pre-irradiated DOM solutions were changed in a sunlight simulator. The performance of DOMs in photosensitized degradation of several contaminants was investigated. For a 20h exposure, the observed degradation rate constant (kobs) of some contaminants decreased as a function of exposure time, and highly depended on the properties of both DOM and contaminant. Degradation of contaminants with lower kobs was more susceptible to DOM photobleaching-induced decrease in kobs. Under the current experimental conditions, the photobleaching-induced decrease of DOM photo-reactivity in contaminant degradation was mainly attributed to indirect phototransformation of DOM caused by the interactions between photo-inductive DOM moieties and photochemically-produced reactive species. Reactive contaminants can inhibit DOM indirect photobleaching by scavenging reactive species, photosensitized degradation of these contaminants exhibited a stable kobs as a result. This is the first study to report DOM photobleaching-induced changes in the simultaneous DOM photosensitized degradation of contaminants and the inhibitory effect of reactive contaminants on DOM photobleaching.

Oligonucleotides as probes for studying polymerization reactions in dilute aqueous solution

Science.gov (United States)

Kolb, V.; Orgel, L. E.; Miller, S. L. (Principal Investigator)

1994-01-01

We have prepared a [32P]-labled oligonucleotide probe carrying a free primary amine at its 3'-terminus. This probe is used to initiate polymerization of aziridine (ethyleneimine) in aqueous solution. The nature of the oligomeric products and the kinetics of their formation are then monitored by gel electrophoresis. Our results are generally consistent with those obtained using conventional techniques. We have also investigated the effect of polyanionic templates on the rate of oligomerization of aziridine. We find that water-soluble polyanions generally accelerate the polymerization. The sodium salt of polymethacrylic acid is the most effective of the templates that we studied. The methods introduced in this paper should be applicable to a variety of polymerization reactions in aqueous solution. They should greatly simplify the screening of potentially prebiotic polymerization reactions.

In vitro characterization of a novel polymeric system for preparation of amorphous solid drug dispersions.

Science.gov (United States)

Mahmoudi, Zahra N; Upadhye, Sampada B; Ferrizzi, David; Rajabi-Siahboomi, Ali R

2014-07-01

Preparation of amorphous solid dispersions using polymers is a commonly used formulation strategy for enhancing the solubility of poorly water-soluble drugs. However, often a single polymer may not bring about a significant enhancement in solubility or amorphous stability of a poorly water-soluble drug. This study describes application of a unique and novel binary polymeric blend in preparation of solid dispersions. The objective of this study was to investigate amorphous solid dispersions of glipizide, a BCS class II model drug, in a binary polymeric system of polyvinyl acetate phthalate (PVAP) and hypromellose (hydroxypropyl methylcellulose, HPMC). The solid dispersions were prepared using two different solvent methods: rotary evaporation (rotavap) and fluid bed drug layering on sugar spheres. The performance and physical stability of the dispersions were evaluated with non-sink dissolution testing, powder X-ray diffraction (PXRD), and modulated differential scanning calorimetry (mDSC). PXRD analysis demonstrated an amorphous state for glipizide, and mDSC showed no evidence of phase separation. Non-sink dissolution testing in pH 7.5 phosphate buffer indicated more than twofold increase in apparent solubility of the drug with PVAP-HPMC system. The glipizide solid dispersions demonstrated a high glass transition temperature (Tg) and acceptable chemical and physical stability during the stability period irrespective of the manufacturing process. In conclusion, the polymeric blend of PVAP-HPMC offers a unique formulation approach for developing amorphous solid dispersions with the flexibility towards the use of these polymers in different ratios and combined quantities depending on drug properties.

Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

Energy Technology Data Exchange (ETDEWEB)

Barik, Atanu; Indira Priyadarsini, K; Mohan, Hari; Bajaj, P N; Sapre, A V; Mittal, J P; Mukherjee, T [Radiation and Photochemistry Div., Bhabha Atomic Research Centre, Mumbai (India)

2006-10-15

Singlet molecular oxygen ({sup 1}O{sub 2}) is an excited state of molecular oxygen, having antiparallel spin in the same {pi} antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

International Nuclear Information System (INIS)

Barik, Atanu; Indira Priyadarsini, K.; Hari Mohan; Bajaj, P.N.; Sapre, A.V.; Mittal, J.P.; Mukherjee, T.

2006-10-01

Singlet molecular oxygen ( 1 O 2 ) is an excited state of molecular oxygen, having antiparallel spin in the same π antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

Interaction Studies between Newly Synthesized Photosensitive Polymer and Ionic Liquids

Directory of Open Access Journals (Sweden)

In Tae Kim

2015-01-01

Full Text Available In this information age, different kinds of photosensitive materials have been used in the manufacture of information storage devices. But these photosensitive materials have the bane of low diffraction efficiency. In order to solve this problem, we have synthesized a novel photosensitive polymer from epoxy-based azopolymers (with three types of azochromophores. Furthermore, we have studied the interaction between this newly synthesized azopolymer and ionic liquids (ILs. For this purpose, we have used the ammonium and imidazolium families of ILs, such as diethylammonium dihydrogen phosphate (DEAP, tributylammonium methyl sulfate (TBMS, triethylammonium 4-aminotoluene-3-sulfonic acid (TASA, and 1-methylimidazolium chloride ([Mim]Cl. To investigate the molecular interaction between azopolymer and ILs, we have used the following spectroscopic methods of analysis: UV-visible spectroscopy, photoluminescence (PL spectroscopy, Fourier transformed infrared spectroscopy (FT-IR, and confocal Raman spectroscopy. In this study, we have developed new photosensitive materials by combining polymer with ILs.

Drug-delivery and multifunction possibilities of hypocrellin photosensitizers

Directory of Open Access Journals (Sweden)

Hong Deng

2015-01-01

Full Text Available Photodynamic therapy (PDT has been a routine treatment of tumors and some microvascular diseases, but clinically available photosensitizers are still scarce. Among all kinds of photosensitizers, hypocrellins possess the most characteristics of ideal photosensitizers, such as, high photo-activity but low dark toxicity, fast clearance from tissues. This review is focused on two main topics, drug-delivery problem of hypocrellins and how the environment-sensitive fluorescence of hypocrellins was used for recognition of various biomolecules. Drug-delivery of hypocrellins was mainly achieved in two strategies — preparing the drug-delivery vehicles and finding quantitatively amphiphilic derivatives. Hypocrellin fluorescence originated from the intramolecular proton transfer is very distinct from other kinds of photosensitizers. Recently, it was proved that quantitative hypocrellin fluorescence could not only recognize various biomolecules, including proteins, polysaccharides and lipids, but also distinguish the specific binding from nonspecific binding with some kind of biomolecules. Meantime, hypocrellin fluorescence was pH-sensitive. It is known that tumor cells or tissues have the features of a large amount of lipid, neonatal collagen, over-expression of polysaccharides, and lower pH values compared to normal tissues. According to the relative but not absolute specificity, further studies on quantitative recognition of various biomolecules at a cellular level, may find a new clue to treat tumors by joint usage of photodynamic diagnosis (PDD and PDT.

DFT application for chlorin derivatives photosensitizer drugs modeling

Science.gov (United States)

Machado, Neila; Carvalho, B. G.; Téllez Soto, C. A.; Martin, A. A.; Favero, P. P.

2018-04-01

Photodynamic therapy is an alternative form of cancer treatment that meets the desire for a less aggressive approach to the body. It is based on the interaction between a photosensitizer, activating light, and molecular oxygen. This interaction results in a cascade of reactions that leads to localized cell death. Many studies have been conducted to discover an ideal photosensitizer, which aggregates all the desirable characteristics of a potent cell killer and generates minimal side effects. Using Density Functional Theory (DFT) implemented in the program Vienna Ab-initio Simulation Package, new chlorin derivatives with different functional groups were simulated to evaluate the different absorption wavelengths to permit resonant absorption with the incident laser. Gaussian 09 program was used to determine vibrational wave numbers and Natural Bond Orbitals. The chosen drug with the best characteristics for the photosensitizer was a modified model of the original chlorin, which was called as Thiol chlorin. According to our calculations it is stable and is 19.6% more efficient at optical absorption in 708 nm in comparison to the conventional chlorin e6. Vibrational modes, optical and electronic properties were predicted. In conclusion, this study is an attempt to improve the development of new photosensitizer drugs through computational methods that save time and contribute to decrease the numbers of animals for model application.

78 FR 18999 - Prospective Grant of Start-Up Exclusive License: Photosensitizing Antibody-Fluorophore Conjugates...

Science.gov (United States)

2013-03-28

...-Up Exclusive License: Photosensitizing Antibody-Fluorophore Conjugates for Photoimmunotherapy AGENCY...-205-2010/0-US-01), and entitled ``Photosensitizing Antibody- Fluorophore Conjugates,'' to Aspyrian... invention. The field of use may be limited to ``use of photosensitizing antibody-fluorophore conjugate by...

Conductive cotton prepared by polyaniline in situ polymerization using laccase.

Science.gov (United States)

Zhang, Ya; Dong, Aixue; Wang, Qiang; Fan, Xuerong; Cavaco-Paulo, Artur; Zhang, Ying

2014-09-01

The high-redox-potential catalyst laccase, isolated from Aspergillus, was first used as a biocatalyst in the oxidative polymerization of water-soluble conductive polyaniline, and then conductive cotton was prepared by in situ polymerization under the same conditions. The polymerization of aniline was performed in a water dispersion of sodium dodecylbenzenesulfonate (SDBS) micellar solution with atmospheric oxygen serving as the oxidizing agent. This method is ecologically clean and permits a greater degree of control over the kinetics of the reaction. The conditions for polyaniline synthesis were optimized. Characterizations of the conducting polyaniline and cotton were carried out using Fourier transform infrared spectroscopy, UV-vis spectroscopy, cyclic voltammetry, the fabric induction electrostatic tester, and the far-field EMC shielding effectiveness test fixture.

Tuning the Solubility of Copper Complex in Atom Transfer Radical Self-Condensing Vinyl Polymerizations to Control Polymer Topology via One-Pot to the Synthesis of Hyperbranched Core Star Polymers

Directory of Open Access Journals (Sweden)

Zong-Cheng Chen

2014-09-01

Full Text Available In this paper, we propose a simple one-pot methodology for proceeding from atom transfer reaction-induced conventional free radical polymerization (AT-FRP to atom transfer self-condensing vinyl polymerization (AT-SCVP through manipulation of the catalyst phase homogeneity (i.e., CuBr/2,2'-bipyridine (CuBr/Bpy in a mixture of styrene (St, 4-vinyl benzyl chloride (VBC, and ethyl 2-bromoisobutyrate. Tests of the solubilities of CuBr/Bpy and CuBr2/Bpy under various conditions revealed that both temperature and solvent polarity were factors affecting the solubility of these copper complexes. Accordingly, we obtained different polymer topologies when performing AT-SCVP in different single solvents. We investigated two different strategies to control the polymer topology in one-pot: varying temperature and varying solvent polarity. In both cases, different fractions of branching revealed the efficacy of varying the polymer topology. To diversify the functionality of the peripheral space, we performed chain extensions of the resulting hyperbranched poly(St-co-VBC macroinitiator (name as: hbPSt MI with either St or tBA (tert-butyl acrylate. The resulting hyperbranched core star polymer had high molecular weights (hbPSt-g-PSt: Mn = 25,000, Đ = 1.77; hbPSt-g-PtBA: Mn = 27,000, Đ = 1.98; hydrolysis of the tert-butyl groups of the later provided a hyperbranched core star polymer featuring hydrophilic poly(acrylic acid segments.

The protective effect of caffeine on DNA photosensitive damage: a gel electrophoresis

International Nuclear Information System (INIS)

Huang Liping; Ma Jianhua

2009-01-01

Agarose gel electrophoresis was performed to study interaction effect of caffeine on photosensitive injury of DNA caused by anthraquinone-2-sulphonic acid disodium (AQS), a model compound of strong photosensitizer, under 254 nm or 365nm UV irradiation Photosensitive injury of DNA induced by AQS under deoxidized condition was used as control. The results show that caffeine may resist effectively the injury effect of photosensitive damage and strong UV irradiation on DNA. The effects depend on the caffeine and AQS concentration, and irradiation time. Caffeine in concentration of 0.01-3.0 μg/μL, may prevent DNA from damage induced by UV light, but caffeine in concentration of >5.0 μg/μL accelerates the DNA damage. In particular, in the aqueous solution system of DNA, caffeine and AQS, at pH 6.25-7.35, the caffeine in concentration of 2.5-4.50 μg/μL may resist the photosensitive injury of DNA caused by AQS under the deoxidized condition and exposure by 254 nm UV for 10 min. And caffeine in concentration of 5 μg/μL would present a synergetic effect on the photosensitive injury of DNA. Possible molecular mechanism also is discussed. (authors)

Electroluminescence and photosensitivity spectra of organic diode structures based on zinc complexes

Science.gov (United States)

Kaplunov, M. G.; Krasnikova, S. S.; Nikitenko, S. L.; Yakushchenko, I. K.

2017-01-01

Devices based on zinc complexes with sulphanylaminosubstituted ligands are characterized by dual function - electroluminescence (EL) and photosensitivity. Both EL and photosensitivity are associated with the formation of exciplexes.

Electroluminescence and photosensitivity spectra of organic diode structures based on zinc complexes

International Nuclear Information System (INIS)

Kaplunov, M.G.; Krasnikova, S.S.; Nikitenko, S.L.; Yakushchenko, I.K.

2017-01-01

Devices based on zinc complexes with sulphanylaminosubstituted ligands are characterized by dual function – electroluminescence (EL) and photosensitivity. Both EL and photosensitivity are associated with the formation of exciplexes.

CHD2 variants are a risk factor for photosensitivity in epilepsy

DEFF Research Database (Denmark)

Galizia, Elizabeth C.; Myers, Candace T.; Leu, Costin

2015-01-01

Photosensitivity is a heritable abnormal cortical response to flickering light, manifesting as particular electroencephalographic changes, with or without seizures. Photosensitivity is prominent in a very rare epileptic encephalopathy due to de novo CHD2 mutations, but is also seen in epileptic e...

Radiation carcinogenesis: radioprotectors and photosensitizers

International Nuclear Information System (INIS)

Fry, R.J.M.

1982-01-01

This paper outlines 1) some of the salient features of radiation carcinogenesis that are pertinent to the questions of how the carcinogenic effects might be influenced, 2) the effects of radioprotectors on ionizing radiation-induced cancer, and 3) the effect of photosensitizers on UVR-induced skin cancer

Radiation carcinogenesis: radioprotectors and photosensitizers

Energy Technology Data Exchange (ETDEWEB)

Fry, R.J.M.

1982-01-01

This paper outlines 1) some of the salient features of radiation carcinogenesis that are pertinent to the questions of how the carcinogenic effects might be influenced, 2) the effects of radioprotectors on ionizing radiation-induced cancer, and 3) the effect of photosensitizers on UVR-induced skin cancer.

A new probe of solvent accessibility of bound photosensitizers. 1. Ruthenium(II) and osmium(II) photosensitizers in sodium lauryl sulfate micelles

International Nuclear Information System (INIS)

Hauenstein, B.L. Jr.; Dressick, W.J.; Buell, S.L.; Demas, J.N.; DeGraff, B.A.

1983-01-01

A new method of measuring solvent accessibility of photosensitizers bound to organized media is presented. In particular, the solvent accessibility of a series of ruthenium(II) and osmium(II) photosensitizers bound to sodium lauryl sulfate micelles has been determined. The method takes advantage of the large solvent deuterium effect on the excited-state lifetimes of these complexes. The solvent accessibility of the bound complexes correlates with the hydrophobicity of the ligands. The potential application of this method to a variety of other systems is mentioned

Bactericidal action of photogenerated singlet oxygen from photosensitizers used in plaque disclosing agents.

Directory of Open Access Journals (Sweden)

Kirika Ishiyama

Full Text Available BACKGROUND: Photodynamic therapy (PDT has been suggested as an efficient clinical approach for the treatment of dental plaque in the field of dental care. In PDT, once the photosensitizer is irradiated with light of a specific wavelength, it transfers the excitation energy to molecular oxygen, which gives rise to singlet oxygen. METHODOLOGY/PRINCIPAL FINDINGS: Since plaque disclosing agents usually contain photosensitizers such as rose bengal, erythrosine, and phloxine, they could be used for PTD upon photoactivation. The aim of the present study is to compare the ability of these three photosensitizers to produce singlet oxygen in relation to their bactericidal activity. The generation rates of singlet oxygen determined by applying an electron spin resonance technique were in the order phloxine > erythrosine ≒ rose bengal. On the other hand, rose bengal showed the highest bactericidal activity against Streptococcus mutans, a major causative pathogen of caries, followed by erythrosine and phloxine, both of which showed activity similar to each other. One of the reasons for the discrepancy between the singlet oxygen generating ability and bactericidal activity was the incorporation efficiency of the photosensitizers into the bacterial cells. The incorporation rate of rose bengal was the highest among the three photosensitizers examined in the present study, likely leading to the highest bactericidal activity. Meanwhile, the addition of L-histidine, a singlet oxygen quencher, cancelled the bactericidal activity of any of the three photoactivated photosensitizers, proving that singlet oxygen was responsible for the bactericidal action. CONCLUSIONS: It is strongly suggested that rose bengal is a suitable photosensitizer for the plaque disclosing agents as compared to the other two photosensitizers, phloxine and erythrosine, when used for PDT.

Laser inactivation of periodontal bacteria using photosensitizing dyes

Science.gov (United States)

Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

1996-12-01

We demonstrate the killing of the oral bacteria Prevotella nigrescens using a photosensitizer and light from a 10 Hz, frequency doubled, Q-switched Nd:YAG pumped dye laser, with modified oscillator to increase output power. This system produced light at wavelengths close to 620 nm, the absorption maximum of the photosensitizing agent, malachite green isothiocyanate, a wavelength that is not significantly absorbed by tissue. A bacterial reduction of 97.5 percent was achieved at an energy density of 0.67 J/cm2 and exposure times of 300 seconds.

Induction of photosensitivity in sheep with Erodium moschatum (L. L'Hérit

Directory of Open Access Journals (Sweden)

J.C. Stroebel

2002-07-01

Full Text Available Erodium moschatum is an exotic weed in the southern and southwestern coastal areas of the Western Cape Province (WCP, South Africa. It has been suspected as the cause of photosensitivity in sheep. However, attempts to induce photosensitivity by dosing it to sheep have thus far been unsuccessful. During August 1999, 2 sheep suffering from severe photosensitivity were presented for clinical examination to the Western Cape Provincial Veterinary Laboratory (WCPVL. One sheep was sacrificed for autopsy. Except for skin lesions associated with photosensitivity, no icterus or other lesions were present. Histopathological examination of affected skin revealed epidermal necrosis while the liver had no microscopic lesions. It was therefore concluded that the sheep might have been suffering from primary photosensitivity. The farmfrom which the sheep came, situated in the Malmesbury district, WCP, was visited to determine the source of the photodynamic agent. The flock from which the sheep originated had been grazing in a camp where E. moschatum was growing abundantly and had been heavily grazed. Some remaining Erodium in the camp was collected, pulped and dosed over a period of 7 days to an adult sheep. Another sheep was dosed simultaneously with Erodium growing on the premises of the WCPVL. Both sheep developed mild photosensitivity, which was confirmed by histopathological examination of skin biopsies. It was concluded that E. moschatum can induce photosensitivity (probably the primary type in sheep if ingested in large quantities.

The study of polymeric hydro-gels with unique properties obtained by polymerization with gamma radiation processing

International Nuclear Information System (INIS)

Dragusin, M.

1995-01-01

This thesis presents the work carried out on polymeric hydro-gels obtained by radiation processing using 60 Co gamma rays from the irradiation facility IETI-10.000 (10 k Ci), and on the polymeric hydro-gels obtained by irradiation with the electron beams from a linear accelerator (6 MeV). The aim of the study was to determine the effect of the rate dose and total dose absorbed in the materials. There are presented the preparation methods of homo- and co-polymer hydro-gels (acrylics, namely anionic and neutral monomers (acrylamide, acrylic acid, vinyl acetate) and cationic monomers (di-methyl di-allyl ammonium chloride)) such as floculants, additives, absorbers, etc. Concerning with these we have analysed the preparation methods, the mechanical, thermal, diffusivity, and swelling properties of polymeric hydro-gels in a large variety of gels of type I or II. The technological aspects and end use were studied in connection with the characteristics of the radiation processing of these hydro-gels as a function of chemical composition rate and absorbed dose, swelling degree (low and very high hydro-soluble), mechanical and diffusional properties. (author) 33 figs., 12 tabs., 101 refs

Novel micellar systems for the formulation of poorly water soluble drugs : biocompatibility aspects and pharmaceutical applications

OpenAIRE

Dumontet Mondon, Karine

2010-01-01

Amongst the large number of novel drugs, 95% are lipophilic and poorly water soluble. Particularly, this renders their aqueous formulation very difficult. In this regard this thesis focused on polymeric micelles based on novel MPEG-hexPLA copolymers forming a hydrophilic shell and a very hydrophobic core that favors the incorporation of poorly water soluble drugs. Although the drug hydrophobicity and water solubility are the main parameters in respect to their incorporation efficiency, struct...

Encapsulation of magnetic nanoparticles with polystyrene via emulsifier-free miniemulsion polymerization

International Nuclear Information System (INIS)

Faridi-Majidi, R.; Sharifi-Sanjani, N.; Agend, F.

2006-01-01

Magnetite nanoparticles (Fe 3 O 4 ), with an average size of about 10 nm, were encapsulated with polystyrene using a new method based on emulsifier-free miniemulsion polymerization in the presence of 2, 2' azobis (2-amidinopropane) dihydrochloride (V-50) as a cationic ionizable water-soluble initiator and hexadecane as a hydrophobe. Transmission electron microscopy (TEM) proved the presence of magnetite in polymer particles which appeared to be monodisperse in size, approximately 100-300 nm in diameter, through TEM and scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) measurement was used to determine the percentage of magnetite in the products. The results of emulsifier-free miniemulsion polymerization were compared with those of conventional emulsifier-free emulsion polymerization using (V-50) as the initiator in both cases

(1-Adamantyl)methyl glycidyl ether: a versatile building block for living polymerization.

Science.gov (United States)

Moers, Christian; Wrazidlo, Robert; Natalello, Adrian; Netz, Isabelle; Mondeshki, Mihail; Frey, Holger

2014-06-01

(1-Adamantyl)methyl glycidyl ether (AdaGE) is introduced as a versatile monomer for oxyanionic polymerization, enabling controlled incorporation of adamantyl moieties in aliphatic polyethers. Via copolymerization with ethoxyethyl glycidyl ether (EEGE) and subsequent cleavage of the acetal protection groups of EEGE, hydrophilic linear polyglycerols with an adjustable amount of pendant adamantyl moieties are obtained. The adamantyl unit permits control over thermal properties and solubility profile of these polymers (LCST). Additionally, AdaGE is utilized as a termination agent in carbanionic polymerization, affording adamantyl-terminated polymers. Using these structures as macroinitiators for the polymerization of ethylene oxide affords amphiphilic, in-chain adamantyl-functionalized block copolymers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-vitro singlet oxygen threshold dose at PDT with Radachlorin photosensitizer

Science.gov (United States)

Klimenko, V. V.; Shmakov, S. V.; Kaydanov, N. E.; Knyazev, N. A.; Kazakov, N. V.; Rusanov, A. A.; Bogdanov, A. A.; Dubina, M. V.

2017-07-01

In this present study we investigate the Radachlorin photosensitizer accumulation in K562 cells and Hela cells and determined the cell viability after PDT. Using the macroscopic singlet oxygen modeling and cellular photosensitizer concentration the singlet oxygen threshold doses for K562 cells and Hela cells were calculated.

Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch

International Nuclear Information System (INIS)

Say, R.; Şenay, R. Hilal; Biçen, Özlem; Ersöz, Arzu; Şişman Yılmaz, Filiz; Akgöl, Sinan; Denizli, Adil

2013-01-01

α-Amylase (EC 3.2.1.1; α-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. K m values were 0.26 and 0.87 mM and V max values were 0.36 IU mg −1 and 22.32 IU mg −1 for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70–80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. - Highlights: ► Developing to prepare nanoprotein particles carrying α-amylase ► Characterization of nanostructured α-amylase ► Usability of α-amylase nanoparticles in hydrolysis of starch

Polymeric amylase nanoparticles as a new semi-synthetic enzyme system for hydrolysis of starch

Energy Technology Data Exchange (ETDEWEB)

Say, R. [Anadolu University, Faculty of Science, Chemistry Department, Yunus Emre Campus, Eskişehir (Turkey); Şenay, R. Hilal [Ege University, Faculty of Science, Biochemistry Department, 35100 Bornova-Izmir (Turkey); Biçen, Özlem; Ersöz, Arzu; Şişman Yılmaz, Filiz [Anadolu University, Faculty of Science, Chemistry Department, Yunus Emre Campus, Eskişehir (Turkey); Akgöl, Sinan, E-mail: sinanakgol@yahoo.co.uk [Ege University, Faculty of Science, Biochemistry Department, 35100 Bornova-Izmir (Turkey); Denizli, Adil [Hacettepe University, Faculty of Science, Chemistry Department, 06532 Ankara (Turkey)

2013-05-01

α-Amylase (EC 3.2.1.1; α-D-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-D-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. K{sub m} values were 0.26 and 0.87 mM and V{sub max} values were 0.36 IU mg{sup −1} and 22.32 IU mg{sup −1} for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70–80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst. - Highlights: ► Developing to prepare nanoprotein particles carrying α-amylase ► Characterization of nanostructured α-amylase ► Usability of α-amylase nanoparticles in hydrolysis of starch.

The effect of solids retention times on the characterization of extracellular polymeric substances and soluble microbial products in a submerged membrane bioreactor.

Science.gov (United States)

Duan, Liang; Song, Yonghui; Yu, Huibin; Xia, Siqing; Hermanowicz, Slawomir W

2014-07-01

In this study, the effect of solids retention times (SRTs) on extracellular polymeric substances (EPS) and soluble microbial products (SMPs) were investigated in a membrane bioreactor (MBR) at SRTs of 10, 5 and 3 days. The results showed that more carbohydrates and proteins were accumulated at short SRT, which can due to the higher biomass activity in the reactor. The molecular weight (MW) distribution analysis suggested that macromolecules (MW>30 kDa) and small molecules (MW<1 kDa) were the dominant fraction of EPS and SMP, respectively. The reactor at shorter SRT had more small molecules and less macromolecules of carbohydrates. The MW distribution of total organic carbon (TOC) suggested that other organic moieties were exuded by microbes into the solution. The shorter SRT had more undefined microbial by-product-like substances and different O − H bonds in hydroxyl functional groups. Copyright © 2014 Elsevier Ltd. All rights reserved.

Functional bio-based polyesters by enzymatic polymerization

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Hoffmann, Christian; Andersen, Christian

During recent years enzymatic polymerization has become increasingly popular as an alternative to classical polyesterification processes. The high regioselectivity observed for lipases permits preparation of novel polyesters with a high number of functional groups.1 This is particularly interesting...... polymerization was applied to prepare functional water soluble polyesters based on dimethyl itaconate and poly(ethyleneglycol).2 The monomer permits postfunctionalization using thiol-ene chemistry or aza-michael additions, which was used to illustrate the possibilites of preparing functional hydrogels. Hydrogels...... based on the polyesters were shown to be degradable and could be prepared either from the pure polyester or from prefunctionalized polyesters, though the thiol-ene reactions were found to be less effective. Since then a new monomer, trans-2,5-dihydroxy-3-pentenoic acid methyl ester (DPM) has been...

Synthesis and characterization of completely soluble polyaniline salts via inverse emulsion polymerization using a mixture of chloroform and 2- butanol as a dispersing medium

International Nuclear Information System (INIS)

Gul, S.; Bilal, S.

2011-01-01

Polyaniline (PANI) is one of the most promising candidates for possible technological applications. PANI has potential applications in batteries, anion exchanger, tissue engineering, inhibition of steel corrosion, fuel cell, sensors and so on. However, its insolubility in common organic solvents limits its range of applications. In the present study an attempt has been made to synthesize soluble polyaniline salt via inverse polymerization pathway using benzoyl peroxide as oxidant and dodecylbenzenesulfonic acid (DBSA) as dopant as well as a surfactant. A mixture of chloroform and 2-butanol was used as dispersion medium for the first time. The influence of synthesis parameters such as concentration of aniline, benzoyl peroxide and DBSA on the yield and other properties of the resulting PANI salt was studied. The synthesized PANI salt was found to be completely soluble in DMSO, DMF, chloroform and in a mixture of toluene and 2-propanol. The synthesized polymer salt was also characterized with cyclic voltammetry, SEM, XRD, UV-Vis spectroscopy and viscosity measurements. TGA was used to analyze the thermal properties of synthesized polymer. The extent of doping of the PANI salt was determined from UV-Vis spectra and TGA analysis. The activation energy for the degradation of the polymer was calculated with the help of TGA. (author)

New Approach to Inactivation of Harmful and Pathogenic Microorganisms by Photosensitization

Directory of Open Access Journals (Sweden)

Živile Lukšiene

2005-01-01

Full Text Available Photosensitization is a treatment involving the administration of a photoactive compound that selectively accumulates in the target cells or microorganisms and is followed by irradiation with visible light. The combination of the two absolutely nontoxic elements, drug and light, in the presence of oxygen results in the selective destruction of target microorganism. It is important to note that truly major advances have been made in photosensitized antimicrobial chemotherapy, in particular disinfection of the blood and blood products, or treating local infections. By no means, prevention of any disease by microbial control of environment, including food manufacturing, is of greatest importance. Thus, development of new antimicrobial methods is necessary. In this context, photosensitization has been shown to be really effective: different microorganisms such as drug-resistant bacteria, yeasts, viruses and parasites can be inactivated by this method. So far, a photosensitization phenomenon can open new and interesting avenues for the development of novel, effective and ecologically friendly antimicrobial treatment, which might be applied to increase food safety.

HPMA-based polymeric micelles for curcumin solubilization and inhibition of cancer cell growth

NARCIS (Netherlands)

Naksuriya, Ornchuma; Shi, Yang; Van Nostrum, Cornelus F.|info:eu-repo/dai/nl/134498690; Anuchapreeda, Songyot; Hennink, Wim E.|info:eu-repo/dai/nl/070880409; Okonogi, Siriporn

2015-01-01

Abstract Curcumin (CM) has been reported as a potential anticancer agent. However, its pharmaceutical applications as therapeutic agent are hampered because of its poor aqueous solubility. The present study explores the advantages of polymeric micelles composed of block copolymers of

Flexible and fragmentable tandem photosensitive nanocrystal skins

Science.gov (United States)

Akhavan, S.; Uran, C.; Bozok, B.; Gungor, K.; Kelestemur, Y.; Lesnyak, V.; Gaponik, N.; Eychmüller, A.; Demir, H. V.

2016-02-01

We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the current-matching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of single monolayers of colloidal water-soluble CdTe and CdHgTe nanocrystals (NCs) in adjacent junctions on a Kapton polymer tape. Owing to the usage of a single NC layer in each junction, noise generation was significantly reduced while keeping the resulting PNS films considerably transparent. In each junction, photogenerated excitons are dissociated at the interface of the semi-transparent Al electrode and the NC layer, with holes migrating to the contact electrode and electrons trapped in the NCs. As a result, the tandem PNSs lead to an open-circuit photovoltage buildup equal to the sum of those of the two single junctions, exhibiting a total voltage buildup of 128.4 mV at an excitation intensity of 75.8 μW cm-2 at 350 nm. Furthermore, we showed that these flexible PNSs could be bent over 3.5 mm radius of curvature and cut out in arbitrary shapes without damaging the operation of individual parts and without introducing any significant loss in the total sensitivity. These findings indicate that the NC skins are promising as building blocks to make low-cost, flexible, large-area UV/visible sensing platforms with highly efficient full-spectrum conversion.We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the current-matching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of

Development of water-borne thermosetting paint by radiation-induced emulsion polymerization

International Nuclear Information System (INIS)

Makuuchi, K.; Katakai, A.; Nakayama, H.

1981-01-01

In previous papers the features of γ-ray induced emulsion polymerization were studied to use the emulsion as vehicles for water-borne paint. In this paper, the physical properties of thermosetting paints made with emulsions containing N-(n-butoxymethyl)acrylamide (NBM) and hydroxyl and carboxyl functionality were investigated. Since NBM moieties can react with amide, hydroxyl, and carboxyl groups, NBM copolymer emulsions prepared in this study have the self-crosslinking capability. As far as it was investigated, it was difficult to prepare a stable emulsion containing 10% of NBM by the conventional emulsion polymerization by using a water soluble radical initiator such as persulfate. In addition to 1-liter reactor, a pilot-scale plant of 70 liters reactor was used for γ-ray induced emulsion polymerization. Experimental details are given, and results are discussed. (author)

Encapsulation of magnetic nanoparticles with polystyrene via emulsifier-free miniemulsion polymerization

Energy Technology Data Exchange (ETDEWEB)

Faridi-Majidi, R. [School of Chemistry, University College of Science, Tehran University, Tehran (Iran, Islamic Republic of)]. E-mail: refaridi@khayam.ut.ac.ir; Sharifi-Sanjani, N. [School of Chemistry, University College of Science, Tehran University, Tehran (Iran, Islamic Republic of); Agend, F. [Malek-Ashtar University, Lavizan, Tehran (Iran, Islamic Republic of)

2006-09-25

Magnetite nanoparticles (Fe{sub 3}O{sub 4}), with an average size of about 10 nm, were encapsulated with polystyrene using a new method based on emulsifier-free miniemulsion polymerization in the presence of 2, 2' azobis (2-amidinopropane) dihydrochloride (V-50) as a cationic ionizable water-soluble initiator and hexadecane as a hydrophobe. Transmission electron microscopy (TEM) proved the presence of magnetite in polymer particles which appeared to be monodisperse in size, approximately 100-300 nm in diameter, through TEM and scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) measurement was used to determine the percentage of magnetite in the products. The results of emulsifier-free miniemulsion polymerization were compared with those of conventional emulsifier-free emulsion polymerization using (V-50) as the initiator in both cases.

Catalytic olefin polymerization with early transition metal compounds

OpenAIRE

Eshuis, Johan Jan Willem

1991-01-01

The catalysis of organic reactions by soluble metal complexes has become a major tool in synthesis, both in the laboratory and in the chemical industry. Processes catalyzed by transition metal complexes include carbonylation, olefin polymerization, olefin addition, olefin oxidation and alkane and arene oxidation. Traditionally, heterogeneous catalysts have been used for the production of large-scale commodity chemicals such as methanol and ammonia and in the production of high octane gasoline...

Chlorin photosensitizers sterically designed to prevent self-aggregation.

Science.gov (United States)

Uchoa, Adjaci F; de Oliveira, Kleber T; Baptista, Mauricio S; Bortoluzzi, Adailton J; Iamamoto, Yassuko; Serra, Osvaldo A

2011-11-04

The synthesis and photophysical evaluation of new chlorin derivatives are described. The Diels-Alder reaction between protoporphyrin IX dimethyl ester and substituted maleimides furnishes endo-adducts that completely prevent the self-aggregation of the chlorins. Fluorescence, resonant light scattering (RLS) and (1)H NMR experiments, as well as X-ray crystallographic have demonstrated that the configurational arrangement of the synthesized chlorins prevent π-stacking interactions between macrocycles, thus indicating that it is a nonaggregating photosensitizer with high singlet oxygen (Φ(Δ)) and fluorescence (Φ(f)) quantum yields. Our results show that this type of synthetic strategy may provide the lead to a new generation of PDT photosensitizers.

STUDY ON THE POLYMERIZATION KINETICS AND STABILITY OF P(UA)/MMA MICROEMULSION

Institute of Scientific and Technical Information of China (English)

Hong-tao Zhang; Tian-bin Ren; Zhao-hui Yin

2001-01-01

Urethane acrylate anionomer (APUA) as a kind of new type polymerizable emulsifier was synthesized using 2,4-toluene diisocyanate (TDI), polypropylene glycol (PPG), 2-hydroxyethyl methacrylate (HEMA) and dimethylolpropionic acid (DMPA). The critical micelle concentration (CMC) of APUA was measured by the methods of conductance and surface tension. The comparative studies between polymerizable emulsifier AUPA and conventional emulsifier sodium dodecyl sulfate (SDS) were carried out in the emulsion polymerization of methyl methacrylate (MMA). Polymerization kinetics,stability, size and morphology of the latex particles were investigated. It was found that in APUA both water soluble initiator potassium persulfate (KPS) and oil soluble initiator 2,2'-azobisisobutyronitrile (AIBN) can start the reaction of MMA, and the polymerization rate and yield were very high. On using AIBN as an initiator, the conversion-time behavior of MMA with APUA as emulsifier was different to that of SDS as emulsifier, signifying a different nucleation mechanism of the polymer latex particle. The average size of the two kinds of particles is about 50 nm. The particle size decreases with increasing emulsifier concentration. On using KPS as the initiator, APUA as emulsifier, cross-linking hydrogel of PMMA would be formed, but SDS was used as emulsifier and the hydrogel of PMMA was not present.

Extractive biotransformation for production of metabolites of poorly soluble compounds: synthesis of 32-hydroxy-rifalazil.

Science.gov (United States)

Mozhaev, Vadim V; Mozhaeva, Lyudmila V; Michels, Peter C; Khmelnitsky, Yuri L

2008-10-01

A novel reaction system was developed for the production of metabolites of poorly water-soluble parent compounds using mammalian liver microsomes. The system includes the selection and use of an appropriate hydrophobic polymeric resin as a reservoir for the hydrophobic parent compounds and its metabolites. The utility of the extractive biotransformation approach was shown for the production of a low-yielding, synthetically challenging 32-hydroxylated metabolite of the antibiotic rifalazil using mouse liver microsomes. To address the low solubility and reactivity of rifalazil in the predominantly aqueous microsomal catalytic system, a variety of strategies were tested for the enhanced delivery of hydrophobic substrates, including the addition of mild detergents, polyvinylpyrrolidone, glycerol, bovine serum albumin, and hydrophobic polymeric resins. The latter strategy was identified as the most suitable for the production of 32-hydroxy-rifalazil, resulting in up to 13-fold enhancement of the volumetric productivity compared with the standard aqueous system operating at the solubility limit of rifalazil. The production process was optimized for a wide range of reaction parameters; the most important for improving volumetric productivity included the type and amount of the polymeric resin, cofactor recycling system, concentrations of the biocatalyst and rifalazil, reaction temperature, and agitation rate. The optimized extractive biotransformation system was used to synthesize 32-hydroxy-rifalazil on a multimilligram scale.

Preparation and tribology properties of water-soluble fullerene derivative nanoball

Directory of Open Access Journals (Sweden)

Guichang Jiang

2017-02-01

Full Text Available Water-soluble fullerene derivatives were synthesized via radical polymerization. They are completely soluble in water, yielding a clear brown solution. The products were characterized by FTIR, UV–Vis, 1H-NMR, 13CNMR, GPC, TGA, and SEM. Four-ball tests show that the addition of a certain concentration of the fullerene derivatives to base stock (2 wt.% triethanolamine aqueous solution can effectively increase both the load-carrying capacity (PB value, and the resistance to wear. SEM observations confirm the additive results in a reduced diameter of the wear scar and decreased wear.

Leveraging Engineering of Indocyanine Green-Encapsulated Polymeric Nanocomposites for Biomedical Applications.

Science.gov (United States)

Han, Ya-Hui; Kankala, Ranjith Kumar; Wang, Shi-Bin; Chen, Ai-Zheng

2018-05-24

In recent times, photo-induced therapeutics have attracted enormous interest from researchers due to such attractive properties as preferential localization, excellent tissue penetration, high therapeutic efficacy, and minimal invasiveness, among others. Numerous photosensitizers have been considered in combination with light to realize significant progress in therapeutics. Along this line, indocyanine green (ICG), a Food and Drug Administration (FDA)-approved near-infrared (NIR, >750 nm) fluorescent dye, has been utilized in various biomedical applications such as drug delivery, imaging, and diagnosis, due to its attractive physicochemical properties, high sensitivity, and better imaging view field. However, ICG still suffers from certain limitations for its utilization as a molecular imaging probe in vivo, such as concentration-dependent aggregation, poor in vitro aqueous stability and photodegradation due to various physicochemical attributes. To overcome these limitations, much research has been dedicated to engineering numerous multifunctional polymeric composites for potential biomedical applications. In this review, we aim to discuss ICG-encapsulated polymeric nanoconstructs, which are of particular interest in various biomedical applications. First, we emphasize some attractive properties of ICG (including physicochemical characteristics, optical properties, metabolic features, and other aspects) and some of its current limitations. Next, we aim to provide a comprehensive overview highlighting recent reports on various polymeric nanoparticles that carry ICG for light-induced therapeutics with a set of examples. Finally, we summarize with perspectives highlighting the significant outcome, and current challenges of these nanocomposites.

Photophysicochemical, calf thymus DNA binding and in vitro photocytotoxicity properties of tetra-morpholinoethoxy-substituted phthalocyanines and their water-soluble quaternized derivatives.

Science.gov (United States)

Koçan, Halit; Kaya, Kerem; Özçeşmeci, İbrahim; Sesalan, B Şebnem; Göksel, Meltem; Durmuş, Mahmut; Burat, Ayfer Kalkan

2017-12-01

In this study, morpholinoethoxy-substituted metal-free (3), zinc(II) (4) and indium(III) (5) phthalocyanines were synthesized. These phthalocyanines were converted to their water-soluble quaternized derivatives (3Q-5Q) using excess methyl iodide as a quaternization agent. All these phthalocyanines (Pcs) were characterized by elemental analysis and different spectroscopic methods such as FT-IR, 1 H NMR, UV-Vis and mass spectrometry. The photophysical and photochemical properties such as fluorescence and generation of singlet oxygen were investigated for determination of these phthalocyanines as photosensitizers in photodynamic therapy (PDT) applications. The binding properties of quaternized phthalocyanines (3Q-5Q) to calf thymus DNA (CT-DNA) were investigated by UV-Vis and fluorescence spectrophotometric methods. The quenching effect of all quaternized phthalocyanines on the fluorescence intensity of SYBR Green-DNA complex was determined. The mixtures of 3Q, 4Q or 5Q and DNA solutions were used to determine the change in T m of double helix DNA with thermal denaturation profile. In addition, thermodynamic parameters considering their aggregation in buffer solution, which shows the spontaneity of the reactions between DNA and quaternized Pcs were investigated. On the other hand, in vitro phototoxicity and cytotoxicity behavior of the quaternized water-soluble phthalocyanine photosensitizers (3Q-5Q) were tested against the cervical cancer cell line named HeLa for evaluation of their suitability for treatment of cancer by PDT method. Peripherally tetra-substituted neutral and quaternized metal-free and metallophthalocyanines (MPcs) (Zn, In) bearing morpholinoethoxy groups were prepared. The binding of quaternized compounds (3Q-5Q) to CT-DNA were examined using UV-Vis, fluorescence spectra, thermal denaturation profiles and K SV values. Besides, thermodynamic studies indicated that binding of 3Q-5Q to DNA was spontaneous. On the other hand, in vitro phototoxicity and

Refuse derived soluble bio-organics enhancing tomato plant growth and productivity

Energy Technology Data Exchange (ETDEWEB)

Sortino, Orazio [Dipartimento di Scienze Agronomiche Agrochimiche e delle Produzioni Animali, Universita degli Studi di Catania, Via Valdisavoia 5, 95123 Catania (Italy); Dipasquale, Mauro [Dipartimento di Chimica, Universita di Torino, Via P. Giuria 7, 10125 Torino (Italy); Montoneri, Enzo, E-mail: enzo.montoneri@unito.it [Dipartimento di Chimica, Universita di Torino, Via P. Giuria 7, 10125 Torino (Italy); Tomasso, Lorenzo; Perrone, Daniele G. [Dipartimento di Chimica, Universita di Torino, Via P. Giuria 7, 10125 Torino (Italy); Vindrola, Daniela; Negre, Michele; Piccone, Giuseppe [Dipartimento di Valorizzazione e Protezione delle Risorse Agroforestali, Universita di Torino, Via L. da Vinci 44, 10095 Grugliasco (Italy)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Municipal bio-wastes are a sustainable source of bio-based products. Black-Right-Pointing-Pointer Refuse derived soluble bio-organics promote chlorophyll synthesis. Black-Right-Pointing-Pointer Refuse derived soluble bio-organics enhance plant growth and fruit ripening rate. Black-Right-Pointing-Pointer Sustainable chemistry exploiting urban refuse allows sustainable development. Black-Right-Pointing-Pointer Chemistry, agriculture and the environment benefit from biowaste technology. - Abstract: Municipal bio-refuse (CVD), containing kitchen wastes, home gardening residues and public park trimmings, was treated with alkali to yield a soluble bio-organic fraction (SBO) and an insoluble residue. These materials were characterized using elemental analysis, potentiometric titration, and 13C NMR spectroscopy, and then applied as organic fertilizers to soil for tomato greenhouse cultivation. Their performance was compared with a commercial product obtained from animal residues. Plant growth, fruit yield and quality, and soil and leaf chemical composition were the selected performance indicators. The SBO exhibited the best performance by enhancing leaf chlorophyll content, improving plant growth and fruit ripening rate and yield. No product performance-chemical composition relationship could be assessed. Solubility could be one reason for the superior performance of SBO as a tomato growth promoter. The enhancement of leaf chlorophyll content is discussed to identify a possible link with the SBO photosensitizing properties that have been demonstrated in other work, and thus with photosynthetic performance.

Refuse derived soluble bio-organics enhancing tomato plant growth and productivity

International Nuclear Information System (INIS)

Sortino, Orazio; Dipasquale, Mauro; Montoneri, Enzo; Tomasso, Lorenzo; Perrone, Daniele G.; Vindrola, Daniela; Negre, Michele; Piccone, Giuseppe

2012-01-01

Highlights: ► Municipal bio-wastes are a sustainable source of bio-based products. ► Refuse derived soluble bio-organics promote chlorophyll synthesis. ► Refuse derived soluble bio-organics enhance plant growth and fruit ripening rate. ► Sustainable chemistry exploiting urban refuse allows sustainable development. ► Chemistry, agriculture and the environment benefit from biowaste technology. - Abstract: Municipal bio-refuse (CVD), containing kitchen wastes, home gardening residues and public park trimmings, was treated with alkali to yield a soluble bio-organic fraction (SBO) and an insoluble residue. These materials were characterized using elemental analysis, potentiometric titration, and 13C NMR spectroscopy, and then applied as organic fertilizers to soil for tomato greenhouse cultivation. Their performance was compared with a commercial product obtained from animal residues. Plant growth, fruit yield and quality, and soil and leaf chemical composition were the selected performance indicators. The SBO exhibited the best performance by enhancing leaf chlorophyll content, improving plant growth and fruit ripening rate and yield. No product performance-chemical composition relationship could be assessed. Solubility could be one reason for the superior performance of SBO as a tomato growth promoter. The enhancement of leaf chlorophyll content is discussed to identify a possible link with the SBO photosensitizing properties that have been demonstrated in other work, and thus with photosynthetic performance.

Identification of singlet oxygen photosensitizes in lambs drinking water in an alveld risk area in West Norway

DEFF Research Database (Denmark)

Tønnesen, Hanne Hjorth; Mysterud, Ivar; Karlsen, Jan

2013-01-01

Alveld is a hepatogenous photosensitivity disorder in lambs. Although alveld has been known in Norway for more than 100years, there are still questions related to the cause of the disease. Phytoporphyrin has long been incriminated as the photosensitizer in hepatogenous photosensitivity diseases...... but previous findings suggest that the photosensitizing mechanism in alveld is more complex, possibly involving other co-factors. The current work investigates the presence of non-hepatogenous photosensitizers originating in lamb's drinking water from various sources. In addition samples of two....... Meteorological data indicate a warm and wet May with a high radiation exposure leading up to a colder and wet June with an even higher solar irradiance. The seasonal variation in the amount of photosensitizers in lamb's drinking water combined meteorological data can be important to predict the outbreak...

Prevalence of pesticides in postconsumer agrochemical polymeric packaging.

Science.gov (United States)

Eras, J; Costa, J; Vilaró, F; Pelacho, A M; Canela-Garayoa, R; Martin-Closas, L

2017-02-15

Pesticide remains contained in agrochemical packaging waste are a source of uncontrolled risk for human health; they are also a quality feedstock for the plastic recycling industry. Many governments have recently started to establish laws and regulations to develop systems for recovering and recycling the polymeric packages used for pesticides. There is also a demand in having a procedure to control the suitability of the pesticide packages to be reused. We have developed a two-step operation process to assess the pesticide residues in agricultural containers made of a variety of polymeric matrices. The procedure is based on an extraction with a solvent mixture followed by UPLC-MS/MS determination. Solvents for neutral pesticides were selected considering the Hildebrand solubility (δ) of solvents and polymers together with those estimated for the pesticides. The proposed technique is effective in recovering imbibed pesticides in polymeric matrices. Also, a simplified extraction procedure has been tested to become a routine method for these wastes. We have found that in many cases a significant amount of pesticides remain into the polymeric matrix, even after a standardized cleaning; the impact of releasing these hazardous compounds into the environment is to be of further consideration. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis, characterization and fluorescent properties of water-soluble glycopolymer bearing curcumin pendant residues.

Science.gov (United States)

Zhang, Haisong; Yu, Meng; Zhang, Hailei; Bai, Libin; Wu, Yonggang; Wang, Sujuan; Ba, Xinwu

2016-08-01

Curcumin is a potential natural anticancer drug with low oral bioavailability because of poor water solubility. The aqueous solubility of curcumin is enhanced by means of modification with the carbohydrate units. Polymerization of the curcumin-containing monomer with carbohydrate-containing monomer gives the water-soluble glycopolymer bearing curcumin pendant residues. The obtained copolymers (P1 and P2) having desirable water solubility were well-characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), UV-Vis absorption spectroscopy, and photoluminescence spectroscopy. The copolymer P2 with a molar ratio of 1:6 (curcumin/carbohydrate) calculated from the proton NMR results exhibits a similar anticancer activity compared to original curcumin, which may serve as a potential chemotherapeutic agent in the field of anticancer medicine.

Tetrapyrrole-photosensitizers vectorization and plasma LDL: a physico-chemical approach.

Science.gov (United States)

Bonneau, Stéphanie; Vever-Bizet, Christine; Mojzisova, Halina; Brault, Daniel

2007-11-01

A photosensitizer is defined as a chemical entity able to induce, under light-irradiation effect, a chemical or physical alteration of another chemical entity. Thanks to their preferential retention in proliferating tissues, some photosensitizers are therapeutically used such as in photodynamic therapy (PDT). Besides, this method has already been approved for several indications. The selectivity of photosenzitizers for cells in proliferation involves both their association with low density lipoproteins (LDLs) and their ability to cross membranes under various pH conditions. The photosensitizers used are in most cases based on the porphyrin structure, but other compounds, of which far-red-light absorption properties are most compatible with biological tissues irradiation, have been developed, such as phthalocyanines. This paper presents physico-chemical studies of the interaction of a disulfonated aluminium phthalocyanine (AlPcS2) with human LDLs. The data obtained are compared with the parameters of the interaction of these lipoproteins with deuteroporphyrin (DP) and chlorin e6 (Ce6). A close attention is paid to the dynamic aspects of these phenomena. The data obtained on these simple systems then allowed us to interpret the sub-cellular localization of the photosensitizers on a human line of fibroblasts, and to evaluate the influence of LDLs on the intracellular distribution of the compounds. This last point is of major importance because the localization of such photosensitizers (in particular AlPcS2) in endocytic vesicles and their subsequent ability to induce a release of the contents of these vesicles - including externally added macromolecules - into the cytosol is the basis for a recent method for macromolecule activation, named photochemical internalization (PCI). PCI has been shown to potentiate the biological activity of a large variety of macromolecules. The comprehension of the mechanisms governing this particular sub-cellular localization could allow

Synthesis of polyalkylacrylate nanolatexes by microemulsion polymerization method

Directory of Open Access Journals (Sweden)

A.M. Al-Sabagh

2012-12-01

Full Text Available The paper concerns with the radical polymerization of [octadecyl acrylate (ODA, isooctyl acrylate (iso-OA and α-olefins 1-Octene (n-O]. These microemulsions were stabilized by sodium dodecyl sulfate (SDS and initiated by water-soluble initiator potassium persulfate (KPS. The nanolatex particle sizes were determined by transmission electron microscope (TEM. They were situated between 10 and 100 nm. The microstructures were confirmed by FT-IR and molecular weights determined by Gel permeation chromatography (GPC. The obtained M. wt. were (≈70 × 103, 101 × 103 and 153 × 103 g/mol. The polydispersity, molecular weights, and particle sizes were discussed in the light of micelle formation and shape of the alkyl group via emulsion polymerization.

Radiation polymerization of acrylamide with super-high molecular weight in inverse emulsion

International Nuclear Information System (INIS)

Ye Qiang; Ge Xuewu; Xu Xiangling; Zhang Zhicheng

1998-01-01

The inverse emulsion polymerization of acrylamide has been studied with γ-ray initiation. Polyacrylamide with super high molecular weight over ten million (11 x 10 6 ), which is very important in application as flocculant, is obtained. In this work, some methods are taken to enhance the molecular weight as follows: (1) In order to prepare soluble polyacrylamide with super high molecular weight, the better conditions are: the emulsifier content is about 2% and the monomer concentration is about 20%∼24% in the composition of monomer emulsion, and the absorbed dose is about 500∼600 Gy. (2) Initiating with high dose rate and polymerizing with low dose rate can not only enhance the molecular weight of product, but also curtail the polymerizing time. (3) Stopping radiation when the conversion gets to about 10% and post-polymerizing outside the radiation source until the conversion gets to 82% can obtain polyacrylamide with super high molecular weight, and shorten the irradiation time as well

Synthesis, spectroscopy and photosensitizing properties of hydroxynitrophenyl porphyrins

Energy Technology Data Exchange (ETDEWEB)

Maestrin, Ana Paula J.; Tedesco, Antonio Claudio; Neri, Claudio R.; Gandini, Maria Elisa F.; Serra, Osvaldo A.; Iamamoto, Yassuko [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Inst. de Quimica]. E-mail: osaserra@usp.br

2004-10-01

The hydroxynitrophenyl porphyrins, 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrin and 5-mono(carboxyphenyl)-10,15,20-tris(2-hydroxy-5-nitrophenyl)porphyrin described in this work were prepared through Adler's method. These compounds were characterized by {sup 1}H NMR and light absorption and emission spectroscopy in the visible region. In order to demonstrate the involvement of {sup 1}O{sub 2} production, the uric (UA) acid test was carried out, which considers the decrease in the absorbance of UA at 293 nm following laser light irradiation of a solution containing UA and a photosensitizer. The results obtained demonstrate that these hydroxynitrophenyl porphyrins can be considered as promising photosensitizers in PDT. (author)

Enhancement of dissolution and oral bioavailability of lacidipine via pluronic P123/F127 mixed polymeric micelles: formulation, optimization using central composite design and in vivo bioavailability study.

Science.gov (United States)

Fares, Ahmed R; ElMeshad, Aliaa N; Kassem, Mohamed A A

2018-11-01

This study aims at preparing and optimizing lacidipine (LCDP) polymeric micelles using thin film hydration technique in order to overcome LCDP solubility-limited oral bioavailability. A two-factor three-level central composite face-centered design (CCFD) was employed to optimize the formulation variables to obtain LCDP polymeric micelles of high entrapment efficiency and small and uniform particle size (PS). Formulation variables were: Pluronic to drug ratio (A) and Pluronic P123 percentage (B). LCDP polymeric micelles were assessed for entrapment efficiency (EE%), PS and polydispersity index (PDI). The formula with the highest desirability (0.959) was chosen as the optimized formula. The values of the formulation variables (A and B) in the optimized polymeric micelles formula were 45% and 80%, respectively. Optimum LCDP polymeric micelles had entrapment efficiency of 99.23%, PS of 21.08 nm and PDI of 0.11. Optimum LCDP polymeric micelles formula was physically characterized using transmission electron microscopy. LCDP polymeric micelles showed saturation solubility approximately 450 times that of raw LCDP in addition to significantly enhanced dissolution rate. Bioavailability study of optimum LCDP polymeric micelles formula in rabbits revealed a 6.85-fold increase in LCDP bioavailability compared to LCDP oral suspension.

Advanced Polymeric and Organic–Inorganic Membranes for Pressure-Driven Processes

KAUST Repository

Le, Ngoc Lieu; Phuoc, Duong; Nunes, Suzana Pereira

2017-01-01

The state-of-the-art of membranes for reverse osmosis, nanofiltration, and gas separation is shortly reviewed, taking in account the most representative examples currently in application. Emphasis is also done on recent developments of advanced polymeric and organic–inorganic materials for pressure-driven processes. Many of the more recent membranes are not only polymeric but also contain an inorganic phase. Tailoring innovative materials with organic and inorganic phases coexisting in a nanoscale with multifunctionalization is an appealing approach to control at the same time diffusivity and gas solubility. Other advanced materials that are now being considered for membrane development are organic or organic–inorganic self-assemblies, metal-organic frameworks, and different forms of carbon fillers.

Advanced Polymeric and Organic–Inorganic Membranes for Pressure-Driven Processes

KAUST Repository

Le, Ngoc Lieu

2017-02-13

The state-of-the-art of membranes for reverse osmosis, nanofiltration, and gas separation is shortly reviewed, taking in account the most representative examples currently in application. Emphasis is also done on recent developments of advanced polymeric and organic–inorganic materials for pressure-driven processes. Many of the more recent membranes are not only polymeric but also contain an inorganic phase. Tailoring innovative materials with organic and inorganic phases coexisting in a nanoscale with multifunctionalization is an appealing approach to control at the same time diffusivity and gas solubility. Other advanced materials that are now being considered for membrane development are organic or organic–inorganic self-assemblies, metal-organic frameworks, and different forms of carbon fillers.

Functionalization of lanthanum hydroxide nanowires by atom transfer radical polymerization

International Nuclear Information System (INIS)

Zhou Mi; Yuan Jinying; Yuan Weizhong; Yin Yingwu; Hong Xiaoyin

2007-01-01

Atom transfer radical polymerization (ATRP) has been used to prepare a core-shell hybrid nanostructure successfully: a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of polystyrene (PS) brushes. Transmission electron microscopy (TEM) images indicated that the resulting products presented special structures and different thicknesses of polymer layers. The chemical components and grafted PS quantities of the samples were measured by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The polymers showed narrow polydispersity, which proved that the lanthanum hydroxide nanowires initiated the 'living'/controlled polymerization of styrene. With the modifiability of lanthanum hydroxide nanowires, the solubility increased, which affords a new way to functionalize nanowires

Time-resolved luminescence measurements of the magnetic field effect on paramagnetic photosensitizers in photodynamic reactions

Science.gov (United States)

Mermut, O.; Bouchard, J.-P.; Cormier, J.-F.; Desroches, P.; Diamond, K. R.; Fortin, M.; Gallant, P.; Leclair, S.; Marois, J.-S.; Noiseux, I.; Morin, J.-F.; Patterson, M. S.; Vernon, M.

2008-02-01

The development of multimodal molecular probes and photosensitizing agents for use in photodynamic therapy (PDT) is vital for optimizing and monitoring cytotoxic responses. We propose a combinatorial approach utilizing photosensitizing molecules that are both paramagnetic and luminescent with multimodal functionality to perturb, control, and monitor molecular-scale reaction pathways in PDT. To this end, a time-domain single photon counting lifetime apparatus with a 400 nm excitation source has been developed and integrated with a variable low field magnet (0- 350mT). The luminescence lifetime decay function was measured in the presence of a sweeping magnetic field for a custom designed photosensitizing molecule in which photoinduced electron transfer was studied The photosensitizer studied was a donor-acceptor complex synthesized using a porphyrin linked to a fullerene molecule. The magneto-optic properties were investigated for the free-base photosensitizer complex as well as those containing either diamagnetic (paired electron) or paramagnetic (unpaired electron) metal centers, Zn(II) and Cu(II). The magnetic field was employed to affect and modify the spin states of radical pairs of the photosensitizing agents via magnetically induced hyperfine and Zeeman effects. Since the Type 1 reaction pathway of an excited triplet state photosensitizer involves the production of radical species, lifetime measurements were conducted at low dissolved oxygen concentration (0.01ppm) to elucidate the dependence of the magnetic perturbation on the photosensitization mechanistic pathway. To optimize the magnetic response, a solvent study was performed examining the dependence of the emission properties on the magnetic field in solutions of varying dielectric constants. Lastly, the cytotoxicity in murine tumor cell suspensions was investigated for the novel porphyrin-fullerene complex by inducing photodynamic treatments and determining the associated cell survival.

Extended rhodamine photosensitizers for photodynamic therapy of cancer cells.

Science.gov (United States)

Davies, Kellie S; Linder, Michelle K; Kryman, Mark W; Detty, Michael R

2016-09-01

Extended thio- and selenorhodamines with a linear or angular fused benzo group were prepared. The absorption maxima for these compounds fell between 640 and 700nm. The extended rhodamines were evaluated for their potential as photosensitizers for photodynamic therapy in Colo-26 cells. These compounds were examined for their photophysical properties (absorption, fluorescence, and ability to generate singlet oxygen), for their dark and phototoxicity toward Colo-26 cells, and for their co-localization with mitochondrial-specific agents in Colo-26 and HUT-78 cells. The angular extended rhodamines were effective photosensitizers toward Colo-26 cells with 1.0Jcm(-2) laser light delivered at λmax±2nm with values of EC50 of (2.8±0.4)×10(-7)M for sulfur-containing analogue 6-S and (6.4±0.4)×10(-8)M for selenium-containing analogue 6-Se. The linear extended rhodamines were effective photosensitizers toward Colo-26 cells with 5 and 10Jcm(-2) of broad-band light (EC50's⩽2.4×10(-7)M). Copyright © 2016 Elsevier Ltd. All rights reserved.

The (6-4) Dimeric Lesion as a DNA Photosensitizer.

Science.gov (United States)

Vendrell-Criado, Victoria; Rodríguez-Muñiz, Gemma M; Lhiaubet-Vallet, Virginie; Cuquerella, M Consuelo; Miranda, Miguel A

2016-07-04

Based on our previous investigations into the photophysical properties of the 5-methyl-2-pyrimidone (Pyo) chromophore, we now extend our studies to the photobehavior of the dimeric (6-4) thymine photoproducts (6-4 PP) to evaluate their capability to act as instrinsic DNA photosensitizers. The lesion presents significant absorption in the UVB/UVA region, weak fluorescence emission, a singlet-excited-state energy of approximately 351 kJ mol(-1) , and a triplet-excited-state energy of 297 kJ mol(-1) . Its triplet transient absorption has a maximum at 420-440 nm, a lifetime of around 7 μs, and a high formation quantum yield, ΦISC =0.86. This species is efficiently quenched by thymidine. Its DNA photosensitizing properties are demonstrated by a series of experiments run on a pBR322 plasmid. The lesion photoinduces both single-strand breaks and the formation of cyclobutane thymine dimers. Altogether, these results show that, the substitution of the pyrimidone ring at C4 by a 5-hydroxy-5,6-dihydrothymine does not cancel out the photosensitization properties of the chromophore. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dosimetry of photosensitization by ultraviolet in patients treated with Haloperidol and Piportil

International Nuclear Information System (INIS)

Barros, M. de; Araujo, C.C.

1982-01-01

It has been postulated that visible light on UV may induce photosensitization in chronic psycotics, under phenotiazine or butyrofenone therapy. The possible sensitization with UV, in patients with Haloperidol (Johnson and Johnson) or Piportil (Rhodia) treatments is described. Under experimental conditions, a surpassable photosensitizations in reaction groups aren't finding, when paired with the control ones. (M.A.C.) [pt

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

Directory of Open Access Journals (Sweden)

Jane C. Quinn

2014-01-01

Full Text Available Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems.

Intracellular distribution and mechanisms of actions of photosensitizer Zinc(II)-phthalocyanine solubilized in Cremophor EL against human hepatocellular carcinoma HepG2 cells.

Science.gov (United States)

Shao, Jingwei; Dai, Yongchao; Zhao, Wenna; Xie, Jingjing; Xue, Jinping; Ye, Jianhui; Jia, Lee

2013-03-01

Zinc(II)-phthalocyanine (ZnPc) is a metal photosensitizer. In the present study, we formulated the poorly-soluble ZnPc in Cremophor EL solution to enhance its solubility and determined its intracellular distribution and mechanisms of action on human hepatocellular carcinoma HepG2 cells. ZnPc uptake by the cells reached a plateau by 8h. ZnPc primarily located in mitochondria, lysosome and endoplasmic reticulum. The concentration-growth inhibition curves of ZnPc on the cell lines were pharmacodynamically enhanced by 10-50 folds by irradiation. Once irradiated, ZnPc produced significant amount of reactive oxygen species (ROS), activated caspase-3 and caspase-9, arrested cell cycle mainly at G2/M stage, and decreased membrane potential (ΔΨm) of HepG2 cells. In conclusion, the present study first elucidated cellular and molecular mechanisms of ZnPc on HepG2 cells. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Biochemical synthesis of water soluble conducting polymers

Science.gov (United States)

Bruno, Ferdinando F.; Bernabei, Manuele

2016-05-01

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

Biochemical synthesis of water soluble conducting polymers

Energy Technology Data Exchange (ETDEWEB)

Bruno, Ferdinando F., E-mail: Ferdinando-Bruno@uml.edu [US Army Natick Soldier Research, Development and Engineering Center, Natick, MA 01760 (United States); Bernabei, Manuele [ITAF, Test Flight Centre, Chemistry Dept. Pratica di Mare AFB, 00071 Pomezia (Rome), Italy (UE) (Italy)

2016-05-18

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

Biochemical synthesis of water soluble conducting polymers

International Nuclear Information System (INIS)

Bruno, Ferdinando F.; Bernabei, Manuele

2016-01-01

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

How predictive are photosensitive epilepsy models as proof of principle trials for epilepsy?

Science.gov (United States)

Yuen, Eunice S M; Sims, John R

2014-06-01

Human photosensitive epilepsy models have been used as proof of principle (POP) trials for epilepsy. Photosensitive patients are exposed to intermittent photic stimulation and the reduction in sensitivity to the number of standard visual stimulation frequencies is used as an endpoint. The aim of this research was to quantify the predictive capabilities of photosensitive POP trials, through a survey of current literature. A literature search was undertaken to identify articles describing photosensitive POP trials. Minimally efficacious doses (MEDs) in epilepsy were compared to doses in the POP trials that produced 50-100% response (ED50-100). Ratios of these doses were calculated and summarised statistically. The search identified ten articles describing a total of 17 anti-epileptic drugs. Of these, data for both MED and ED50-100 were available for 13 anti-epileptic drugs. The average ratio of MED to ED50-100 was 0.95 (95% CI 0.60-1.30). The difference in MED to ED50-100 ratios between partial epilepsy (0.82) was not significantly different from that of generalised epilepsy (1.08) (p=0.51). Photosensitive POP trials are a useful tool to quantitatively predict efficacy in epilepsy, and can be useful as early and informative indicators in anti-epileptic drug discovery and development. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Polymerization reactivity of sulfomethylated alkali lignin modified with horseradish peroxidase.

Science.gov (United States)

Yang, Dongjie; Wu, Xiaolei; Qiu, Xueqing; Chang, Yaqi; Lou, Hongming

2014-03-01

Alkali lignin (AL) was employed as raw materials in the present study. Sulfomethylation was conducted to improve the solubility of AL, while sulfomethylated alkali lignin (SAL) was further polymerized by horseradish peroxidase (HRP). HRP modification caused a significant increase in molecular weight of SAL which was over 20 times. It was also found to increase the amount of sulfonic and carboxyl groups while decrease the amount of phenolic and methoxyl groups in SAL. The adsorption quantity of self-assembled SAL film was improved after HRP modification. Sulfonation and HRP modification were mutually promoted. The polymerization reactivity of SAL in HRP modification was increased with its sulfonation degree. Meanwhile, HRP modification facilitated SAL's radical-sulfonation reaction. Copyright © 2014. Published by Elsevier Ltd.

Surface water retardation around single-chain polymeric nanoparticles: critical for catalytic function?

Science.gov (United States)

Stals, Patrick J M; Cheng, Chi-Yuan; van Beek, Lotte; Wauters, Annelies C; Palmans, Anja R A; Han, Songi; Meijer, E W

2016-03-01

A library of water-soluble dynamic single-chain polymeric nanoparticles (SCPN) was prepared using a controlled radical polymerisation technique followed by the introduction of functional groups, including probes at targeted positions. The combined tools of electron paramagnetic resonance (EPR) and Overhauser dynamic nuclear polarization (ODNP) reveal that these SCPNs have structural and surface hydration properties resembling that of enzymes.

Stability of bisphenol A (BPA) in oil-in water emulsions under riboflavin photosensitization.

Science.gov (United States)

Jang, Eun Yeong; Park, Chan Uk; Kim, Mi-Ja; Lee, JaeHwan

2012-08-01

Effects of riboflavin photosensitization on the degradation of bisphenol A (BPA) were determined in oil-in-water (O/W) emulsions containing ethylenediaminetetraacetic acid (EDTA) or sodium azide, which are a metal chelator or a singlet oxygen quencher, respectively. Also, the distribution of BPA between the continuous and dispersed phases in O/W emulsions was analyzed by high-performance liquid chromatography (HPLC). The concentration of BPA in O/W emulsions significantly decreased by 38.6% after 2 h under visible light irradiation and in the presence of riboflavin (P riboflavin photosensitization (P riboflavin photodegradation in O/W emulsions. Concentration of BPA, an endocrine disrupting chemical, was decreased significantly in oil-in-water emulsions under riboflavin and visible light irradiation. BPA in continuous aqueous phase was major target of riboflavin photosensitization. However, BPA was distributed more densely in lipid phase and more protected from riboflavin photosensitized O/W emulsions. This study can help to decrease the level of BPA in foods made of O/W emulsions containing riboflavin, which could be displayed under visible light irradiation. © 2012 Institute of Food Technologists®

Optimization of Photosensitized Tryptophan Oxidation in the Presence of Dimegin-Polyvinylpyrrolidone-Chitosan Systems.

Science.gov (United States)

Solovieva, Anna B; Kardumian, Valeria V; Aksenova, Nadezhda A; Belovolova, Lyudmila V; Glushkov, Mikhail V; Bezrukov, Evgeny A; Sukhanov, Roman B; Kotova, Svetlana L; Timashev, Peter S

2018-05-23

By the example of a model process of tryptophan photooxidation in the aqueous medium in the presence of a three-component photosensitizing complex (porphyrin photosensitizer-polyvinylpyrrolidone- chitosan, PPS-PVP-CT) in the temperature range of 20-40 °С, we have demonstrated a possibility of modification of such a process by selecting different molar ratios of the components in the reaction mixture. The actual objective of this selection is the formation of a certain PPS-PVP-CT composition in which PVP macromolecules would coordinate with PPS molecules and at the same time practically block the complex binding of PPS molecules with chitosan macromolecules. Such blocking allows utilization of the bactericidal properties of chitosan to a greater extent, since chitosan is known to depress the PPS photosensitizing activity in PPS-PVP-CT complexes when using those in photodynamic therapy (PDT). The optimal composition of photosensitizing complexes appears to be dependent on the temperature at which the PDT sessions are performed. We have analyzed the correlations of the effective rate constants of tryptophan photooxidation with the photophysical characteristics of the formed complexes.

Long-wavelength photosensitivity in coral planula larvae.

Science.gov (United States)

Mason, Benjamin M; Cohen, Jonathan H

2012-04-01

Light influences the swimming behavior and settlement of the planktonic planula larvae of coral, but little is known regarding the photosensory biology of coral at this or any life-history stage. Here we used changes in the electrical activity of coral planula tissue upon light flashes to investigate the photosensitivity of the larvae. Recordings were made from five species: two whose larvae are brooded and contain algal symbionts (Porites astreoides and Agaricia agaricites), and three whose larvae are spawned and lack algal symbionts (Acropora cervicornis, Acropora palmata,and Montastrea faveolata). Photosensitivity originated from the coral larva rather than from, or in addition to, its algal symbionts as species with and without symbionts displayed similar tissue-level electrical responses to light. All species exhibited as much (or more) sensitivity to red stimuli as to blue/green stimuli, which is consistent with a role for long-wavelength visible light in the preference for substrata observed during settlement and in facilitating vertical positioning of larvae in the water column.

Phototreatment of Water by Organic Photosensitizers and Comparison with Inorganic Semiconductors

Directory of Open Access Journals (Sweden)

Merlyn Thandu

2015-01-01

Full Text Available Phototreatment of water is drawing the attention of many as a promising alternative to replace methods like chlorination, ozonization, and other oxidation processes, used in current disinfection methods limiting harmful side-products and by-products that can cause damage to the fauna and flora. Porphyrins, phthalocyanines, and other related organic dyes are well known for their use in photodynamic therapy (PDT. These photosensitizers cause cell death by generating reactive oxygen species (ROS especially singlet oxygen in the presence of light. Such molecules are also being explored for photodynamically treating microbial infections, killing of unwanted pathogens in the environment, and oxidation of chemical pollutants. The process of photosensitisation (phototreatment can be applied for obtaining clean, microbe-free water, thus exploiting the versatile properties of photosensitizers. This review collects the various attempts carried out for phototreatment of water using organic photosensitizers. For comparison, some reports of semiconductors (especially TiO2 used in photocatalytic treatment of water are also mentioned.

A novel in vitro method for the detection and characterization of photosensitizers.

Directory of Open Access Journals (Sweden)

Nadine Karschuk

Full Text Available Photoactivation and binding of photoactive chemicals to proteins is a known prerequisite for the formation of immunogenic photoantigens and the induction of photoallergy. The intensive use of products and the availability of new chemicals, along with an increasing exposure to sun light contribute to the risk of photosensitizing adverse reactions. Dendritic cells (DC play a pivotal role in the induction of allergic contact dermatitis. Human peripheral blood monocyte derived dendritic cells (PBMDC were thus perceived as an obvious choice for the development of a novel in vitro photosensitization assay using the modulation of cell surface protein expression in response to photosensitizing agents. In this new protocol, known chemicals with photosensitizing, allergenic or non-allergenic potential were pre-incubated with PBMDCs prior to UVA irradiation (1 J/cm(2. Following a 48 h incubation, the expression of the cell surface molecules CD86, HLA-DR and CD83 was measured by flow cytometry. All tested photosensitizers induced a significant and dose-dependent increase of CD86 expression after irradiation compared to non-irradiated controls. Moreover, the phototoxicity of the chemicals could also be determined. In contrast, (i CD86 expression was not affected by the chosen irradiation conditions, (ii increased CD86 expression induced by allergens was independent of irradiation and (iii no PBMDC activation was observed with the non-allergenic control. The assay proposed here for the evaluation of the photoallergenic potential of chemicals includes the assessment of their allergenic, phototoxic and toxic potential in a single and robust test system and is filling a gap in the in vitro photoallergenicity test battery.

Chitin nanofiber elucidates the elicitor activity of polymeric chitin in plants

Directory of Open Access Journals (Sweden)

Mayumi eEgusa

2015-12-01

Full Text Available Chitin, an N-acetyl-D-glucosamine polymer, is a component of fungal cell walls and a microbe/pathogen-associated molecular pattern that elicits plant defense responses. As polymeric chitin is difficult to handle due to its insolubility in water, many studies on chitin-induced immune responses have used water-soluble low-molecular weight chitin instead. Thus, it is unclear if polymeric chitin can induce resistance. Here, we examined the elicitor activity of chitin nanofiber (CNF of submicron thickness prepared from polymeric chitin. CNF showed a high dispersing ability in water and induced both reactive oxygen species (ROS production and chitin-induced defense-related gene expression in Arabidopsis thaliana seedlings. The Arabidopsis chitin elicitor receptor kinase 1 (Atcerk1 mutant, which is impaired in chitin perception, also failed to respond to CNF. CNF exposure triggered ROS generation in suspension-cultured cells from Oryza sativa. Furthermore, pre-treatment of Arabidopsis leaves with CNF effectively reduced pathogen infection by both the fungus Alternaria brassicicola and the bacterium Pseudomonas syringae pv. tomato DC3000. These results demonstrate that CNF has elicitor activity and will help define the role of polymeric chitin in plant immune responses.

REVIEW: CHITOSAN BASED HYDROGEL POLYMERIC BEADS – AS DRUG DELIVERY SYSTEM

Directory of Open Access Journals (Sweden)

Manjusha Rani

2010-11-01

Full Text Available Chitosan obtained by alkaline deacetylation of chitin is a non-toxic, biocompatible, and biodegradable natural polymer. Chitosan-based hydrogel polymeric beads have been extensively studied as micro- or nano-particulate carriers in the pharmaceutical and medical fields, where they have shown promise for drug delivery as a result of their controlled and sustained release properties, as well as biocompatibility with tissue and cells. To introduce desired properties and enlarge the scope of the potential applications of chitosan, graft copolymerization with natural or synthetic polymers on it has been carried out, and also, various chitosan derivatives have been utilized to form beads. The desired kinetics, duration, and rate of drug release up to therapeutical level from polymeric beads are limited by specific conditions such as beads material and their composition, bead preparation method, amount of drug loading, drug solubility, and drug polymer interaction. The present review summarizes most of the available reports about compositional and structural effects of chitosan-based hydrogel polymeric beads on swelling, drug loading, and releasing properties. From the studies reviewed it is concluded that chitosan-based hydrogel polymeric beads are promising drug delivery systems.

Role of polymer matrix on photo-sensitivity of CdSe polymer nanocomposites

Science.gov (United States)

Kaur, Ramneek; Tripathi, S. K.

2018-04-01

This paper reports the effect of three different polymer matrices (PVP, PMMA and PVK) and Ag doping on the photo-sensitivity of CdSe polymer nanocomposites. The results reveal that the photoconductivity is high for linear chain polymer nanocomposites as compared to aromatic ones with decreasing trend as: CdSe-PMMA > CdSe-PVP > CdSe-PVK. The large substituents or branches along the polymer backbone hinder the stacking sequences in CdSe-PVK nanocomposites resulting in lowest photoconductivity. On contrary, CdSe-PVK nanocomposite exhibit highest photosensitivity. The reason behind it is the low value of dark conductivity in CdSe-PVK nanocomposite and photoconductive PVK matrix. With Ag doping, no considerable effect on the value of photosensitivity has been observed. The obtained results indicate that the photo-conducting properties of these polymer nanocomposites can be tuned by using different polymer matrices.

Effects of Polymeric Additives on the Crystallization and Release Behavior of Amorphous Ibuprofen

Directory of Open Access Journals (Sweden)

Su Yang Lee

2013-01-01

Full Text Available Some polymeric additives were studied to understand their effects on the amorphous phase of ibuprofen (IBU, used as a poorly water soluble pharmaceutical model compound. The amorphous IBU in bulk, as well as in nanopores (diameter ~24 nm of anodic aluminum oxide, was examined with the addition of poly(acrylic acid, poly(N-vinyl pyrrolidone, or poly(4-vinylphenol. Results of bulk crystallization showed that they were effective in limiting the crystal growth, while the nucleation of the crystalline phase in contact with water was nearly instantaneous in all cases. Poly(N-vinyl pyrrolidone, the most effective additive, was in specific interaction with IBU, as revealed by IR spectroscopy. The addition of the polymers was combined with the nanoscopic confinement to further stabilize the amorphous phase. Still, the IBU with addition of polymeric additives showed sustained release behavior. The current study suggested that the inhibition of the crystal nucleation was probably the most important factor to stabilize the amorphous phase and fully harness its high solubility.

A Study of the Operation of Especially Designed Photosensitive Gaseous Detectors at Cryogenic Temperatures

CERN Document Server

Periale, L; Lund-Jensen, B; Pavlopoulos, P; Peskov, Vladimir; Picchi, P; Pietropaolo, F

2006-01-01

In some experiments and applications there is need for large-area photosensitive detectors to operate at cryogenic temperatures. Nowadays, vacuum PMs are usually used for this purpose. We have developed special designs of planar photosensitive gaseous detectors able to operate at cryogenic temperatures. Such detectors are much cheaper PMs and are almost insensitive to magnetic fields. Results of systematic measurements of their quantum efficiencies, the maximum achievable gains and long-term stabilities will be presented. The successful operation of these detectors open realistic possibilities in replacing PMs by photosensitive gaseous detectors in some applications dealing with cryogenic liquids; for example in experiments using noble liquid TPCs or noble liquid scintillating calorimeters.

Photochemical events during photosensitization of colloidal ZnO ...

Indian Academy of Sciences (India)

The photosensitization of colloidal ZnO nanoparticles with riboflavin (RF) was investigated using absorption, fluorescence spectroscopic measurements and time resolved fluorescence measurements. Riboflavin adsorbed strongly on the surface of ZnO nanoparticles. Apparent association constant was obtained from the ...

Riboflavin-mediated photosensitization of Vinca alkaloids distorts drug sensitivity assays.

Science.gov (United States)

Granzow, C; Kopun, M; Kröber, T

1995-11-01

Poor reproducibility of cytotoxicity tests with Vinca alkaloids has frequently been reported. A commonly presumed light sensitivity of the drugs could not be confirmed. However, we found that they are photosensitized by riboflavin (vitamin B2), an obligatory component of cell culture media. Light of wavelengths below 500 nm triggered rapid photoreactions of riboflavin with vinblastine, vincristine, and vindesine in aqueous solutions. The photoreactions altered the absorption spectra of these alkaloids and yielded degradation products that could be separated by TLC. In cell cultures, both immediate and persisting, riboflavin-mediated photoreactivity could be distinguished. They preclude reliable determinations of sensitivity and resistance to Vinca alkaloids, as exemplified on chemosensitive and multidrug-resistant mouse ascites cells. In experiments involving photosensitization, the 50% inhibitory concentration values of sensitive and resistant cells were overlapping and fluctuated in the ranges from 3 to 30 nM and 15 to 360 nM vinblastine, respectively. Corresponding values from series of experiments protected from photosensitization were 1.02 +/- 0.22 nM and 18.5 +/- 3.42 nM. Hence, riboflavin-mediated photoreactions must be fully prevented in assays of cellular drug sensitivity. Procedures for eliminating immediate as well as persisting photoreactivity were established.

Addition of photosensitive dopants to the D0 liquid argon calorimeter

International Nuclear Information System (INIS)

Amos, N.A.; Anderson, D.F.

1992-10-01

The addition of photosensitive dopants to liquid argon greatly enhances the signal from heavily ionizing particles. Since binding energy losses we correlated with the heavily ionizing component in hadronic showers, the addition of photosensitive dopants has been suggested as a mechanism to tune the e/π ratio in liquid argon calorimeters. A measurement was performed at the FNAL test beam, adding 4 ppM tetramethylgermanium to the Dφ uranium-liquid argon calorimeter. An increase in response for electromagnetic and hadronic showers was observed, with no net change in the e/π ratio

In situ localization of chloroquine and immunohistological studies in UVB-irradiated skin of photosensitive patients

NARCIS (Netherlands)

Sjölin-Forsberg, G.; Berne, B.; Eggelte, T. A.; Karlsson-Parra, A.

1995-01-01

Chloroquine can prevent photosensitivity reactions, but its mechanism of action is poorly understood. To investigate if the drug may interfere with inflammatory or immunological mechanisms of the UV-induced erythema of photosensitive patients, we studied the localization of chloroquine in the skin

Riboflavin as a photosensitizer. Effects on human health and food quality.

Science.gov (United States)

Cardoso, Daniel R; Libardi, Silvia H; Skibsted, Leif H

2012-05-01

Riboflavin, vitamin B₂, and flavins (as riboflavin building blocks or degradation products) are efficient photosensitizers inducing oxidative damage to light-exposed tissue and food by substrate-dependent mechanisms, for which protection is offered by specific nutrients. Phenolic and N-heterocyclic amino acids and their peptides and proteins deactivate triplet-excited state riboflavin in diffusion controlled processes, efficiently competing with deactivation by oxygen, resulting in direct (so called Type I) protein degradation through electron transfer or proton-coupled electron transfer. In light-exposed tissue, such often long lived protein radicals may as primary photoproducts initiate lipid and vitamin oxidation. In contrast, for lipid systems, oxygen deactivation of triplet-excited state riboflavin, resulting in formation of singlet oxygen, is under aerobic conditions faster than direct deactivation by lipids, which otherwise under anaerobic conditions occurs as hydrogen atom transfer from polyunsaturated lipids to triplet riboflavin. Singlet oxygen adds to unsaturated lipids and forms lipid hydroperoxides as primary lipid oxidation products or oxidizes proteins (Type II mechanism). Carotenoids seem not to deactivate triplet riboflavin, while chromanols like vitamin E and plant polyphenols are efficient in such deactivation yielding protection of proteins and lipids by these phenols. Indirect protection against the triplet reactivity of riboflavin is further important for polyphenols as riboflavin singlet excited state quenchers in effectively preventing riboflavin intersystem crossing to yield the reactive triplet state. Riboflavin photosensitization becomes critical for degradation of proteins, unsaturated lipids, and folate, thiamine, ascorbate and other vitamins during light exposure of food during storage. For skin, eye and other tissue exposed to high intensity light, dietary polyphenols like flavonoids are important in direct protection against

Redox reactions in micellar systems. communication 4. Eosin-photosensitized reduction of methylviologen

Energy Technology Data Exchange (ETDEWEB)

Nadtochenko, V.; Dzhabiev, T.S.; Rubtsov, I.V.

1985-12-10

The authors present data on photosensitized reduction of methylviologen (MV/sup 2 +/) by disodium ethylenediaminetetraacetate (EDTA) in micellar systems modeling, in a first approximation, the structural organization of components of the chain of energy and electron transfer in natural photosynthesis. Photosensitized reduction of methylviologen by EDTA in micellar solutions can model photosystem I of plants with structure formation of reagents and transfer of excitation energy before the step of occurrence of a redox reaction in the active center.

Effect of monomer concentration on the kinetics of emulsifier-free emulsion polymerization of Vinyl Acetate and Methyl Acrylate

International Nuclear Information System (INIS)

Mohammad Beigi, H. R.

2001-01-01

The effect of monomer concentration on the kinetics of the emulsifier-free emulsion polymerization of vinyl acetate and methyl acrylate were studied. The polymerizations were carried out using potassium persulfate as the initiator. Form the electron micrographs of the resulting lattices, monodisperse PVAc and PMA lattices with particle diameters varying between 149-443 mm and 112-497 nm, respectively were processed. Uniformity of particle size indicated that nucleation of stable particle occurs early in the polymerization process. The polymerization rate was found to be proportional to the 0.88 and 1.5 power of the initial monomer concentration of vinyl acetate and methyl acrylate, respectively. Higher monomer concentration results in fewer particles and larger final particle diameter. With increasing monomer solubility in water the size of particle decreases and its distribution broadens

A novel pH-sensitive polymeric fluorescent probe: Synthesis, characterization and optical properties

Energy Technology Data Exchange (ETDEWEB)

Chen Dongyun; Xu Qingfeng; Xia Xuewei; Ge Jianfeng [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Lu Jianmei, E-mail: lujm@suda.edu.cn [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Li Najun, E-mail: linajun@sina.com [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China)

2010-04-15

A novel initiator containing proflavine derivative moiety, 3,6-dibromo-isobutyramide acridine (DIA), was synthesized and initiated the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). A water-soluble monomer, N,N-dimethylacrylamide (DMAA) was also initiated by DIA for comparison. The obtained fluorescent polymers, PMMA-DIA and PDMAA-DIA, were characterized by {sup 1}H NMR, GPC and TGA. The emission spectra of the fluorescent polymers exhibit obvious changes in color and fluorescence intensity along with pH varied in range of 3.0-9.0. In addition, the obtained polymers present good film-forming capacity and the films also have a high quantum yield and pH response. Both oil-soluble PMMA-DIA and water-soluble PDMAA-DIA have steady optical and chemical properties by containing proflavine moiety in the main chain.

Inactivation of Bacillus cereus by Na-chlorophyllin-based photosensitization on the surface of packaging.

Science.gov (United States)

Luksiene, Z; Buchovec, I; Paskeviciute, E

2010-11-01

This study was focused on the possibility to inactivate food-borne pathogen Bacillus cereus by Na-chlorophyllin (Na-Chl)-based photosensitization in vitro and after attachment to the surface of packaging material. Bacillus cereus in vitro or attached to the packaging was incubated with Na-Chl (7·5×10(-8) to 7·5×10(-5) mol l(-1) ) for 2-60min in phosphate buffer saline. Photosensitization was performed by illuminating cells under a light with a λ of 400nm and an energy density of 20mW cm(-2) . The illumination time varied 0-5min and subsequently the total energy dose was 0-6J cm(-2) . The results show that B. cereus vegetative cells in vitro or attached to the surface of packaging after incubation with 7·5×10(-7) mol l(-1) Na-Chl and following illumination were inactivated by 7log. The photoinactivation of B. cereus spores in vitro by 4log required higher (7·5×10(-6) mol l(-1) ) Na-Chl concentration. Decontamination of packaging material from attached spores by photosensitization reached 5log at 7·5×10(-5) mol l(-1) Na-Chl concentration. Comparative analysis of different packaging decontamination treatments indicates that washing with water can diminish pathogen population on the surface by packaging material. Spores are more resistant than vegetative cells to photosensitization-based inactivation. Comparison of different surface decontamination treatments indicates that Na-Chl-based photosensitization is much more effective antibacterial tool than washing with water or 200ppm Na-hypochlorite. Our data support the idea that Na-Chl-based photosensitization has great potential for future application as an environment-friendly, nonthermal surface decontamination technique. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

Singlet Oxygen Detection Using Red Wine Extracts as Photosensitizers.

Science.gov (United States)

Lagunes, Irene; Vázquez-Ortega, Fernanda; Trigos, Ángel

2017-09-01

Moderate consumption of red wine provides beneficial effects to health. This is attributed to polyphenol compounds present in wine such as resveratrol, quercetin, gallic acid, rutin, and vanillic acid. The amount of these antioxidants is variable; nevertheless, the main beneficial effects of red wine are attributed to resveratrol. However, it has been found that resveratrol and quercetin are able to photosensitize singlet oxygen generation and conversely, gallic acid acts as quencher. Therefore, and since resveratrol and quercetin are some of the most important antioxidants reported in red wines, the aim of this research was to evaluate the photosensitizing ability of 12 red wine extracts through photo-oxidation of ergosterol. The presence of 1 O 2 was detected by ergosterol conversion into peroxide of ergosterol through 1 H NMR analysis. Our results showed that 10 wine extracts were able to act as photosensitizers in the generation of singlet oxygen. The presence of 1 O 2 can damage other compounds of red wine and cause possible organoleptic alterations. Finally, although the reaction conditions employed in this research do not resemble the inherent conditions in wine making processing or storing, or even during its consumption, this knowledge could be useful to prevent possible pro-oxidant effects and avoid detrimental effects in red wines. © 2017 Institute of Food Technologists®.

Polymeric nanoparticles: potent vectors for vaccine delivery targeting cancer and infectious diseases.

Science.gov (United States)

Bolhassani, Azam; Javanzad, Shabnam; Saleh, Tayebeh; Hashemi, Mehrdad; Aghasadeghi, Mohammad Reza; Sadat, Seyed Mehdi

2014-01-01

Nanocarriers with various compositions and biological properties have been extensively applied for in vitro/in vivo drug and gene delivery. The family of nanocarriers includes polymeric nanoparticles, lipid-based carriers (liposomes/micelles), dendrimers, carbon nanotubes, and gold nanoparticles (nanoshells/nanocages). Among different delivery systems, polymeric carriers have several properties such as: easy to synthesize, inexpensive, biocompatible, biodegradable, non-immunogenic, non-toxic, and water soluble. In addition, cationic polymers seem to produce more stable complexes led to a more protection during cellular trafficking than cationic lipids. Nanoparticles often show significant adjuvant effects in vaccine delivery since they may be easily taken up by antigen presenting cells (APCs). Natural polymers such as polysaccharides and synthetic polymers have demonstrated great potential to form vaccine nanoparticles. The development of new adjuvants or delivery systems for DNA and protein immunization is an expanding research field. This review describes polymeric carriers especially PLGA, chitosan, and PEI as vaccine delivery systems.

Photokinetic and ultrastructural studies on porphyrin photosensitization of HeLa cells

International Nuclear Information System (INIS)

Milanesi, Carla; Sorgato, Fiorella; Jori, Giulio

1989-01-01

Liposome-bound haematoporphyrin or haematoporphyrin dimethylester, as well as haematoporphyrin dissolved in phosphate-buffered saline, were added to HeLa cell monolayers at a dose of 1 μg of porphyrin per 10 5 cells. After 2 min or 20 min incubation liposome-bound porphyrins were accumulated by cells in an about two-fold larger amount than the water-dissolved haematoporphyrin. This caused a more efficient photosensitization of HeLa cells by liposome-delivered porphyrins upon illumination with 366 nm light. Ultrastructural studies of HeLa cells, which had been incubated in a physiological medium for 24 h after the end of irradiation, showed that liposomal porphyrins induce an early and extensive endocytoplasmic damage, leading to mitochondrial swelling and vesiculation; changes of permeability of the cytoplasmic membrane are also evident, especially in the case of haematoporphyrin dimethylester. On the other hand, water-dissolved haematoporphyrin predominantly photosensitizes damage of the plasma membrane. The different pattern of cell photodamage probably reflects a different subcellular distribution of the photosensitizing drugs. (author)

Fluorescence Imaging Assisted Photodynamic Therapy Using Photosensitizer-Linked Gold Quantum Clusters.

Science.gov (United States)

Nair, Lakshmi V; Nazeer, Shaiju S; Jayasree, Ramapurath S; Ajayaghosh, Ayyappanpillai

2015-06-23

Fluorescence imaging assisted photodynamic therapy (PDT) is a viable two-in-one clinical tool for cancer treatment and follow-up. While the surface plasmon effect of gold nanorods and nanoparticles has been effective for cancer therapy, their emission properties when compared to gold nanoclusters are weak for fluorescence imaging guided PDT. In order to address the above issues, we have synthesized a near-infrared-emitting gold quantum cluster capped with lipoic acid (L-AuC with (Au)18(L)14) based nanoplatform with excellent tumor reduction property by incorporating a tumor-targeting agent (folic acid) and a photosensitizer (protoporphyrin IX), for selective PDT. The synthesized quantum cluster based photosensitizer PFL-AuC showed 80% triplet quantum yield when compared to that of the photosensitizer alone (63%). PFL-AuC having 60 μg (0.136 mM) of protoporphyrin IX was sufficient to kill 50% of the tumor cell population. Effective destruction of tumor cells was evident from the histopathology and fluorescence imaging, which confirm the in vivo PDT efficacy of PFL-AuC.

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.

Solubility improvement of an anthelmintic benzimidazole carbamate by association with dendrimers

International Nuclear Information System (INIS)

Fernandez, L.; Sigal, E.; Santo, M.; Otero, L.; Silber, J. J.

2011-01-01

The improvement of aqueous solubility of methyl (5-[propylthio]-1H-benzimidazole-2-yl) carbamate, albendazole (ABZ) using polyamidoamine (PAMAM) dendrimers as solubility enhancers was investigated. Full generation PAMAM dendrimers with amine terminal groups, (G3), with hydroxyl terminal groups (G3OH) and half generation PAMAM dendrimers with carboxylate terminal groups (G2.5 and G3.5), were chosen for this study. The nature of dendrimer-ABZ association was investigated by UV absorption, fluorescence emission measurements and by 1 H-NMR spectroscopy. The results obtained show that these polymeric structures have the capacity to enhance the solubility of ABZ, both lipophilic and specific hydrogen bond interactions contributing to the guest-host association. Although all studied dendrimers have hydrophobic internal nanoenvironments with similar dimensions, their surfaces differ significantly and the nature and the localization of the interactions involved in ABZ-dendrimer association depend on the type of terminal groups. (author)

Effect of tamoxifen in RAFT miniemulsion polymerization during the synthesis of polymer nanoparticles

Directory of Open Access Journals (Sweden)

Tailane Sant'Anna Moreira

2014-01-01

Full Text Available Tamoxifen (TXF is currently the only hormonal agent used for treatment of breast cancer. Although very effective, TXF presents low solubility in water, which affects its absorption and bioavailability. A common strategy to overcome this barrier is the formulation of a drug delivery system (DDS in order to increase the drug stability and improve the treatment effectiveness. Reversible addition-fragmentation chain transfer (RAFT polymerization is the most versatile method of controlled/living radical polymerization (CLRP, allowing for synthesis of well-defined polymers and being adapted to a wide range of polymerization systems. Miniemulsion polymerization is a dispersed system that is commonly used to prepare nanoparticles (NP with 50 to 500 nm of diameter. The aim of this work was to evaluate the effect of the in situ incorporation of TXF during miniemulsion conventional and RAFT polymerizations, using methyl methacrylate (MMA as monomer. Although the in situ addition of TXF promoted a slight reduction of the reaction rate, it did not affect the final particle size distribution of the latex or the molecular weight control exerted by the RAFT agent. The obtained results suggest that in situ incorporation of TXF during the synthesis of polymer NP via RAFT polymerization allows for production of a polymer DDS for different uses, such as the breast cancer treatment.

Construction of dual-functional polymer nanomaterials with near-infrared fluorescence imaging and polymer prodrug by RAFT-mediated aqueous dispersion polymerization.

Science.gov (United States)

Tian, Chun; Niu, Jinyun; Wei, Xuerui; Xu, Yujie; Zhang, Lifen; Cheng, Zhenping; Zhu, Xiulin

2018-05-31

The performance of functional polymer nanomaterials is a vigorously discussed topic in polymer science. We devoted ourselves to investigating polymer nanomaterials based on near-infrared (NIR) fluorescence imaging and polymer prodrug in this study. Aza-boron dipyrromethene (BODIPY) is an important organic dye, having characteristics such as environmental resistance, light resistance, high molar extinction coefficient, and fluorescence quantum yield. We incorporated it into our target monomer, which can be polymerized without changing its parent structure in a polar solvent and copolymerized with water-soluble monomer to improve the solubility of the dye in an aqueous solution. At the same time, the hydrophobic drug camptothecin (CPT) was designed as a prodrug monomer, and the polymeric nanoparticles (NPs) with NIR fluorescence imaging and prodrug were synthesized in situ in reversible addition-fragmentation chain transfer (RAFT)-mediated aqueous dispersion polymerization. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed the final uniform size of the dual-functional polymeric NPs morphology. The dual-functional polymeric NPs had a strong absorption and emission signal in the NIR region (>650 nm) based on the fluorescence tests. In consideration of the long-term biological toxicity, confocal laser scanning microscopy (CLSM) results indicated that the dual-functional NPs with controlled drug content exhibited effective capability of killing HeLa cells. In addition, in vivo imaging of the dual-functional NPs was observed in real time, and the fluorescent signals clearly demonstrated the dynamic process of prodrug transfer.

A Nanophase-Separated, Quasi-Solid-State Polymeric Single-Ion Conductor: Polysulfide Exclusion for Lithium–Sulfur Batteries

Energy Technology Data Exchange (ETDEWEB)

Lee, Jinhong; Song, Jongchan; Lee, Hongkyung; Noh, Hyungjun; Kim, Yun-Jung; Kwon, Sung Hyun; Lee, Seung Geol; Kim, Hee-Tak

2017-04-19

Formation of soluble polysulfide (PS), which is a key feature of lithium sulfur (Li–S) batteries, provides a fast redox kinetic based on a liquid–solid mechanism; however, it imposes the critical problem of PS shuttle. Here, we address the dilemma by exploiting a solvent-swollen polymeric single-ion conductor (SPSIC) as the electrolyte medium of the Li–S battery. The SPSIC consisting of a polymeric single-ion conductor and lithium salt-free organic solvents provides Li ion hopping by forming a nanoscale conducting channel and suppresses PS shuttle according to the Donnan exclusion principle when being employed for Li–S batteries. The organic solvents at the interface of the sulfur/carbon composite and SPSIC eliminate the poor interfacial contact and function as a soluble PS reservoir for maintaining the liquid–solid mechanism. Furthermore, the quasi-solid-state SPSIC allows the fabrication of a bipolar-type stack, which promises the realization of a high-voltage and energy-dense Li–S battery.

Photosensitization and phototherapy with furocoumarins: A quantum-chemical study

International Nuclear Information System (INIS)

Serrano-Perez, Juan Jose; Serrano-Andres, Luis; Merchan, Manuela

2008-01-01

The effect of electromagnetic radiation on biological objects extends from heating to complex photochemistry, and includes DNA alteration, that properly modified in damaged cells may entail beneficial effects. In this regard, psoralen + UV-A (PUVA) therapy, in which furocoumarins, psoralen-like chromophores, are used as photosensitizers and photoreactants with DNA bases, is one of the most promising strategies against a plethora of diseases. Understanding the underlying photochemical mechanisms is crucial to design effective drugs without undesired side effects. We have undertaken a quantum-mechanical study on the photophysics and photochemistry of furocoumarins, analyzing firstly the most efficient way in which the lowest excited triplet state, as protagonist of the photosensitizing action, is populated from the initially promoted singlet states, and secondly the basics of the formation of furocoumarin-DNA photoadducts

Reactivity of polymeric proanthocyanidins toward salivary proteins and their contribution to young red wine astringency.

Science.gov (United States)

Sun, Baoshan; de Sá, Marta; Leandro, Conceição; Caldeira, Ilda; Duarte, Filomena L; Spranger, Isabel

2013-01-30

Recent studies have indicated the presence of significant amount of highly polymerized and soluble proanthocyanidins in red wine and such compounds interacted readily with proteins, suggesting that they might be particularly astringent. Thus, the objective of this work was to verify the astringency of polymeric proanthocyanidins and their contribution to red wine astringency. The precipitation reactions of the purified oligomeric procyanidins (degree of polymerization ranging from 2 to 12-15) and polymeric procyanidins (degree of polymerization ranging from 12-15 to 32-34) with human salivary proteins were studied; salivary proteins composition changes before and after the reaction was verified by SDS-PAGE and procyanidins composition changes by spectrometric, direct HPLC and thiolysis-HPLC methods. The astringency intensity of these two procyanidin fractions was evaluated by a sensory analysis panel. For verifying the correlation between polymeric proanthocyanidins and young red wine astringency, the levels of total oligomeric and total polymeric proanthocyanidins and other phenolic composition in various young red wines were quantified and the astringency intensities of these wines were evaluated by a sensory panel. The results showed that polymeric proanthocyanidins had much higher reactivity toward human salivary proteins and higher astringency intensity than the oligomeric ones. Furthermore, young red wine astringency intensities were highly correlated to levels of polymeric proanthocyanidins, particularly at low concentration range (correlation coefficient r = 0.9840) but not significant correlated to total polyphenols (r = 0.2343) or other individual phenolic compounds (generally r wine astringency and the levels of polymeric polyphenols in red wines may be used as an indicator for its astringency.

Photosensitive TRPs.

Science.gov (United States)

Hardie, Roger C

2014-01-01

The Drosophila "transient receptor potential" channel is the prototypical TRP channel, belonging to and defining the TRPC subfamily. Together with a second TRPC channel, trp-like (TRPL), TRP mediates the transducer current in the fly's photoreceptors. TRP and TRPL are also implicated in olfaction and Malpighian tubule function. In photoreceptors, TRP and TRPL are localised in the ~30,000 packed microvilli that form the photosensitive "rhabdomere"-a light-guiding rod, housing rhodopsin and the rest of the phototransduction machinery. TRP (but not TRPL) is assembled into multimolecular signalling complexes by a PDZ-domain scaffolding protein (INAD). TRPL (but not TRP) undergoes light-regulated translocation between cell body and rhabdomere. TRP and TRPL are also found in photoreceptor synapses where they may play a role in synaptic transmission. Like other TRPC channels, TRP and TRPL are activated by a G protein-coupled phospholipase C (PLCβ4) cascade. Although still debated, recent evidence indicates the channels can be activated by a combination of PIP2 depletion and protons released by the PLC reaction. PIP2 depletion may act mechanically as membrane area is reduced by cleavage of PIP2's bulky inositol headgroup. TRP, which dominates the light-sensitive current, is Ca(2+) selective (P Ca:P Cs >50:1), whilst TRPL has a modest Ca(2+) permeability (P Ca:P Cs ~5:1). Ca(2+) influx via the channels has profound positive and negative feedback roles, required for the rapid response kinetics, with Ca(2+) rapidly facilitating TRP (but not TRPL) and also inhibiting both channels. In trp mutants, stimulation by light results in rapid depletion of microvillar PIP2 due to lack of Ca(2+) influx required to inhibit PLC. This accounts for the "transient receptor potential" phenotype that gives the family its name and, over a period of days, leads to light-dependent retinal degeneration. Gain-of-function trp mutants with uncontrolled Ca(2+) influx also undergo retinal degeneration

Glucose, fructose and sucrose increase the solubility of protein-tannin complexes and at high concentration, glucose and sucrose interfere with bisulphite bleaching of wine pigments.

Science.gov (United States)

Harbertson, James F; Yuan, Chunlong; Mireles, Maria S; Hanlin, Rachel L; Downey, Mark O

2013-05-01

Wines were modified with increasing sugar concentrations and decreasing tannin concentrations and analysed by a combination of protein precipitation and bisulphite bleaching. Increasing sugar concentration decreased the precipitation of tannin and protein-precipitable polymeric pigments (PPP). The use of a hydrogen bond disruptor (urea) to reduce protein-tannin and protein-pigment complex formation showed that the effect of sugar concentration occurred by increasing the solubility of the tannin-protein complex, not by interfering with protein-tannin complex formation. By increasing the solubility of pigment-protein complexes, non-protein-precipitable polymeric pigments (nPPP) appeared to increase. There was also an increase in total polymeric pigments at each tannin concentration with increasing glucose and sucrose concentration, indicating that sugar concentration might also affect bisulphite bleaching of wine pigments. While a significant effect of sugar concentration on tannin-protein complex solubility was observed, these effects were greatest at sugar concentrations far in excess of normal wine making conditions. Under normal wine making conditions, sugar concentration will have a negligible effect on protein-precipitable tannin, PPP and nPPP concentrations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Endogenous UVA-photosensitizers: mediators of skin photodamage and novel targets for skin photoprotection.

Science.gov (United States)

Wondrak, Georg T; Jacobson, Myron K; Jacobson, Elaine L

2006-02-01

Endogenous chromophores in human skin serve as photosensitizers involved in skin photocarcinogenesis and photoaging. Absorption of solar photons, particularly in the UVA region, induces the formation of photoexcited states of skin photosensitizers with subsequent generation of reactive oxygen species (ROS), organic free radicals and other toxic photoproducts that mediate skin photooxidative stress. The complexity of endogenous skin photosensitizers with regard to molecular structure, pathways of formation, mechanisms of action, and the diversity of relevant skin targets has hampered progress in this area of photobiology and most likely contributed to an underestimation of the importance of endogenous sensitizers in skin photodamage. Recently, UVA-fluorophores in extracellular matrix proteins formed posttranslationally as a consequence of enzymatic maturation or spontaneous chemical damage during chronological and actinic aging have been identified as an abundant source of light-driven ROS formation in skin upstream of photooxidative cellular stress. Importantly, sensitized skin cell photodamage by this bystander mechanism occurs after photoexcitation of sensitizers contained in skin structural proteins without direct cellular photon absorption thereby enhancing the potency and range of phototoxic UVA action in deeper layers of skin. The causative role of photoexcited states in skin photodamage suggests that direct molecular antagonism of photosensitization reactions using physical quenchers of photoexcited states offers a novel chemopreventive opportunity for skin photoprotection.

Preclinical studies of vascular acting photosensitizer bacteriopheophorbide for the treatment of prostate cancer

Science.gov (United States)

Hetzel, Fred W.; Chen, Qun; Luck, David; Beckers, Jill; Huang, Zheng

2004-06-01

Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. In vivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the IV infused photosensitizer drug. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week post PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Prostate lesions could be detected by MRI scan as early as 48 h post PDT. Maximum lesion size of 1.5 cm3 and 2.9 cm3 could be achieved at 50 J/cm and 100 J/cm, respectively, with interstitial treatment using a single 1-cm diffuser fiber, suggesting the Tookad-PDT is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat localized prostate cancer.

Click polymerization for the synthesis of reduction-responsive polymeric prodrug

Science.gov (United States)

Zhang, Xiaojin; Wang, Hongquan; Dai, Yu

2018-05-01

Click polymerization is a powerful polymerization technique for the construction of new macromolecules with well-defined structures and multifaceted functionalities. Here, we synthesize reduction-responsive polymeric prodrug PEG- b-(PSS- g-MTX)- b-PEG containing disulfide bonds and pendant methotrexate (MTX) via two-step click polymerization followed by conjugating MTX to pendant hydroxyl. MTX content in polymeric prodrug is 13.5%. Polymeric prodrug is able to form polymeric micelles by self-assembly in aqueous solution. Polymeric micelles are spherical nanoparticles with tens of nanometers in size. Of note, polymeric micelles are reduction-responsive due to disulfide bonds in the backbone of PEG- b-(PSS- g-MTX)- b-PEG and could release pendant drugs in the presence of the reducing agents such as dl-dithiothreitol (DTT).

Phase solubility, 1H NMR and molecular modelling studies of bupivacaine hydrochloride complexation with different cyclodextrin derivates

Science.gov (United States)

Jug, Mario; Mennini, Natascia; Melani, Fabrizio; Maestrelli, Francesca; Mura, Paola

2010-11-01

A novel method, which simultaneously exploits experimental (NMR) and theoretically calculated data obtained by a molecular modelling technique, was proposed, to obtain deeper insight into inclusion geometry and possible stereoselective binding of bupivacaine hydrochloride with selected cyclodextrin derivatives. Sulphobuthylether-β-cyclodextrin and water soluble polymeric β-cyclodextrin demonstrated to be the best complexing agents for the drug, resulting in formation of the most stable inclusion complexes with the highest increase in aqueous drug solubility. The drug-carrier binding modes with these cyclodextrins and phenomena which may be directly related to the higher stability and better aqueous solubility of complexes formed were discussed in details.

Pulsed-laser polymerization in compartmentalized liquids. 1. Polymerization in vesicles

NARCIS (Netherlands)

Jung, M.; Casteren, van I.A.; Monteiro, M.J.; Herk, van A.M.; German, A.L.

2000-01-01

Polymerization in vesicles is a novel type of polymerization in heterogeneous media, leading to parachute-like vesicle-polymer hybrid morphologies. To explore the kinetics of vesicle polymerizations and to learn more about the actual locus of polymerization we applied the pulsed-laser polymerization

Bovine serum albumin nanoparticles loaded with Photosens photosensitizer for effective photodynamic therapy

Science.gov (United States)

Khanadeev, Vitaly; Khlebtsov, Boris; Packirisamy, Gopinath; Khlebtsov, Nikolai

2017-03-01

Polymeric nanoparticles (NPs) are widely used for drug delivery applications due to high biodegradability, low toxicity and high loading capacity. The focus of this study is the development of photosensitizer Photosens (PS) loaded albumin NPs for efficient photodynamic therapy (PDT). To fabricate PS-loaded bovine serum albumin nanoparticles (BSA-PS NPs), we used a coacervation method with glutaraldehyde followed by passive loading of PS. Successful loading of PS was confirmed by appearance of characteristic peak in absorption spectrum which allows to determine the PS loading in BSA NPs. The synthesized BSA-PS NPs demonstrated low toxicity to HeLa cells at therapeutic concentrations of loaded PS. Compared to free PS solution, the synthesized BSA-PS NPs generated the singlet oxygen more effectively under laser irradiation at 660 nm. In addition, due to presence of various chemical groups on the surface of BSA-PS NPs, they are capable to adsorb on cell surface and accumulate in cells due to cellular uptake mechanisms. Owing to combination of PD and cell uptake advantages, BSA-PS NPs demonstrated higher efficacy of photodynamic damage to cancer cells as compared to free PS at equivalent concentrations. These results suggest that non-targeted BSA-PS NPs with high PD activity and low-fabrication costs of are promising candidates for transfer to PD clinic treatments.

Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

Science.gov (United States)

Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

2012-01-01

A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

The effect of UV exposure and heat treatment on crystallization behavior of photosensitive glasses

Science.gov (United States)

Kıbrıslı, Orhan; Ersundu, Ali Erçin

2018-05-01

In this study, photosensitive glasses in the Na2O-ZnO-Al2O3-SiO2 system with photosensitizing agents (cerium, silver, tin, antimony) and halogenides (NaF and KBr) were synthesized through a conventional melt-quenching technique. The crystallization mechanism was investigated for solely heat-treated and UV-exposed + heat-treated samples using differential thermal analysis (DTA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) techniques to understand the effect of UV exposure on crystallization behavior of photosensitive glasses. Accordingly, non-isothermal DTA measurements were performed at different heating rates to determine crystallization peak, T p, and onset, T c, temperatures. For solely heat-treated samples, the kinetic parameters such as the Avrami constant, n, and morphology index, m, were calculated as 1 from the Ozawa method indicating surface crystallization and the value of crystallization activation energy was calculated as 944 kJ/mol using modified Kissinger method. On the contrary, bulk crystallization was found to be predominant for UV exposed + heat-treated samples revealing that UV exposure is the primary cause of bulk crystallization in photosensitive glasses.

Photodynamic effect of photosensitizer-loaded hollow silica nanoparticles for hepatobiliary malignancies: an in vitro and in vivo study

Science.gov (United States)

Deng, Xiaofeng; Xiong, Li; Wen, Yu; Liu, Zhongtao; Pei, Dongni; Huang, Yaxun; Miao, Xiongying

2014-03-01

Background and aims: Nanoparticles have been explored recently as an efficient delivery system for photosensitizers in photodynamic therapy. In this study, polyhematoporphyrin (C34H38N4NaO5,) was loaded into hollow silica nanoparticles (HSNP) by one-step wet chemical-based synthetic route. We evaluate the efficacy and safety of polyhematoporphyrin-loaded HSNP with hepatobiliary malignant cells and in vivo models. Methods: Human liver cancer, cholangiocarcinoma and gallbladder cancer cells were cultured with the HSNP and cellular viability was determined by MTT assay. Apoptotic and necrotic cells were measured by flow cytometry. Finally, we investigate its effect in vivo. Results: In MTT assay, the cell viability of QBC939, Huh-7, GBC-SD and HepG2 cells of the HSNP was 6.4+/-1.3%, 6.5+/-1.2%, 3.7+/-1.2% and 4.7+/-2.0%, respectively, which were significant different from that of free polyhematoporphyrin 62.4+/-4.7%, 62.5+/-6.0%, 33.4+/-6.5% and 44.3+/-1.9%. Flow cytometry demonstrated the laser-induced cell death with polyhematoporphyrin-loaded HSNP was much more severe. Similarly, in vivo results of each kind of cell revealed 14 days post-photoradiated, tumor sizes of the HSNP group were significantly smaller. Administration of the HSNP without illumination cannot cause killing effect both in vitro and in vivo experiments. Conclusions: HSNP is a desirable delivery system in photodynamic therapy for hepatobiliary malignacies, with improved aqueous solubility, stability and transport efficiency of photosensitizers.

Solubility improvement of an anthelmintic benzimidazole carbamate by association with dendrimers

Directory of Open Access Journals (Sweden)

L. Fernández

2011-12-01

Full Text Available The improvement of aqueous solubility of methyl (5-[propylthio]-1H-benzimidazol-2-yl carbamate, albendazole (ABZ using polyamidoamine (PAMAM dendrimers as solubility enhancers was investigated. Full generation PAMAM dendrimers with amine terminal groups, (G3, with hydroxyl terminal groups (G3OH and half generation PAMAM dendrimers with carboxylate terminal groups (G2.5 and G3.5, were chosen for this study. The nature of dendrimer-ABZ association was investigated by UV absorption, fluorescence emission measurements and by ¹H-NMR spectroscopy. The results obtained show that these polymeric structures have the capacity to enhance the solubility of ABZ, both lipophilic and specific hydrogen bond interactions contributing to the guest-host association. Although all studied dendrimers have hydrophobic internal nanoenvironments with similar dimensions, their surfaces differ significantly and the nature and the localization of the interactions involved in ABZ-dendrimer association depend on the type of terminal groups.

Solubility improvement of an anthelmintic benzimidazole carbamate by association with dendrimers

Energy Technology Data Exchange (ETDEWEB)

Fernandez, L.; Sigal, E.; Santo, M., E-mail: msanto@exa.unrc.edu.ar [Departamento de Fisica, Facultad de Ciencias Exactas Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto (Argentina); Otero, L.; Silber, J. J. [Departamento de Quimica. Facultad de Ciencias Exactas Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto, Rio Cuarto (Argentina)

2011-10-15

The improvement of aqueous solubility of methyl (5-[propylthio]-1H-benzimidazole-2-yl) carbamate, albendazole (ABZ) using polyamidoamine (PAMAM) dendrimers as solubility enhancers was investigated. Full generation PAMAM dendrimers with amine terminal groups, (G3), with hydroxyl terminal groups (G3OH) and half generation PAMAM dendrimers with carboxylate terminal groups (G2.5 and G3.5), were chosen for this study. The nature of dendrimer-ABZ association was investigated by UV absorption, fluorescence emission measurements and by {sup 1}H-NMR spectroscopy. The results obtained show that these polymeric structures have the capacity to enhance the solubility of ABZ, both lipophilic and specific hydrogen bond interactions contributing to the guest-host association. Although all studied dendrimers have hydrophobic internal nanoenvironments with similar dimensions, their surfaces differ significantly and the nature and the localization of the interactions involved in ABZ-dendrimer association depend on the type of terminal groups. (author)

Local piezoelectric response of ZnO nanoparticles embedded in a photosensitive polymer

Energy Technology Data Exchange (ETDEWEB)

Prashanthi, K.; Zhang, H.; Thundat, T. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta (Canada); Ramgopal Rao, V. [Department of Electrical Engineering, Indian Institute of Technology, Bombay, Mumbai (India)

2012-02-15

Local piezoelectric properties of ZnO nanoparticles (NPs) embedded in a photo-epoxy polymer are investigated by piezoresponse force microscopy (PFM). Integrating ZnO NPs into a photosensitive SU-8 polymer matrix not only retains the highly desired piezoelectric properties of the ZnO, but also preserves photosensitivity and optical transparency of the SU-8 polymer. These results have strong implications for simple photolithography based low-cost fabrication of piezoelectric microelectromechanicalsystems (MEMS) and nanoelectromechanicalsystems (NEMS) in both sensing and energy harvesting applications. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Quenching-induced deactivation of photosensitizer by nanoencapsulation to improve phototherapy of cancer.

Science.gov (United States)

Zeisser-Labouèbe, Magali; Mattiuzzo, Marc; Lange, Norbert; Gurny, Robert; Delie, Florence

2009-09-01

Photodynamic therapy has emerged as a promising alternative to current cancer treatment. However, conventional photosensitizers have several limitations due to their unsuitable pharmaceutical formulations and lack of selectivity. Our strategy was to exploit the advantages of nanoparticles and the quenching-induced deactivation of the model photosensitizer hypericin to produce "activatable" drug delivery systems. Efficient fluorescence and activity quenching were achieved by increasing the drug-loading rate of nanoparticles. In vitro assays confirmed the reversibility of hypericin deactivation, as the hypericin fluorescence and photodynamic activity were recovered upon cell internalization.

Adhesion of Pharmaceutical Binding Agents I-Adhesion to polymeric materials

Directory of Open Access Journals (Sweden)

Hossain Orafai

1996-08-01

Full Text Available Adhesion of three commonly used pharmaceutical binding agents, HPMC , PVP and Gelatin to five different polymeric sheet materials was studied. After conditioning, the bond strength of the specimens were measured by shear testing method using a suitablely designed apparatus. The results were correlated to the surface energies and the solubiiity parameters of the adherends. It is concluded that the thermodynamic properties and the solubility parameters are dominant when the mechanisms of adhesion are by adsorption and diffusion respectively.

SORPTION AND SOLUBILITY OF LOW-SHRINKAGE RESIN-BASED DENTAL COMPOSITES

Directory of Open Access Journals (Sweden)

Sevda Yantcheva

2016-04-01

Full Text Available Background: Resin-based composites are well-established restorative materials. However, these materials may absorb significant amounts of water when exposed to aqueous environments. Sorption and solubility are affecting composite restorations by two different mechanisms; the first is the up taking of water producing an increased weight and the second is the dissolution of materials in water, leading to a weight reduction of the final conditioned samples. Objective: To measure the water sorption and solubility of different low-shrinkage resin-based composites. Six materials were selected: Filtek P60, Filtek Ultimate, SonicFill, Filtek Silorane, Kalore and Venus Diamond. Materials and methods: Five disc specimens were prepared of each material and polymerized with diode light-curing unit. Water sorption and solubility of the different materials were were calculated by means of weighting the samples before and after water immersion and desiccation. Data were statistically analyzed using Shapiro-Wilk One Way Analysis of Variance followed by the Holm-Sidak comparison test . Results: There were significant differences (p<=0.001 between materials regarding sorption and solubility. Regarding sorption F. Silorane showed lowest values, followed by SonicFill, without significant difference between them. Statistical significant differences exist between F. Silorane and F.P60, F. Ultimate, Kalore. Significant differences exist between SonicFill and F. Ultimate. F.Silorane (-0.018 and Kalore (-0.010 showed lowest values of solubility but there were marginal difference among all composites investigated. Conclusions: 1.The material with lowest values of sorption and solubility was F.Silorane. 2. The attained sorption and solubility values for composites are influenced by the differences in resin matrix composition and filler contend. 3. Modifications of dimethacrylate matrix did not minimize significantly sorption and solubility of composites. 4. Besides water

Ionic compounds lamination reaction and characteristics of photosensitive copper indium sulfide on titania nanotube arrays

Energy Technology Data Exchange (ETDEWEB)

Chang, Horng-Yi, E-mail: hychang@mail.ntou.edu.tw [Department of Marine Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Tzeng, Wei-Jei [Department of Marine Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Lin, Chia-Hsin; Cheng, Syh-Yuh [Ceramic Microengineering Laboratory, Material and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 31060, Taiwan (China)

2011-09-01

Graphical abstract: Highlights: > Only good photocurrent density under UV irradiation for TiO{sub 2} (or TiCl{sub 4}) modified titania nanotubes (T-TNAs) demonstrates the response to visible light actually due to the CuInS{sub 2} photosensitivity on T-TNAs. > The suitable CuInS{sub 2} (CIS) film thickness can be completed to achieve the well crystallinity, coverage and high photosensitivity of CIS by combining the precursor concentration with deposition cycles. > An n-type CIS with a lower band gap (<1.5 eV) extending the absorption of the large solar spectrum into the infra-red range demonstrates the inorganic CIS potentially instead of organic dye to use in photosensitive solar cells by simple ionic compounds lamination reaction (ICLR) process. - Abstract: This study investigates using an inorganic photosensitive CuInS{sub 2} (CIS) coating instead of an organic dye on TiO{sub 2} nanotube arrays (TNAs). The stoichiometric characteristics by use of various deposition parameters such as precursor concentrations (0.1 M, 0.05 M, and 0.01 M) and deposition cycles (1-60 cycles) are then analyzed in relation to the crystallinity and photosensitivity. TNAs are synthesized by anodic oxidation of Ti metal, modified by the TiO{sub 2} film, and are subsequently annealed at 450 deg. C for 30 min, producing what are named T-TNAs. They show high photocatalytic efficiency and photosensitivity under UV-illumination. The photosensitive CIS coatings on the T-TNAs are processed by an ionic compounds lamination reaction (ICLR) method. The more immersion cycles and the higher the precursor concentration of copper sulfide, the more CIS peeled off as precipitates formed, which result in less indium sulfide deposition being required for reacting with the copper sulfide to reach stoichiometry. Near stoichiometric CIS can be obtained by controlling the precursor concentration and deposition cycles of the ICLR process. Good crystallinity and n-type characteristics are achieved by controlling

A Closer Look at Dark Toxicity of the Photosensitizer TMPyP in Bacteria.

Science.gov (United States)

Eckl, Daniel B; Dengler, Linda; Nemmert, Marina; Eichner, Anja; Bäumler, Wolfgang; Huber, Harald

2018-01-01

Photodynamic inactivation of bacteria (PIB) is based on photosensitizers which absorb light and generate reactive oxygen species (ROS), killing cells via oxidation. PIB is evaluated by comparing viability with and without irradiation, where reduction of viability in the presence of the photosensitizer without irradiation is considered as dark toxicity. This effect is controversially discussed for photosensitizers like TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluensulfonate). TMPyP shows a high absorption coefficient for blue light and a high yield of ROS production, especially singlet oxygen. Escherichia coli and Bacillus atrophaeus were incubated with TMPyP and irradiated with different light sources at low radiant exposures (μW per cm²), reflecting laboratory conditions of dark toxicity evaluation. Inactivation of E. coli occurs for blue light, while no effect was detectable for wavelengths >450 nm. Being more susceptible toward PIB, growth of B. atrophaeus is even reduced for light with emission >450 nm. Decreasing the light intensities to nW per cm² for B. atrophaeus, application of TMPyP still caused bacterial killing. Toxic effects of TMPyP disappeared after addition of histidine, quenching residual ROS. Our experiments demonstrate that the evaluation of dark toxicity of a powerful photosensitizer like TMPyP requires low light intensities and if necessary additional application of substances quenching any residual ROS. © 2017 The American Society of Photobiology.

HPLC separation of triacylglycerol positional isomers on a polymeric ODS column.

Science.gov (United States)

Kuroda, Ikuma; Nagai, Toshiharu; Mizobe, Hoyo; Yoshimura, Nobuhito; Gotoh, Naohiro; Wada, Shun

2008-07-01

A polymeric ODS column was applied to the resolution of triacylglycerol positional isomers (TAG-PI), i.e. 1,3-dioleoyl-2-palmitoyl-glycerol (OPO) and 1,2-dioleoyl-3-palmitoyl-rac-glycerol (OOP), with a recycle HPLC system. To investigate the ODS column species and the column temperatures for the resolution of a TAG-PI pair, a mixture of OPO and OOP was subjected to an HPLC system equipped with a non-endcapped polymeric, endcapped monomeric, endcapped intermediate, or non-endcapped monomeric ODS column at three different column temperatures (40, 25, or 10 degrees C). Only the non-endcapped polymeric ODS column achieved the separation of OPO and OOP, and the lowest column temperature (10 degrees C) showed the best resolution for them. The other pair of TAG-PI, a mixture of 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO) was also subjected to the system equipped with a non-endcapped polymeric or monomeric ODS column at five different column temperatures (40, 32, 25, 17, and 10 degrees C). Thus, POP and PPO were also separated on only the non-endcapped polymeric ODS column at 25 degrees C. However, no clear peak appeared at 10 degrees C. These results would indicate that the polymeric ODS stationary phase has an ability to recognize the structural differences between TAG-PI pairs. Also, the column temperature is a very important factor for separating the TAG-PI pair, and the optimal temperature would relate to the solubility of TAG-PI in the mobile phase. Furthermore, the recycle HPLC system provided measurements for the separation and analysis of TAG-PI pairs.

Graft polymerization of vinyl acetate onto starch. Saponification to starch-g-poly(vinyl alcohol)

International Nuclear Information System (INIS)

Fanta, G.F.; Burr, R.C.; Doane, W.M.; Russell, C.R.

1979-01-01

Graft polymerizations of vinyl acetate onto granular cornstarch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinyl acetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. Over half of the polymer was present as ungrafted poly(vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only 34% grafted synthetic polymer (34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acrylamide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficency. Grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate--methyl methacrylate was carried out near 0 0 C; although conversion of monomers to polymer was low and grafted polymer contained 40 to 50% poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hydroxide to convert starch-g-poly(vinyl acetate) to starch-g-poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety was about 30,000. The solubility of starch-g-poly(vinyl alcohol) in hot water was less than 50; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dispersed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch-g-poly

In Vitro Antimicrobial Photodynamic Therapy Against Trichophyton mentagrophytes Using New Methylene Blue as the Photosensitizer.

Science.gov (United States)

López-Chicón, P; Gulías, Ò; Nonell, S; Agut, M

2016-11-01

Antimicrobial photodynamic therapy combines the use of a photosensitizing drug with light and oxygen to eradicate pathogens. Trichophyton mentagrophytes is a dermatophytic fungus able to invade the skin and keratinized tissues. We have investigated the use of new methylene blue as the photosensitizing agent for antimicrobial photodynamic therapy to produce the in vitro inactivation of T mentagrophytes. A full factorial design was employed to optimize the parameters for photoinactivation of the dermatophyte. The parameters studied were new methylene blue concentration, contact time between the photosensitizing agent and the fungus prior to light treatment, and the fluence of red light (wavelength, 620-645nm) applied. The minimum concentration of new methylene blue necessary to induce the death of all T. mentagrophytes cells in the initial suspension (approximate concentration, 10 6 colony forming units per milliliter) was 50μM for a fluence of 81J/cm 2 after a contact time of 10minutes with the photosensitizing-agent. Increasing the concentration to 100μM allowed the fluence to be decreased to 9J/cm 2 . Comparison of our data with other published data shows that the susceptibility of T. mentagrophytes to antimicrobial photodynamic therapy with new methylene blue is strain-dependent. New methylene blue is a photosensitizing agent that should be considered for the treatment of fungal skin infections caused by this dermatophyte. Copyright © 2016 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.

Living Polymerization of N -Substituted β-Alanine N -Carboxyanhydrides: Kinetic Investigations and Preparation of an Amphiphilic Block Copoly-β-Peptoid

KAUST Repository

Grossmann, Arlett; Luxenhofer, Robert

2012-01-01

attention. Here we present results that suggest that while N-substituted β-alanine N-carboxyanhydrides can undergo a living nucleophilic ring-opening polymerization, the solubility of poly(β-peptoid)s can be very poor, which contributes to the limited

Semiconductor nanocrystals for novel optical applications

Science.gov (United States)

Moon, Jong-Sik

Inspired by the promise of enhanced spectral response, photorefractive polymeric composites photosensitized with semiconductor nanocrystals have emerged as an important class of materials. Here, we report on the photosensitization of photorefractive polymeric composites at visible wavelengths through the inclusion of narrow band-gap semiconductor nanocrystals composed of PbS. Through this approach, internal diffraction efficiencies in excess of 82%, two-beam-coupling gain coefficients in excess of 211 cm-1, and response times 34 ms have been observed, representing some of the best figures-of-merit reported on this class of materials. In addition to providing efficient photosensitization, however, extensive studies of these hybrid composites have indicated that the inclusion of nanocrystals also provides an enhancement in the charge-carrier mobility and subsequent reduction in the photorefractive response time. Through this approach with PbS as charge-carrier, unprecedented response times of 399 micros were observed, opening the door for video and other high-speed applications. It is further demonstrated that this improvement in response time occurs with little sacrifice in photorefractive efficiency and with internal diffraction efficiencies of 72% and two- beam-coupling gain coefficients of 500 cm-1 being measured. A thorough analysis of the experimental data is presented, supporting the hypothesized mechanism of the enhanced charge mobility without the accompaniment of superfluous traps. Finally, water soluble InP/ZnS and CdSe/ZnS quantum dots interacted with CPP and Herceptin to apply them as a bio-maker. Both of quantum dots showed the excellent potential for use in biomedical imaging and drug delivery applications. It is anticipated that these approaches can play a significant role in the eventual commercialization of these classes of materials.

Seneciosis in cattle associated with photosensitization

OpenAIRE

Giaretta,Paula R.; Panziera,Welden; Galiza,Glauco J.A.; Brum,Juliana S.; Bianchi,Ronaldo M.; Hammerschmitt,Márcia E.; Bazzi,Talissa; Barros,Claudio S.L.

2014-01-01

Senecio spp. poisoning is the main cause of cattle mortality in the central region of Rio Grande do Sul. This paper reports an outbreak of seneciosis in cattle with high prevalence of photosensitization, where 83 out of 162 cows (51.3%) presented this clinical sign. The outbreak occurred in September 2013, affecting adult cows that were held in a 205 hectare-pasture from April to October 2013 with abundant Senecio brasiliensis infestation. Main clinical signs were weight loss, excessive lacri...

Photosensitive semiconducting polymer-incorporated nanofibers for promoting the regeneration of skin wound

Energy Technology Data Exchange (ETDEWEB)

Jin, Guorui [Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis Way, Innovis, #08-03, 138634 (Singapore); The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi' an Jiaotong University, School of Life Science and Technology, Xi' an 710049 (China); Li, Jun [Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis Way, Innovis, #08-03, 138634 (Singapore); Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ (United Kingdom); Li, Kai, E-mail: kai_li_cn@hotmail.com [Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis Way, Innovis, #08-03, 138634 (Singapore); Department of Radiology and Molecular Imaging Program at Stanford (MIPS), Stanford School of Medicine, Stanford, 94305 (United States)

2017-01-01

Photosensitive semiconducting polymer (SP) combined with light stimulation has shown the capability in promoting the proliferation of human dermal fibroblasts (HDFs). However, the high cytotoxicity of the used SP hindered its further application in bioactive scaffolds. In this contribution, we designed and synthesized a SP, poly (N,N-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c] pyrrole-1,4-dione-alt-thieno[3,2-b]thiophene) (PDBTT) with low cytotoxicity and strong absorbance in red and near-infrared region (600–1200 nm). The photosensitive SP was then applied in electrospun poly(ε-caprolactone) (PCL) nanofibrous scaffold and evaluated its proliferative effect on HDFs under the illumination from red light-emitting diode (LED) with high tissue penetration. After 9 days of continuous stimulation, the hybrid electrospun PCL/PDBTT nanofibers with low cytotoxicity showed excellent support for HDFs adhesion, proliferation and collagen secretion than neat PCL nanofibers and HDFs on the stimulated PCL/PDBTT nanofibers gained typical spindle morphology, indicating the well cell spreading on the stimulated PCL/PDBTT nanofibers. The incorporation of functional materials within synthetic biomaterials could be a novel way in improving the performance of engineered tissue constructs by providing multiple cues (e.g. electrical stimulation) to the attached cells. - Highlights: • A photosensitive semiconducting polymer (SP) was applied in electrospun nanofibrous scaffold. • The SP-incorporated scaffold could promote cell proliferation upon light stimulation. • The designed photosensitive SP could be applied as functional material with low cost and high durability in skin tissue engineering.

Mechanisms of photosensitization by drugs: Involvement of tyrosines in the photomodification of proteins mediated by tiaprofenic acid in vitro.

Science.gov (United States)

Miranda, M A; Castell, J V; Sarabia, Z; Hernández, D; Puertes, I; Morera, I M; Gómez-Lechón, M J

1997-10-01

The photosensitizing potential of drugs must be related to their photoreactivity towards the target biomolecules. In this context, a representative photosensitizing drug (tiaprofenic acid) was co-irradiated with a model protein, bovine serum albumin (BSA). This led to a significant degree of protein crosslinking and to the formation of trace amounts of drug-BSA photoadducts. Amino acid analysis of the hydrolysed (HC1) protein showed that His and Tyr undergo a dramatic decrease (approx. 90%) as a consequence of drug-mediated photodynamic processes. When the drug was irradiated in the presence of the pure amino acids, extensive phototransformation of the latter was observed. Other photosensitizing drugs gave rise to similar processes when irradiated in the presence of BSA or the isolated amino acids. In conclusion, histidine and tyrosine appear to be key sites for the photosensitized damage to proteins. Photodegradation of the isolated amino acids in vitro may be an indicator of the photosensitizing potential of drugs.

Improved combination of photosensitivity elements for use in radiography

International Nuclear Information System (INIS)

Doorselaer, M.K.

1975-01-01

It is stated that manufacturers of photosensitive elements incorporating silver halide emulsions for use in radiography are often faced with performance requirements that place conflicting demands on the composition of the photosensitive elements. Amongst such performance requirements are a minimum photographic speed, a short processing time, and a minimum standard of image density and resolution. With a view to achieving some degree of reconciliation between maximum optical image density requirements and economy in processing time, and in particular fixing time, it is advantageous to have the total silver halide content distributed in emulsion layers on opposite sides of the emulsion layer support. Such 'double sided' elements are usually exposed between two intensifying screens, that may be separate elements of integral parts of a single element that also incorporates the silver halide emulsion layers. During exposure of these 'double sided' elements light from one intensifying screen irradiates the adjacent emulsion layer and also that on the opposite side of the support; this is referred to as 'cross over'. Due to refraction and other light deflection processes within the photosensitive element this, however, impairs image definition. In commercial systems a relatively high concentration of siver halide is usually employed in order to obtain good contrast and maximum image density, but this adversely affects processing time. Instead of such high silver halide concentrations emulsions of small silver halide grain size may be used, but this lowers the photographic speed. Elements having properties that mitigate these difficulties are described, and examples of their application are given. (U.K.)

Photopatch and UV-irradiated patch testing in photosensitive dermatitis

Directory of Open Access Journals (Sweden)

Reena Rai

2016-01-01

Full Text Available Background: The photopatch test is used to detect photoallergic reactions to various antigens such as sunscreens and drugs. Photosensitive dermatitis can be caused due to antigens like parthenium, fragrances, rubbers and metals. The photopatch test does not contain these antigens. Therefore, the Indian Standard Series (ISS along with the Standard photopatch series from Chemotechnique Diagnostics, Sweden was used to detect light induced antigens. Aim: To detect light induced antigens in patients with photosensitive dermatitis. Methods: This study was done in a descriptive, observer blinded manner. Photopatch test and ISS were applied in duplicate on the patient's back by the standard method. After 24 hours, readings were recorded according to ICDRG criteria. One side was closed and other side irradiated with 14 J/cm2 of UVA and a second set of readings were recorded after 48 hrs. Result: The highest positivity was obtained with parthenium, with 18 out of 35 (51% patients showing a positive patch test reaction with both photoallergic contact dermatitis and photoaggravation. Four patients (11% showed positive patch test reaction suggestive of contact dermatitis to potassium dichromate and fragrance mix. Six patients had contact dermatitis to numerous antigens such as nickel, cobalt, chinoform and para-phenylenediamine. None of these patients showed photoaggravation on patch testing. Conclusion: Parthenium was found to cause photoallergy, contact dermatitis with photoaggravation and contact allergy. Hence, photopatch test and UV irradiated patch test can be an important tool to detect light induced antigens in patients with photosensitive dermatitis.

Formulation and characterization of polymeric films containing combinations of antiretrovirals (ARVs) for HIV prevention.

Science.gov (United States)

Akil, Ayman; Agashe, Hrushikesh; Dezzutti, Charlene S; Moncla, Bernard J; Hillier, Sharon L; Devlin, Brid; Shi, Yuan; Uranker, Kevin; Rohan, Lisa Cencia

2015-02-01

To develop polymeric films containing dual combinations of anti-HIV drug candidate tenofovir, maraviroc and dapivirine for vaginal application as topical microbicides. A solvent casting method was used to manufacture the films. Solid phase solubility was used to identify potential polymers for use in the film formulation. Physical and chemical properties (such as water content, puncture strength and in vitro release) and product stability were determined. The bioactivity of the film products against HIV was assessed using the TZM-bl assay and a cervical explant model. Polymers identified from the solid phase solubility study maintained tenofovir and maraviroc in an amorphous state and prevented drug crystallization. Three combination film products were developed using cellulose polymers and polyvinyl alcohol. The residual water content in all films was 50% of film drug content within 30 min. Stability testing confirmed that the combination film products were stable for 12 months at ambient temperature and 6 months under stressed conditions. Antiviral activity was confirmed in TZM-bl and cervical explant models. Polymeric films can be used as a stable dosage form for the delivery of antiretroviral combinations as microbicides.

Supported Catalysts Useful in Ring-Closing Metathesis, Cross Metathesis, and Ring-Opening Metathesis Polymerization

Directory of Open Access Journals (Sweden)

Jakkrit Suriboot

2016-04-01

Full Text Available Ruthenium and molybdenum catalysts are widely used in synthesis of both small molecules and macromolecules. While major developments have led to new increasingly active catalysts that have high functional group compatibility and stereoselectivity, catalyst/product separation, catalyst recycling, and/or catalyst residue/product separation remain an issue in some applications of these catalysts. This review highlights some of the history of efforts to address these problems, first discussing the problem in the context of reactions like ring-closing metathesis and cross metathesis catalysis used in the synthesis of low molecular weight compounds. It then discusses in more detail progress in dealing with these issues in ring opening metathesis polymerization chemistry. Such approaches depend on a biphasic solid/liquid or liquid separation and can use either always biphasic or sometimes biphasic systems and approaches to this problem using insoluble inorganic supports, insoluble crosslinked polymeric organic supports, soluble polymeric supports, ionic liquids and fluorous phases are discussed.

Monoglyceride-based self-assembling copolymers as carriers for poorly water-soluble drugs.

Science.gov (United States)

Rouxhet, L; Dinguizli, M; Latere Dwan'isa, J P; Ould-Ouali, L; Twaddle, P; Nathan, A; Brewster, M E; Rosenblatt, J; Ariën, A; Préat, V

2009-12-01

To develop self-assembling polymers forming polymeric micelles and increasing the solubility of poorly soluble drugs, amphiphilic polymers containing a hydrophilic PEG moiety and a hydrophobic moiety derived from monoglycerides and polyethers were designed. The biodegradable copolymers were obtained via a polycondensation reaction of polyethylene glycol (PEG), monooleylglyceride (MOG) and succinic anhydride (SA). Polymers with molecular weight below 10,000 g/mol containing a minimum of 40 mol% PEG and a maximum of 10 mol% MOG self-assembled spontaneously in aqueous media upon gentle mixing. They formed particles with a diameter of 10 nm although some aggregation was evident. The critical micellar concentration varied between 3x10(-4) and 4x10(-3) g/ml, depending on the polymer. The cloud point (> or = 66 degrees C) and flocculation point (> or = 0.89 M) increased with the PEG chain length. At a 1% concentration, the polymers increased the solubility of poorly water-soluble drug candidates up to 500-fold. Drug solubility increased as a function of the polymer concentration. HPMC capsules filled with these polymers disintegrated and released model drugs rapidly. Polymer with long PEG chains had a lower cytotoxicity (MTT test) on Caco-2 cells. All of these data suggest that the object polymers, in particular PEG1000/MOG/SA (45/5/50) might be potential candidates for improving the oral biopharmaceutical performance of poorly soluble drugs.

Studies of vascular acting photosensitizer Tookad for the photodynamic therapy of prostate cancer

Science.gov (United States)

Huang, Zheng; Chen, Qun; Blanc, Dominique; Hetzel, Fred W.

2005-01-01

In this pre-clinical study, photodynamic therapy (PDT) mediated with a vascular acting photosensitizer Tookad (palladium-bacteriopheophorbide) is investigated as an alternative treatment modality for the ablation of prostate cancer. Canine prostate was used as the animal model. PDT was performed by interstitially irradiating the surgically exposed prostates with a diode laser (763 nm) to activate the IV infused photosensitizer. The effects of drug dose, drug-light interval, and light fluence rate on PDT efficacy were evaluated. The prostates and adjacent tissues were harvested at one-week post PDT and subjected to histopathological examination. The dogs recovered well with little or no urethral complications. Urinalysis showed trace blood. Histological examination showed minimal damage to the prostatic urethra. These indicated that the urethra was well preserved. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis with a clear demarcation. Maximum lesion volume of ~3 cm3 could be achieved with a single 1-cm diffuser fiber at a dose level of 1 mg/kg and 200 J/cm, suggesting the therapy is very effective in ablating prostatic tissue. PDT induced lesion could reach the capsule layers but adjacent tissues were well preserved. The novel photosensitizer is a vascular drug and cleared rapidly from the circulation. Light irradiation can be performed during drug infusion thereby eliminating waiting time. The novel vascular acting photosensitizer Tookad-mediated PDT could provide an effective alternative to treat prostate cancer.

A pulse radiolysis study of emulsion polymerization

International Nuclear Information System (INIS)

McAskill, N.A.

1976-01-01

The emulsion polymerisation of slightly water soluble monomers such as styrene occurs initially in micelles of surfactant swollen with monomer and later in larger particles consisting of polymer swollen with monomer and stabilized with an outer layer of surfactant. There is considerable controversy on whether the reaction sites of polymerization are inside or on the surface of the particle or micelle. The relative amounts of micelle and particles present at various stages of the polymerization are also nuclear. In the present study the OH radical formed by pulse radiolysis has been used as a probe to investigate the site of solubilization of styrene in various surfactant micelles. Two products can be distinguished by UV spectrometry, a benzyl type radical formed by OH addition to the side chain of styrene and a cyclohexadienyl type radical formed by addition to the ring. Wide differences in the relative amounts of each product were observed suggesting that in some surfactants the styrene ring is buried inside the micelle whilst in other systems the styrene appears to be so solubilized at the interface leaving both the ring and the side chain open to attack by the OH radical. (author)

The amorphous solid dispersion of the poorly soluble ABT-102 forms nano/microparticulate structures in aqueous medium: impact on solubility

Directory of Open Access Journals (Sweden)

Frank KJ

2012-11-01

-performance liquid chromatography–ultraviolet-visible. The polymeric and the micellar fraction contributed to the substantial increase in apparent solubility of ABT-102. Furthermore, a microparticulate fraction was isolated by centrifugation and analyzed by scanning electron microscopy, X-ray scattering, and infrared spectroscopy. The microparticles were found to be amorphous and to contain two of the surfactants besides ABT-102 as the main component. The amorphous microparticles are assumed to be the origin of the observed increase in molecular solubility ("true" supersaturation.Keywords: solid dispersion, AFlFFF, micelles, solubility, supersaturation

Validation of Quantitative Structure-Activity Relationship (QSAR Model for Photosensitizer Activity Prediction

Directory of Open Access Journals (Sweden)

Sharifuddin M. Zain

2011-11-01

Full Text Available Photodynamic therapy is a relatively new treatment method for cancer which utilizes a combination of oxygen, a photosensitizer and light to generate reactive singlet oxygen that eradicates tumors via direct cell-killing, vasculature damage and engagement of the immune system. Most of photosensitizers that are in clinical and pre-clinical assessments, or those that are already approved for clinical use, are mainly based on cyclic tetrapyrroles. In an attempt to discover new effective photosensitizers, we report the use of the quantitative structure-activity relationship (QSAR method to develop a model that could correlate the structural features of cyclic tetrapyrrole-based compounds with their photodynamic therapy (PDT activity. In this study, a set of 36 porphyrin derivatives was used in the model development where 24 of these compounds were in the training set and the remaining 12 compounds were in the test set. The development of the QSAR model involved the use of the multiple linear regression analysis (MLRA method. Based on the method, r2 value, r2 (CV value and r2 prediction value of 0.87, 0.71 and 0.70 were obtained. The QSAR model was also employed to predict the experimental compounds in an external test set. This external test set comprises 20 porphyrin-based compounds with experimental IC50 values ranging from 0.39 µM to 7.04 µM. Thus the model showed good correlative and predictive ability, with a predictive correlation coefficient (r2 prediction for external test set of 0.52. The developed QSAR model was used to discover some compounds as new lead photosensitizers from this external test set.

X ray photoelectron spectroscopy (XPS) analysis of Photosensitive ZrO2 array

Science.gov (United States)

Li, Y.; Zhao, G.; Zhu, R.; Kou, Z.

2018-03-01

Based on organic zirconium source as the starting material, by adding chemical modifiers which are made up with photosensitive ZrO2 sol. A uniformed ZrO2 array dot was fabricated with a mean diameter of around 800 nm. By using UV-vis spectra and X-ray photoelectron spectroscopy analysis method, studies the photosensitive ZrO2 gel film of photochemical reaction process and the photosensitive mechanism, to determine the zirconium atom centered chelate structure, reaction formed by metal chelate Zr atom for the center, and to establish the molecular model of the chelate. And studied the ultraviolet light in the process of the variation of the XPS spectra, Zr3d5/2 to 184.9 eV corresponding to the binding energy of the as the combination of state peak gradually reduce; By combining with the status of Zr-O peak gradually increase; The strength of the peak is gradually decline. This suggests that in the process of ultraviolet light photo chemical reaction happened. This study is of great significance to the micro fabrication of ZrO2 array not only to the memory devices but also to the optical devices.

Photosensitive Layer-by-Layer Assemblies Containing Azobenzene Groups: Synthesis and Biomedical Applications

Directory of Open Access Journals (Sweden)

Uichi Akiba

2017-10-01

Full Text Available This review provides an overview of the syntheses of photosensitive layer-by-layer (LbL films and microcapsules modified with azobenzene derivatives and their biomedical applications. Photosensitive LbL films and microcapsules can be prepared by alternate deposition of azobenzene-bearing polymers and counter polymers on the surface of flat substrates and microparticles, respectively. Azobenzene residues in the films and microcapsules exhibit trans-to-cis photoisomerization under UV light, which causes changes in the physical or chemical properties of the LbL assemblies. Therefore, azobenzene-functionalized LbL films and microcapsules have been used for the construction of photosensitive biomedical devices. For instance, cell adhesion on the surface of a solid can be controlled by UV light irradiation by coating the surface with azobenzene-containing LbL films. In another example, the ion permeability of porous materials coated with LbL films can be regulated by UV light irradiation. Furthermore, azobenzene-containing LbL films and microcapsules have been used as carriers for drug delivery systems sensitive to light. UV light irradiation triggers permeability changes in the LbL films and/or decomposition of the microcapsules, which results in the release of encapsulated drugs and proteins.

Strong memory in time series of human magnetoencephalograms can identify photosensitive epilepsy

International Nuclear Information System (INIS)

Yulmetyev, R. M.; Yulmetyeva, D. G.; Haenggi, P.; Shimojo, S.; Bhattacharya, J.

2007-01-01

To discuss the salient role of statistical memory effects in human brain functioning, we have analyzed a set of stochastic memory quantifiers that reflects the dynamical characteristics of neuromagnetic responses of magnetoencephalographic signals to a flickering stimulus of different color combinations from a group of control subjects, and compared them with those for a patient with photosensitive epilepsy. We have discovered that the emergence of strong memory and the accompanying transition to a regular and robust regime of chaotic behavior of signals in separate areas for a patient most likely identifies the regions where the protective mechanism against the occurrence of photosensitive epilepsy is located

Ultrasonic activation and chemical modification of photosensitizers enhances the effects of photodynamic therapy against Enterococcus faecalis root-canal isolates.

Science.gov (United States)

Tennert, C; Drews, A M; Walther, V; Altenburger, M J; Karygianni, L; Wrbas, K T; Hellwig, E; Al-Ahmad, A

2015-06-01

The aim of this study was to evaluate the effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilms in artificially infected root canals using modified photosensitizers and passive ultrasonic activation. Two hundred and seventy extracted human teeth with one root canal were instrumented utilizing ProTaper files, autoclaved, infected with E. faecalis T9 for 72 h and divided into different groups: irrigation with 3% sodium hypochlorite (NaOCl), 20% ethylenediaminetetraacetic acid (EDTA), or 20% citric acid, PDT without irrigation, PDT accompanied by irrigation with NaOCl, EDTA, or citric acid, PDT using an EDTA-based photosensitizer or a citric-acid-based photosensitizer and PDT with ultrasonic activation of the photosensitizer. A 15 mg/ml toluidine blue served as the photosensitizer, activated by a 100 mW LED light source. Sterile paper points were used for sampling the root canals and dentin chips were collected to assess the remaining contamination after treatment. Samples were cultured on blood agar plates and colony forming units were quantified. PDT alone achieved a reduction in E. faecalis counts by 92.7%, NaOCl irrigation alone and combined with PDT by 99.9%. The antibacterial effects increased by the combination of irrigation using EDTA or citric acid and PDT compared to irrigation alone. More than 99% of E. faecalis were killed using PDT with the modified photosensitizers and ultrasonic activation. NaOCl based disinfection achieved the highest antimicrobial effect. Using PDT with an EDTA-based or citric-acid-based phozosensitizer or activating the photosensitizer with ultrasound resulted in a significantly higher reduction in E. faecalis counts compared to conventional PDT. Copyright © 2015 Elsevier B.V. All rights reserved.

Is colour modulation an independent factor in human visual photosensitivity?

NARCIS (Netherlands)

Parra, J.; Lopes da Silva, F.H.; Stroink, H.; Kalitzin, S.

2007-01-01

Considering that the role of colour in photosensitive epilepsy (PSE) remains unclear, we designed a study to determine the potential of different colours, colour combinations and white light to trigger photoparoxysmal responses (PPRs) under stringent controlled conditions. After assessing their

pH- and temperature-sensitive polymeric microspheres for drug delivery: the dissolution of copolymers modulates drug release.

Science.gov (United States)

Fundueanu, Gheorghe; Constantin, Marieta; Stanciu, Cristina; Theodoridis, Georgios; Ascenzi, Paolo

2009-12-01

Most pH-/temperature-responsive polymers for controlled release of drugs are used as cross-linked hydrogels. However, the solubility properties of the linear polymers below and above the lower critical solution temperature (LCST) are not exploited. Here, the preparation and characterization of poly (N-isopropylacrylamide-co-methacrylic acid-co-methyl methacrylate) (poly (NIPAAm-co-MA-co-MM)) and poly (N-isopropylacrylamide-co-acrylamide) (poly (NIPAAm-co-AAm)), known as "smart" polymers (SP), is reported. Both poly (NIPAAm-co-MA-co-MM) and poly (NIPAAm-co-AAm) display pH- and temperature-responsive properties. Poly (NIPAAm-co-MA-co-MM) was designed to be insoluble in the gastric fluid (pH = 1.2), but soluble in the intestinal fluid (pH = 6.8 and 7.4), at the body temperature (37 degrees C). Poly (NIPAAm-co-AAm) was designed to have a lower critical solution temperature (LCST) corresponding to 37 degrees C at pH = 7.4, therefore it is not soluble above the LCST. The solubility characteristics of these copolymers were exploited to modulate the rate of release of drugs by changing pH and/or temperature. These copolymers were solubilized with hydrophobic cellulose acetate butyrate (CAB) and vitamin B(12) (taken as a water soluble drug model system) in an acetone/methanol mixture and dispersed in mineral oil. By a progressive evaporation of the solvent, the liquid droplets were transformed into loaded CAB/SP microspheres. Differential scanning calorimetric studies and scanning electron microscopy analysis demonstrated that the polymeric components of the microspheres precipitated separately during solvent evaporation forming small microdomains. Moreover, vitamin B(12) was found to be molecularly dispersed in both microdomains with no specific affinity for any polymeric component of microspheres. The release of vitamin B(12) was investigated as a function of temperature, pH, and the CAB/SP ratio.

Synthesis and characterization of water-soluble and conducting sulfonated polyaniline/para-phenylenediamine-functionalized multi-walled carbon nanotubes nano-composite

International Nuclear Information System (INIS)

Xu Jun; Yao Pei; Li Xuan; He Fei

2008-01-01

Water-soluble and conducting sulfonated polyaniline (SPAN)/phenylamine groups contained MWNTs (p-MWNTs) nano-composite were synthesized by in situ oxidation polymerization followed by sulfonation and hydrolysis. TEM, Raman spectroscopy, FTIR, XPS, TGA and standard four-probe methods were employed to characterize morphology, chemical structure and performance of the nano-composite. The results show that phenylamine groups are grafted on the surface of p-MWNTs via amide bond and oxidized phenylamine groups initiate polyaniline polymerized on the surface of p-MWNTs. SPAN chains covalently attached to p-MWNTs render p-MWNTs compatibility with SPAN matrix and lead to SPAN/p-MWNTs nano-composite highly soluble and stable in water. Improved thermal stability illuminate existence of a new phase in the nano-composite where there is chemical interaction between p-MWNTs and SPAN coatings. Owing to incorporation of p-MWNTs conductivity of the nano-composite at room temperature is increased by about two orders of magnitude over neat SPAN

Nanotechnology-Based Drug Delivery Systems for Photodynamic Therapy of Cancer: A Review.

Science.gov (United States)

Calixto, Giovana Maria Fioramonti; Bernegossi, Jéssica; de Freitas, Laura Marise; Fontana, Carla Raquel; Chorilli, Marlus

2016-03-11

Photodynamic therapy (PDT) is a promising alternative approach for improved cancer treatment. In PDT, a photosensitizer (PS) is administered that can be activated by light of a specific wavelength, which causes selective damage to the tumor and its surrounding vasculature. The success of PDT is limited by the difficulty in administering photosensitizers (PSs) with low water solubility, which compromises the clinical use of several molecules. Incorporation of PSs in nanostructured drug delivery systems, such as polymeric nanoparticles (PNPs), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), gold nanoparticles (AuNPs), hydrogels, liposomes, liquid crystals, dendrimers, and cyclodextrin is a potential strategy to overcome this difficulty. Additionally, nanotechnology-based drug delivery systems may improve the transcytosis of a PS across epithelial and endothelial barriers and afford the simultaneous co-delivery of two or more drugs. Based on this, the application of nanotechnology in medicine may offer numerous exciting possibilities in cancer treatment and improve the efficacy of available therapeutics. Therefore, the aim of this paper is to review nanotechnology-based drug delivery systems for photodynamic therapy of cancer.

Nanotechnology-Based Drug Delivery Systems for Photodynamic Therapy of Cancer: A Review

Directory of Open Access Journals (Sweden)

Giovana Maria Fioramonti Calixto

2016-03-01

Full Text Available Photodynamic therapy (PDT is a promising alternative approach for improved cancer treatment. In PDT, a photosensitizer (PS is administered that can be activated by light of a specific wavelength, which causes selective damage to the tumor and its surrounding vasculature. The success of PDT is limited by the difficulty in administering photosensitizers (PSs with low water solubility, which compromises the clinical use of several molecules. Incorporation of PSs in nanostructured drug delivery systems, such as polymeric nanoparticles (PNPs, solid lipid nanoparticles (SLNs, nanostructured lipid carriers (NLCs, gold nanoparticles (AuNPs, hydrogels, liposomes, liquid crystals, dendrimers, and cyclodextrin is a potential strategy to overcome this difficulty. Additionally, nanotechnology-based drug delivery systems may improve the transcytosis of a PS across epithelial and endothelial barriers and afford the simultaneous co-delivery of two or more drugs. Based on this, the application of nanotechnology in medicine may offer numerous exciting possibilities in cancer treatment and improve the efficacy of available therapeutics. Therefore, the aim of this paper is to review nanotechnology-based drug delivery systems for photodynamic therapy of cancer.

Effects of hypericin and a chlorin based photosensitizer alone or in combination in squamous cell carcinoma cells in the dark.

OpenAIRE

Besic Gyenge Emina; Forny Patrick; Lüscher Daniel; Laass Andrea; Walt Heinrich; Maake Caroline

2012-01-01

INTRODUCTION The toxic influence of photosensitizers in the dark is poorly investigated. In our study we used the photosensitizers liposomal meso tetrahydroxyphenyl chlorin derivative (Foslipos(®)) and hypericin as well as their 1:1 combination on two different head and neck squamous cell carcinoma (HNSCC) cell lines (UMB SCC 745 and UMB SCC 969). MATERIALS AND METHODS We examined uptake efflux and localization of the photosensitizers with confocal microscopy. Fluorescence quantification was ...

Clinical trials of a new chlorin photosensitizer for photodynamic therapy of malignant tumors

Science.gov (United States)

Privalov, Valeriy A.; Lappa, Alexander V.; Seliverstov, Oleg V.; Faizrakhmanov, Alexey B.; Yarovoy, Nicolay N.; Kochneva, Elena V.; Evnevich, Michail V.; Anikina, Alla S.; Reshetnicov, Andrey V.; Zalevsky, Igor D.; Kemov, Yuriy V.

2002-06-01

Photodynamic therapy (PDT) was performed with a new photosensitizer, a water soluble form of chlorins (Radachlorin, Russia) possessing an absorption peak around 662 nm. As light source there was used the diode laser (ML-662-SP, Russia) with 662 nm wavelength and 2.5 W optical power. The sensitizer had passed broad pre-clinical in vitro and in vivo studies, which showed safety and efficiency of it. PDT was applied to 51 patients with basal cell cancer of the skin (about 60% of all cases), breast cancer, lip cancer, melanoma, cancer of esophagus, stomach, and rectum, cancer and leucoplacia of vulva, malignant ganglioneuroma, sarcoma of soft tissue, cancer and reticular sarcoma of thyroid gland, cancer of ductus choledochus. Most of non-basalioma patients had either forth stage or recurrence of disease. The sensitizer was injected intravenously or applied externally (Radachlorin gel). There were used surface, endoscopic, and interstitial ways of irradiation. Full tumor regression with excellent cosmetic effect was reached in 100% cases of 1-3 stage basal cell cancer patients treated with intravenous Radachlorin injection. In most other (non-basalioma) cases significant regression of tumors and improvement of life quality of patients (recanalization and regain of conductivity) was obtained.

CHARACTERIZATION OF TERNARY SYSTEM OF POORLY SOLUBLE DRUG IN VARIOUS HYDROPHILIC CARRIERS

OpenAIRE

Vijay Kumar; Shankaraiah MM; Venkatesh JS; Rangaraju D; C.Nagesh

2011-01-01

The present study aims to experiment the solid dispersion of poorly water soluble drug fenbendazole as model drug. Fenbendazole is an Antihelmintic drug (BCS class 2).The purpose of this study was to enhance the dissolution of Fenbendazole by solid dispersions consisting of the drug, a polymeric carrier, Binary and ternary system were prepared by kneading method using hydrophilic polymers like polyvinylpyrrolidone K-25 (PVP K25), beta-cyclodextrin (BCD),mannitol and urea. The prepared form...

Biomimetic PEGylation of carbon nanotubes through surface-initiated RAFT polymerization.

Science.gov (United States)

Shi, Yingge; Zeng, Guanjian; Xu, Dazhuang; Liu, Meiying; Wang, Ke; Li, Zhen; Fu, Lihua; Zhang, Qingsong; Zhang, Xiaoyong; Wei, Yen

2017-11-01

Carbon nanotubes (CNTs) are a type of one-dimensional carbon nanomaterials that possess excellent physicochemical properties and have been potentially utilized for a variety of applications. Surface modification of CNTs with polymers is a general route to expand and improve the performance of CNTs and has attracted great research interest over the past few decades. Although many methods have been developed previously, most of these methods still showed some disadvantages, such as low efficiency, complex experimental procedure and harsh reaction conditions etc. In this work, we reported a practical and novel way to fabricate CNTs based polymer composites via the combination of mussel inspired chemistry and reversible addition fragmentation chain transfer (RAFT) polymerization. First, the amino group was introduced onto the surface of CNTs via self-polymerization of dopamine. Then, chain transfer agent can be immobilized on the amino groups functionalized CNTs to obtain CNT-PDA-CTA, which can be utilized for surface-initiated RAFT polymerization. A water soluble and biocompatible monomer poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) was adopted to fabricate pPEGMA functionalized CNTs through RAFT polymerization. The successful preparation of CNTs based polymer composites (CNT-pPEGMA) was confirmed by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy in details. The CNT-pPEGMA showed good dispersibility and desirable biocompatibility, making them highly potential for biomedical applications. More importantly, a large number of CNTs based polymer composites could also be fabricated through the same strategy when different monomers were used due to the good monomer adaptability of RAFT polymerization. Therefore, this strategy should be a general method for preparation of various multifunctional CNTs based polymer composites. Copyright © 2017 Elsevier B.V. All rights

Wavelength dependence of the efficiency of singlet oxygen generation upon photoexcitation of photosensitizers

Directory of Open Access Journals (Sweden)

Starukhin A.

2017-01-01

Full Text Available The dependence of the efficiency of singlet oxygen (1Δg generation upon excitation of photosensitizer at different wavelength was observed for several derivatives of palladium porphyrin in carbon tetrachloride. The efficiency of singlet oxygen generation upon excitation in a blue region of the spectrum (Soret band exceeds by several times the efficiency at excitation in the red spectral region (Q band. The effect of enhancement of singlet oxygen generation upon CW photoexcitation to Soret band of photosensitizer may be explained by influence of high laying triplet states of a donor molecule on the triplet-triplet energy transfer.

Studies of a novel photosensitizer Pd-bacteriopheophorbide (Tookad) for the prostate cancer PDT in canine model

Science.gov (United States)

Huang, Zheng; Chen, Qun; Brun, Pierre-Herve; Wilson, Brian C.; Scherz, Avigdor; Salomon, Yoram; Luck, David L.; Beckers, Jill; Hetzel, Fred W.

2003-12-01

Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. In vivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the i.v. infused photosensitizer drug. The effects of two-session PDT were evaluated. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week, post second-session PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. Two-session PDT or one single session PDT induced a similar extent of damage. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Maximum lesion size of over 3 cm in dimension could be achieved with a single 1-cm interstitial treatment, suggesting the therapy is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat prostate cancer.

Radical-Mediated Enzymatic Polymerizations

Science.gov (United States)

Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

2016-01-01

Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

Ultraviolet photosensitivity of sulfur-doped micro- and nano-crystalline diamond

International Nuclear Information System (INIS)

Mendoza, Frank; Makarov, Vladimir; Hidalgo, Arturo; Weiner, Brad; Morell, Gerardo

2011-01-01

The room-temperature photosensitivity of sulfur-doped micro- (MCD), submicro- (SMCD) and nano- (NCD) crystalline diamond films synthesized by hot-filament chemical vapor deposition was studied. The structure and composition of these diamond materials were characterized by Raman spectroscopy, scanning electron microscopy and X-ray diffraction. The UV sensitivity and response time were studied for the three types of diamond materials using a steady state broad UV excitation source and two pulsed UV laser radiations. It was found that they have high sensitivity in the UV region, as high as 10 9 sec -1 mV -1 range, linear response in a broad spectral range below 320 nm, photocurrents around ∼10 -5 A, and short response time better than 100 ns, which is independent of fluency intensity. A phenomenological model was applied to help understand the role of defects and dopant concentration on the materials' photosensitivity

Effects of riboflavin photosensitization on the degradation of bisphenol A (BPA) in model and real-food systems.

Science.gov (United States)

Ha, Dong-Oh; Jeong, Min Kyu; Park, Chan Uk; Park, Min Hee; Chang, Pahn-Shick; Lee, Jae Hwan

2009-06-01

Effects of riboflavin photosensitizations on the stability of bisphenol A (BPA), a well-known endocrine disrupting chemical, were studied in model and real-food systems by high-performance liquid chromatography (HPLC). Concentration of BPA was significantly decreased under light exposure (P 0.05). Addition of 50, 100, and 200 microM sodium azide significantly increased the stability of BPA in riboflavin photosensitization with concentration dependent manner (P canned tea beverages with different phenolic contents. BPA was more stable in the beverage sample with higher total phenolic contents and free radical scavenging ability. The photodegradation of BPA in riboflavin photosensitization can be an efficient way to decrease the concentration of BPA from environmental or food systems.

Self-Propagating Frontal Polymerization in Water at Ambient Pressure

Science.gov (United States)

Olten, Nesrin; Kraigsley, Alison; Ronney, Paul D.

2003-01-01

boiling point solutions are needed because in order to produce a propagating front, a high front temperature is needed to produce sufficiently rapid decomposition of the free radical initiator and subsequent free radical polymerization and heat release at a rate faster than heat losses remove thermal energy from the system. (While the conduction heat loss rate increases linearly with temperature, the free radical initiator decomposition is a high activation energy process whose rate increases much more rapidly than linearly with temperature, thus as the temperature decreases, the ratio of heat loss to heat generation increases, eventually leading to extinction of the front if the temperature is too low.) In order to obtain atmospheric pressure frontal polymerization in water, it is necessary to identify a monomer/initiator combination that is water soluble and will not extinguish even when the peak temperature (T*) is less than 100 C. In this work acrylic acid (AA) was chosen as the monomer because is it one of the most reactive monomers and can polymerize readily at low temperatures even without initiators. Ammonium persulfate (AP) was chosen as the initiator because it decomposes readily at low temperatures, produces relatively few bubbles and is commercially available. The propagation rates and extinction conditions of the fronts are studied for a range of AA and AP concentrations. Small amounts of fumed silica powder (Cab-o-sil, Cabot Corporation) were added to the solutions to inhibit buoyancy induced convection in the solutions; future studies will investigate the effects of buoyant convection within the solutions.

Scintigraphic evaluation of the pharmacokinetics of a soluble polymeric drug carrier

International Nuclear Information System (INIS)

Pimm, M.V.; Perkins, A.C.; Hudecz, F.

1992-01-01

There is a growing interest in the use of macromolecular carriers for therapeutic agents. If these carriers can be labelled with an appropriate gamma-emitter, their biodistribution could be followed by scintigraphy. We have imaged the biodistribution of a synthetic branched polypeptide, based on a poly-L-lysine backbone (average molecular mass 45 kDa). The polymer was conjugated to diethylene triamine penta-acetic acid and labelled by chelation with indium-111. Mice were injected i.v. with labelled material and imaged with a gamma-camera with a pin-hole collimator. Images showed the majority of tracer remaining in the blood pool, but about 35% appeared in the urinary bladder within 1.5 h. When the 111 In-polymer was fractionated by gel filtration chromatography on S-300, the imaging showed that the early eluting material was retained, the intermediate showed some renal clearance, and the late was rapidly excreted. These findings show the value of gamma-scintigraphy for biodistribution studies with such polymeric drug carriers and its potential for clinical pharmacokinetic studies. (orig.)

Isolation and characterization of inulin with a high degree of polymerization from roots of Stevia rebaudiana (Bert.) Bertoni.

Science.gov (United States)

Lopes, Sheila M S; Krausová, Gabriela; Rada, Vojtěch; Gonçalves, José E; Gonçalves, Regina A C; de Oliveira, Arildo J B

2015-06-26

The polysaccharide inulin has great importance in the food and pharmaceutical industries. The degree of polymerization (DP) of inulin influences important properties, such as, solubility, thermal stability, sweetness power and prebiotic activity. Molecules with a high degree of polymerization are obtained through physical techniques for enrichment of the inulin chains because they are not commonly obtained from plants extract. Gas chromatography/Mass Spectrometry and (1)H Nuclear Magnetic Resonance analysis showed that inulin from Stevia rebaudiana roots has a degree of polymerization (DPn 28) higher than the value of DPn 12-15 for inulins from other plant species. Furthermore, the methodology of freeze/thaw to enrich the chains allowed us to increase the DP, similarly to other methodologies used for the enrichment of inulin chains. The prebiotic assays confirm that inulin from S. rebaudiana has a high DP. The combined use of these molecules with low degree of polymerization fructans seems to be advantageous to prolong the prebiotic effect in the colon. Our results suggest that S. rebaudiana roots are a promising source of high degree polymerization inulins. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of proportional counters using photosensitive gases and liquids

International Nuclear Information System (INIS)

Anderson, D.F.

1984-10-01

An introduction to the history and to the principle of operation of wire chambers using photosensitive gases and liquids is presented. Their use as light sensors coupled to Gas Scintillation Proportional Counters and BaF 2 , as well as their use in Cherenkov Ring imaging, is discussed in some detail. 42 references, 21 figures

Measuring incident light on grape clusters using photosensitive paper and image analysis

International Nuclear Information System (INIS)

Price, S.F.; Schuette, M.L.; Tassie, E.

1995-01-01

Digital imaging and analysis was used to quantify and characterize the light exposure patterns of photosensitive paper tubes placed in representative cluster positions in two grape (Vitis vinifera L.) canopies: a minimally pruned and a vertically trained canopy. Blue pixel values of the captured images had a negative correlation with the log of irradiance from an integrating quantum sensor (r2 = 0.9308). The spectral response of the photosensitive paper was not measured. Histograms of incident light distribution on individual paper tubes were developed using imaging software. Histograms were able to quantify the distribution of incident light on individual tubes and were clearly related to the tube's exposure in the canopy. Average population curves of pixel light distribution of 20 tubes in each canopy were able to differentiate the typical cluster light environment in the two canopies. Tubes in the minimally pruned canopy had a larger proportion of their surface exposed to irradiances > 50 micromoles.s-1 m-2 and 65% higher average irradiance than the vertical canopy. Image analysis of photosensitive paper appears to be a workable method to record the distribution of incident light in plant canopies and may have utility in a range of ecological studies

Biodegradable Polyelectrolyte Obtained by Radiation Polymerization

International Nuclear Information System (INIS)

Craciun, G.; Martin, D.; Manaila, E.; Nemtanu, M.; Brasoveanu, M.; Ighigeanu, D.

2009-01-01

Poly electrolytes are water-soluble polymers carrying ionic charge along the polymer chain. Depending upon the charge, these polymers are anionic or cationic. The inherent solid - liquid separating efficiency makes these poly electrolytes a unique class of polymers which find extensive application in potable water, industrial raw and process water, municipal sewage treatment, mineral processing and metallurgy, oil drilling and recovery, etc. Also, due to their ability to produce advanced induced coagulation, a considerable amount of bacteria and viruses are precipitated together with the suspended solids. Especially the acrylamide polymers are very efficacious for water treatment but acrylamide is a toxic monomer and therefore their use are governed by international standards that provide the residual acrylamide monomer content (RAMC) in them be less than 0.05%. Under these circumstances our attention was focused on the following research steps that are presented in this paper: 1) Preparation of a special class of poly electrolytes, named Pn, with very low RAMC values, based on electron beam (EB), microwave (MW) and EB + MW induced co-polymerization of aqueous solutions containing appropriate mixtures of acrylamide (AMD) and acrylic acid (AA) monomers (AMD - AA co-polymers). The Pn were obtained by radiation technology with very small RAMC (under 0.01%) as well as in a wide range of molecular weights and charge densities. Very low AMD monomer content of Pn is due to the major advantages of radiation induced polymerization in aqueous solution containing monomers. Due to water presence in the EB irradiated system, irradiated water radicals facilitate the polymerization process and increase rate and level of monomers conversion in co-polymers. Also, once again, by the presence of water, which absorbs MW energy very strongly, the MW polymerization reaction rate is much enhanced resulting in a reaction time about 50-100 times lowers than by conventional heating. Also

Elektroaktive polymerer

DEFF Research Database (Denmark)

West, K.

Traditionelt tænker vi på polymerer (plastik) som elektrisk isolerende materialer - det som er udenpå ledningerne. I dag kender vi imidlertid også polymerer med intrinsisk elektrisk ledningsevne, og plast er på vej ind i anvendelser, der tidligereudelukkende var baseret på metaller og uorganiske...... halvledere. Hertil kommer, at en del af de ledende polymerer kan stimuleres til at skifte mellem en ledende og en halvledende tilstand, hvorved de ændret både form og farve. I foredraget gives der enrække eksempler på anvendelse af polymerer som elektriske komponenter - rækkende fra polymer elektronik over...

Tooth color change caused by photosensitizers after photodynamic therapy: An in vitro study.

Science.gov (United States)

Costa, Larissa Menezes; Matos, Felipe de Souza; Correia, Ayla Macyelle de Oliveira; Carvalho, Nayane Chagas; Faria-E-Silva, André Luís; Paranhos, Luiz Renato; Ribeiro, Maria Amália Gonzaga

2016-07-01

This study aimed to perform an in vitro evaluation of the effect of photosensitizers used in photodynamic therapy (PDT) on tooth color change when used in combination with conventional endodontic treatment. Forty extracted human mandibular premolars were accessed and underwent root canal therapy and PDT. Photosensitizers were used in accordance with the experimental groups: MB (n=10) - PDT with Methylene Blue at 0.01%; TB (n=10) - PDT with Toluidine Blue at 0.01%; MG (n=10) - PDT with Malachite Green at 0.01%, at the concentration of 0.1mg/mL; and PC (n=10) - positive control, PDT with Endo-PTC cream stained with Methylene Blue at 25%. The samples were irradiated with 660-nm diode laser by means of a 330-μm-diameter optical fiber cable at a power density of 40mW for 120s. After light curing, the photosensitizers were removed from the specimens with 10mL sodium hypochlorite at 1%. A reflectance spectrometer was used for evaluation of color prior to and 60days after the experimental procedure based on the CIE L*a*b* system. According to ANOVA test, there were statistically significant differences between the experimental groups (p=0.003). Tukey's test showed a significant difference between PC and TB (p=0.008), as well as between MG and TB (p=0.009). However, there was no statistically significant difference between PC, MG (p=0.957) and MB (p=0.103). It was concluded that the use of PDT as an adjuvant to root canal therapy, using different photosensitizers, led to color change in tooth structure. Copyright © 2016 Elsevier B.V. All rights reserved.

UV causation of melanoma in Xiphophorus is dominated by melanin photosensitized oxidant production

Science.gov (United States)

Wood, Simon R.; Berwick, Marianne; Ley, Ronald D.; Walter, Ronald B.; Setlow, Richard B.; Timmins, Graham S.

2006-01-01

Controversy continues both as to which wavelengths of sunlight cause melanoma and the mechanisms by which these different wavelengths act. Direct absorption of UVB by DNA is central in albino animal models, but melanin-pigmented models have shown major contributions by wavelengths longer than UVB that are thought to be mediated by photosensitized oxidant production. The only model for which the action spectrum of melanoma causation is known is a genetically melanoma-susceptible specific cross of Xiphophorus fish. We used electron paramagnetic resonance to quantitatively detect the UV induction of reactive melanin radicals in situ in the melanin-containing cells in the skin of this model and derived the action spectrum for melanin-photosensitized oxidant production (Φox). This action spectrum was identical to that for melanoma induction (Φmel). These results confirm the hypothesis that melanin-photosensitized radical production is the major causative step of melanoma in this model and demonstrate that the wavelengths and mechanisms of melanoma causation in different models are dependent on the presence of melanin. This approach should be applicable to humans, thus providing an accurate surrogate for Φmel for prevention studies. PMID:16537493

Area-selective atomic layer deposition of platinum using photosensitive polyimide

NARCIS (Netherlands)

Vervuurt, R.H.J.; Sharma, A.; Jiao, Y.; Kessels, W.M.M.; Bol, A.A.

2016-01-01

Area-selective atomic layer deposition (AS-ALD) of platinum (Pt) was studied using photosensitive polyimide as a masking layer. The polyimide films were prepared by spin-coating and patterned using photolithography. AS-ALD of Pt using poly(methyl-methacrylate) (PMMA) masking layers was used as a

Lower lip squamous cell carcinoma in patients with photosensitive disorders: Analysis of cases treated at the Brazilian National Cancer Institute (INCA) from 1999 to 2012.

Science.gov (United States)

Borges, J-F-P; Lanaro, N-D; Bernardo, V-G; Albano, R-M; Dias, F; de Faria, P-A-S; Pinto, L-F-R; Lourenço, S-Q-C

2018-01-01

Lower lip squamous cell carcinoma (LLSCC) is a common malignancy of the head and neck, being mainly a consequence of a chronic exposure to ultraviolet (UV) light solar radiation. Here, we evaluated the clinicopathological profile of patients with photosensitive disorders (xeroderma pigmentosum, lupus erythematosus and albinism) that developed LLSCC. Data from patients who had a diagnosed LLSCC with a prior xeroderma pigmentosum, lupus erythematosus or albinism diagnosis that were treated at INCA from 1999 to 2012 were collected from patients medical records (n=16). The control group was composed of 68 patients with LLSCC without a medical history of photosensitivity. The clinicopathological data of this study population were collected and the association between these variables was analyzed by Fisher's exact test. Survival curves were constructed using the Kaplan-Meier method and compared by log-rank test. All statistical analyses were performed using SPSS statistics package. The mean age of patients in the photosensitive and non-photosensitive groups was 42 years and 67 years, respectively (p<0.0001). A previous history of malignant diseases was more common in the photosensitive group (p=0.001). In both groups, most tumors showed a pathological stage I/II disease. Overall and cancer-specific survival were not statistically different. However, disease-free interval showed a significant difference (p=0.01) between the photosensitive and non-photosensitive patients. Photosensitive patients presented LLSCC at earlier age but it usually was not the primary tumor in these patients. Furthermore, a more aggressive pathological behavior was not seen when compared with tumors from non-photosensitive patients. The disease-free interval was lower in photosensitive patients, as expected.

EGFR targeted nanobody-photosensitizer conjugates for photodynamic therapy in a pre-clinical model of head and neck cancer.

Science.gov (United States)

van Driel, Pieter B A A; Boonstra, Martin C; Slooter, Maxime D; Heukers, Raimond; Stammes, Marieke A; Snoeks, Thomas J A; de Bruijn, Henriette S; van Diest, Paul J; Vahrmeijer, Alexander L; van Bergen En Henegouwen, Paul M P; van de Velde, Cornelis J H; Löwik, Clemens W G M; Robinson, Dominic J; Oliveira, Sabrina

2016-05-10

Photodynamic therapy (PDT) induces cell death through local light activation of a photosensitizer (PS) and has been used to treat head and neck cancers. Yet, common PS lack tumor specificity, which leads to collateral damage to normal tissues. Targeted delivery of PS via antibodies has pre-clinically improved tumor selectivity. However, antibodies have long half-lives and relatively poor tissue penetration, which could limit therapeutic efficacy and lead to long photosensitivity. Here, in this feasibility study, we evaluate at the pre-clinical level a recently introduced format of targeted PDT, which employs nanobodies as targeting agents and a water-soluble PS (IRDye700DX) that is traceable through optical imaging. In vitro, the PS solely binds to cells and induces phototoxicity on cells overexpressing the epidermal growth factor receptor (EGFR), when conjugated to the EGFR targeted nanobodies. To investigate whether this new format of targeted PDT is capable of inducing selective tumor cell death in vivo, PDT was applied on an orthotopic mouse tumor model with illumination at 1h post-injection of the nanobody-PS conjugates, as selected from quantitative fluorescence spectroscopy measurements. In parallel, and as a reference, PDT was applied with an antibody-PS conjugate, with illumination performed 24h post-injection. Importantly, EGFR targeted nanobody-PS conjugates led to extensive tumor necrosis (approx. 90%) and almost no toxicity in healthy tissues, as observed through histology 24h after PDT. Overall, results show that these EGFR targeted nanobody-PS conjugates are selective and able to induce tumor cell death in vivo. Additional studies are now needed to assess the full potential of this approach to improving PDT. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

The water soluble composite poly(vinylpyrrolidone–methylaniline: A new class of corrosion inhibitors of mild steel in hydrochloric acid media

Directory of Open Access Journals (Sweden)

R. Karthikaiselvi

2017-02-01

Full Text Available In recent years poly methyl aniline has been reported as one of the efficient corrosion inhibitors of mild steel in acidic media. In view of the major limitation of the insolubility of polymethyl aniline PMA, we propose to convert PMA into a water soluble composite using supporting polymer polyvinylpyrrolidone to get higher solubility and corrosion inhibition efficiency. The water soluble composite poly(vinylpyrrolidone-methyl aniline was synthesized by chemical oxidative polymerization and its inhibitive effect on mild steel in 1 M HCl has been investigated using weight loss and electrochemical techniques (potentiodynamic polarization studies and impedance spectroscopy. SEM and EDX analyses are carried out to establish a protective film formation on the metal surface.

Characterization of nanostructured photosensitive cadmium sulphide thin films grown by SILAR deposition technique

International Nuclear Information System (INIS)

Ubale, A.U.; Bargal, A.N.

2010-01-01

This paper reports the preparation of photosensitive nanostructured CdS thin films by successive ionic layer adsorption and reaction (SILAR) method at room temperature. To obtain good quality CdS thin films, preparative conditions such as concentration of cationic and anionic precursors, adsorption and rinsing time durations etc. are optimized. The structural, optical and electrical characterizations of the as-deposited and annealed CdS thin films were carried out using X-ray diffraction, scanning electron microscopy, optical absorption and electrical resistivity methods. The photoconductivity studies showed that the annealed films are more than that photosensitive. The TEP measurement shows that deposited films are of n-type. (author)

A Versatile Approach to Unimolecular Water-Soluble Carriers: ATRP of PEGMA with Hydrophobic Star-Shaped Polymeric Core Molecules as an Alternative for PEGylation

NARCIS (Netherlands)

Schramm, O.G.; Pavlov, G.M.; Erp, van H.H.P; Meier, M.A.R.; Hoogenboom, R.; Schubert, U.S.

2009-01-01

New amphiphilic star-shaped architectures with dense hydrophilic shells were synthesized by a combination of ring-opening polymerization (ROP) of e-caprolactone (CL) and atom transfer radical polymerization (ATRP) of different poly(ethylene glycol) methacrylates (PEGMAs). The PCL hydrophobic cores

Living Polymerization of N -Substituted β-Alanine N -Carboxyanhydrides: Kinetic Investigations and Preparation of an Amphiphilic Block Copoly-β-Peptoid

KAUST Repository

Grossmann, Arlett

2012-07-03

Poly(α-peptoid)s (N-substituted polyglycines) are interesting peptidomimetic biomaterials that have been discussed for many applications. Poly(β-peptoid)s (N-substituted poly-β-alanines), although equally intriguing, have received much less attention. Here we present results that suggest that while N-substituted β-alanine N-carboxyanhydrides can undergo a living nucleophilic ring-opening polymerization, the solubility of poly(β-peptoid)s can be very poor, which contributes to the limited accessibility using other synthetic approaches. The living character of the polymerization was utilized for the preparation of the first polymerized amphiphilic block copoly-β-peptoid. Our results may open a new route towards highly defined functional poly(β-peptoid)s which could represent biomaterials. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aqueous dispersion polymerization: a new paradigm for in situ block copolymer self-assembly in concentrated solution.

Science.gov (United States)

Sugihara, Shinji; Blanazs, Adam; Armes, Steven P; Ryan, Anthony J; Lewis, Andrew L

2011-10-05

Reversible addition-fragmentation chain transfer polymerization has been utilized to polymerize 2-hydroxypropyl methacrylate (HPMA) using a water-soluble macromolecular chain transfer agent based on poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC). A detailed phase diagram has been elucidated for this aqueous dispersion polymerization formulation that reliably predicts the precise block compositions associated with well-defined particle morphologies (i.e., pure phases). Unlike the ad hoc approaches described in the literature, this strategy enables the facile, efficient, and reproducible preparation of diblock copolymer spheres, worms, or vesicles directly in concentrated aqueous solution. Chain extension of the highly hydrated zwitterionic PMPC block with HPMA in water at 70 °C produces a hydrophobic poly(2-hydroxypropyl methacrylate) (PHPMA) block, which drives in situ self-assembly to form well-defined diblock copolymer spheres, worms, or vesicles. The final particle morphology obtained at full monomer conversion is dictated by (i) the target degree of polymerization of the PHPMA block and (ii) the total solids concentration at which the HPMA polymerization is conducted. Moreover, if the targeted diblock copolymer composition corresponds to vesicle phase space at full monomer conversion, the in situ particle morphology evolves from spheres to worms to vesicles during the in situ polymerization of HPMA. In the case of PMPC(25)-PHPMA(400) particles, this systematic approach allows the direct, reproducible, and highly efficient preparation of either block copolymer vesicles at up to 25% solids or well-defined worms at 16-25% solids in aqueous solution.

Polymeric micelles for ocular drug delivery: From structural frameworks to recent preclinical studies.

Science.gov (United States)

Mandal, Abhirup; Bisht, Rohit; Rupenthal, Ilva D; Mitra, Ashim K

2017-02-28

Effective intraocular drug delivery poses a major challenge due to the presence of various elimination mechanisms and physiological barriers that result in low ocular bioavailability after topical application. Over the past decades, polymeric micelles have emerged as one of the most promising drug delivery platforms for the management of ocular diseases affecting the anterior (dry eye syndrome) and posterior (age-related macular degeneration, diabetic retinopathy and glaucoma) segments of the eye. Promising preclinical efficacy results from both in-vitro and in-vivo animal studies have led to their steady progression through clinical trials. The mucoadhesive nature of these polymeric micelles results in enhanced contact with the ocular surface while their small size allows better tissue penetration. Most importantly, being highly water soluble, these polymeric micelles generate clear aqueous solutions which allows easy application in the form of eye drops without any vision interference. Enhanced stability, larger cargo capacity, non-toxicity, ease of surface modification and controlled drug release are additional advantages with polymeric micelles. Finally, simple and cost effective fabrication techniques render their industrial acceptance relatively high. This review summarizes structural frameworks, methods of preparation, physicochemical properties, patented inventions and recent advances of these micelles as effective carriers for ocular drug delivery highlighting their performance in preclinical studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Photosensitivity and double vision as initial symptoms of colon cancer

DEFF Research Database (Denmark)

Rasmussen, René; Laursen, Christian Borbjerg; Graumann, Ole

2015-01-01

A 75-year-old man suffering from rheumatoid arthritis, myxoedema and type II diabetes mellitus, presented with occasional double vision and photosensitivity. The patient underwent an MRI of the brain showing a tumour located in the right of the sphenoid bone. A subsequent diagnostic CT scan of th...

Roles of N-glycans in the polymerization-dependent aggregation of mutant Ig-μ chains in the early secretory pathway.

Science.gov (United States)

Giannone, Chiara; Fagioli, Claudio; Valetti, Caterina; Sitia, Roberto; Anelli, Tiziana

2017-02-03

The polymeric structure of secretory IgM allows efficient antigen binding and complement fixation. The available structural models place the N-glycans bound to asparagines 402 and 563 of Ig-μ chains within a densely packed core of native IgM. These glycans are found in the high mannose state also in secreted IgM, suggesting that polymerization hinders them to Golgi processing enzymes. Their absence alters polymerization. Here we investigate their role following the fate of aggregation-prone mutant μ chains lacking the Cμ1 domain (μ∆). Our data reveal that μ∆ lacking 563 glycans (μ∆5) form larger intracellular aggregates than μ∆ and are not secreted. Like μ∆, they sequester ERGIC-53, a lectin previously shown to promote polymerization. In contrast, μ∆ lacking 402 glycans (μ∆4) remain detergent soluble and accumulate in the ER, as does a double mutant devoid of both (μ∆4-5). These results suggest that the two C-terminal Ig-μ glycans shape the polymerization-dependent aggregation by engaging lectins and acting as spacers in the alignment of individual IgM subunits in native polymers.

Self assembling nanocomposites for protein delivery: supramolecular interactions of soluble polymers with protein drugs.

Science.gov (United States)

Salmaso, Stefano; Caliceti, Paolo

2013-01-02

Translation of therapeutic proteins to pharmaceutical products is often encumbered by their inadequate physicochemical and biopharmaceutical properties, namely low stability and poor bioavailability. Over the last decades, several academic and industrial research programs have been focused on development of biocompatible polymers to produce appropriate formulations that provide for enhanced therapeutic performance. According to their physicochemical properties, polymers have been exploited to obtain a variety of formulations including biodegradable microparticles, 3-dimensional hydrogels, bioconjugates and soluble nanocomposites. Several soluble polymers bearing charges or hydrophobic moieties along the macromolecular backbone have been found to physically associate with proteins to form soluble nanocomplexes. Physical complexation is deemed a valuable alternative tool to the chemical bioconjugation. Soluble protein/polymer nanocomplexes formed by physical specific or unspecific interactions have been found in fact to possess peculiar physicochemical, and biopharmaceutical properties. Accordingly, soluble polymeric systems have been developed to increase the protein stability, enhance the bioavailability, promote the absorption across the biological barriers, and prolong the protein residence in the bloodstream. Furthermore, a few polymers have been found to favour the protein internalisation into cells or boost their immunogenic potential by acting as immunoadjuvant in vaccination protocols. Copyright © 2011 Elsevier B.V. All rights reserved.

Tamoxifen-loaded polymeric micelles: preparation, physico-chemical characterization and in vitro evaluation studies.

Science.gov (United States)

Cavallaro, Gennara; Maniscalco, Laura; Licciardi, Mariano; Giammona, Gaetano

2004-11-20

Several samples of polymeric micelles, formed by amphiphilic derivatives of PHEA, obtained by grafting into polymeric backbone of PEGs and/or hexadecylamine groups (PHEA-PEG-C(16) and PHEA-C(16)) and containing different amount of Tamoxifen, were prepared. All Tamoxifen-loaded polymeric micelles showed to increase drug water solubility. TEM studies provided evidence of the formation of supramolecular core/shell architectures containing drug, in the nanoscopic range and with spherical shape. Samples with different amount of encapsulated Tamoxifen were subjected to in vitro cytotoxic studies in order to evaluate the effect of Tamoxifen micellization on cell growth inhibition. All samples of Tamoxifen-loaded polymeric micelles showed a significantly higher antiproliferative activity in comparison with free drug, probably attributable to fluidification of cellular membranes, caused by amphiphilic copolymers, that allows a higher penetration of the drug into tumoral cells. To gain preliminary information about the potential use of prepared micelles as Tamoxifen drug delivery systems, studies evaluating drug release ability of micelle systems in media mimicking biological fluids (buffer solutions at pH 7.4 and 5.5) and in human plasma were carried out. These studies, performed evaluating the amount of Tamoxifen that remains in solution as a function of time, showed that at pH 7.4, as well as in plasma, PHEA-C(16) polymeric micelles were able to release lower drug amounts than PHEA-PEG(5000)-C(16) ones, while at pH 5.5, the behavior difference between two kind of micelles was less pronounced.

Synthesis of highly reactive polyisobutylene catalyzed by EtAlCl 2/Bis(2-chloroethyl) ether soluble complex in hexanes

KAUST Repository

Kumar, Rajeev Ananda; Zheng, Bin; Huang, Kuo-Wei; Emert, Jack I.; Faust, Rudolf

2014-01-01

The polymerization of isobutylene (IB) to yield highly reactive polyisobutylene (HR PIB) with high exo-olefin content using GaCl3 or FeCl3·diisopropyl ether complexes has been previously reported.1 In an effort to further improve polymerization rates and exo-olefin content, we have studied ethylaluminum dichloride (EADC) complexes with diisopropyl ether, 2-chloroethyl ethyl ether (CEEE), and bis(2-chloroethyl) ether (CEE) as catalysts in conjunction with tert-butyl chloride as initiator in hexanes at different temperatures. All three complexes were readily soluble in hexanes. Polymerization, however, was only observed with CEE. At 0 °C polymerization was complete in 5 min at [t-BuCl] = [EADC·CEE] = 10 mM and resulted in PIB with ∼70% exo-olefin content. Studies on complexation using ATR FTIR and 1H NMR spectroscopy revealed that at 1:1 stoichiometry a small amount of EADC remains uncomplexed. By employing an excess of CEE, exo-olefin contents increased up to 90%, while polymerization rates decreased only slightly. With decreasing temperature, polymerization rates decreased while molecular weights as well as exo-olefin contents increased, suggesting that isomerization has a higher activation energy than β-proton abstraction. Density functional theory (DFT) studies on the Lewis acid·ether binding energies indicated a trend consistent with the polymerization results. The polymerization mechanism proposed previously for Lewis acid·ether complexes1 adequately explains all the findings. © 2014 American Chemical Society.

Synthesis of highly reactive polyisobutylene catalyzed by EtAlCl 2/Bis(2-chloroethyl) ether soluble complex in hexanes

KAUST Repository

Kumar, Rajeev Ananda

2014-03-25

The polymerization of isobutylene (IB) to yield highly reactive polyisobutylene (HR PIB) with high exo-olefin content using GaCl3 or FeCl3·diisopropyl ether complexes has been previously reported.1 In an effort to further improve polymerization rates and exo-olefin content, we have studied ethylaluminum dichloride (EADC) complexes with diisopropyl ether, 2-chloroethyl ethyl ether (CEEE), and bis(2-chloroethyl) ether (CEE) as catalysts in conjunction with tert-butyl chloride as initiator in hexanes at different temperatures. All three complexes were readily soluble in hexanes. Polymerization, however, was only observed with CEE. At 0 °C polymerization was complete in 5 min at [t-BuCl] = [EADC·CEE] = 10 mM and resulted in PIB with ∼70% exo-olefin content. Studies on complexation using ATR FTIR and 1H NMR spectroscopy revealed that at 1:1 stoichiometry a small amount of EADC remains uncomplexed. By employing an excess of CEE, exo-olefin contents increased up to 90%, while polymerization rates decreased only slightly. With decreasing temperature, polymerization rates decreased while molecular weights as well as exo-olefin contents increased, suggesting that isomerization has a higher activation energy than β-proton abstraction. Density functional theory (DFT) studies on the Lewis acid·ether binding energies indicated a trend consistent with the polymerization results. The polymerization mechanism proposed previously for Lewis acid·ether complexes1 adequately explains all the findings. © 2014 American Chemical Society.

Boric acid solubility in the presence of alkali metal nitrides

Energy Technology Data Exchange (ETDEWEB)

Skvortsov, V G; Tsekhanskij, R S; Molodkin, A K; Sadetdinov, Sh V [Chuvashskij Gosudarstvennyj Univ., Cheboksary (USSR); Universitet Druzhby Narodov, Moscow (USSR))

1983-01-01

Methods of solubility and refractometry at 25 deg C have been applied to state that systems boric acid-lithium (sodium, potassium) nitrite-water are simple eutonic type systems. Nitrites salt in the acid and their lyotropic effect increases from lithium salt to potassium salt. The disclosed succession in change of the effect is determined by the character of cation hydration in the medium the acidic reaction of which is conditioned by boric acid polymerization and partial oxidation of nitrite ion into nitrate ion. Boric acid is salted out from solutions containing lithium and sodium cations with increase of nitrate ion.

Boric acid solubility in the presence of alkali metal nitrides

International Nuclear Information System (INIS)

Skvortsov, V.G.; Tsekhanskij, R.S.; Molodkin, A.K.; Sadetdinov, Sh.V.

1983-01-01

Methods of solubility and refractometry at 25 deg C have been applied to state that systems boric acid-lithium (sodiUm, potassium) nitrite-water are simple eutonic type systems. Nitrites salt in the acid and their lyotropic effect increases from lithium salt to potassium salt. The disclosed succession in change of the effect is determined by the character of cation hydration in the medium the acidic reaction of which is conditioned by boric acid polymerization and partial oxidation of nitrite ion into nitrate ion Boric acid is salted out form solutions containing lithium and sodium cations with increase of nitrate ion

Immobilization and controlled release of drug using plasma polymerized thin film

Energy Technology Data Exchange (ETDEWEB)

Myung, Sung-Woon [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of); Jung, Sang-Chul [Department of Environmental Engineering, Sunchon National University, Sunchon 540-742 (Korea, Republic of); Kim, Byung-Hoon, E-mail: kim5055@chosun.ac.kr [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of)

2015-06-01

In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release.

Immobilization and controlled release of drug using plasma polymerized thin film

International Nuclear Information System (INIS)

Myung, Sung-Woon; Jung, Sang-Chul; Kim, Byung-Hoon

2015-01-01

In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release

Hydrolysis of fish protein by Bacillus megaterium cells immobilized in radiation induced polymerized wood

International Nuclear Information System (INIS)

Ghosh, S.; Alur, M.D.; Nerkar, D.P.

1992-01-01

The immobilization of Bacillus megaterium cells in radiation-induced polymerized wood was studied for hydrolysis of trash fish protein. The optimum conditions and reaction kinetics for hydrolysis of protein by free and immobilized cells were found to be similar. Maximum hydrolysis occurred at 50 o C and at pH 7.5 with 15-20% (w/v) of immobilized matrix. The soluble content of the resultant hydrolysate about 2.4% (w/v). (author). 10 refs., 4 figs

Visible-Light-Induced Nickel-Catalyzed Negishi Cross-Couplings by Exogenous-Photosensitizer-Free Photocatalysis.

Science.gov (United States)

Abdiaj, Irini; Fontana, Alberto; Gomez, M Victoria; de la Hoz, Antonio; Alcázar, Jesús

2018-03-22

The merging of photoredox and transition-metal catalysis has become one of the most attractive approaches for carbon-carbon bond formation. Such reactions require the use of two organo-transition-metal species, one of which acts as a photosensitizer and the other one as a cross-coupling catalyst. We report herein an exogenous-photosensitizer-free photocatalytic process for the formation of carbon-carbon bonds by direct acceleration of the well-known nickel-catalyzed Negishi cross-coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross-coupling chemistry that involve the direct visible-light absorption of organometallic catalytic complexes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photosensitization of human diploid cell cultures by intracellular flavins and protection by antioxidants

International Nuclear Information System (INIS)

Pereira, O.M.; Smith, J.R.; Packer, L.

1976-01-01

The damaging effects of near ultraviolet and visible light on WI-38 human diploid lung fibroblasts were investigated. WI-38 cells in culture were killed by light doses ranging from 2 to 10 x 10 3 W/m 2 h. There was an inverse correlation between culture age, i.e. population doubling level and photosensitivity. However, this effect could not be related to capacity for DNA synthesis and cell division. Flavins were clearly implicated as endogenous photosensitizers, and antioxidants such as d,l-α-tocopherol (vitamin E), BHT and ascorbic acid were found to afford the cells protection from light damage. Furthermore, products of lipid peroxidation could be detected in cell homogenates irradiated in the presence of riboflavin. (author)

Effects of riboflavin photosensitization on the changes of isoflavones in soymilk.

Science.gov (United States)

Lee, S W; Chang, P-S; Lee, J H

2008-09-01

Effects of riboflavin photosensitization on the distribution of isoflavones in commercially available soymilk were analyzed using high-performance liquid chromatography (HPLC). Total isoflavones (TI) in soymilk with riboflavin (1000 ppm, w/v) under light were significantly different from those stored in the dark for 24 h (P riboflavin were not significant from each other in dark conditions (P > 0.05). To test the effects of the concentration of riboflavin on TI, soymilk was mixed with riboflavin to make 0, 100, 250, and 500 ppm (w/v) and stored under light at 25 degrees C for 24 h. TI in soymilk with 100 ppm riboflavin under light significantly decreased by 13.5% for 24 h (P 0.05). Daidzin and genistin were predominant isoflavones in soymilk, and the rate of photo degradation of genistin was higher than that of daidzin for 24 h in soymilk under riboflavin photosensitization.

Genotoxic evaluation of polymeric nanoparticles

Directory of Open Access Journals (Sweden)

Tamara Iglesias Alonso

2015-06-01

Full Text Available An important strategy for optimizing the therapeutic efficacy of many conventional drugs is the development of polymeric nanoparticles (NPs, as it may expand their activities, reduce their toxicity, increase their bioactivity and improve biodistribution. The main objective of this study was to evaluate the genotoxicity of 8 different poly (anhydride NPs designed for the oral administration of therapeutic compounds by using the comet assay in combination with the enzyme formamidopypiridine DNA-glycosylase (FPG. Furthermore, the mitogen capacity of the NPs was evaluated by the proliferation assay. All NPs were tested at four concentrations (0, 0.5, 1 and 2 mg/mL in Caco-2 cells after 3 hours of treatment while selected NPs were also tested after 24 h. The comet assay was performed immediately after the treatment and cell proliferation was assessed by counting the treated cells after their incubation at 37 °C for 48h. Cells treated with 1 µM of the photosensitizer Ro 19-8022 plus 5 min of light, as well as cells treated with 100 µM H2O2 were included as positive controls in all the experiments. All NPs studied did not result in any increase in the frequency of strand breaks or alkali-labile sites in Caco-2 cells but they induced a slight concentration-dependent increase in net FPG sensitive sites (oxidized and/or alkylated bases. Furthermore, treated cells did not show changes in levels of proliferation in comparison with the negative control.

Poly(glycolide multi-arm star polymers: Improved solubility via limited arm length

Directory of Open Access Journals (Sweden)

Florian K. Wolf

2010-06-01

Full Text Available Due to the low solubility of poly(glycolic acid (PGA, its use is generally limited to the synthesis of random copolyesters with other hydroxy acids, such as lactic acid, or to applications that permit direct processing from the polymer melt. Insolubility is generally observed for PGA when the degree of polymerization exceeds 20. Here we present a strategy that allows the preparation of PGA-based multi-arm structures which significantly exceed the molecular weight of processable oligomeric linear PGA (<1000 g/mol. This was achieved by the use of a multifunctional hyperbranched polyglycerol (PG macroinitiator and the tin(II-2-ethylhexanoate catalyzed ring-opening polymerization of glycolide in the melt. With this strategy it is possible to combine high molecular weight with good molecular weight control (up to 16,000 g/mol, PDI = 1.4–1.7, resulting in PGA multi-arm star block copolymers containing more than 90 wt % GA. The successful linkage of PGA arms and PG core via this core first/grafting from strategy was confirmed by detailed NMR and SEC characterization. Various PG/glycolide ratios were employed to vary the length of the PGA arms. Besides fluorinated solvents, the materials were soluble in DMF and DMSO up to an average arm length of 12 glycolic acid units. Reduction in the Tg and the melting temperature compared to the homopolymer PGA should lead to simplified processing conditions. The findings contribute to broadening the range of biomedical applications of PGA.

Sunlight exposure behaviour and vitamin D status in photosensitive patients: longitudinal comparative study with healthy individuals at U.K. latitude.

Science.gov (United States)

Rhodes, L E; Webb, A R; Berry, J L; Felton, S J; Marjanovic, E J; Wilkinson, J D; Vail, A; Kift, R

2014-12-01

Low vitamin D status is prevalent in wintertime in populations at northerly latitudes. Photosensitive patients are advised to practise sun avoidance, but their sunlight exposure levels, photoprotective measures and resulting vitamin D status are unknown. To examine seasonal vitamin D status in photosensitive patients relative to healthy individuals and to assess quantitatively behavioural and demographic contributors. This was a longitudinal prospective cohort study (53·5°N) examining year-round 25-hydroxyvitamin D [25(OH)D] levels, sun-exposure behaviour and oral vitamin D intake in photosensitive patients diagnosed at a photoinvestigation unit (n = 53), compared with concurrently assessed healthy adults (n = 109). Photosensitive patients achieved seasonal 25(OH)D variation, but insufficient (vitamin D intake was low in both groups (photosensitive: 2·94 μg per day). Supplementation and summer surface area exposure predicted summer peak and winter trough 25(OH)D levels. A 1 μg per day increment in supplementary vitamin D raised summer and winter 25(OH)D by 5% (95% CI 3-7) and 9% (95% CI 5-12), respectively (both P vitamin D status. Guidance on oral measures should target this patient group and their physicians. © 2014 British Association of Dermatologists.

Controlled porosity solubility modulated osmotic pump tablets of gliclazide.

Science.gov (United States)

Banerjee, Arti; Verma, P R P; Gore, Subhash

2015-06-01

A system that can deliver drug at a controlled rate is very important for the treatment of various chronic diseases such as diabetes, asthma, and heart disease. Poorly water-soluble drug with pH-dependent solubility such as gliclazide (GLZ) offers challenges in the controlled-release formulation because of low dissolution rate and poor bioavailability. Solid dispersion (SD) of GLZ consisted of hydroxypropyl cellulose (HPC-SSL) as a polymeric solubilizer was manufactured by hot melt extrusion (HME) technology. Then, controlled porosity osmotic pump (CPOP) tablet of gliclazide was designed to deliver drug in a controlled manner up to 16 h. The developed formulation was optimized for type and level of pore former and coating weight gain. The optimized formulation was found to exhibit zero order kinetics independent of pH and agitation speed but depends on osmotic pressure of dissolution media indicated that mechanism of drug release was osmotic pressure. The in vivo performance prediction of developed formulation using convolution approach revealed that the developed formulation was superior to the existing marketed extended-release formulation in terms of attaining steady state plasma levels and indicated adequate exposure in translating hypoglycemic response. The prototype solubilization method combined with controlled porosity osmotic pump based technique could provide a unique way to increase dissolution rate and bioavailability of many poorly water-soluble, narrow therapeutic index drugs used in diabetes, cardiovascular diseases, etc.

Electrospun photosensitive nanofibers: potential for photocurrent therapy in skin regeneration.

Science.gov (United States)

Jin, Guorui; Prabhakaran, Molamma P; Kai, Dan; Kotaki, Masaya; Ramakrishna, Seeram

2013-01-01

Poly(3-hexylthiophene) (P3HT) is one of the most promising photovoltaic (PV) polymers in photocurrent therapy. A novel photosensitive scaffold for skin tissue engineering was fabricated by blending P3HT with polycaprolactone (PCL) and electrospun to obtain composite PCL/P3HT nanofibers with three different weight ratios of PCL : P3HT (w/w) of 150 : 2 [PCL/P3HT(2)], 150 : 10 [PCL/P3HT(10)] and 150 : 20 [PCL/P3HT(20)]. The photosensitive properties of the blend solutions and the composite nanofibers of PCL/P3HT were investigated. The incident photon-to-electron conversion efficiencies of the PCL/P3HT(2), PCL/P3HT(10), PCL/P3HT(20) were identified as 2.0 × 10(-6), 1.6 × 10(-5) and 2.9 × 10(-5), respectively, which confirm the photosensitive ability of the P3HT-containing scaffolds. The biocompatibility of the scaffold was evaluated by culturing human dermal fibroblasts and the results showed that the proliferation of HDFs under light stimulation on PCL/P3HT(10) was 12.8%, 11.9%, and 11.6% (p ≤ 0.05) higher than the cell growth on PCL, PCL/P3HT(2) and PCL/P3HT(20), respectively. Human dermal fibroblasts cultured under light stimulation on PCL/P3HT(10) not only showed better cell proliferation but also retained cell morphology similar to the phenotype observed on tissue culture plates (control). Our experimental results suggest novel and potential application of an optimized amount of P3HT-containing scaffold, especially PCL/P3HT(10) nanofibrous scaffold in photocurrent therapy for skin regeneration.

Suitable photo-resists for two-photon polymerization using femtosecond fiber lasers

KAUST Repository

Rajamanickam, V.P.

2014-06-01

We present suitable materials with good optical and mechanical properties, simple processing, efficient and optimized for two-photon polymerization (TPP) with femtosecond fiber lasers. We selected readily available acrylic monomer Bisphenol A ethoxylate diacrylate (BPA-EDA) with three different photo-initiators (PIs), isopropyl thioxanthone (ITX), 7-diethylamino-3-thenoylcoumarin (DETC), and 4,4′ bis(diethylamino) benzophenone (BDEB), since their absorption spectra match well with the laser wavelength at 780 nm. These PIs grant efficient radical generation, reactivity and high solubility in acrylic monomers. Finally, good optical and mechanical properties are demonstrated by the fabrication of different micro-structures.

Study on properties of UV-curable films based on alkali-soluble photosensitive polysiloxane urethane acrylate oligomer

International Nuclear Information System (INIS)

Sun Fang; Zhang Nan; Du Hongguang; Jiang Shengling

2011-01-01

A UV-curable alkali-soluble polysiloxane urethane acrylate (APSUA) for solder mask was designed and synthesized in this work. The effect of composition of APSUA on physical and mechanical properties of UV curing APSUA materials including water resistance, volume shrinkage, hardness, tensile strength, elongation and heat resistance, was investigated in this paper. The results showed that reactive monomers with hydroxyl bonding could increase water absorption of the APSUA. The water absorption of the APSUA decreased with increasing crosslinking yields. The volume shrinkage of the APSUA decreased with increasing APSUA concentrations in the system and the volume shrinkage of investigated APSUA was lower than 6%. Multi-functional monomer and acrylate monomer with rigid structure could improve hardness of APSUA. When functionality of reactive monomer increased the heat resistance of APSUA could enhanced. The APSUA possesses excellent compatibility with most of acrylate monomers. (authors)

Resveratrol immobilization and release in polymeric hydrogels

International Nuclear Information System (INIS)

Momesso, Roberta Grazzielli Ramos Alves Passarelli

2010-01-01

Resveratrol (3, 4', 5-trihydroxystilbene) is a polyphenolic produced by a wide variety of plants in response to injury and found predominantly in grape skins. This active ingredient has been shown to possess benefits for the health, such as the antioxidant capacity which is related to the prevention of several types of cancer and skin aging. However, the oral bioavailability of resveratrol is poor and makes its topical application interesting. The purpose of this study was to immobilize resveratrol in polymeric hydrogels to obtain a release device for topical use. The polymeric matrices composed of poli(N-vinyl-2-pyrrolidone) (PVP), poly(ethyleneglycol) (PEG) and agar or PVP and glycerol irradiated at 20 kGy dose were physical-chemically characterized by gel fraction and swelling tests and its preliminary biocompatibility by in vitro test of cytotoxicity using the technique of neutral red uptake. Due to low solubility of resveratrol in water, the addition of 2% ethanol to the matrices was verified. All matrices showed a high crosslinking degree, capacity of swelling and the preliminary cytotoxicity test showed nontoxicity effect. The devices were obtained by resveratrol immobilization in polymeric matrices, carried out in a one-or-two-steps process, that is, before or after irradiation, respectively. The one step resveratrol devices were characterized by gel fraction, swelling tests and preliminary biocompatibility, and their properties were maintained even after the resveratrol incorporation. The devices containing 0,05% of resveratrol obtained by one-step process and 0,1% of resveratrol obtained by two-steps process were submitted to the release test during 24 h. Resveratrol quantification was done by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that only the devices obtained by two-step process release the resveratrol, which demonstrate antioxidant capacity after the release. (author)

(Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes

NARCIS (Netherlands)

Wenczl, E.; Schans, G.P. van der; Roza, L.; Kolb, R.M.; Timmerman, A.J.; Smit, N.P.M.; Pavel, S.; Schothorst, A.A.

1998-01-01

The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by

Radiation chemistry of polymeric system

International Nuclear Information System (INIS)

Machi, Sueo; Ishigaki, Isao

1978-01-01

Among wide application of radiation in the field of polymer chemistry, practices of polymerization, graft polymerization, bridging, etc. are introduced hereinafter. As for the radiation sources of radiation polymerization, in addition to the 60 Co-γ ray with long permeation distance which has been usually applied, electron beam accelerators with high energy, large current and high reliability have come to be produced, and the liquid phase polymerization by electron beam has attracted attention industrially. Concerning polymerizing reactions, explanations were given to electron beam polymerization under high dose rate, the polymerization in supercooling state or under high pressure, and emulsifying polymerization. As for radiation bridging, radiation is applied for the bridging of hydrogel, acceleration of bridging and improvement of radiation resistance. It is also utilized for reforming membranes by graft polymerization, and synthesis of polymers for medical use. Application of fixed enzymes in the medical field has been investigated by fixing various enzymes by low temperature γ-ray polymerization with glassy monomers such as HEMA. (Kobatake, H.)

Fabrication and characterization of photosensitive n-ZnO/p-InSe heterojunctions

Energy Technology Data Exchange (ETDEWEB)

Kudrynskyi, Z., E-mail: kudrynskyi@gmail.com [Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Chernivtsi Branch, Str. I. Vilde 5, 58001 Chernivtsi (Ukraine); Khomyak, V. [Yuriy Fedkovich Chernivtsi National University, Str. Kotsubinsky 2, 58012 Chernivtsi (Ukraine); Katerynchuk, V.; Kovalyuk, M.; Netyaga, V.; Kushnir, B. [Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Chernivtsi Branch, Str. I. Vilde 5, 58001 Chernivtsi (Ukraine)

2015-05-01

Indium monochalcogenide (InSe) with a band gap of 1.25 eV is a promising material for photovoltaic applications. In this work, photosensitive anisotype n-ZnO/p-InSe heterojunctions were fabricated by means of radio-frequency magnetron sputtering of the zinc oxide onto freshly cleaved (0001) van der Waals surface of p-InSe single-crystal. Structural properties of the obtained heterostructures were investigated by means of X-ray diffraction. Surface morphology of the grown ZnO thin films was studied by means of atomic force microscopy. The electrical and photoelectrical properties of the heterojunctions were investigated using the current-voltage characteristics measured at different temperatures, capacitance-voltage characteristics and photoresponse spectra. The dominating current transport mechanisms through the heterojunctions under investigation were determined at forward and reverse biases. It was found that the developed heterojunctions n-ZnO/p-InSe show photosensitivity in the photon energy range (1.25-3.20 eV) at room temperature. In addition, we analyzed the influence of vacuum annealing of the heterojunctions at different temperatures on their photoelectric properties. - Highlights: • Thin ZnO films were grown onto van der Waals surface of InSe substrate. • n-ZnO/p-InSe heterojunctions were fabricated. • The heterojunctions are photosensitive in photon energy range from 1.12 to 3.75 eV. • Despite the lattice mismatch of 19% the heterojunctions exhibit diode-like behavior. • Vacuum annealing improves electrical properties of the heterojunctions.

A pH-responsive carboxylic β-1,3-glucan polysaccharide for complexation with polymeric guests.

Science.gov (United States)

Lien, Le Thi Ngoc; Shiraki, Tomohiro; Dawn, Arnab; Tsuchiya, Youichi; Tokunaga, Daisuke; Tamaru, Shun-ichi; Enomoto, Naoya; Hojo, Junichi; Shinkai, Seiji

2011-06-07

The helix-forming nature of β-1,3-glucan polysaccharides is a characteristic that has potential for producing gene carriers, bio-nanomaterials and other chiral nanowires. Herein, carboxylic curdlan (CurCOOH) bearing the β-1,3-polyglucuronic acid structure was successfully prepared from β-1,3-glucan polysaccharide curdlan (Cur) by one-step oxidation using a 4-acetamido-TEMPO/NaClO/NaClO(2) system as the oxidant. The resulting high-molecular-weight CurCOOH was proved to bear the 6-COOH group in 100% purity. The optical rotatory dispersion (ORD) spectra indicated that the obtained CurCOOH behaves as a water-soluble single-strand in various pH aqueous media. This advantage has allowed us to use CurCOOH as a polymeric host to form various macromolecular complexes. For example, complexation of CurCOOH with single-walled carbon nanotubes (SWNTs) resulted in a water-soluble one-dimensional architecture, which formed a dispersion in aqueous solution that was stable for several months, and much more stable than SWNTs complexes of the similar negatively-charged polyacrylic acid (PAA) and polymethacrylic acid (PMAA). It was shown that in the complex, SWNTs are effectively wrapped by a small amount of CurCOOH, enabling them to avoid electrostatic repulsion. This pH-responsive CurCOOH formed a very stable complex with cationic water-soluble polythiophenes (PT-1), which was stabilized not only by the hydrophobic interaction but also by the electrostatic attraction between trimethylammonium cations in PT-1 and dissociated anionic COO(-) groups in CurCOOH. The included PT-1 became CD-active only in the neutral to basic pH region, and the positive Cotton effect suggested that the conjugated main chain is twisted in the right-handed direction. We also found that CurCOOH can interact with polycytidylic acid (poly(C)) only under high NaCl concentrations, the binding and release of which could be controlled by a change in the salt concentration. We believe, therefore, that Cur

Melanin photosensitization and the effect of visible light on epithelial cells.

Directory of Open Access Journals (Sweden)

Orlando Chiarelli-Neto

Full Text Available Protecting human skin from sun exposure is a complex issue that involves unclear aspects of the interaction between light and tissue. A persistent misconception is that visible light is safe for the skin, although several lines of evidence suggest otherwise. Here, we show that visible light can damage melanocytes through melanin photosensitization and singlet oxygen (1O2 generation, thus decreasing cell viability, increasing membrane permeability, and causing both DNA photo-oxidation and necro-apoptotic cell death. UVA (355 nm and visible (532 nm light photosensitize 1O2 with similar yields, and pheomelanin is more efficient than eumelanin at generating 1O2 and resisting photobleaching. Although melanin can protect against the cellular damage induced by UVB, exposure to visible light leads to pre-mutagenic DNA lesions (i.e., Fpg- and Endo III-sensitive modifications; these DNA lesions may be mutagenic and may cause photoaging, as well as other health problems, such as skin cancer.

Azobenzene-containing LC polymethacrylates highly photosensitive in broad spectral range

Czech Academy of Sciences Publication Activity Database

Bobrovsky, A.; Shibaev, V.; Cigl, Martin; Hamplová, Věra; Pociecha, D.; Bubnov, Alexej

2016-01-01

Roč. 54, č. 18 (2016), s. 2962-2970 ISSN 0887-624X R&D Projects: GA ČR GA16-12150S; GA MŠk(CZ) LH15305 Institutional support: RVO:68378271 Keywords : liquid crystals * polymethacrylate * photosensitive * azo group * smectic A * photo-optical properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.952, year: 2016

Photosensitive N channel MOSFET device on silicon on sapphire substrate

International Nuclear Information System (INIS)

Le Goascoz, V.; Borel, J.

1975-01-01

An anomalous behavior of the N channel output current characteristic in a SOS MOSFET with a floating bulk is described. Such a phenomenon can be used in a photosensitive device with internal gain. Such devices can be used on SOS substrates to achieve integrated circuits with high insulating voltages and data transmission by optical means [fr

Polymerization of acrylamide initiated with Ce(IV- and KMnO4–mercaptosuccinic acid redox systems in acid-aqueous medium

Directory of Open Access Journals (Sweden)

2007-03-01

Full Text Available By using mercaptosuccinic acid-cerium(IV sulfate and mercaptosuccinic acid-KMnO4 redox systems in acid aqueous medium, the polymerization of acrylamide monomer was performed at room temperatures. Water soluble acrylamide polymers which contain mercaptosuccinic acid end-groups were synthesized. The dependence of polymerization yield and the molecular weight of polymer on the initiator concentration(nMSA=nCe(IV at different acid concentrations, polymerization time, temperature, and concentration of sulfuric acid was investigated. The decrease in the initiator concentration resulted in an increase in the molecular weights but a decrease in the yield. The increase of reaction temperature from 20 to 60°C resulted in an increase in the molecular weights and slight decrease of the yield of polymer. Cerium and manganese ions are reduced to Ce(III and Mn(II ions respectively in polymerization reaction. The existence of Ce(III ion bound to polymer was investigated by UV-visible spectrometry and fluorescence measurements. The amount of Mn(II which is incorporated to the polymer was determined.

Photoprocesses of photosensitizing drugs within cyclodextrin cavities.

Science.gov (United States)

Monti, Sandra; Sortino, Salvatore

2002-09-01

Recently some interest has been focused on the photobehavior of CD-drug inclusion complexes in relation to the problem of the biological photosensitization by drugs. This review is dedicated to the illustration of the mechanistic aspects of the photoprocesses occurring in some non-steroidal anti-inflammatory drugs (NSAIDs), with photosensitising side effects, within CD cavities. It is shown how the photobehavior of the CD-drug associates can help to model the photoreactivity of the drugs in biological sites. The limitations for the use of CDs as protective systems for the clinical administration of photosensitising drugs is also evidenced.

Phototherapeutic, photobiologic, and photosensitizing properties of khellin

International Nuclear Information System (INIS)

Morliere, P.; Hoenigsmann, H.A.; Averbeck, D.; Dardalhon, M.; Hueppe, G.O.; Ortel, B.; Santus, R.; Dubertret, L.

1988-01-01

Khellin, whose chemical structure closely resembles that of psoralen, is reported to be an efficient drug for treating vitiligo when combined with ultraviolet A irradiation. Photobiological activity on yeast is found to be much lower than that of bifunctional psoralens such as 5-methoxypsoralen. In vitro experiments reveal that khellin is a poor photosensitizer. It behaves as a monofunctional agent with respect to DNA photoaddition. It does not photoinduce cross-links in DNA in vitro or in Chinese hamster cells in vivo. This behavior may explain the low photogenotoxicity in yeast and the lack of phototoxic erythemal response when treating vitiligo with khellin

Oxidative Stability in Oil-in-Water Emulsions with Quercetin or Rutin Under Iron Catalysis or Riboflavin Photosensitization.

Science.gov (United States)

Yi, BoRa; Ka, HaeJung; Kwon, YongJun; Choi, HyungSeok; Kim, Sunghwa; Kim, Jisu; Kim, Mi-Ja; Lee, JaeHwan

2017-04-01

The effects of quercetin and rutin on the oxidative stability of oil-in-water (O/W) emulsions were tested under riboflavin (RF) photosensitization in the presence or absence of FeCl 2 . The degree of oxidation in O/W emulsions was determined by headspace oxygen content, conjugated dienes, and lipid hydroperoxides. Quercetin chelated more metal than did rutin in iron catalyzed O/W emulsions. Generally, 0.1 mM quercetin and rutin was oxidative while 0.5 and 1.0 mM quercetin and rutin was antioxidative in O/W emulsions under RF photosensitization. Depending on the analysis method, the antioxidants had different strengths. The antioxidative or oxidative properties of quercetin and rutin vary in O/W emulsions and depend the quercetin and rutin concentrations and oxidative forces like transition metals, RF photosensitization, or a combination thereof. © 2017 Institute of Food Technologists®.

Study of Photosensitive Dry Films Absorption for Printed Circuit Boards by Photoacoustic Technique

Science.gov (United States)

Hernández, R.; Zaragoza, J. A. Barrientos; Jiménez-Pérez, J. L.; Orea, A. Cruz; Correa-Pacheco, Z. N.

2017-08-01

In this work, the study of photosensitive dry-type films by photoacoustic technique is proposed. The dry film photoresist is resistant to chemical etching for printed circuit boards such as ferric chloride, sodium persulfate or ammonium, hydrochloric acid. It is capable of faithfully reproducing circuit pattern exposed to ultraviolet light (UV) through a negative. Once recorded, the uncured portion is removed with alkaline solution. It is possible to obtain good results in surface mount circuits with tracks of 5 mm. Furthermore, the solid resin films are formed by three layers, two protective layers and a UV-sensitive optical absorption layer in the range of 325 nm to 405 nm. By means of optical absorption of UV-visible rays emitted by a low-power Xe lamp, the films transform this energy into thermal waves generated by the absorption of optical radiation and subsequently no-radiative de-excitation occurs. The photoacoustic spectroscopy is a useful technique to measure the transmittance and absorption directly. In this study, the optical absorption spectra of the three layers of photosensitive dry-type films were obtained as a function of the wavelength, in order to have a knowledge of the absorber layer and the protective layers. These analyses will give us the physical properties of the photosensitive film, which are very important in curing the dry film for applications in printed circuit boards.

Twin screw extruders as polymerization reactors for a free radical homo polymerization

NARCIS (Netherlands)

Ganzeveld, K.J.; Janssen, L.P.B.M.

The bulk polymerization of n-butylmethacrylate was investigated in a counter-rotating twin screw extruder. It appeared that the gel effect, occurring with bulk polymerizations, affected the polymerization progress very strongly. Due to this effect the conversion of the reaction is independent of the

Exogenous indirect photoinactivation of bacterial pathogens and indicators in water with natural and synthetic photosensitizers in simulated sunlight with reduced UVB.

Science.gov (United States)

Maraccini, P A; Wenk, J; Boehm, A B

2016-08-01

To investigate the UVB-independent and exogenous indirect photoinactivation of eight human health-relevant bacterial species in the presence of photosensitizers. Eight bacterial species were exposed to simulated sunlight with greatly reduced UVB light intensity in the presence of three synthetic photosensitizers and two natural photosensitizers. Inactivation curves were fit with shoulder log-linear or first-order kinetic models, from which the presence of a shoulder and magnitude of inactivation rate constants were compared. Eighty-four percent reduction in the UVB light intensity roughly matched a 72-95% reduction in the overall bacterial photoinactivation rate constants in sensitizer-free water. With the UVB light mostly reduced, the exogenous indirect mechanism contribution was evident for most bacteria and photosensitizers tested, although most prominently with the Gram-positive bacteria. Results confirm the importance of UVB light in bacterial photoinactivation and, with the reduction of the UVB light intensity, that the Gram-positive bacteria are more vulnerable to the exogenous indirect mechanism than Gram-negative bacteria. UVB is the most important range of the sunlight spectrum for bacterial photoinactivation. In aquatic environments where photosensitizers are present and there is high UVB light attenuation, UVA and visible wavelengths can contribute to exogenous indirect photoinactivation. © 2016 The Society for Applied Microbiology.

Light-driven photosensitizer uptake increases Candida albicans photodynamic inactivation.

Science.gov (United States)

Romano, Renan A; Pratavieira, Sebastião; Silva, Ana P da; Kurachi, Cristina; Guimarães, Francisco E G

2017-11-01

Photodynamic Inactivation (PDI) is based on the use of a photosensitizer (PS) and light that results mainly in the production of reactive oxygen species, aiming to produce microorganism cell death. PS incubation time and light dose are key protocol parameters that influence PDI response; the correct choice of them can increase the efficiency of inactivation. The results of this study show that a minor change in the PDI protocol, namely light-driven incubation leads to a higher photosensitizer and more uniform cell uptake inside the irradiated zone. Furthermore, as the uptake increases, the damage caused by PDI also increases. The proposed light-driven incubation prior to the inactivation illumination dose has advantages when compared to the traditional PDI treatments since it can be more selective and effective. Using a violet light as pre-illumination (light-driven incubation) source and a red-light system as PDI source, it was possible to demonstrate that when compared to the traditional protocol of dark incubation, the pre-illuminated cell culture showed an inactivation increase of 7 log units. These in vitro results performed in Candida albicans cells may result in the introduction of a new protocol for PDI. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanocatalytic polymerization and cross-linking in a polymeric matrix

NARCIS (Netherlands)

Jakobs, R.T.M.; Ma, Shuang; Sijbesma, R.P.

2013-01-01

A latent olefin metathesis catalyst, bearing two polymeric NHC ligands, was embedded in a semicrystalline polymer matrix containing cyclic olefins. The catalyst was activated by straining the solid material under compression, resulting in polymerization and cross-linking reactions of the monomers in

Water-Soluble Pd8L4 Self-assembled Molecular Barrel as an Aqueous Carrier for Hydrophobic Curcumin.

Science.gov (United States)

Bhat, Imtiyaz Ahmad; Jain, Ruchi; Siddiqui, Mujahuddin M; Saini, Deepak K; Mukherjee, Partha Sarathi

2017-05-01

A tetrafacial water-soluble molecular barrel (1) was synthesized by coordination driven self-assembly of a symmetrical tetrapyridyl donor (L) with a cis-blocked 90° acceptor [cis-(en)Pd(NO 3 ) 2 ] (en = ethane-1,2-diamine). The open barrel structure of (1) was confirmed by single crystal X-ray diffraction. The presence of a hydrophobic cavity with large windows makes it an ideal candidate for encapsulation and carrying hydrophobic drug like curcumin in an aqueous medium. The barrel (1) encapsulates curcumin inside its molecular cavity and protects highly photosensitive curcumin from photodegradation. The photostability of encapsulated curcumin is due to the absorption of a high proportion of the incident photons by the aromatic walls of 1 with a high absorption cross-sectional area, which helps the walls to shield the guest even against sunlight/UV radiations. As compared to free curcumin in water, we noticed a significant increase in solubility as well as cellular uptake of curcumin upon encapsulation inside the water-soluble molecular barrel (1) in aqueous medium. Fluorescence imaging confirmed that curcumin was delivered into HeLa cancer cells by the aqueous barrel (1) with the retention of its potential anticancer activity. While free curcumin is inactive toward cancer cells in aqueous medium at room temperature due to negligible solubility, the determined IC 50 value of ∼14 μM for curcumin in aqueous medium in the presence of the barrel (1) reflects the efficiency of the barrel as a potential curcumin carrier in aqueous medium without any other additives. Thus, two major challenges of increasing the bioavailability and stability of curcumin in aqueous medium even in the presence of UV light have been addressed by using a new supramolecular water-soluble barrel (1) as a drug carrier.

Barrier Properties of Polymeric Packaging Materials to Major Aroma Volatiles in Herbs

Directory of Open Access Journals (Sweden)

Leelaphiwat Pattarin

2016-01-01

Full Text Available This study determined the main transport coefficients (diffusion, solubility and permeability of key aroma compounds present in tropical herbs (eucalyptol and estragol through low‒density polyethylene (LDPE, polypropylene (PP, nylon (Nylon, polyethylene terephthalate (PET, metalized‒polyethylene terephthalate (MPET and poly(lactic acid (PLA films at 15 and 25 °C. The concentration of aroma compounds permeating through the films were evaluated at various time intervals using a gas chromatograph flame ionization detector (GC–FID. Results showed that the diffusion coefficients of aroma compounds were highest in LDPE whereas the solubility coefficients were highest in PLA at both temperatures. PLA had the highest permeability coefficients for estragol at both temperatures. PP and LDPE had the highest permeability coefficients for eucalyptol at 15 and 25 °C, respectively. MPET had the lowest permeability for both aroma compounds studied. Aroma barrier properties can be used when selecting polymeric packaging materials to prevent aroma loss in various food and consumer products.

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

Directory of Open Access Journals (Sweden)

Christian Dollendorf

2013-08-01

Full Text Available A redox-responsive polycationic system was synthesized via copolymerization of N,N-diethylacrylamide (DEAAm and 2-(dimethylaminoethyl methacrylate (DMAEMA. N,N’-bis(4-chlorobutanoylcystamine was used as disulfide-containing cross-linker to form networks by the quaternization of tertiary amine groups. The insoluble cationic hydrogels become soluble by reduction of disulfide to mercaptanes by use of dithiothreitol (DTT, tris(2-carboxyethylphosphine (TCEP or cysteamine, respectively. The soluble polymeric system can be cross-linked again by using oxygen or hydrogen peroxide under basic conditions. The redox-responsive polymer networks can be used for molecular inclusion and controlled release. As an example, phenolphthalein, methylene blue and reactive orange 16 were included into the network. After treatment with DTT a release of the dye could be recognized. Physical properties of the cross-linked materials, e.g., glass transition temperature (Tg, swelling behavior and cloud points (Tc were investigated. Redox-responsive behavior was further analyzed by rheological measurements.

Antimicrobial photodynamic therapy with two photosensitizers on two oral streptococci: an in vitro study

Science.gov (United States)

Vahabi, S.; Fekrazad, R.; Ayremlou, S.; Taheri, S.; Lizarelli, R. F. Z.; Kalhori, K. A. M.

2011-12-01

Periodontal diseases are caused by infection of tissues supporting the teeth due to complex aggregate of bacteria known as biofilm and firstly colonized by streptococci. The aim of this in vitro study was to evaluate the effect of Radachlorin® and Toluidine Blue O (TBO)-mediated photodynamic therapy (PDT) on the viability of two oral streptococci. Bacterial suspensions of Streptococcus mutans and Streptococcus sanguis were subjected to either TBO or Radachlorin®, Then exposed to two different diode laser light at energy densities of 3, 6 J/cm2 at 633 nm and 6, 12 J/cm2 at 662 nm, respectively. The control groups were subjected to laser light alone, photosensitizer alone or received neither photosensitizer nor light exposure. The suspensions were then spread over specific agar mediums and viable microorganisms were counted after overnight incubation aerobically at 37°C, 5% CO2 and then reported as colony forming unit. The results indicated that photosensitization by the energy density of 6 J/cm2 with Radachlorin® and both 3 and 6 J/cm2 with TBO caused significant reduction in bacterial colony formation ( p < 0.05). Radachlorin® and TBO-mediated photodynamic therapy seem to show excellent potential in significantly killing of two oral streptococci in vitro.

Design of water-soluble, thiol-reactive polymers of controlled molecular weight: a novel multivalent scaffold

Science.gov (United States)

Carrillo, Alvaro; Gujraty, Kunal V.; Rai, Prakash R.; Kane, Ravi S.

2005-07-01

Multivalent molecules, i.e. scaffolds presenting multiple copies of a suitable ligand, constitute an emerging class of nanoscale therapeutics. We present a novel approach for the design of multivalent ligands, which allows the biofunctionalization of polymers with proteins or peptides in a controlled orientation. It consists of the synthesis of water-soluble, activated polymer scaffolds of controlled molecular weight, which can be biofunctionalized with various thiolated ligands in aqueous media under mild conditions. These polymers were synthesized by ring-opening metathesis polymerization (ROMP) and further modified to make them water-soluble. The incorporation of chloride groups activated the polymers to react with thiol-containing peptides or proteins, and the formation of multivalent ligands in aqueous media was demonstrated. This strategy represents a convenient route for synthesizing multivalent ligands of controlled dimensions and valency.

Effect of soybean lecithin on iron-catalyzed or chlorophyll-photosensitized oxidation of canola oil emulsion.

Science.gov (United States)

Choe, Jeesu; Oh, Boyoung; Choe, Eunok

2014-11-01

The effect of soybean lecithin addition on the iron-catalyzed or chlorophyll-photosensitized oxidation of emulsions consisting of purified canola oil and water (1:1, w/w) was studied based on headspace oxygen consumption using gas chromatography and hydroperoxide production using the ferric thiocyanate method. Addition levels of iron sulfate, chlorophyll, and soybean lecithin were 5, 4, and 350 mg/kg, respectively. Phospholipids (PLs) during oxidation of the emulsions were monitored by high performance liquid chromatography. Addition of soybean lecithin to the emulsions significantly reduced and decelerated iron-catalyzed oil oxidation by lowering headspace oxygen consumption and hydroperoxide production. However, soybean lecithin had no significant antioxidant effect on chlorophyll-photosensitized oxidation of the emulsions. PLs in soybean lecithin added to the emulsions were degraded during both oxidation processes, although there was little change in PL composition. Among PLs in soybean lecithin, phosphatidylethanolamine and phosphatidylinositol were degraded the fastest in the iron-catalyzed and the chlorophyll-photosensitized oxidation, respectively. The results suggest that addition of soybean lecithin as an emulsifier can also improve the oxidative stability of oil in an emulsion. © 2014 Institute of Food Technologists®

Photosensitive graphene transistors.

Science.gov (United States)

Li, Jinhua; Niu, Liyong; Zheng, Zijian; Yan, Feng

2014-08-20

High performance photodetectors play important roles in the development of innovative technologies in many fields, including medicine, display and imaging, military, optical communication, environment monitoring, security check, scientific research and industrial processing control. Graphene, the most fascinating two-dimensional material, has demonstrated promising applications in various types of photodetectors from terahertz to ultraviolet, due to its ultrahigh carrier mobility and light absorption in broad wavelength range. Graphene field effect transistors are recognized as a type of excellent transducers for photodetection thanks to the inherent amplification function of the transistors, the feasibility of miniaturization and the unique properties of graphene. In this review, we will introduce the applications of graphene transistors as photodetectors in different wavelength ranges including terahertz, infrared, visible, and ultraviolet, focusing on the device design, physics and photosensitive performance. Since the device properties are closely related to the quality of graphene, the devices based on graphene prepared with different methods will be addressed separately with a view to demonstrating more clearly their advantages and shortcomings in practical applications. It is expected that highly sensitive photodetectors based on graphene transistors will find important applications in many emerging areas especially flexible, wearable, printable or transparent electronics and high frequency communications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chelating polymeric membranes

KAUST Repository

Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

2015-01-01

microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

Properties of uncharged water-soluble tetra({omega}-methoxypolyethyleneoxy)phthalocyanine free base: Viable switching of the optical response by means of H{sub 3}O{sup +} ions

Energy Technology Data Exchange (ETDEWEB)

Mineo, Placido [Department of Chemistry, University of Catania and INSTM UdR of Catania, Viale Andrea Doria 6, 95125 Catania (Italy); Istituto per i Processi Chimico Fisici - CNR, Viale Ferdinando Stagno D' Alcontres, 37, 98158 Messina (Italy); Lupo, Fabio; Fragala, Ignazio; Scamporrino, Emilio [Department of Chemistry, University of Catania and INSTM UdR of Catania, Viale Andrea Doria 6, 95125 Catania (Italy); Gulino, Antonino, E-mail: agulino@unict.it [Department of Chemistry, University of Catania and INSTM UdR of Catania, Viale Andrea Doria 6, 95125 Catania (Italy)

2012-02-15

An uncharged water-soluble tetra ({omega}-methoxypolyethyleneoxy)phthalocyanine was characterized by MALDI-TOF mass spectrometry, UV-vis and luminescence measurements. The polyether substituents render water soluble this uncharged phthalocyanine. Relevant changes are observed in emission measurements upon protonation. The phthalocyanine free base and its protonated forms can be switched alternating H{sub 3}O{sup +} and OH{sup -} ions as inputs, being the intensity of the luminescence spectra the output. Binary codes 1 or 0 can be assigned to the high luminescent phthalocyanine free base state or to the low luminescent protonated state, respectively. The read-out procedure is fast and the system is reversible. In addition, the exploiting of the luminescent properties of the present water soluble phthalocyanine could be of relevance also for biological applications (photosensitizers for the photodynamic therapy). Highlights: Black-Right-Pointing-Pointer An uncharged water soluble tetra ({omega}-methoxypolyethyleneoxy)phthalocyanine was characterized. Black-Right-Pointing-Pointer Phthalocyanine protonation changes the luminescence output. Black-Right-Pointing-Pointer The system can be switched alternating H{sub 3}O{sup +} and OH{sup -} as inputs. Black-Right-Pointing-Pointer The read-out procedure is fast and reversible. Black-Right-Pointing-Pointer Binary codes are assigned to the high and low luminescent states, respectively.

Photosensitive Ox/GaAs heterojunctions: Creation and properties

Energy Technology Data Exchange (ETDEWEB)

Rud' , V. Yu. [St. Petersburg State Polytechnical University (Russian Federation); Rud' , Yu. V., E-mail: yuryrud@mail.ioffe.ru; Terukov, E. I.; Ushakova, T. N. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2012-06-15

A method for the thermal oxidation of GaAs crystals in air is suggested and the first photosensitive Ox/n-GaAs heterojunctions, where Ox is a native oxide, are fabricated. The steady current-voltage characteristics and spectra of relative quantum efficiency of the new structures are studied. The features of the spectra of photoactive absorption of the obtained heterojunctions are discussed. The potential of using vacuumfree thermal oxidation of the GaAs crystals in air to fabricate broadband heterophotoconverters of optical radiation on their basis is established.

New photosensitive systems for volume phase holography

Science.gov (United States)

Bianco, Andrea; Colella, Letizia; Galli, Paola; Zanutta, Alessio; Bertarelli, Chiara

2017-05-01

Volume phase holographic elements are becoming attractive thanks to the large efficiency and good optical quality. They are based on photosensitive materials where a modulation of the refractive index is induced. In this paper, we highlight the strategies to obtain a change in the refractive index in a dielectric material, namely a change in the material density and/or in the molecular polarizability. Moreover, we show the results achieved for materials that undergo the photo-Fries reaction as function of the molecular structure and the illumination conditions. We also report the results on a system based on the diazo Meldrum's acid where volatile molecules are produced upon light exposure.

White matter microstructural changes of thalamocortical networks in photosensitivity and idiopathic generalized epilepsy

DEFF Research Database (Denmark)

Groppa, Sergiu; Moeller, Friederike; Siebner, Hartwig

2012-01-01

Photosensitivity or photoparoxysmal response (PPR) is an electroencephalography trait that is highly associated with idiopathic generalized epilepsies (IGEs) and characterized by changes in cortical excitability in response to photic stimulation. Studying functional and structural changes of PPR ...

Reactive oxygen species explicit dosimetry (ROSED) of a type 1 photosensitizer

Science.gov (United States)

Ong, Yi Hong; Kim, Michele M.; Huang, Zheng; Zhu, Timothy C.

2018-02-01

Type I photodynamic therapy (PDT) is based on the use of photochemical reactions mediated through an interaction between a tumor-selective photosensitizer, photoexcitation with a specific wavelength of light, and production of reactive oxygen species (ROS). The goal of this study is to develop a model to calculate reactive oxygen species concentration ([ROS]rx) after Tookad®-mediated vascular PDT. Mice with radiation-induced fibrosarcoma (RIF) tumors were treated with different light fluence and fluence rate conditions. Explicit measurements of photosensitizer drug concentration were made via diffuse reflective absorption spectrum using a contact probe before and after PDT. Blood flow and tissue oxygen concentration over time were measured during PDT as a mean to validate the photochemical parameters for the ROSED calculation. Cure index was computed from the rate of tumor regrowth after treatment and was compared against three calculated dose metrics: total light fluence, PDT dose, reacted [ROS]rx. The tumor growth study demonstrates that [ROS]rx serves as a better dosimetric quantity for predicting treatment outcome, as a clinically relevant tumor growth endpoint.

On the problem of silica solubility at high pH

International Nuclear Information System (INIS)

Eikenberg, J.

1990-07-01

The aqueous system Na 2 O-H 2 O-SiO 2 is considered to play an important role when strong alkaline pore waters of a cement based intermediate level radioactive waste repository intrude into the rock formations surrounding the near field. Under such conditions unknown quantities of silica may dissolve. Therefore the pH-dependence of the solubility of amorphous silica and quartz is investigated by a parameter variation study using the geochemical speciation code MINEQL/EIR. Published silica solubility data obtained in sodium hydroxide solutions at 25 and 90 o C are compared with the results of four models which use different proposed values of the rather uncertain equilibrium constants. Of main interest is the question of whether, in a high pH region, the silica solubility can be explained with different monomeric species only, or to what extent additional polymeric silica species have to be considered as well. The solubility of amorphous silica at 25 o C is well understood up to a pH of about 10.5, where it is determined by the solubility product and the first dissociation constant of monomeric silic acid. The most probable cause of the increased solubility of amorphous silica in the region between pH 10.5 and 11.3 is the formation of dimers, trimers and tetramers. Below a total silica concentration of 0.001 M and pH ≤ 10.0, however, polymerisation proves to be insignificant. Besides low temperature studies using amorphous silica, the solubility of quartz has also been measured in NaOH solutions at 90 o C. As is the case at lower temperatures, the reported values for the second dissociation constant at 90 o C scatter widely. It can be shown that in a NaOH medium up to 0.1 M only mononuclear silica species are stable. Therefore it is concluded that the trend of monomers to form polymers decreases strongly with temperature. In strong NaOH solutions at elevated temperatures, silica-sodium ion pairing seems to gain importance. (author) 12 figs., 9 tabs., 65 refs

Effects of water temperature on photosensitization in bath-PUVA therapy with 8-methoxypsoralen

Energy Technology Data Exchange (ETDEWEB)

Gruss, C.; Kobyletzki, G. von; Reuther, T.; Husebo, L.; Altmeyer, P. [Ruhr-Univ. of Bochum, Bochum (Germany); Behrens, S.; Kerscher, M. [Univ. of Ulm, Dept. of Dermatology, Ulm (Germany)

1998-10-01

The pharmacokinetic aspects of bath-PUVA are not completely clarified. Therefore, we determined the phototoxic response of human skin following psoralen baths at temperatures ranging from 32 deg. C to 42 deg. C (71.6-107.6 deg. F) and UVA doses ranging from 0.5 to 5.5 J/cm{sup 2}. The highest therapeutical photosensitization (i.e. lowest minimal phototoxic dose) was assessed at temperatures of 37 deg. C (98.6 deg. F) and above. Photosensitization was significantly decreased at lower temperatures. These data indicate that a bath temperature of 37 deg. C (98.6 deg. F) should be used to gain optimal therapeutic efficiency in a clinical setting. Furthermore, in order to minimize the risk of adverse phototoxic effects in bath-PUVA, it is important to use a constant temperature during the psoralen bath. (au) 13 refs.

Effects of water temperature on photosensitization in bath-PUVA therapy with 8-methoxypsoralen

International Nuclear Information System (INIS)

Gruss, C.; Kobyletzki, G. von; Reuther, T.; Husebo, L.; Altmeyer, P.; Behrens, S.; Kerscher, M.

1998-01-01

The pharmacokinetic aspects of bath-PUVA are not completely clarified. Therefore, we determined the phototoxic response of human skin following psoralen baths at temperatures ranging from 32 deg. C to 42 deg. C (71.6-107.6 deg. F) and UVA doses ranging from 0.5 to 5.5 J/cm 2 . The highest therapeutical photosensitization (i.e. lowest minimal phototoxic dose) was assessed at temperatures of 37 deg. C (98.6 deg. F) and above. Photosensitization was significantly decreased at lower temperatures. These data indicate that a bath temperature of 37 deg. C (98.6 deg. F) should be used to gain optimal therapeutic efficiency in a clinical setting. Furthermore, in order to minimize the risk of adverse phototoxic effects in bath-PUVA, it is important to use a constant temperature during the psoralen bath. (au)

Photosensitive naturally derived resins toward optical 3-D printing

Science.gov (United States)

Skliutas, Edvinas; Kasetaite, Sigita; Jonušauskas, Linas; Ostrauskaite, Jolita; Malinauskas, Mangirdas

2018-04-01

Recent advances in material engineering have shown that renewable raw materials, such as plant oils or glycerol, can be applied for synthesis of polymers due to ready availability, inherent biodegradability, limited toxicity, and existence of modifiable functional groups and eventually resulting to a potentially lower cost. After additional chemical modifications (epoxidation, acrylation, double bonds metathesis, etc.), they can be applied in such high-tech areas as stereolithography, which allows fabrication of three-dimensional (3-D) objects. "Autodesk's" 3-D optical printer "Ember" using 405-nm light was implemented for dynamic projection lithography. It enabled straightforward spatio-selective photopolymerization on demand, which allows development of various photosensitive materials. The bio-based resins' photosensitivity was compared to standard "Autodesk" "PR48" and "Formlabs" "Clear" materials. It turned out that the bioresins need a higher energy dose to be cured (a least 16 J · cm - 2 for a single layer varying from 100 to 130 μm). Despite this, submillimeter range 2.5-D structural features were formed, and their morphology was assessed by optical profilometer and scanning electron microscope. It was revealed that a higher exposition dose (up to 26 J · cm - 2) results in a linear increase in the formed structures height, proving controllability of the undergoing process. Overall, the provided results show that naturally derived resins are suitable candidates for tabletop gray-tone lithography.

The circadian response of intrinsically photosensitive retinal ganglion cells.

Directory of Open Access Journals (Sweden)

Andrew J Zele

Full Text Available Intrinsically photosensitive retinal ganglion cells (ipRGC signal environmental light level to the central circadian clock and contribute to the pupil light reflex. It is unknown if ipRGC activity is subject to extrinsic (central or intrinsic (retinal network-mediated circadian modulation during light entrainment and phase shifting. Eleven younger persons (18-30 years with no ophthalmological, medical or sleep disorders participated. The activity of the inner (ipRGC and outer retina (cone photoreceptors was assessed hourly using the pupil light reflex during a 24 h period of constant environmental illumination (10 lux. Exogenous circadian cues of activity, sleep, posture, caffeine, ambient temperature, caloric intake and ambient illumination were controlled. Dim-light melatonin onset (DLMO was determined from salivary melatonin assay at hourly intervals, and participant melatonin onset values were set to 14 h to adjust clock time to circadian time. Here we demonstrate in humans that the ipRGC controlled post-illumination pupil response has a circadian rhythm independent of external light cues. This circadian variation precedes melatonin onset and the minimum ipRGC driven pupil response occurs post melatonin onset. Outer retinal photoreceptor contributions to the inner retinal ipRGC driven post-illumination pupil response also show circadian variation whereas direct outer retinal cone inputs to the pupil light reflex do not, indicating that intrinsically photosensitive (melanopsin retinal ganglion cells mediate this circadian variation.

Sixtieth Anniversary of Ziegler-Natta Catalysts and Stereospecific Polymerization

Directory of Open Access Journals (Sweden)

Janović Z.

2015-07-01

Full Text Available This review article highlights the history of the discoveries of organometallic catalysts and stereospecific polymerization of α-olefins, dienes and a number of vinyl monomers by Karl Ziegler and Giulio Natta sixty years ago, their developments and recent progress. As one of the most important achievements in the field of catalysis, macromolecular science and polymer materials, their inventors were awarded the Nobel Prize in Chemistry in 1963 “for their discoveries in the field of chemistry and technology of high polymers”. These discoveries have stimulated an intensive, both basic and applied research all over the world, up to the present times, leading to great development of the polymer industry. The important biographical data and scientific advancements of K. Ziegler and G. Natta are presented as well. Karl Ziegler, a German scientist, Director of Max Planck Institute for Coal Research in Mülheim, besides many scientific achievements, in 1953 discovered a new process for the polymerization of ethylene into linear polyethylene under mild conditions by using titanium chloride and alkyl aluminium catalytic system that was superior to all existing polymerization. Giulio Natta, an Italian scientist, Director of the Department of Industrial Chemistry at Polytechnic, University of Milan, besides many achievements in petrochemical processes, in 1954 obtained for the first time isotactic polypropylene and Montecatini Co. started its production already in 1958. He conducted pioneering studies on the chain microstructure of synthetic organic polymers and postulated the mechanisms of stereospecific polymerizations. Since the discovery of the Zeigler-Natta catalyst, stereospecific polymerization and processes, significant developments have occurred. The breakthrough in polymerization processes such as fluid bed, liquid phase loop reactor and reactor granule technology led to significant development and growth of polyolefin production. In the 1980s

A novel approach to fabricate dye-encapsulated polymeric micro- and nanoparticles by thin film dewetting technique.

Science.gov (United States)

Chatterjee, Manosree; Hens, Abhiram; Mahato, Kuldeep; Jaiswal, Namita; Mahato, Nivedita; Nagahanumaiah; Chanda, Nripen

2017-11-15

A new method is reported for fabrication of polymeric micro- and nanoparticles from an intermediate patterned surface originated by dewetting of a polymeric thin film. Poly (d, l-lactide-co-glycolide) or PLGA, a biocompatible polymer is used to develop a thin film over a clean glass substrate which dewets spontaneously in the micro-/nano-patterned surface of size range 50nm to 3.5µm. Since another water-soluble polymer, poly vinyl alcohol (PVA) is coated on the same glass substrate before PLGA thin film formation, developed micro-/nano-patterns are easily extracted in water in the form of micro- and nanoparticle mixture of size range 50nm to 3.0µm. This simplified method is also used to effectively encapsulate a dye molecule, rhodamine B inside the PLGA micro-/nanoparticles. The developed dye-encapsulated nanoparticles, PLGA-rhodamine are separated from the mixture and tested for in-vitro delivery application of external molecules inside human lung cancer cells. For the first time, the use of thin film dewetting technique is reported as a potential route for the synthesis of polymeric micro-/nanoparticles and effective encapsulation of external species therein. Copyright © 2017 Elsevier Inc. All rights reserved.

Lethal photosensitization of biofilm-grown bacteria

Science.gov (United States)

Wilson, Michael

1997-12-01

Antibacterial agents are increasingly being used for the prophylaxis and treatment of oral diseases. As these agents can be rendered ineffective by resistance development in the target organisms there is a need to develop alternative antimicrobial approaches. Light-activated antimicrobial agents release singlet oxygen and free radicals which can kill adjacent bacteria and a wide range of cariogenic and periodontopathogenic bacteria has been shown to be susceptible to such agents. In the oral cavity these organisms are present as biofilms (dental plaques) which are less susceptible to traditional antimicrobial agents than bacterial suspensions. The results of these studies have shown that biofilm-grown oral bacteria are also susceptible to lethal photosensitization although the light energy doses required are grater than those needed to kill the organisms when they are grown as aqueous suspensions.

The (6-4) Dimeric Lesion as a DNA Photosensitizer

OpenAIRE

Vendrell Criado, Victoria; Rodríguez Muñiz, Gemma María; Lhiaubet ., Virginie Lyria; Cuquerella Alabort, Maria Consuelo; Miranda Alonso, Miguel Ángel

2016-01-01

[EN] Based on our previous investigations into the photophysical properties of the 5-methyl-2-pyrimidone (Pyo) chromophore, we now extend our studies to the photobehavior of the dimeric (6-4) thymine photoproducts (6-4 PP) to evaluate their capability to act as instrinsic DNA photosensitizers. The lesion presents significant absorption in the UVB/UVA region, weak fluorescence emission, a singlet-excited-state energy of approximately 351 kJ mol(-1), and a triplet-excited-state energy of 297 kJ...

Polymerization of Phenylacetylene-Based Monodendrons with Alkoxy Peripheral Groups and Oxygen/Nitrogen Permeation Behavior of Their Membranes

Directory of Open Access Journals (Sweden)

Takashi Kaneko

2012-01-01

Full Text Available Monodendron monomers with alkoxy peripheral groups were synthesized, and the focal point of monodendrons, terminal acetylene, was polymerized with rhodium catalyst to yield corresponding polydendrons with a high molecular weight. The polydendrons were soluble in common organic solvents and readily formed membranes. Oxygen permselectivity was improved in the polydendrons with a space-persistent dendritic crowd. It was found that the well-defined dendritic and rod-like structure of the polydendrons was useful for permselective membrane.

Role of complex formation in the photosensitized degradation of DNA induced by N'-formylkynurenine

International Nuclear Information System (INIS)

Walrant, P.; Santus, R.; Charlier, M.

1976-01-01

N'-Formylkynurenine derivatives efficiently bind to DNA or polynucleotides. Homopolynucleotides and DNA displayed marked differences in the binding process. Association constants were derived which indicated that the oxidized indole ring is more strongly bound to DNA than the unoxidized one. Irradiation of such complexes with wavelengths greater than 320 nm induced pyrimidine dimer formation as well as DNA chain breaks. Complex formation is shown to play an important role in these photosensitized reactions. The photodynamic action of N-formylkynurenine on DNA constituents was negligible at neutral pH but guanine and xanthine derivatives were sensitizable at higher pH. Thymine dimer splitting can occur in aggregated frozen aqueous solutions of N'-formylkynurenine and thymine dimer but this photosensitized splitting was negligible in liquid solutions at room temperature. (author)

Highly reliable photosensitive organic-inorganic hybrid passivation layers for a-InGaZnO thin-film transistors

Science.gov (United States)

Bermundo, Juan Paolo; Ishikawa, Yasuaki; Yamazaki, Haruka; Nonaka, Toshiaki; Fujii, Mami N.; Uraoka, Yukiharu

2015-07-01

We report the fabrication of a photosensitive hybrid passivation material on amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) that greatly enhance its stability and improve its electrical characteristics. The hybrid passivation based on polysilsesquioxane is transparent and fabricated using a simple solution process. Because the passivation is photosensitive, dry etching was never performed during TFT fabrication. TFTs passivated with this material had a small threshold voltage shift of 0.5 V during positive bias stress, 0.5 V during negative bias stress, and -2.5 V during negative bias illumination stress. Furthermore, TFTs passivated by this layer were stable after being subjected to high relative humidity stress — confirming the superb barrier ability of the passivation. Analysis of secondary ion mass spectrometry showed that a large amount of hydrogen, carbon, and fluorine can be found in the channel region. We show that both hydrogen and fluorine reduced oxygen vacancies and that fluorine stabilized weak oxygen and hydroxide bonds. These results demonstrate the large potential of photosensitive hybrid passivation layers as effective passivation materials.

Polymeric micelles for drug targeting.

Science.gov (United States)

Mahmud, Abdullah; Xiong, Xiao-Bing; Aliabadi, Hamidreza Montazeri; Lavasanifar, Afsaneh

2007-11-01

Polymeric micelles are nano-delivery systems formed through self-assembly of amphiphilic block copolymers in an aqueous environment. The nanoscopic dimension, stealth properties induced by the hydrophilic polymeric brush on the micellar surface, capacity for stabilized encapsulation of hydrophobic drugs offered by the hydrophobic and rigid micellar core, and finally a possibility for the chemical manipulation of the core/shell structure have made polymeric micelles one of the most promising carriers for drug targeting. To date, three generations of polymeric micellar delivery systems, i.e. polymeric micelles for passive, active and multifunctional drug targeting, have arisen from research efforts, with each subsequent generation displaying greater specificity for the diseased tissue and/or targeting efficiency. The present manuscript aims to review the research efforts made for the development of each generation and provide an assessment on the overall success of polymeric micellar delivery system in drug targeting. The emphasis is placed on the design and development of ligand modified, stimuli responsive and multifunctional polymeric micelles for drug targeting.

Rapid profiling of polymeric phenolic acids in Salvia miltiorrhiza by hybrid data-dependent/targeted multistage mass spectrometry acquisition based on expected compounds prediction and fragment ion searching.

Science.gov (United States)

Shen, Yao; Feng, Zijin; Yang, Min; Zhou, Zhe; Han, Sumei; Hou, Jinjun; Li, Zhenwei; Wu, Wanying; Guo, De-An

2018-04-01

Phenolic acids are the major water-soluble components in Salvia miltiorrhiza (>5%). According to previous studies, many of them contribute to the cardiovascular effects and antioxidant effects of S. miltiorrhiza. Polymeric phenolic acids can be considered as the tanshinol derived metabolites, e.g., dimmers, trimers, and tetramers. A strategy combined with tanshinol-based expected compounds prediction, total ion chromatogram filtering, fragment ion searching, and parent list-based multistage mass spectrometry acquisition by linear trap quadropole-orbitrap Velos mass spectrometry was proposed to rapid profile polymeric phenolic acids in S. miltiorrhiza. More than 480 potential polymeric phenolic acids could be screened out by this strategy. Based on the fragment information obtained by parent list-activated data dependent multistage mass spectrometry acquisition, 190 polymeric phenolic acids were characterized by comparing their mass information with literature data, and 18 of them were firstly detected from S. miltiorrhiza. Seven potential compounds were tentatively characterized as new polymeric phenolic acids from S. miltiorrhiza. This strategy facilitates identification of polymeric phenolic acids in complex matrix with both selectivity and sensitivity, which could be expanded for rapid discovery and identification of compounds from complex matrix. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymerization Using Phosphazene Bases

KAUST Repository

Zhao, Junpeng

2015-09-01

In the recent rise of metal-free polymerization techniques, organic phosphazene superbases have shown their remarkable strength as promoter/catalyst for the anionic polymerization of various types of monomers. Generally, the complexation of phosphazene base with the counterion (proton or lithium cation) significantly improves the nucleophilicity of the initiator/chain end resulting in highly enhanced polymerization rates, as compared with conventional metalbased initiating systems. In this chapter, the general features of phosphazenepromoted/catalyzed polymerizations and the applications in macromolecular engineering (synthesis of functionalized polymers, block copolymers, and macromolecular architectures) are discussed with challenges and perspectives being pointed out.

Phosphazene-promoted anionic polymerization

KAUST Repository

Zhao, Junpeng

2014-01-01

In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

Riboflavin and chlorophyll as photosensitizers in electroformed giant unilamellar vesicles as food models

DEFF Research Database (Denmark)

Wang, Hui Jing; Liang, Ran; du, Hui Hui

2017-01-01

Electroformed giant unilamellar vesicles (GUVs) were found to have optimal sizes (~10 µm average diameter) for studying effects of photosensitizers and antioxidants in lipid bilayers as food models. By using optical microscopy and digital image processing techniques, no membrane damage was found ...

New 1,3,4-Oxadiazole Based Photosensitizers for Dye Sensitized Solar Cells (DSSCs

Directory of Open Access Journals (Sweden)

Umer Mehmood

2015-01-01

Full Text Available 1,3,4-Oxadiazole based photosensitizers with biphenyl, naphthalene, anthracene, and triphenylamine as the electron-donating moiety were synthesized for solar cell applications. In these photosensitizers, cyano groups were introduced as the electron acceptor and the anchor group because of their high electron-withdrawing ability and strong bonding to the semiconductor. Oxadiazole isomers were used as the π-conjugation system, which bridges the donor-acceptor systems. The electrochemical and optical properties of the sensitizers were investigated both in their native form and upon incorporation into dye sensitized solar cells. The results of UV-visible absorption spectroscopy, electrochemical impedance spectroscopic measurements, and photocurrent voltage characteristics indicate that 1,3,4-oxadiazole pi-spacer with the anthracene moiety has the highest efficiency of 2.58%. Density functional theory was employed to optimize the structures of the sensitizers and the TiO2 cluster.

Implication for photosensitive patients of ultraviolet A exposure in vehicles.

Science.gov (United States)

Hampton, P J; Farr, P M; Diffey, B L; Lloyd, J J

2004-10-01

Photosensitive patients sometimes report disease flares during journeys by car. Window glass blocks all UVB but not all UVA. All car windscreens are made from laminated glass. Side and rear windows are usually made of nonlaminated glass. To determine which types of glass provide most protection from UVA with particular reference to the implications for patients with polymorphic light eruption (PLE). The percentage transmission of UVA was determined for a selection of glass, both laminated and nonlaminated, and with differing colour tints. Laminated glass transmits less UVA than nonlaminated glass. Tinted glass transmits less UVA than clear glass. Nonlaminated clear glass transmitted the highest percentage of UVA (62.8%) and grey laminated glass the lowest (0.9%). A dose of 5 J cm(-2) UVA, enough to trigger PLE in some patients, could be transmitted through clear nonlaminated glass in 30 min but would take 50 h through grey laminated glass. Patients with severe UVA-induced PLE and other photosensitivity disorders may have disease flares from solar UVA transmission through side-window glass. Protective measures such as wearing long-sleeved clothing, keeping the arm beneath the bottom of the window aperture, or choosing tinted and laminated car windows may be helpful.

Platelet-activating factor receptor agonists mediate xeroderma pigmentosum A photosensitivity.

Science.gov (United States)

Yao, Yongxue; Harrison, Kathleen A; Al-Hassani, Mohammed; Murphy, Robert C; Rezania, Samin; Konger, Raymond L; Travers, Jeffrey B

2012-03-16

To date, oxidized glycerophosphocholines (Ox-GPCs) with platelet-activating factor (PAF) activity produced non-enzymatically have not been definitively demonstrated to mediate any known disease processes. Here we provide evidence that these Ox-GPCs play a pivotal role in the photosensitivity associated with the deficiency of the DNA repair protein xeroderma pigmentosum type A (XPA). It should be noted that XPA-deficient cells are known to have decreased antioxidant defenses. These studies demonstrate that treatment of human XPA-deficient fibroblasts with the pro-oxidative stressor ultraviolet B (UVB) radiation resulted in increased reactive oxygen species and PAF receptor (PAF-R) agonistic activity in comparison with gene-corrected cells. The UVB irradiation-generated PAF-R agonists were inhibited by antioxidants. UVB irradiation of XPA-deficient (Xpa-/-) mice also resulted in increased PAF-R agonistic activity and skin inflammation in comparison with control mice. The increased UVB irradiation-mediated skin inflammation and TNF-α production in Xpa-/- mice were blocked by systemic antioxidants and by PAF-R antagonists. Structural characterization of PAF-R-stimulating activity in UVB-irradiated XPA-deficient fibroblasts using mass spectrometry revealed increased levels of sn-2 short-chain Ox-GPCs along with native PAF. These studies support a critical role for PAF-R agonistic Ox-GPCs in the pathophysiology of XPA photosensitivity.

Conducting Polymeric Materials

DEFF Research Database (Denmark)

Hvilsted, Søren

2016-01-01

The overall objective of this collection is to provide the most recent developments within the various areas of conducting polymeric materials. The conductivity of polymeric materials is caused by electrically charged particles, ions, protons and electrons. Materials in which electrons...

Antiviral properties of photosensitizers

International Nuclear Information System (INIS)

Hudson, J.B.; Towers, G.H.N.

1988-01-01

We have studied the antiviral properties of three different groups of photo-sensitizers, viz. (i) various furyl compounds; (ii) β-carboline alkaloids; (iii) thiophenes and their acetylene derivatives. In general the antiviral potency of the furyl compounds correlated with their ability to produce DNA photoadducts. Among the naturally occurring β-carboline alkaloids, harmine was considerably more potent (in the presence of long wavelength UV radiation, UVA) than several other harmane-related compounds. Slight alterations in chemical structure had profound effects on their antiviral activities. Harmine was shown to inactivate the DNA-virus murine cytomegalovirus (MCMV) by inhibiting viral gene expression, although other targets may also exist. Several eudistomins, carboline derivatives isolated from a tunicate, were also photoactive against viruses. Various plant thiophenes and polyacetylenes were studied in detail. These compounds also required UVA for antiviral activity, and some of them were extremely potent against viruses with membranes, e.g. α-terthienyl, which showed significant activity at only 10 -5 μg/ml. When MCMV had been treated with α-terthienyl plus UVA, the virus retained its integrity and penetrated cells normally; but the virus did not replicate. (author)

Calcium carbonate formation on mica supported extracellular polymeric substance produced by Rhodococcus opacus

Energy Technology Data Exchange (ETDEWEB)

Szcześ, Aleksandra, E-mail: aszczes@poczta.umcs.lublin.pl [Department of Physical Chemistry – Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Skłodowska University, Lublin 20-031 (Poland); Czemierska, Magdalena; Jarosz-Wilkołazka, Anna [Department of Biochemistry, Maria Curie-Skłodowska University, Lublin 20-031 (Poland)

2016-10-15

Extracellular polymeric substance (EPS) extracted from Rhodococcus opacus bacterial strain was used as a matrix for calcium carbonate precipitation using the vapour diffusion method. The total exopolymer and water-soluble exopolymer fraction of different concentrations were spread on the mica surface by the spin-coating method. The obtained layers were characterized using the atomic force microscopy measurement and XPS analysis. The effects of polymer concentration, initial pH of calcium chloride solution and precipitation time on the obtained crystals properties were investigated. Raman spectroscopy and scanning electron microscopy were used to characterize the precipitated minerals. It was found that the type of precipitated CaCO{sub 3} polymorph and the crystal size depend on the kind of EPS fraction. The obtained results indicates that the water soluble fraction favours vaterite dissolution and calcite growth, whereas the total EPS stabilizes vaterite and this effect is stronger at basic pH. It seems to be due to different contents of the functional group of EPS fractions. - Highlights: • CaCO{sub 3} crystal size and polymorph can be controlled by EPS substance obtained from R. opacus. • The water soluble fraction favours vaterite dissolution and calcite growth. • The total EPS stabilizes vaterite. • This effect is stronger at basic pH.

Calcium carbonate formation on mica supported extracellular polymeric substance produced by Rhodococcus opacus

International Nuclear Information System (INIS)

Szcześ, Aleksandra; Czemierska, Magdalena; Jarosz-Wilkołazka, Anna

2016-01-01

Extracellular polymeric substance (EPS) extracted from Rhodococcus opacus bacterial strain was used as a matrix for calcium carbonate precipitation using the vapour diffusion method. The total exopolymer and water-soluble exopolymer fraction of different concentrations were spread on the mica surface by the spin-coating method. The obtained layers were characterized using the atomic force microscopy measurement and XPS analysis. The effects of polymer concentration, initial pH of calcium chloride solution and precipitation time on the obtained crystals properties were investigated. Raman spectroscopy and scanning electron microscopy were used to characterize the precipitated minerals. It was found that the type of precipitated CaCO 3 polymorph and the crystal size depend on the kind of EPS fraction. The obtained results indicates that the water soluble fraction favours vaterite dissolution and calcite growth, whereas the total EPS stabilizes vaterite and this effect is stronger at basic pH. It seems to be due to different contents of the functional group of EPS fractions. - Highlights: • CaCO 3 crystal size and polymorph can be controlled by EPS substance obtained from R. opacus. • The water soluble fraction favours vaterite dissolution and calcite growth. • The total EPS stabilizes vaterite. • This effect is stronger at basic pH.

Microencapsulation of Ethion by Interfacial Polymerization Utilizing Potassium Phthalimide-N-oxyl (PPINO) as a Promoter

International Nuclear Information System (INIS)

Moghbeli, M. R.; Abedi, V.; Dekamin, M. G.

2011-01-01

Poly urea microcapsules containing an active agent, i.e. ethion as pesticide, have been prepared by interfacial polymerization between 2, 4-toluene diisocyanate (TDI) and diethylenetriamine (DETA) in an oil-in-water (O/W) emulsion system. The effects of the nature of the emulsifier, the monomer weight ratio, and a novel promoter, i.e. potassium phthalimide-N-oxyl (PPINO), on the morphology, microstructure, and thermal stability of the microcapsules have been investigated. PPINO was used as a water-soluble promoter capable of dimerizing and trimerizing the isocyanate reactant in the interfacial polymerization. The transmission electron microscopy micrographs showed that the addition of the promoter had no significant effect on the microcapsule shell thickness. Increasing the amount of PPINO caused the degree of crystallinity of the polymer shell to decrease considerably. In addition, increasing the amount of promoter up to 2 wt % caused the thermal stability of the microcapsules to decrease, while using promoter beyond this level resulted in higher thermal stability.

Synthesis and Characterization of Well-Defined Soluble Alq3- and Znq2-Functionalized Polymers via RAFT Copolymerization

Directory of Open Access Journals (Sweden)

Chengchao Wang

2010-01-01

Full Text Available The reversible addition-fragmentation chain transfer (RAFT copolymerizations of 2-((8-hydroxyquinolin-5-ylmethoxyethyl methacrylate (HQHEMA with styrene (St or methyl methacrylate (MMA were successfully carried out in the presence of 2-cyanoprop-2-yl dithionaphthalenoate (CPDN. The polymerization behaviors showed the typical living natures by the first-order polymerization kinetics, the linear dependence of molecular weights of the polymers on the monomer conversions with the relatively narrow molecular weight distributions (Mw/Mn, and the successful chain extension experiments. The soluble polymers having tris(8-hydroxyquinolinealuminum (Alq3 and bis(8-hydroxyquinoline znic(II (Znq2 side chains were obtained via complexation of the polymers with aluminium isopropoxide or zinc acetate in the presence of monomeric 8-hydroxyquinoline, which had strong fluorescent emission at 520 nm. The obtained polymers were characterized by GPC, NMR, UV-vis, and fluorescent spectra.

Synergic phototoxic effect of visible light or Gallium-Arsenide laser in the presence of different photo-sensitizers on Porphyromonas gingivalis and Fusobacterium nucleatum

Directory of Open Access Journals (Sweden)

Habibollah Ghanbari

2015-01-01

Conclusion: Within the limitations of this study, the synergic phototoxic effect of visible light in combination with each of the photosensitizers on P. gingivalis and F. nucleatum. However, the synergic phototoxic effect of laser exposure and hydrogen peroxide and curcumin as photosensitizers on F. nucleatum was not shown.

Formulation strategies for optimizing the morphology of polymeric bulk heterojunction organic solar cells: a brief review

Science.gov (United States)

Vongsaysy, Uyxing; Bassani, Dario M.; Servant, Laurent; Pavageau, Bertrand; Wantz, Guillaume; Aziz, Hany

2014-01-01

Polymeric bulk heterojunction (BHJ) organic solar cells represent one of the most promising technologies for renewable energy with a low fabrication cost. Control over BHJ morphology is one of the key factors in obtaining high-efficiency devices. This review focuses on formulation strategies for optimizing the BHJ morphology. We address how solvent choice and the introduction of processing additives affect the morphology. We also review a number of recent studies concerning prediction methods that utilize the Hansen solubility parameters to develop efficient solvent systems.

Photosensitive bent-core liquid crystals based on methyl substituted 3-hydroxybenzoic acid.

Czech Academy of Sciences Publication Activity Database

Kohout, M.; Alaasar, M.; Poryvai, A.; Novotná, Vladimíra; Poppe, S.; Tschierske, C.; Svoboda, J.

2017-01-01

Roč. 7, č. 57 (2017), s. 35805-35813 ISSN 2046-2069 R&D Projects: GA ČR GA16-12150S Institutional support: RVO:68378271 Keywords : liquid crystals * photosensitivity * bent-core liquid crystals * 3-hydroxybenzoic acid Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 3.108, year: 2016

Applied bioactive polymeric materials

CERN Document Server

Carraher, Charles; Foster, Van

1988-01-01

The biological and biomedical applications of polymeric materials have increased greatly in the past few years. This book will detail some, but not all, of these recent developments. There would not be enough space in this book to cover, even lightly, all of the major advances that have occurred. Some earlier books and summaries are available by two of this book's Editors (Gebelein & Carraher) and these should be consul ted for additional information. The books are: "Bioactive Polymeric Systems" (Plenum, 1985); "Polymeric Materials In Medication" (Plenum, 1985); "Biological Acti vi ties of Polymers" (American Chemical Society, 1982). Of these three, "Bioacti ve Polymeric Systems" should be the most useful to a person who is new to this field because it only contains review articles written at an introductory level. The present book primarily consists of recent research results and applications, with only a few review or summary articles. Bioactive polymeric materials have existed from the creation of life...

Radiation induced emulsion polymerization

International Nuclear Information System (INIS)

Stannett, V.T.; Stahel, E.P.

1990-01-01

High energy radiation is particularly favored for the initiation of emulsion polymerization. The yield of free radicals, for example, from the radiolysis of the aqueous phase, is high; G(radical) values of 5-7. In addition, the rather special kinetics associated with emulsion polymerization lead, in general, to very large kinetic chain lengths, even with 'non-ideal' monomers such as vinyl acetate. Together, high polymerization rates at low doses become possible. There are some important advantages of radiation polymerization compared with chemical initiators, such as potassium persulfate. Perhaps the most important among them is the temperature independence of the initiation step. This makes low temperature polymerization very accessible. With monomers such as vinyl acetate, where chain termination to monomer is predominant, low temperatures lead to often highly desirable higher molecular weights. With styrene, the classical ideally behaved monomer, there are the advantages such as, for example, the feasibility of using cationic monomers. These and some attendant disadvantages are discussed in detail, including pilot plant studies

Species difference in reactivity to lignin-like enzymatically polymerized polyphenols on interferon-γ synthesis and involvement of interleukin-2 production in mice.

Science.gov (United States)

Yamanaka, Daisuke; Ishibashi, Ken-Ichi; Adachi, Yoshiyuki; Ohno, Naohito

2016-09-01

Recent studies have revealed that lignin-like polymerized polyphenols can activate innate immune systems. In this study, we aimed to evaluate whether these polymerized polyphenols could activate leukocytes from different murine strains. Splenocytes from 12 mouse strains were investigated. Our results revealed species differences in reactivity to phenolic polymers on interferon-γ (IFN-γ) release. Mice that possessed the H2(a) or H2(k) haplotype antigens were the highly responsive strains. To clarify these different points in soluble factors, multiplex cytokine profiling analysis was carried out and we identified interleukin (IL)-2 as a key molecule for IFN-γ induction by polymerized polyphenols. Furthermore, inhibition of IL-2 and IL-2Rα by neutralizing antibodies significantly decreased cytokine production in the highly responsive mice strains. Our results indicate that species difference in reactivity to phenolic polymers is mediated by adequate release of IL-2 and its receptor, IL-2Rα. Copyright © 2016 Elsevier B.V. All rights reserved.

Photosensitive response of azobenzene containing films towards pure intensity or polarization interference patterns

Energy Technology Data Exchange (ETDEWEB)

Yadavalli, Nataraja Sekhar; Santer, Svetlana, E-mail: santer@uni-potsdam.de [Department of Experimental Physics, Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam (Germany); Saphiannikova, Marina [Leibniz Institute of Polymer Research Dresden, 01069 Dresden (Germany)

2014-08-04

In this paper, we report on differences in the response of photosensitive azobenzene containing films upon irradiation with the intensity or polarization interference patterns. Two materials are studied differing in the molecular weight: an azobenzene-containing polymer and a molecular glass formed from a much smaller molecule consisting of three connected azobenzene units. Topography changes occurring along with the changes in irradiation conditions are recorded using a homemade set-up combining an optical part for generation and shaping of interference patterns and an atomic force microscope for acquiring the kinetics of film deformation. In this way, we could reveal the unique behavior of photosensitive materials during the first few minutes of irradiation: the change in topography is initially driven by an increase in the azobenzene free volume along with the trans-cis isomerization, followed by the mass transport finally resulting in the surface relief grating. This study demonstrates the great potential of our setup to experimentally highlight puzzling processes governing the formation of surface relief gratings.

DNA Photosensitization by an "Insider": Photophysics and Triplet Energy Transfer of 5-Methyl-2-pyrimidone Deoxyribonucleoside.

Science.gov (United States)

Bignon, Emmanuelle; Gattuso, Hugo; Morell, Christophe; Dumont, Elise; Monari, Antonio

2015-08-03

The main chromophore of (6-4) photoproducts, namely, 5-methyl-2-pyrimidone (Pyo), is an artificial noncanonical nucleobase. This chromophore has recently been reported as a potential photosensitizer that induces triplet damage in thymine DNA. In this study, we investigate the spectroscopic properties of the Pyo unit embedded in DNA by means of explicit solvent molecular-dynamics simulations coupled to time-dependent DFT and quantum-mechanics/molecular-mechanics techniques. Triplet-state transfer from the Pyo to the thymine unit was monitored in B-DNA by probing the propensity of this photoactive pyrimidine analogue to induce a Dexter-type triplet photosensitization and subsequent DNA damage. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carboxyl-Functionalized Polymeric Microspheres Prepared by One-Stage Photoinitiated RAFT Dispersion Polymerization

Directory of Open Access Journals (Sweden)

Jianbo Tan

2017-12-01

Full Text Available Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT dispersion copolymerization of methyl methacrylate (MMA and methyl methacrylic (MAA for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag composite microspheres were prepared by in situ reduction of AgNO3 using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB with NaBH4 as a reductant.

Modeling and sensitivity analysis of mass transfer in active multilayer polymeric film for food applications

Science.gov (United States)

Bedane, T.; Di Maio, L.; Scarfato, P.; Incarnato, L.; Marra, F.

2015-12-01

The barrier performance of multilayer polymeric films for food applications has been significantly improved by incorporating oxygen scavenging materials. The scavenging activity depends on parameters such as diffusion coefficient, solubility, concentration of scavenger loaded and the number of available reactive sites. These parameters influence the barrier performance of the film in different ways. Virtualization of the process is useful to characterize, design and optimize the barrier performance based on physical configuration of the films. Also, the knowledge of values of parameters is important to predict the performances. Inverse modeling and sensitivity analysis are sole way to find reasonable values of poorly defined, unmeasured parameters and to analyze the most influencing parameters. Thus, the objective of this work was to develop a model to predict barrier properties of multilayer film incorporated with reactive layers and to analyze and characterize their performances. Polymeric film based on three layers of Polyethylene terephthalate (PET), with a core reactive layer, at different thickness configurations was considered in the model. A one dimensional diffusion equation with reaction was solved numerically to predict the concentration of oxygen diffused into the polymer taking into account the reactive ability of the core layer. The model was solved using commercial software for different film layer configurations and sensitivity analysis based on inverse modeling was carried out to understand the effect of physical parameters. The results have shown that the use of sensitivity analysis can provide physical understanding of the parameters which highly affect the gas permeation into the film. Solubility and the number of available reactive sites were the factors mainly influencing the barrier performance of three layered polymeric film. Multilayer films slightly modified the steady transport properties in comparison to net PET, giving a small reduction

Intrinsically photosensitive retinal ganglion cell function in relation to age

DEFF Research Database (Denmark)

Herbst, Kristina; Sander, Birgit; Lund-Andersen, Henrik

2012-01-01

The activity of melanopsin containing intrinsically photosensitive ganglion retinal cells (ipRGC) can be assessed by a means of pupil responses to bright blue (appr.480 nm) light. Due to age related factors in the eye, particularly, structural changes of the lens, less light reaches retina. The aim...... of this study was to examine how age and in vivo measured lens transmission of blue light might affect pupil light responses, in particular, mediated by the ipRGC....

Impact of photosensitized oxidation and singlet oxygen on degradation of stabilized polymers

Czech Academy of Sciences Publication Activity Database

Pospíšil, Jan; Nešpůrek, Stanislav; Pilař, Jan

2008-01-01

Roč. 93, č. 9 (2008), s. 1681-1688 ISSN 0141-3910 R&D Projects: GA AV ČR IAA100100622; GA AV ČR KAN400720701; GA AV ČR IAA400500804 Institutional research plan: CEZ:AV0Z40500505 Keywords : photosensitized oxidation * singlet molecular oxygen * oxygenation Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.320, year: 2008

Synthesis and characterization of hydrophobically modified polymeric betaines

Directory of Open Access Journals (Sweden)

Alexey Shakhvorostov

2015-09-01

Full Text Available Polymeric betaines containing long alkyl chains C12H25, C14H29, C16H33 and C18H37 were synthesized by Michael addition reaction of alkylaminocrotonates and methacrylic acid (MAA. They were characterized by FTIR, 13C NMR, DSC, DLS, GPC, cryo-TEM, viscometry and zeta-potential measurements. The polymers were fully soluble in DMF, THF and DMSO, partially dissolved in aromatic hydrocarbons (benzene, toluene, o-xylene and formed colloid solutions in aqueous KOH. In aqueous KOH and DMSO solutions, hydrophobically modified polymeric betaines behaved as polyelectrolytes. The average hydrodynamic size and zeta potential of diluted aqueous solutions of hydrophobic polybetainess containing dodecyl-, tetradecyl-, hexadecyl-, and octadecyl groups were studied as a function of pH. Anomalous low values of the isoelectric point (IEP of amphoteric macromolecules were found to be in the range of pH 2.7-3.4. According to DLS data, the average size of macromolecules tends to decrease with dilution. Zeta-potential of amphoteric macromolecules in aqueous solution is much higher than that in DMSO. The cryo-TEM results revealed that in both aqueous KOH and DMSO media, the micron- and nanosized vesicles existed. The structural organization of vesicles in water and DMSO is discussed. The wax inhibition effect of hydrophobic polybetaines at a decrease of the pour point temperatures of high paraffinic oils was better in comparison with commercial available ethylene-vinylacetate copolymers (EVA.

"Click" i polymerer 2

DEFF Research Database (Denmark)

Hvilsted, Søren

2012-01-01

"Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer......"Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer...

Decarboxylation of indole-3-acetic acid and inhibition of growth in Avena sativa seedlings by plant-derived photosensitizers

Energy Technology Data Exchange (ETDEWEB)

Brennan, T.M. [Dickinson Coll., Carlisle, PA (United States). Dept. of Biology

1996-12-01

A number of plant phototoxins, when supplemented with UVA (320-400 nm) radiation, are capable of sensitizing the decomposition of indole-3-acetic acid (IAA), as measured by release of {sup 14}CO{sub 2} from carboxyl-labeled IAA. Alpha-terthienyl ({alpha}T) and harmine caused significant rates of IAA decarboxylation at concentrations as low as 1 nM and were approximately 80% as effective as riboflavin and flavin mononucleotide. Partial inhibition by sodium azide indicates that the {alpha}T-induced decarboxylation of IAA is predominately, but not entirely, a type II reaction mediated by singlet oxygen. Based on changes in UV absorption spectra, it appears that the hormones gibberellic acid, abscisic acid and 6-benzylaminopurine (a cytokinin) are less susceptible to photosensitized decomposition than is IAA. Alpha-terthienyl plus UVA also inhibited elongation growth and reduced endogenous IAA levels in Avena sativa L. coleoptile sections and promoted senescence in intact Avena seedlings. These results confirm the alelopathic potential of plant photosensitizers such as {alpha}T and indicate that the phytohormone IAA may represent an additional target for the action of photosensitizers. (Author).

Survey and research on precision polymerization polymeric materials; Seimitsu jugo kobunshi zairyo ni kansuru chosa kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

Survey and research on the precision control of primary structure of polymeric materials and the precision evaluation technology have been conducted to develop advanced polymeric materials. It is proposed that the three basic processes of polymer synthesis, i.e., addition, condensation, and biomimesis, in forming the precision polymerization skeleton are to be covered through a centralized joint research effort with participation of industry, academia, and the government institute and under the leadership of researchers from academic institutions as the team leaders. For the study of technology trends, international conferences held in UK, Germany, and Hawaii are introduced, and domestic meetings, i.e., Annual Polymer Congress and Polymer Conference, are summarized. In addition, Precision Polymerization Forum and International Workshop on Precision Polymerization were held. The basic studies include a quantum-chemical elucidation of the elementary process in polymerization reaction, time-resolved analysis of polymerization process and polymer properties, synthesis of polymers with controlled microstructures by coordination polymerization using metal complexes, synthesis of polymer with controlled microstructures by precision polycondensation, molecular recognition in catalyst-reaction site, and synthesis of imprinting polymers. 246 refs., 117 figs., 14 tabs.

Synthesis of magnetic polymeric microspheres

Energy Technology Data Exchange (ETDEWEB)

Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

2010-05-13

The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

Synthesis of magnetic polymeric microspheres

International Nuclear Information System (INIS)

Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I

2010-01-01

The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

Evaluation of the skin phototoxicity and photosensitivity of honeybee venom.

Science.gov (United States)

Han, Sang Mi; Hong, In Phyo; Woo, Soon Ok; Kim, Se Gun; Jang, He Rye; Park, Kwan Kyu

2017-12-01

Bee (Apis mellifera L.) venom (BV) has been used as a cosmetic ingredient owing to its anti-aging, anti-inflammatory, and antibacterial effects. The aim of this study was to assess the skin safety of BV. For this purpose, skin phototoxicity and sensitization tests were conducted in healthy male Hartley guinea pigs. The animals were divided into three groups (n=5) for the phototoxicity test: G1 (negative control), G2 (BV gel treatment), and G3 (positive control). After specified treatments, the animals were irradiated with ultraviolet A (15 J/cm 2 ). The photosensitivity test was also performed in three groups: G4 (negative control, n=5), G5 (BV gel treatment, n=10), and G6 (positive control, n=5). Erythema and edema were observed after 24, 48, and 72 hours in the positive control group, but not in the negative control and BV gel groups. Application of BV to the guinea pig skin had no toxic effects on any clinical signs, body weight, or mortality. In addition, it did not evoke a skin reaction in both either the skin phototoxicity and skin photosensitization tests. Therefore, it can be concluded that BV has the potential to be developed as a drug ingredient for topical uses. © 2017 The Authors. Journal of Cosmetic Dermatology Published by Wiley Periodicals, Inc.

Polymeric nanoparticle-encapsulated curcumin ("nanocurcumin": a novel strategy for human cancer therapy

Directory of Open Access Journals (Sweden)

Maitra Amarnath

2007-04-01

Full Text Available Abstract Background Curcumin, a yellow polyphenol extracted from the rhizome of turmeric (Curcuma longa, has potent anti-cancer properties as demonstrated in a plethora of human cancer cell line and animal carcinogenesis models. Nevertheless, widespread clinical application of this relatively efficacious agent in cancer and other diseases has been limited due to poor aqueous solubility, and consequently, minimal systemic bioavailability. Nanoparticle-based drug delivery approaches have the potential for rendering hydrophobic agents like curcumin dispersible in aqueous media, thus circumventing the pitfalls of poor solubility. Results We have synthesized polymeric nanoparticle encapsulated formulation of curcumin – nanocurcumin – utilizing the micellar aggregates of cross-linked and random copolymers of N-isopropylacrylamide (NIPAAM, with N-vinyl-2-pyrrolidone (VP and poly(ethyleneglycolmonoacrylate (PEG-A. Physico-chemical characterization of the polymeric nanoparticles by dynamic laser light scattering and transmission electron microscopy confirms a narrow size distribution in the 50 nm range. Nanocurcumin, unlike free curcumin, is readily dispersed in aqueous media. Nanocurcumin demonstrates comparable in vitro therapeutic efficacy to free curcumin against a panel of human pancreatic cancer cell lines, as assessed by cell viability and clonogenicity assays in soft agar. Further, nanocurcumin's mechanisms of action on pancreatic cancer cells mirror that of free curcumin, including induction of cellular apoptosis, blockade of nuclear factor kappa B (NFκB activation, and downregulation of steady state levels of multiple pro-inflammatory cytokines (IL-6, IL-8, and TNFα. Conclusion Nanocurcumin provides an opportunity to expand the clinical repertoire of this efficacious agent by enabling ready aqueous dispersion. Future studies utilizing nanocurcumin are warranted in pre-clinical in vivo models of cancer and other diseases that might benefit

Design and syntheses of MMP inhibitors and photosensitive lipid nanoparticle formulations for drug delivery

Science.gov (United States)

Subramaniam, Rajesh

Drug administration without any compromise to the quality of life and lifespan is the ideal goal for disease management. The molecular mechanisms of several pathologies have shown that site-specific delivery of target-specific drugs seems to be a promising avenue to achieve this goal. This thesis describes the initial steps that we have taken toward that goal. Matrix metalloproteinases (MMPs) are a family of about 23 isozymes in humans that were actively targeted for treating a multitude of pathologies. Clinical studies carried out on cancer patients have revealed the complexity of the working of this enzyme family and necessitated the development of isozyme-specific MMP inhibitors. Our studies toward the development of isozyme-specific inhibitors have resulted in the development of several inhibitors that seem to be selective toward some MMP isozymes. Our understanding on the molecular mechanism that confers this selectivity is documented in this thesis. Another aspect of discussion in the thesis is the development of photosensitive liposomes for drug delivery that could be triggered to release the drug by irradiation with light of appropriate wavelength. Development of such delivery vehicles, in principle, would confer external spatiotemporal control on drug delivery. This could potentially lead to better disease management by minimizing side effects and enhancing patient compatibility. The thesis discusses our attempts toward the development of photosensitive liposomes. These liposomes incorporated a photosensitive lipid (PSL) that would be cleaved upon irradiation with UV light, causing liposomal destabilization and release of the enclosed drug. The discussion includes: (i) the syntheses of the PSLs, (ii) formulation of the photosensitive liposomes that contained a model drug, (iii) light-mediated release of the drug and (iv) the mechanism of photocleavage of the PSL that leads to content release from liposomes. The thesis concludes with suggestions toward the

Plutonium solubilities

International Nuclear Information System (INIS)

Puigdomnech, I.; Bruno, J.

1991-02-01

Thermochemical data has been selected for plutonium oxide, hydroxide, carbonate and phosphate equilibria. Equilibrium constants have been evaluated in the temperature range 0 to 300 degrees C at a pressure of 1 bar to T≤100 degrees C and at the steam saturated pressure at higher temperatures. Measured solubilities of plutonium that are reported in the literature for laboratory experiments have been collected. Solubility data on oxides, hydroxides, carbonates and phosphates have been selected. No solubility data were found at temperatures higher than 60 degrees C. The literature solubility data have been compared with plutonium solubilities calculated with the EQ3/6 geochemical modelling programs, using the selected thermodynamic data for plutonium. (authors)

Synthesis and Anchoring of Antineoplastic Ferrocene and Phthalocyanine Derivatives on Water-Soluble Polymeric Drug Carriers Derived from Lysine and Aspartic Acid

OpenAIRE

Maree, M. David; Neuse, Eberhard W.; Erasmus, Elizabeth; Swarts, Jannie C.

2007-01-01

The general synthetic strategy towards water-soluble biodegradable drug carriers and the properties that they must have are discussed. The syntheses of water-soluble biodegradable copolymers of lysine and aspartic acid as potential drug-delivering devices, having amine-functionalised side chains are then described. Covalent anchoring of carboxylic acid derivatives of the antineoplastic ferrocene and photodynamically active phthalocyanine moieties to the amine-containing drug carrier copolymer...

Investigation of the Effect of Plasma Polymerized Siloxane Coating for Enzyme Immobilization and Microfluidic Device Conception

Directory of Open Access Journals (Sweden)

Kalim Belhacene

2016-12-01

Full Text Available This paper describes the impact of a physical immobilization methodology, using plasma polymerized 1,1,3,3, tetramethyldisiloxane, on the catalytic performance of β-galactosidase from Aspergillus oryzae in a microfluidic device. The β-galactosidase was immobilized by a polymer coating grown by Plasma Enhanced Chemical Vapor Deposition (PEVCD. Combined with a microchannel patterned in the silicone, a microreactor was obtained with which the diffusion through the plasma polymerized layer and the hydrolysis of a synthetic substrate, the resorufin-β-d-galactopyranoside, were studied. A study of the efficiency of the immobilization procedure was investigated after several uses and kinetic parameters of immobilized β-galactosidase were calculated and compared with those of soluble enzyme. Simulation and a modelling approach were also initiated to understand phenomena that influenced enzyme behavior in the physical immobilization method. Thus, the catalytic performances of immobilized enzymes were directly influenced by immobilization conditions and particularly by the diffusion behavior and availability of substrate molecules in the enzyme microenvironment.

NATO Advanced Study Institute on Ring-opening Metathesis Polymerization of Olefins and Polymerization of Alkynes

CERN Document Server

1998-01-01

The first NATO Advanced Study Institute on Olefin Metathesis and Polymerization Catalysts was held on September 10-22, 1989 in Akcay, Turkey. Based on the fundamental research of RRSchrock, RGrubbs and K.B.Wagener in the field of ring opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) and alkyne polymerization, these areas gained growing interest within the last years. Therefore the second NATO-ASI held on metathesis reactions was on Ring Opening Metathesis Po­ lymerization of Olefins and Polymerization of Alkynes on September 3-16, 1995 in Akcay, Turkey. The course joined inorganic, organic and polymer chemists to exchange their knowledge in this field. This volume contains the main and short lectures held in Akcay. To include ADMET reactions better into the title of this volume we changed it into: Metathesis Polymerization of Olefins and Alkyne Polymerization. This volume is addressed to research scientists, but also to those who start to work in the area of olefin metathesis and al...

Quenching of porous silicon photoluminescence by molecular oxygen and dependence of this phenomenon on storing media and method of preparation of pSi photosensitizer

Science.gov (United States)

Balaguer, María; Matveeva, Eugenia

2010-10-01

The quenching of porous silicon photoluminescence (pSi PL) by molecular oxygen has been studied in different storing media in an attempt to clarify the mechanism of the energy transfer from the silicon photosensitizer to the oxygen acceptor. Luminescent materials have been prepared by two methods: electrochemical anodizing and chemical etching. Different structural forms were used: porous layers on silicon wafer and two kinds of differently prepared powder. Dry air and liquid water were employed as storing media; quenching behaviour was under observation until total degradation of quenching properties. Singlet oxygen molecules generation through energy transfer from photoluminescent pSi was the only photosensitizing mechanism observed under dry gas conditions. This PL quenching process was preferentially developed at 760 nm (1.63 eV) that corresponds to the formation of the 1Σ singlet oxygen state. Oxidation of the pSi photosensitizer was the main factor that led to its total deactivation in a time scale of few weeks. Regarding water medium, different photosensitizing behaviour was observed. In watery conditions, two preferred energy levels were found: the one detected in dry gas and another centred at approximately 2.2 eV (550 nm). Formation of reactive oxygen species (ROS) different from singlet oxygen, such as superoxide anion or superoxide radical, can be responsible for the second one. This second quenching process developed gradually after the initial contact of pSi photosensitizer with water and then degraded. The process lasted only several hours. Therefore, functionalization of the pSi photosensitizer is probably required to stabilize its PL and quenching properties in the watery physiological conditions required for biomedical applications.

Quenching of porous silicon photoluminescence by molecular oxygen and dependence of this phenomenon on storing media and method of preparation of pSi photosensitizer

Energy Technology Data Exchange (ETDEWEB)

Balaguer, Maria, E-mail: mabara@itq.upv.e [Technical University of Valencia, Nanophotonics Technology Center (Spain); Matveeva, Eugenia, E-mail: eumat@em-silicon.co [EM-Silicon Nano-Technologies, S.L. (Spain)

2010-10-15

The quenching of porous silicon photoluminescence (pSi PL) by molecular oxygen has been studied in different storing media in an attempt to clarify the mechanism of the energy transfer from the silicon photosensitizer to the oxygen acceptor. Luminescent materials have been prepared by two methods: electrochemical anodizing and chemical etching. Different structural forms were used: porous layers on silicon wafer and two kinds of differently prepared powder. Dry air and liquid water were employed as storing media; quenching behaviour was under observation until total degradation of quenching properties. Singlet oxygen molecules generation through energy transfer from photoluminescent pSi was the only photosensitizing mechanism observed under dry gas conditions. This PL quenching process was preferentially developed at 760 nm (1.63 eV) that corresponds to the formation of the {sup 1{Sigma}} singlet oxygen state. Oxidation of the pSi photosensitizer was the main factor that led to its total deactivation in a time scale of few weeks. Regarding water medium, different photosensitizing behaviour was observed. In watery conditions, two preferred energy levels were found: the one detected in dry gas and another centred at approximately 2.2 eV (550 nm). Formation of reactive oxygen species (ROS) different from singlet oxygen, such as superoxide anion or superoxide radical, can be responsible for the second one. This second quenching process developed gradually after the initial contact of pSi photosensitizer with water and then degraded. The process lasted only several hours. Therefore, functionalization of the pSi photosensitizer is probably required to stabilize its PL and quenching properties in the watery physiological conditions required for biomedical applications.

Evaluation of polymeric PLGA nanoparticles conjugated to curcumin for use in aPDT

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Renata Celi Carvalho de Souza Pietra

2017-07-01

Full Text Available ABSTRACT Antimicrobial photodynamic therapy (aPDT involves the association of a photosensitizing agent with a light source with the goal of causing apoptosis or microbial lysing. The use of compounds with natural active principles is gaining prominence throughout the world. Several studies from groups that are linked to the development of innovations in the pharmaceutical market have used natural dyes, such as curcumin, the efficacy of which has been demonstrated in aPDT trials. Difficulties related to physicochemical stability, solubility and cell penetration are some of the challenges associated with this field. The present work aimed to prepare, investigate the characteristics and improve the photodynamic activity of PLGA-based nanoparticles loaded with curcumin for use in aPDT therapy. Using the simple technique of emulsion during the evaporation of a solvent, the particles were built, characterized and tested against microorganisms with importance for medicine and dentistry. The results revealed that the particles were able to protect the curcumin against degradation and eliminate some microorganism species at nanomolar concentrations.

UV-induced reaction kinetics in dilinoleoylphosphatidylcholine monolayers with incorporated photosensitizers

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DEJAN MARKOVIC

2006-04-01

Full Text Available Mixed insoluble monolayers (Langmuir films of 1,2-di-O-linoleoyl-3-sn-phosphatidylcholine (1,2-DLPC and incorporated benzophenone-type photosensitizers at an air-water interface were exposed to prolonged UV-irradiation. The irradiation was initiated at a particular fixed molecular packing value. Changes of the surface pressure during the UV-induced photolysis of the sensitizers were plotted against the irradiation time and the results were interpreted in terms of themolecular lipid / sensitizer ratios inside the monolayers.

Investigating Photosensitized Properties of Natural Organic Matter and Effluent Organic Matter

KAUST Repository

Niu, Xi-Zhi

2013-05-01

The photosensitized processes significantly enhance photolysis of various chemicals in the aqueous system with dissolved organic matter (DOM) as sensitizer. The excitation of chromophores on the DOM molecule further generates reactive species as triplet states DOM, singlet oxygen, hydroxyl radical, carbonate radical etc. We investigated the photosensitization properties of Beaufort Fulvic Acid, Suwannee River Fulvic Acid, South Platte River Fulvic Acid, and Jeddah wastewater treatment plant effluent organic matter with a sunlight simulator. DOM photochemical properties were characterized by observing their performances in 3DOM*, singlet oxygen, hydroxyl radical production with indirect probing protocols. Sensitized degradation of 0.1 μM and 0.02 μM 2, 4, 6- Trimethylphenol exhibited higher pseudo-first-order rate constant than that of 10 μM. Pre-irradiated DOMs were found to be depressed in photochemical properties. Photolysis of 5 different contaminants: ibuprofen, bisphenol A, acetaminophen, cimetidine, and caffeine were found to be enhanced in the presence of sensitizers. The possible reaction pathways were revealed. Long time irradiance induced change in contaminants degradation kinetics in some DOM solutions, which was proposed to be due to the irradiation initiated indirect transformation of DOMs. Key Words: Photolysis Dissolved Organic Matter, Triplet State DOM, Singlet Oxygen, Hydroxyl Radical, Contaminants Degradation.

Polymeric hydrogels containing complexant agents for retention of pollutants containing thorium

International Nuclear Information System (INIS)

Oliveira, Maria Jose A.; Carreiro, Julio C.; Parra, Duclerc F.; Lugao, Ademar B.

2005-01-01

The hydrogels of poly(N-vinyl-2-pyrrolidone) (PVP), constituted of around 90% of water , show properties of retaining great amount of water and consequently can also retain substances that were made soluble, with either particular or specific reactive properties. In the light of this, these matrixes can be used as support for both capture and retention of radioactive substances of contaminated surfaces. Modified hydrogels containing complexant agents had been obtained in solution, in order to capture contaminated substances. The study of the ionizing radiation effect in polymer is of great interest not only to the development of materials which operate in conditions of radiation but also to the usage of the technique with purpose of both polymeric structure modification and acquisition of new materials. Membranes of hydrogels have been obtained with poly(N-vinyl-2-pyrrolidone)-PVP, polyethyleneglycol (PEG), Agar and several concentrations of ethylenediaminetetraacetic acid (EDTA), and sodium citrate. Theses samples were irradiated in 60 Co source, 15 kGy/h dose and submitted to thermal characterization in a Mettler-Toledo SDTA/851 equipment. The hydrogels membranes polymerized by radiation were put in contact with thorium nitrate solution, dehydrated and calcined, after that their ashes were analyzed. In the case of solution containing thorium were analyzed by spectrophotometric. (author)

Raman and fluorescence microscopy to study the internalization and dissolution of photosensitizer nanoparticles into living cells

Science.gov (United States)

Scalfi-Happ, Claudia; Steiner, Rudolf; Wittig, Rainer; Graefe, Susanna; Ryabova, Anastasia; Loschenov, Victor

2015-07-01

In this present study we applied Raman and fluorescence microscopy to investigate the internalisation, cellular distribution and effects on cell metabolism of photosensitizer nanoparticles for photodynamic therapy in fibroblasts and macrophages.

RAFT polymerization mediated bioconjugation strategies

OpenAIRE

Bulmuş, Volga

2011-01-01

This review aims to highlight the use of RAFT polymerization in the synthesis of polymer bioconjugates. It covers two main bioconjugation strategies using the RAFT process: (i) post-polymerization bioconjugations using pre-synthesized reactive polymers, and (ii) bioconjugations via in situ polymerization using biomolecule-modified monomers or chain transfer agents. © 2011 The Royal Society of Chemistry.

In vitro assessment of skin sensitization, photosensitization and phototoxicity potential of commercial glyphosate-containing formulations.

Science.gov (United States)

de Ávila, Renato Ivan; Teixeira, Gabriel Campos; Veloso, Danillo Fabrini Maciel Costa; Moreira, Larissa Cleres; Lima, Eliana Martins; Valadares, Marize Campos

2017-12-01

This study evaluated the applicability of a modified Direct Peptide Reactivity Assay (DPRA) (OECD N° 442C, 2015) through the 10-fold reduction of reaction volume (micro-DPRA, mDPRA) for skin sensitization evaluation of six commercial glyphosate-containing formulations. In addition, another modification of DPRA was proposed by adding a UVA (5J/cm 2 ) irradiation step, namely photo-mDPRA, to better characterize (photo)sensitizer materials. The phototoxicity profile of pesticides was also evaluated using the 3T3 Neutral Red Uptake Phototoxicity Test (3T3-NRU-PT) (OECD N° 432, 2004). The mDPRA could represent an environmentally acceptable test approach, since it reduces costs and organic waste. Peptide depletion was greater in photo-mDPRA and changed the reactivity class of each test material, in comparison to mDPRA. Thus, the association of mDPRA with photo-mDPRA was better for correctly characterizing human (photo)sensitizer substances and pesticides. In general, cysteine depletion was greater than that of lysine for all materials tested in both mDPRA and photo-mDPRA. Furthermore, while 3T3-NRU-PT is unable to predict (photo)sensitizers, it was capable of correctly identifying the phototoxic potential of the tested agrochemical formulations. In conclusion, mDPRA plus photo-mDPRA and 3T3-NRU-PT seem to be preliminary non-animal test batteries for skin (photo)sensitization/phototoxicity assessment of chemicals, agrochemical formulations and their ingredients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Packaging based on polymeric materials

Directory of Open Access Journals (Sweden)

Jovanović Slobodan M.

2005-01-01

Full Text Available In the past two years the consumption of common in the developed countries world wide (high tonnage polymers for packaging has approached a value of 50 wt.%. In the same period more than 50% of the packaging units on the world market were made of polymeric materials despite the fact that polymeric materials present 17 wt.% of all packaging materials. The basic properties of polymeric materials and their environmental and economical advantages, providing them such a position among packaging materials, are presented in this article. Recycling methods, as well as the development trends of polymeric packaging materials are also presented.

High-Efficiency Iron Photosensitizer Explained with Quantum Wavepacket Dynamics

DEFF Research Database (Denmark)

Pápai, Mátyás Imre; Vankó, György; Rozgonyi, Tamas

2016-01-01

designed to destabilize the MC states. Using first-principles quantum nuclear wavepacket simulations we achieve a detailed understanding of the photoexcited decay mechanism, demonstrating that it is dominated by an ultrafast intersystem crossing from 1MLCT–3MLCT proceeded by slower kinetics associated...... with the conversion into the 3MC states. The slowest component of the 3MLCT decay, important in the context of photosensitizers, is much longer than related Fe(II) complexes because the population transfer to the 3MC states occurs in a region of the potential where the energy gap between the 3MLCT and 3MC states...

Pronounced photosensitivity of molecular [Ru(bpy)2(OSO)]+ solutions based on two photoinduced linkage isomers.

Science.gov (United States)

Dieckmann, Volker; Eicke, Sebastian; Rack, Jeffrey J; Woike, Theo; Imlau, Mirco

2009-08-17

Photosensitive properties of [Ru(bpy)(2)(OSO)] PF(6) dissolved in propylene carbonate originating from photoinduced linkage isomerism have been studied by temperature and exposure dependent transmission and UV/Vis absorption spectroscopy. An exceeding photochromic photosensitivity of S = (63 +/- 10) x 10(3) cm l J(-1) mol(-1) is determined. It is attributed to a maximum population of 100% molecules in the photoinduced isomers, a unique absorption cross section per molecule and a very low light exposure of Q(0) = (0.25 +/- 0.03) Ws cm(-2) for isomerism. Relaxation studies of O-bonded to S-bonded isomers at different temperatures verify the existence of two distinct structures of linkage isomers determined by the activation energies of E(A,1) = (0.76 +/- 0.08) eV and E(A,2) = (1.00 +/- 0.14) eV.

Targeted two-photon PDT photo-sensitizers for the treatment of subcutaneous tumors

Science.gov (United States)

Spangler, C. W.; Rebane, A.; Starkey, J.; Drobizhev, M.

2009-06-01

New porphyrin-based photo-sensitizers have been designed, synthesized and characterized that exhibit greatly enhanced intrinsic two-photon absorption. These new photo-sensitizers have been incorporated into triad formulations that also incorporate Near-infrared (NIR) imaging agents, and small-molecule targeting agents that direct the triads to cancerous tumors' over-expressed receptor sites. PDT can be initiated deep into the tissue transparency window at 780-800 nm utilizing a regeneratively amplified Ti:sapphire laser using 100-150 fs pulses of 600-800 mW. Human tumor xenografts of human breast cancer (MDA-MB-231) and both small SCLC (NCI-H69) and NSCLC (A-459) have been successfully treated using octreotate targeting of over-expressed SST2 receptors. In particular, the lung cancer xenografts can be successfully treated by irradiating from the side of the mouse opposite the implanted tumor, thereby passing through ca. 2 cm of mouse skin, tissue and organs with no discernible damage to healthy tissue while causing regression in the tumors. These results suggest a new PDT paradigm for the noninvasive treatment of subcutaneous tumors, including the possibility that the targeting moiety could be matched to individual patient genetic profiles (patient-specific therapeutics).

Combination of photosensitive elements for use in radiography

International Nuclear Information System (INIS)

Bollen, R.H.; Vandenabeele, H.

1976-01-01

A new and improved combination of photosensitive elements is proposed that can be used in radiography. The combination according to the invention is composed of an X-ray fluorescence intensifying screen and a photographic halide of silver containing a color coupler. The color coupler causes a negative silver image and a color image to be formed in the material. The fluorescent layer of the fluorescence screen contains a mixture of lanthanum oxychloride or lanthanum oxybromide activated with terbium or terbium and ytterbium. Detailed information about variants in the composition of the fluorescent substance, the grain sizes of the silver halides, variations of the color couplers and about the coating of the single layers is given. (UWI) [de

Photosensitizers from Spirulina for Solar Cell

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Liqiu Wang

2014-01-01

Full Text Available Spirulina is a kind of blue-green algae with good photosynthetic efficiency and might be used for photovoltaic power generation. So this paper used living spirulina as novel photosensitizer to construct spirulina biosolar cell. The results showed that spirulina had the photoelectric conversion effect, and could let the spirulina biosolar cell have 70 μA photocurrent. Meanwhile, adding glucose sucrose or chitosan in the spirulina anode chamber, they could make the maxima current density of the cell greatly increased by 80 μA, 100 μA, and 84 μA, respectively, and the sucrose could improve the maximum power density of the cell to 63 mW/m−2. Phycobiliprotein played an important role in the photosynthesis of spirulina. So in this paper phycobiliprotein was extracted from spirulina to composite with squaraine dye to sensitize nanocrystalline TiO2 photoanode for building dye sensitized solar cell, and the photoelectric properties of the cell also were investigated.

FLUORESCENT DIAGNOSTICS OF MALIGNANT SKIN TUMORS WITH CHLORIN SERIES PHOTOSENSITIZERS

Directory of Open Access Journals (Sweden)

E. V. Yaroslavtseva-Isaeva

2018-01-01

Full Text Available The article shows possibilities in fluorescence imaging of malignant skin tumors with chlorin series photosensitizers (PS photolon and fotoditazin. The regularities of photosensitizer accumulation from the data of local fluorescence spectroscopy depending on the PS and its dose, the clinical picture and the histological form of the malignant skin neoplasm is investigated. It is shown that the level and selectivity of PS accumulation in the tumor focus depends on the PS dose. In studies on 10 patients with basal cell skin cancer after the introduction of fotoditazin at a dose less than 1 mg/kg, fluorescent contrast between tumor and healthy tissue varied between 1.3 and 9.5, the average was 2.8±0.3; for patients who had the administered fotoditazin dose of 1 mg/kg, fluorescent contrast was 2.9±0.4, varying from 1.4 to 5. In a study with 127 patients after the introduction of photolon in the dose of 0.7-1 mg/kg, the average value of the fluorescence intensity in relative units in the intact skin was 6.9±0.3 (min 4.6, max 12.2, at a dose of 1.1 to 1.4 mg/kg – 8.0±0.3 (min 4.6, max 12.5, at a dose of 1.5-2 mg/kg – 9.9±0.7 (min 5.7, max 20.3. It is also shown that fluorescence intensity of malignant neoplasm of the skin with the same dose of the photosensitizer depends on the neoplasm’s clinical and histological forms. So, 3 hours after the introduction of photolon at a dose of 1.3 mg/kg the average fluorescent contrast in the surface type of skin cancer was 2.7±0.5, in the nodal form – 2.3±0.2, in erosive-ulcerative form – 3.6±0.3. In patients with nodular form of squamous skin cancer after the introduction of photolon at a dose of 1.3 mg/kg fluorescent contrast was significantly higher (p<0.05 (average of 2.8±0.2 than in the nodular form of basal cell carcinoma after the introduction of photolon at the same dose (average of 2.1±0.2.

Sonolytic and Silent Polymerization of Methacrlyic Acid Butyl Ester Catalyzed by a New Onium Salt with bis-Active Sites in a Biphasic System — A Comparative Investigation

Directory of Open Access Journals (Sweden)

Perumberkandgai A. Vivekanand

2013-02-01

Full Text Available Currently, ingenious new analytical and process experimental techniques which are environmentally benign techniques, viz., ultrasound irradiation, have become immensely popular in promoting various reactions. In this work, a novel soluble multi-site phase transfer catalyst (PTC viz., 1,4-bis-(propylmethyleneammounium chloridebenzene (BPMACB was synthesized and its catalytic efficiency was assessed by observing the kinetics of sonolytic polymerization of methacrylic acid butyl ester (MABE using potassium persulphate (PPS as an initiator. The ultrasound–multi-site phase transfer catalysis (US-MPTC-assisted polymerization reaction was compared with the silent (non-ultrasonic polymerization reaction. The effects of the catalyst and various reaction parameters on the catalytic performance were in detail investigated by following the kinetics of polymerization of MABE in an ethyl acetate-water biphasic system. From the detailed kinetic investigation we propose a plausible mechanism. Further the kinetic results demonstrate clearly that ultrasound-assisted phase-transfer catalysis significantly increased the reaction rate when compared to silent reactions. Notably, this environmentally benign and cost-effective process has great potential to be applied in various polymer industries.

Area-selective atomic layer deposition of platinum using photosensitive polyimide.

Science.gov (United States)

Vervuurt, René H J; Sharma, Akhil; Jiao, Yuqing; Kessels, Wilhelmus Erwin M M; Bol, Ageeth A

2016-10-07

Area-selective atomic layer deposition (AS-ALD) of platinum (Pt) was studied using photosensitive polyimide as a masking layer. The polyimide films were prepared by spin-coating and patterned using photolithography. AS-ALD of Pt using poly(methyl-methacrylate) (PMMA) masking layers was used as a reference. The results show that polyimide has excellent selectivity towards the Pt deposition, after 1000 ALD cycles less than a monolayer of Pt is deposited on the polyimide surface. The polyimide film could easily be removed after ALD using a hydrogen plasma, due to a combination of weakening of the polyimide resist during Pt ALD and the catalytic activity of Pt traces on the polyimide surface. Compared to PMMA for AS-ALD of Pt, polyimide has better temperature stability. This resulted in an improved uniformity of the Pt deposits and superior definition of the Pt patterns. In addition, due to the absence of reflow contamination using polyimide the nucleation phase during Pt ALD is drastically shortened. Pt patterns down to 3.5 μm were created with polyimide, a factor of ten smaller than what is possible using PMMA, at the typical Pt ALD processing temperature of 300 °C. Initial experiments indicate that after further optimization of the polyimide process Pt features down to 100 nm should be possible, which makes AS-ALD of Pt using photosensitive polyimide a promising candidate for patterning at the nanoscale.

Chelating polymeric membranes

KAUST Repository

Peinemann, Klaus-Viktor

2015-01-22

The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

Processing and characterization of yttrium-stabilized zirconia thin films on polyimide from aqueous polymeric precursors

International Nuclear Information System (INIS)

Gorman, B.P.; Anderson, H.U.

2004-01-01

Low-temperature deposition of dense, nanocrystalline yttrium-stabilized zirconia (YSZ) thin films on polyimide (PI) substrates is illustrated using an aqueous polymeric precursor spin-coating technique. The polymeric precursor uses low-cost materials, is water-soluble and the viscosity and cation concentrations can be easily adjusted in order to vary the film thickness from 0.02 to 0.3 μm. Due to the use of water as the solvent in the YSZ precursor and the hydrophobic nature of the PI surface, surface modification processes were utilized in order to improve the wetting characteristics. Surface modification of PI substrates using wet chemical and oxygen plasma techniques led to a decrease in the precursor contact angle, and ultimately allowed for uniform film formation on both bulk and thin film PI substrates. Scanning electron microscopy, transmission electron microscopy and UV/Vis absorption illustrate that near full-density nanocrystalline thin films of YSZ can be produced at temperatures as low as 350 deg. C. Thermogravimetric analyses illustrate that the PI substrate does not undergo any weight loss up to these temperatures

Photovoltaic performance of TiO2 electrode adsorbed with gardenia yellow purified by nonionic polymeric sorbent in dye-sensitized solar cells.

Science.gov (United States)

Kwon, Oh Oun; Kim, Eui Jin; Lee, Jae Hyeok; Kim, Tae Young; Park, Kyung Hee; Kim, Sang Yook; Suh, Hwa Jin; Lee, Hyo Jung; Lee, Jae Wook

2015-02-05

To improve the photovoltaic conversion efficiency in dye-sensitized solar cells (DSSCs), TiO2 electrode adsorbed with gardenia yellow purified by nonionic polymeric sorbent was successfully formulated on nanoporous TiO2 surface. Adsorption and desorption properties of crude gardenia yellow solution on a macroporous resin, XAD-1600, were investigated to purify gardenia yellow because of its strong adsorption and desorption abilities as well as high selectivity. To this end, adsorption equilibrium and kinetic data were measured and fitted using adsorption isotherms and kinetic models. Adsorption and desorption breakthrough curves in a column packed with XAD-1600 resin was obtained to optimize the separation process of gardenia yellow. The photovoltaic performance of the photo-electrode adsorbed with the crude and purified gardenia yellow in DSSCs was compared from current-voltage measurements. The results showed that the photovoltaic conversion efficiency was highly dependent on how to separate and purify gardenia yellow as a photosensitizer. Copyright © 2014 Elsevier B.V. All rights reserved.

Issues concerning the determination of solubility products of sparingly soluble crystalline solids. Solubility of HfO2(cr)

International Nuclear Information System (INIS)

Rai, Dhanpat; Kitamura, Akira; Rosso, Kevin M.; Sasaki, Takayuki; Kobayashi, Taishi

2016-01-01

Solubility studies were conducted with HfO 2 (cr) solid as a function HCl and ionic strength ranging from 2.0 to 0.004 mol kg -1 . These studies involved (1) using two different amounts of the solid phase, (2) acid washing the bulk solid phase, (3) preheating the solid phase to 1400 C, and (4) heating amorphous HfO 2 (am) suspensions to 90 C to ascertain whether the HfO 2 (am) converts to HfO 2 (cr) and to determine the solubility from the oversaturation direction. Based on the results of these treatments it is concluded that the HfO 2 (cr) contains a small fraction of less crystalline, but not amorphous, material [HfO 2 (lcr)] and this, rather than the HfO 2 (cr), is the solubility-controlling phase in the range of experimental variables investigated in this study. The solubility data are interpreted using both the Pitzer and SIT models and they provide log 10 K 0 values of -(59.75±0.35) and -(59.48±0.41), respectively, for the solubility product of HfO 2 (lcr)[HfO 2 (lcr) + 2H 2 O ↔ Hf 4+ + 4OH - ]. The log 10 of the solubility product of HfO 2 (cr) is estimated to be < -63. The observation of a small fraction of less crystalline higher solubility material is consistent with the general picture that mineral surfaces are often structurally and/or compositionally imperfect leading to a higher solubility than the bulk crystalline solid. This study stresses the urgent need, during interpretation of solubility data, of taking precautions to make certain that the observed solubility behavior for sparingly-soluble solids is assigned to the proper solid phase.

Functionalization and Polymerization on the CNT Surfaces

KAUST Repository

Albuerne, Julio

2013-07-01

In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

Influence of red laser irradiation and photosensitizers Photoditazine and Dimegin on the growth of methicillin-resistant strain of Staphylococcus aureus

Science.gov (United States)

Brill, G. E.; Egorova, A. V.; Bugaeva, I. O.; Tuchina, E. S.; Morozov, O. A.; Ponomaryov, G. V.; Ushakova, O. V.

2017-03-01

The influence of red laser irradiation on the growth of colonies of methicillin-resistant strain of Staphylococcus aureus and photodynamic effects of the photosensitizers Photoditazine and Dimegin were performed. It was established that the red semiconductor laser (λ - 660 nm, 100 mW/cm2) at 10-, 15- and 30-mins exposure, has a direct bacteriostatic action on the growth of S. aureus. Pre-treatment of bacterial cells by Photoditazine significantly enhances the inhibitory effect. The photosensitizing action of Dimegin does not appear at influence on methicillin-resistant S. aureus.

Comparative Study on Dispersion and Interfacial Properties of Single Walled Carbon Nanotube/Polymer Composites Using Hansen Solubility Parameters

DEFF Research Database (Denmark)

Ma, Jing; Larsen, Mikael

2013-01-01

fabricated by solution blending 1 wt % SWNTs with various modification (nonmodified, nitric acid functionalized, and amine functionalized SWNTs) and three kinds of polymeric materials (polycarbonate, polyvinylidene fluoride, and epoxy). Chemical compatibilities between SWNTs and solvents or polymers...... are calculated by the Hansen solubility parameters (HSP) method. The dispersion of the SWNTs in solvents is evaluated by dynamic light scattering. The dispersion of SWNTs in polymers evaluated by a light optical microscope (LOM) generally agrees with the HSP prediction. The strain transfer from the matrix...

Nanoporous Polymeric Grating-Based Biosensors

KAUST Repository

Gao, Tieyu; Hsiao, Vincent; Zheng, Yue Bing; Huang, Tony Jun

2012-01-01

We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

Nanoporous Polymeric Grating-Based Biosensors

KAUST Repository

Gao, Tieyu

2012-05-02

We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

Photosensitive interaction of RSU 1069 with DNA

Energy Technology Data Exchange (ETDEWEB)

Edwards, D.I.; Knox, R.J.; Skolimowski, I.M.; Zahoor, A.; Knight, R.C.

1984-08-01

RSU 1069 is a 2-nitroimidazole radiosensitizer with an aziridine-containing side chain. In light (360 nm) the absorbance maximum of the nitro group at 325 nm disappears, which is accompanied by expulsion of the nitro group as the nitrite ion. This photosensitive effect was used to determine separately the damage of DNA induced by the reduced nitro group and the alkylating property of the aziridine. The aziridine-induced DNA damage is maximized in the dark when the nitro group is either absent (electrolytically reduced prior to the addition of DNA) or non functional (unreduced). In the light, damage is reduced. Typical DNA damage includes helix disruption leading to single strand breaks and the release of thymidine. Alkaline filter elution studies show evidence only for strand breakage and none for cross-linking indicating the drug is capable of mono-functional alkylation only.

Photosensitive interaction of RSU 1069 with DNA

International Nuclear Information System (INIS)

Edwards, D.I.; Knox, R.J.; Skolimowski, I.M.; Zahoor, A.; Knight, R.C.

1984-01-01

RSU 1069 is a 2-nitroimidazole radiosensitizer with an aziridine-containing side chain. In light (360 nm) the absorbance maximum of the nitro group at 325 nm disappears, which is accompanied by expulsion of the nitro group as the nitrite ion. This photosensitive effect was used to determine separately the damage of DNA induced by the reduced nitro group and the alkylating property of the aziridine. The aziridine-induced DNA damage is maximized in the dark when the nitro group is either absent (electrolytically reduced prior to the addition of DNA) or non functional (unreduced). In the light, damage is reduced. Typical DNA damage includes helix disruption leading to single strand breaks and the release of thymidine. Alkaline filter elution studies show evidence only for strand breakage and none for cross-linking indicating the drug is capable of mono-functional alkylation only

Nanobody Based Immunoassay for Human Soluble Epoxide Hydrolase Detection Using Polymeric Horseradish Peroxidase (PolyHRP) for Signal Enhancement: The Rediscovery of PolyHRP?

Science.gov (United States)

Li, Dongyang; Cui, Yongliang; Morisseau, Christophe; Gee, Shirley J; Bever, Candace S; Liu, Xiangjiang; Wu, Jian; Hammock, Bruce D; Ying, Yibin

2017-06-06

Soluble epoxide hydrolase (sEH) is a potential pharmacological target for treating hypertension, vascular inflammation, cancer, pain, and multiple cardiovascular related diseases. A variable domain of the heavy chain antibody (termed single domain antibody (sdAb), nanobody, or VHH) possesses the advantages of small size, high stability, ease of genetic manipulation, and ability for continuous manufacture, making such nanobody a superior choice as an immunoreagent. In this work, we developed an ultrasensitive nanobody based immunoassay for human sEH detection using polymeric horseradish peroxidase (PolyHRP) for signal enhancement. Llama nanobodies against human sEH were used as the detection antibody in sandwich enzyme linked immunosorbent assays (ELISA) with polyclonal anti-sEH as the capture antibody. A conventional sandwich ELISA using a horseradish peroxidase (HRP) labeled anti-hemeagglutinin (HA) tag as the tracer showed a marginal sensitivity (0.0015 optical density (OD)·mL/ng) and limit of detection (LOD) of 3.02 ng/mL. However, the introduction of the PolyHRP as the tracer demonstrated a 141-fold increase in the sensitivity (0.21 OD·mL/ng) and 57-fold decrease in LOD (0.05 ng/mL). Systematic comparison of three different tracers in four ELISA formats demonstrated the overwhelming advantage of PolyHRP as a label for nanobody based immunoassay. This enhanced sEH immunoassay was further evaluated in terms of selectivity against other epoxide hydrolases and detection of the target protein in human tissue homogenate samples. Comparison with an enzyme activity based assay and a Western blot for sEH detection reveals good correlation with the immunoassay. This work demonstrates increased competiveness of nanobodies for practical sEH protein detection utilizing PolyHRP. It is worthwhile to rediscover the promising potential of PolyHRP in nanobody and other affinity based methods after its low-profile existence for decades.

PERMEABILITY, SOLUBILITY, AND INTERACTION OF HYDROGEN IN POLYMERS- AN ASSESSMENT OF MATERIALS FOR HYDROGEN TRANSPORT

Energy Technology Data Exchange (ETDEWEB)

Kane, M

2008-02-05

Fiber-reinforced polymer (FRP) piping has been identified as a leading candidate for use in a transport system for the Hydrogen Economy. Understanding the permeation and leakage of hydrogen through the candidate materials is vital to effective materials system selection or design and development of safe and efficient materials for this application. A survey of the literature showed that little data on hydrogen permeation are available and no mechanistically-based models to quantitatively predict permeation behavior have been developed. However, several qualitative trends in gaseous permeation have been identified and simple calculations have been performed to identify leakage rates for polymers of varying crystallinity. Additionally, no plausible mechanism was found for the degradation of polymeric materials in the presence of pure hydrogen. The absence of anticipated degradation is due to lack of interactions between hydrogen and FRP and very low solubility coefficients of hydrogen in polymeric materials. Recommendations are made to address research and testing needs to support successful materials development and use of FRP materials for hydrogen transport and distribution.

Design and Synthesis of Self-Assembled Polymeric Nanoparticles for Cancer Drug Delivery

Science.gov (United States)

Logie, Jennifer

Current chemotherapeutics are plagued by poor solubility and selectivity, requiring toxic excipients in formulations and causing a number of dose limiting side effects. Nanoparticle delivery has emerged as a strategy to more effectively deliver chemotherapeutics to the tumour site. Specifically, polymeric micelles enable the solubilization of hydrophobic small molecule drugs within the core and mitigate the necessity of excipients. Notwithstanding the significant progress made in polymeric micelle delivery, translation is limited by poor stability and low drug loading. In this work, a rational design approach is used to chemically modify poly(D,L-lactide-co-2-methyl-2-carboxytrimethylene carbonate)-graft-poly(ethylene glycol) (P(LA-co-TMCC)-g-PEG) in order to overcome these limitations and effectively deliver drug to tumours. The PEG density of the polymer system was optimized to enhance the stability of our polymeric micelles. Higher PEG densities permitted the lyophilization of micelles and enhanced the serum stability of the system. To increase the drug loading of our system, we facilitated specific intermolecular interactions within the micelle core. For drugs that form colloidal aggregates, such as pentyl-PABC doxazolidine, polymers were used to stabilize the colloidal core against aggregation and protein adsorption. For more challenging molecules, where self-assembly cannot be controlled, such as docetaxel, we modified the polymeric backbone with a peptide from the binding site of the drug to achieve loadings five times higher than those achieved in conventional micelle systems. This novel docetaxel nanoparticle was assessed in vivo in an orthotopic mouse model of breast cancer, where it showed a wider therapeutic index than the conventional ethanolic polysorbate 80 formulation. The improved tolerability of this formulation enabled higher dosing regimens and led to heightened efficacy and survival in this mouse model. Combined, these studies validated P

Bright, water-soluble CeF{sub 3} photo-, cathodo-, and X-ray luminescent nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Clement, Sandhya; Deng, Wei; Drozdowicz-Tomsia, Krystyna; Liu, Deming [Macquarie University, Centre for Nanoscale BioPhotonics, Department of Physics and Astronomy (Australia); Zachreson, Cameron [University of Technology Sydney, School of Physics and Advanced Materials (Australia); Goldys, Ewa M., E-mail: ewa.goldys@mq.edu.au [Macquarie University, Centre for Nanoscale BioPhotonics, Department of Physics and Astronomy (Australia)

2015-01-15

Bright, water-soluble CeF{sub 3} nanoparticles with small size and narrow size distribution have been synthesized using a simple co-precipitation method without any ligands. Size control of nanoparticles from 13 ± 2 to 9 ± 2 nm was achieved by varying the reaction time. Colloidal properties have been found to vary with pH and, independently, with dilution. The photoluminescence of the as-synthesized nanoparticles shows a highly photostable UV/Visible fluorescence band due to allowed 5d–4f transitions, also observed in the X-ray luminescence spectrum. This band is suitable for X-ray excitation of a range of photosensitizers. The photoluminescence quantum yield of nanoparticles was also determined to be 31 %. Using the measured fluorescence decay time of 25 ns, the radiative lifetime of Ce in CeF{sub 3} was found to be 80.6 ns. Both photoluminescence and cathodoluminescence emission are affected by the reaction time and measurement temperature. Electron-beam-induced defect annealing is also observed.

Low-resistivity photon-transparent window attached to photo-sensitive silicon detector

International Nuclear Information System (INIS)

Holland, S.E.

2000-01-01

The invention comprises a combination of a low resistivity, or electrically conducting, silicon layer that is transparent to long or short wavelength photons and is attached to the backside of a photon-sensitive layer of silicon, such as a silicon wafer or chip. The window is applied to photon sensitive silicon devices such as photodiodes, charge-coupled devices, active pixel sensors, low-energy x-ray sensors and other radiation detectors. The silicon window is applied to the back side of a photosensitive silicon wafer or chip so that photons can illuminate the device from the backside without interference from the circuit printed on the frontside. A voltage sufficient to fully deplete the high-resistivity photosensitive silicon volume of charge carriers is applied between the low-resistivity back window and the front, patterned, side of the device. This allows photon-induced charge created at the backside to reach the front side of the device and to be processed by any circuitry attached to the front side. Using the inventive combination, the photon sensitive silicon layer does not need to be thinned beyond standard fabrication methods in order to achieve full charge-depletion in the silicon volume. In one embodiment, the inventive backside window is applied to high resistivity silicon to allow backside illumination while maintaining charge isolation in CCD pixels

Solution Properties of Water-Soluble “Smart” Poly(N-acryloyl-N′-ethyl piperazine-co-methyl methacrylate

Directory of Open Access Journals (Sweden)

G. Roshan Deen

2012-01-01

Full Text Available Water-soluble copolymers of N-acryloyl-N′-ethylpiperazine (AcrNEP with methyl methacrylate (MMA were synthesized to high conversion by free-radical solution polymerization. The composition of the copolymers was determined using Fourier Transform Infra-red Spectroscopy (FTIR. Copolymers containing AcrNEP content above 44 mol% were readily soluble in water and exhibited the critical solution temperature behavior. The copolymers were strongly responsive to changes in pH of the external medium due to the presence of tertiary amine functions that could be protonated at low pH. The influence of various factors such as copolymer composition, pH, temperature, salt and surfactant concentration on the LCST of the copolymers were systematically studied. The intrinsic viscosity of the copolymers in dimethyl formamide decreased with increase in temperature due to a decrease in thermodynamic affinity between polymer chains and solvent molecules. The viscosity behavior of the copolymers in sodium chloride solution was similar to that of classical polyelectrolytes and hydrophobically modified polyacrylate systems.

Preparation and Characterization of Water-Soluble Chitosan Microparticles Loaded with Insulin Using the Polyelectrolyte Complexation Method

International Nuclear Information System (INIS)

Wu, S.; Tao, Y.; Zhang, H.; Su, Z.

2011-01-01

Polymeric delivery systems based on microparticles have emerged as a promising approach for peroral insulin delivery. The amount of insulin was quantified by the improved Bradford method. It was shown that water-soluble chitosan/insulin/tripolyphosphate (TPP) mass ratio played an important role in microparticles formation. Stable, uniform, and spherical water-soluble chitosan microparticles (WSC-MPs) with high insulin association efficiency were formed at or close to optimized WSC/insulin/TPP mass ratio. WSC-MPs had higher association efficiency in the ph 4.0 and ph 9.7 of TPP solution. The results showed that association efficiency and loading capacity of insulin-loaded WSC-MPs prepared in 0.01 mol/L HCl of insulin were 48.28 ± 0.90% and 9.52 ± 1.34%. The average size of insulin-loaded WSC-MPs was 292 nm. The presented WSC microparticulate system has promising properties towards the development of an oral delivery system for insulin

Polymer-free nanofibers from vanillin/cyclodextrin inclusion complexes: high thermal stability, enhanced solubility and antioxidant property.

Science.gov (United States)

Celebioglu, Asli; Kayaci-Senirmak, Fatma; İpek, Semran; Durgun, Engin; Uyar, Tamer

2016-07-13

Vanillin/cyclodextrin inclusion complex nanofibers (vanillin/CD-IC NFs) were successfully obtained from three modified CD types (HPβCD, HPγCD and MβCD) in three different solvent systems (water, DMF and DMAc) via an electrospinning technique without using a carrier polymeric matrix. Vanillin/CD-IC NFs with uniform and bead-free fiber morphology were successfully produced and their free-standing nanofibrous webs were obtained. The polymer-free CD/vanillin-IC-NFs allow us to accomplish a much higher vanillin loading (∼12%, w/w) when compared to electrospun polymeric nanofibers containing CD/vanillin-IC (∼5%, w/w). Vanillin has a volatile nature yet, after electrospinning, a significant amount of vanillin was preserved due to complex formation depending on the CD types. Maximum preservation of vanillin was observed for vanillin/MβCD-IC NFs which is up to ∼85% w/w, besides, a considerable amount of vanillin (∼75% w/w) was also preserved for vanillin/HPβCD-IC NFs and vanillin/HPγCD-IC NFs. Phase solubility studies suggested a 1 : 1 molar complexation tendency between guest vanillin and host CD molecules. Molecular modelling studies and experimental findings revealed that vanillin : CD complexation was strongest for MβCD when compared to HPβCD and HPγCD in vanillin/CD-IC NFs. For vanillin/CD-IC NFs, water solubility and the antioxidant property of vanillin was improved significantly owing to inclusion complexation. In brief, polymer-free vanillin/CD-IC NFs are capable of incorporating a much higher loading of vanillin and effectively preserve volatile vanillin. Hence, encapsulation of volatile active agents such as flavor, fragrance and essential oils in electrospun polymer-free CD-IC NFs may have potential for food related applications by integrating the particularly large surface area of NFs with the non-toxic nature of CD and inclusion complexation benefits, such as high temperature stability, improved water solubility and an enhanced

Designing materials for advanced microelectronic patterning applications using controlled polymerization RAFT technology

Science.gov (United States)

Sheehan, Michael T.; Farnham, William B.; Chambers, Charles R.; Tran, Hoang V.; Okazaki, Hiroshi; Brun, Yefim; Romberger, Matthew L.; Sounik, James R.

2011-04-01

Reversible Addition Fragmentation Chain Transfer (RAFT) polymerization technology enables the production of polymers possessing low polydispersity (PD) in high yield for many applications. RAFT technology also enables control over polymer architecture. With synthetic control over these polymer characteristics, a variety of polymers can be designed and manufactured for use in advanced electronic applications. By matching the specific RAFT reagent and monomer combinations, we can accommodate monomer reactivity and optimize acrylate or methacrylate polymerizations (193 and 193i photoresist polymers) or optimize styrenic monomer systems (248 nm photoresist polymers) to yield polymers with PD as low as 1.05. For 193i lithography, we have used RAFT technology to produce block copolymers comprising of a random "resist" block with composition and size based on conventional dry photoresist materials and a "low surface energy" block The relative block lengths and compositions may be varied to tune solution migration behavior, surface energy, contact angles, and solubility in developer. Directed self assembly is proving to be an interesting and innovative method to make 2- and even 3-dimensional periodic, uniform patterns. Two keys to acceptable performance of directed self assembly from block copolymers are the uniformity and the purity of the materials will be discussed.

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer against Pseudomonas aeruginosa PAO1

DEFF Research Database (Denmark)

Orlandi, Viviana Teresa; Rybtke, Morten; Caruso, Enrico

2014-01-01

Photodynamic therapy (PDT) combines the use of organic dyes (photosensitizers, PSs) and visible light in order to elicit a photo-oxidative stress which causes bacterial death. GD11, a recently synthesized PS belonging to the boron-dipyrromethene (BODIPY) class, was demonstrated to be efficient...

Occipital epilepsy versus progressive myoclonic epilepsy in a patient with continuous occipital spikes and photosensitivity in electroencephalogram: A case report.

Science.gov (United States)

Lv, Yudan; Zhang, Nan; Liu, Chang; Shi, Mingchao; Sun, Li

2018-04-01

Progressive myoclonic epilepsy (PME) is rare epilepsy syndrome. Although EEG is a useful neurophysiological technique in the evaluation of epilepsy, few EEG abnormalities have been described in PME. So, how to use EEG hints to establish the suspected diagnosis of PME as soon as possible should be addressed. We presented a case with refractory myoclonic seizures, and progressive neurological deterioration, diagnosed as PME and neuronal ceroid lipofuscinosis disease by gene testing. The patient manifested with a significant regression in her speech ability and motor balance. The mini-mental state examination showed poor scores of 15/30. The magnetic resonance imaging showed diffused atrophy. Her EEG showed slow background with continuous occipital small spikes and photosensitivity. The following genetic testing with mutation in CLN6 confirmed the diagnosis and excluded the occipital epilepsy. Our case showed rare manifestations and special EEG features of PME, which may be confused with occipital epilepsy or photosensitive epilepsy. Thus, if the continuous occipital spikes and photosensitivity were presented in a patient with refractory seizures and developmental regression, PME should be considered.

KINETICS OF SUSPENDED EMULSION POLYMERIZATION OF METHYL METHACRYLATE

Institute of Scientific and Technical Information of China (English)

Yong-zhong Bao; Cheng-xi Wang; Zhi-ming Huang; Zhi-xue Weng

2004-01-01

The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of MMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (Rp0) and steady-state polymerization rate (Rp) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: Rp0 ∝ [I]0.73[S]0.32 and Rp ∝ [I]0.71[S]0.23. The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methyl methacrylate) decreased as the polymerization temperature, [I] and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.

Amphiphilic polymeric micelles originating from 1,4-β-D-glucan-g-polyphenylene oxide as the carriers for delivery of docetaxel and the corresponding release behaviors.

Science.gov (United States)

Yang, Fang; Xiao, Dan; Han, Huaxin; Chen, Yuhuan; Li, Gang

2018-07-15

A novel amphiphilic polymeric drug carrier was synthesized through grafting polymerization of water-soluble 1,4-β-D-glucan from cotton cellulose tailored and polypropylene oxide (PPO), and then use thereof to synthesize graft copolymer 1,4-β-D-glucan-PPO-docetaxel (DTX). The products were characterized by FTIR, 1 H NMR, and 13 C NMR. The physicochemical characteristics of 1,4-β-D-glucan-PPO and 1,4-β-D-glucan-PPO-DTX such as molecular weight distribution (MWD), micro-morphology, size, critical micelle concentration (CMC), aggregation number of micelle (N), in vitro stability and drug pharmacokinetic study in vivo were investigated. The results reveal that the degree of polymerization (DP) of the water-soluble 1,4-β-D-glucan from cotton cellulose tailored is equal to 7; the 1,4-β-D-glucan-PPO surfactant possesses good surface activity while the adduct number of propylene oxide reaches appropriately to 20; the DTX is completely dispersed in water medium with 1,4-β-D-glucan-PPO-DTX micelle and the drug conjugated percent is up to 40.3%; In vitro study confirms that 1,4-β-D-glucan-PPO-DTX has the capacity for sustained drug release; In plasma, 1,4-β-D-glucan-PPO-DTX exhibits a significantly enhanced C max , AUC (0-t) and T 1/2 compared with DTX. These results demonstrate that 1,4-β-D-glucan-PPO has the potential to be used as a novel biocompatible biomaterial for drug delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

Single Molecule Atomic Force Microscopy Studies of Photosensitized Singlet Oxygen Behavior on a DNA Origami Template

DEFF Research Database (Denmark)

Helmig, Sarah Wendelboe; Rotaru, Alexandru; Arian, Dumitru

2010-01-01

DNA origami, the folding of a long single-stranded DNA sequence (scaffold strand) by hundreds of short synthetic oligonucleotides (staple strands) into parallel aligned helices, is a highly efficient method to form advanced self-assembled DNA-architectures. Since molecules and various materials can...... be conjugated to each of the short staple strands, the origami method offers a unique possibility of arranging molecules and materials in well-defined positions on a structured surface. Here we combine the action of light with AFM and DNA nanostructures to study the production of singlet oxygen from a single...... photosensitizer molecule conjugated to a selected DNA origami staple strand on an origami structure. We demonstrate a distance-dependent oxidation of organic moieties incorporated in specific positions on DNA origami by singlet oxygen produced from a single photosensitizer located at the center of each origami....

Issues concerning the determination of solubility products of sparingly soluble crystalline solids. Solubility of HfO{sub 2}(cr)

Energy Technology Data Exchange (ETDEWEB)

Rai, Dhanpat [Rai Enviro-Chem, LLC, Yachats, OR (United States); Kitamura, Akira [Japan Atomic Energy Agency, Ibaraki (Japan); Rosso, Kevin M. [Pacific Northwest National Laboratory, Richland, WA (United States); Sasaki, Takayuki; Kobayashi, Taishi [Kyoto Univ. (Japan)

2016-11-01

Solubility studies were conducted with HfO{sub 2}(cr) solid as a function HCl and ionic strength ranging from 2.0 to 0.004 mol kg{sup -1}. These studies involved (1) using two different amounts of the solid phase, (2) acid washing the bulk solid phase, (3) preheating the solid phase to 1400 C, and (4) heating amorphous HfO{sub 2}(am) suspensions to 90 C to ascertain whether the HfO{sub 2}(am) converts to HfO{sub 2}(cr) and to determine the solubility from the oversaturation direction. Based on the results of these treatments it is concluded that the HfO{sub 2}(cr) contains a small fraction of less crystalline, but not amorphous, material [HfO{sub 2}(lcr)] and this, rather than the HfO{sub 2}(cr), is the solubility-controlling phase in the range of experimental variables investigated in this study. The solubility data are interpreted using both the Pitzer and SIT models and they provide log{sub 10} K{sup 0} values of -(59.75±0.35) and -(59.48±0.41), respectively, for the solubility product of HfO{sub 2}(lcr)[HfO{sub 2}(lcr) + 2H{sub 2}O ↔ Hf{sup 4+} + 4OH{sup -}]. The log{sub 10} of the solubility product of HfO{sub 2}(cr) is estimated to be < -63. The observation of a small fraction of less crystalline higher solubility material is consistent with the general picture that mineral surfaces are often structurally and/or compositionally imperfect leading to a higher solubility than the bulk crystalline solid. This study stresses the urgent need, during interpretation of solubility data, of taking precautions to make certain that the observed solubility behavior for sparingly-soluble solids is assigned to the proper solid phase.

SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

Institute of Scientific and Technical Information of China (English)

Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

2000-01-01

Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

Photosensitizer conjugated iron oxide nanoparticles for simultaneous in vitro magneto-fluorescent imaging guided photodynamic therapy.

Science.gov (United States)

Nafiujjaman, Md; Revuri, Vishnu; Nurunnabi, Md; Cho, Kwang Jae; Lee, Yong-Kyu

2015-04-04

In this study, photosensitizer conjugated iron oxide nanoparticles were strategically designed and prepared for simultaneous PDT and dual-mode fluorescence/MR imaging. The MRI contrast agent Fe3O4 was modified by APTES to functionalize the surface and further to link with heparin-pheophorbide-A conjugates.

Inflation of a Polymeric Menbrane

DEFF Research Database (Denmark)

Kristensen, Susanne B.; Larsen, Johannes R.; Hassager, Ole

1998-01-01

We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane.......We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane....

Blazed vector gratings fabricated using photosensitive polymer liquid crystals and control of polarization diffraction

Science.gov (United States)

Ono, Hiroshi; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro

2014-03-01

The blazed vector grating possessing antisymmetric distributions of the birefringence were fabricated by exposing the line-focused linearly polarized ultraviolet light on the photosensitive polymer liquid crystals. The polarization states of the diffraction beams can be highly and widely controlled by designing the blazed structures, and the diffraction properties were well-explained by Jones calculus.

Fungicidal response of a novel natural photosensitizer (Beta vulgaris) on Candida albicans with low-power laser radiation

International Nuclear Information System (INIS)

Mittal, Subhangi; Srivastava, J N; Roy, Sukhdev

2013-01-01

We report the efficacy of an aqueous extract of Beta vulgaris as a novel, natural photosensitizer for use in photodynamic therapy against Candidiasis disease. This study evaluates the effect of different laser wavelengths (He–Ne: 633 nm, Nd-YAG: 532 nm), power (17, 27 mW) and duration of exposure (5, 10, 15 min) in combination with the Beta vulgaris natural photosensitizer on the viability of Candida albicans causing Candidiasis disease. Although inhibition was observed in all cases, a maximum of 51.91% inhibition takes place with the combination of Beta vulgaris exposed to 532 nm at 27 mW for 15 min by the Agar well diffusion method. The study is important in optimizing different parameters and designing a low-power, compact, non-invasive and portable device for treatment. (paper)

Gas solubilities widespread applications

CERN Document Server

Gerrard, William

1980-01-01

Gas Solubilities: Widespread Applications discusses several topics concerning the various applications of gas solubilities. The first chapter of the book reviews Henr's law, while the second chapter covers the effect of temperature on gas solubility. The third chapter discusses the various gases used by Horiuti, and the following chapters evaluate the data on sulfur dioxide, chlorine data, and solubility data for hydrogen sulfide. Chapter 7 concerns itself with solubility of radon, thoron, and actinon. Chapter 8 tackles the solubilities of diborane and the gaseous hydrides of groups IV, V, and

Primary mechanisms of photosensitization by furocoumarins

International Nuclear Information System (INIS)

Grossweiner, L.I.

1981-01-01

A proper understanding of the PUVA therapy action mechanism requires the synthesis of concepts developed at the level of molecules, single cells and whole organisms. Although progress has been made in identifying key factors within each level of organization, the interrelationships remain obscure. Important unanswered questions at the molecular and cellular levels include: (1) Which excited states of the furocoumarin in molecule (triplet or excited singlet) are involved in the formation of DNA monoadducts, and the conversion of monoadducts to cross-links. (2) How does the spectrum of the incident radiation affect the distribution of the initial photochemical products from the PUVA sensitizers. (3) What are the relative contributions of furocoumarin-DMA monoadducts, furocoumarin-DNA cross-links and singlet oxygen to mutagenesis and lethality in cells, at the furocoumarin and UV-A dose levels corresponging to PUVA therapy. Additional information about these key aspects of furocoumarin photosensitization should lead to a more definitive relationship of the cellular level events to the endpoints observed with PUVA therapy, and suggest directions for potential improvements in the current clinical procedures

Comparison of photosensitivity in germanium doped silica fibers using 244 nm and 266 nm continuous wave lasers

DEFF Research Database (Denmark)

Jensen, Jesper Bo; Varming, Poul; Liu, B.

2001-01-01

Diode pumped continuous-wave UV lasers offer an interesting alternative to frequency doubled argon-ion lasers. We report the first photosensitivity comparison using these lasers on deuterium loaded standard telecommunication fibers and unloaded experimental fibers....

Optimum modality for photodynamic therapy of tumors: gels containing liposomes with hydrophobic photosensitizers

Czech Academy of Sciences Publication Activity Database

Nekvasil, Miloš; Zadinová, M.; Tahotná, Ludmila; Žáčková, Markéta; Poučková, P.; Ježek, Petr

2007-01-01

Roč. 68, č. 5 (2007), s. 235-252 ISSN 0272-4391 R&D Projects: GA MŠk 1P04OE152; GA MPO 2A-1TP1/026; GA MZd NC6564 Institutional research plan: CEZ:AV0Z50110509 Keywords : photodynamic therapy of tumors * liposomal photosensitizer gel * hydroxyl-aluminium phtalocyanine * microfluidizacion Subject RIV: FD - Oncology ; Hematology Impact factor: 0.976, year: 2007

Polymeric membrane materials for artificial organs.

Science.gov (United States)

Kawakami, Hiroyoshi

2008-01-01

Many polymeric materials have already been used in the field of artificial organs. However, the materials used in artificial organs are not necessarily created with the best material selectivity and materials design; therefore, the development of synthesized polymeric membrane materials for artificial organs based on well-defined designs is required. The approaches to the development of biocompatible polymeric materials fall into three categories: (1) control of physicochemical characteristics on material surfaces, (2) modification of material surfaces using biomolecules, and (3) construction of biomimetic membrane surfaces. This review will describe current issues regarding polymeric membrane materials for use in artificial organs.

High Vacuum Techniques for Anionic Polymerization

KAUST Repository

Ratkanthwar, Kedar

2015-09-01

Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

THE EFFECTS OF N-2-HYDROXYETHYL-N-METHYL-P-TOLUIDINE ON METHYL METHACRYLATE RADICAL POLYMERIZATION AND ACRYLONITRILE PHOTOINDUCED POLYMERIZATION

Institute of Scientific and Technical Information of China (English)

QIU Kunyuan; ZHANG Zhanghua; FENG Xinde

1992-01-01

The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.

A novel photosensitization treatment for the inactivation of fungal spores and cells mediated by curcumin.

Science.gov (United States)

Al-Asmari, Fahad; Mereddy, Ram; Sultanbawa, Yasmina

2017-08-01

The global concerns regarding the emergence of fungicide-resistant strains and the impact of the excessive use of fungicidal practises on our health, food, and environment have increased, leading to a demand for alternative clean green technologies as treatments. Photosensitization is a treatment that utilises a photosensitiser, light and oxygen to cause cell damage to microorganisms. The effect of photosensitization mediated by curcumin on Aspergillus niger, Aspergillus flavus, Penicillium griseofulvum, Penicillium chrysogenum, Fusarium oxysporum, Candida albicans and Zygosaccharomyces bailii was investigated using three methods. The viability of spores/cells suspended in aqueous buffer using different concentrations of curcumin solution (100-1000μM) and light dose (0, 24, 48, 72 and 96J/cm 2 ) were determined. Spraying curcumin solution on inoculated surfaces of agar plates followed by irradiation and soaking spores/cells in curcumin solution prior to irradiation was also investigated. In aqueous mixtures, photosensitised spores/cells of F. oxysporum and C. albicans were inhibited at all light doses and curcumin concentrations, while inactivation of A. niger, A. flavus P. griseofulvum, P. chrysogenum and Z. bailii were highly significant (Pcurcumin at 800μM showed complete inhibition for A. niger, F. oxysporum, C. albicans and Z. bailii, while A. flavus P. griseofulvum, and P. chrysogenum reduced by 75%, 80.4% and 88.5% respectively. Soaking spores/cells with curcumin solution prior to irradiation did not have a significant effect on the percentage reduction. These observations suggest that a novel photosensitization mediated curcumin treatment is effective against fungal spores/cells and the variation of percentage reduction was dependent on curcumin concentration, light dosage and fungal species. Copyright © 2017 Elsevier B.V. All rights reserved.

Olefin polymerization from single site catalysts confined within porous media

Science.gov (United States)

Kasi, Rajeswari M.

Single Site Catalysts (SSCs) have been utilized for olefin polymerization. Altering the metal-ligand architecture in the SSCs, polyolefin properties can be enhanced in a rational manner. This influence of the ligands in the SSC on the property of polyolefins prepared can be referred to as the primary ligand influence. Extending this understanding and subsequent control of the metal-ligand framework to the interaction of SSCs within organic and inorganic supports is vital for the synthesis of polyolefins with tailored properties. The motivation behind this thesis was to explore the support influence on the reactivity of the SSC tethered to a support matrix during ethylene homo and copolymerization. In order to address this question of the support influence on the final polyolefin properties, synthetic routes to covalently bind SSCs on different matrices have been explored. Two distinct supported SSCs have been used to prepare branched polyethylenes. Branched polyethylenes can be prepared by either copolymerization (ethylene and alpha-olefin) or oligomerization/copolymerization processes (ethylene and in situ generated alpha-olefin). Synthetic routes to prepare precursor catalysts to Constrained Geometry Catalysts (CGCs) by silyl elimination chemistry have been developed (Chapter 2). Efficient synthetic protocols to assemble CGCs on aminomethylpolysytrene matrices (Chapter 3) and amine-functionalized mesoporous silica (Chapter 4) are also reported. These supported catalysts, with appropriate cocatalysts have been used to prepare ethylene homo and copolymers, the polymer thermal properties and microstructures were analyzed by various analytical techniques. Branched polyethylenes (LLDPE) can be prepared by copolymerization chemistry. It has been observed is that the influence of the support is seen in the production of lower crystalline forms of high density polyethylene (HDPE, 20--50% crystalline), while homogeneous polymerization of analogous soluble CGCs afford HDPE

Photodynamic therapy of cancer with the photosensitizer PHOTOGEM

Science.gov (United States)

Sokolov, Victor V.; Chissov, Valery I.; Filonenko, E. V.; Sukhin, Garry M.; Yakubovskaya, Raisa I.; Belous, T. A.; Zharkova, Natalia N.; Kozlov, Dmitrij N.; Smirnov, V. V.

1995-01-01

The first clinical trials of photodynamic therapy (PDT) in Russia were started in P. A. Hertzen Moscow Research Oncology Institute in October of 1992. Up to now, 61 patients with primary or recurrent malignant tumors of the larynx (3), trachea (1), bronchus (11), nose (1), mouth (3), esophagus (12), vagina and uterine cervix (3), bladder (2), skin (6), and cutaneous and subcutaneous metastases of breast cancer and melanomas (6) have been treated by PDT with the photosensitizer Photogem. At least partial tumor response was observed in all of the cases, but complete remission indicating no evident tumors has been reached in 51% of the cases. Among 29 patients with early and first stage cancer 14 patients had multifocal tumors. Complete remission of tumors in this group reached 86%.

Multilayer photosensitive structures based on porous silicon and rare-earth-element compounds: Study of spectral characteristics

Energy Technology Data Exchange (ETDEWEB)

Kirsanov, N. Yu.; Latukhina, N. V., E-mail: natalat@yandex.ru; Lizunkova, D. A.; Rogozhina, G. A. [Samara National Research University (Russian Federation); Stepikhova, M. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2017-03-15

The spectral characteristics of the specular reflectance, photosensitivity, and photoluminescence (PL) of multilayer structures based on porous silicon with rare-earth-element (REE) ions are investigated. It is shown that the photosensitivity of these structures in the wavelength range of 0.4–1.0 μm is higher than in structures free of REEs. The structures with Er{sup 3+} ions exhibit a luminescence response at room temperature in the spectral range from 1.1 to 1.7 μm. The PL spectrum of the erbium impurity is characterized by a fine line structure, which is determined by the splitting of the {sup 4}I{sub 15/2} multiplet of the Er{sup 3+} ion. It is shown that the structures with a porous layer on the working surface have a much lower reflectance in the entire spectral range under study (0.2–1.0 μm).

Riboflavin photosensitized oxidation of myoglobin.

Science.gov (United States)

Grippa, Juliana M; de Zawadzki, Andressa; Grossi, Alberto B; Skibsted, Leif H; Cardoso, Daniel R

2014-02-05

The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O₂, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation of MbFe(II)O₂ by ³Rib is (3.0 ± 0.5) × 10⁹ L·mol⁻¹·s⁻¹ and (3.1 ± 0.4) × 10⁹ L·mol⁻¹·s⁻¹ for MbFe(III) in phosphate buffer of pH 7.4 at 25 °C as determined by laser flash photolysis. The high rates are rationalized by ground state hydrophobic interactions as detected as static quenching of fluorescence from singlet-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K(a) = (1.2 ± 0.2) × 10⁴ mol·L⁻¹ with ΔH° = -112 ± 22 kJ·mol⁻¹ and ΔS° = -296 ± 75 J·mol⁻¹·K⁻¹. For meat, riboflavin is concluded to be a photosensitizer for protein oxidation but not for discoloration.

Fabrication of an inexpensive photosensitive flow through device for turbidity measurement

International Nuclear Information System (INIS)

Morco, Ryan P.; Dawal, Micah S.; Sucgang, Raymond J.

2014-01-01

The aim of this study is the construction of a portable, simple to use, on-line photosensitive device which measures turbidity in water. The turbidity measuring device uses a light emitting diode, LED, light source shining on a light dependent resistor, LDR, which is connected in series to a circuit supplying a constant voltage and a digital voltmeter, DVM. Light shine through a tube containing the sample, and onto a photosensitive circuit. A clear tube of water is the BLANK and has zero absorbance. A fraction of the incident light that i obstructed by the turbidity of the sample can be used for calculable determination of turbidity in water. The turbidity is related to the absorbance reading, following Beer's law. The amount of incident and transmitted light are expressed in voltage units, by a voltmeter. The sample is delivered into the sampling chamber by a rubber tubing attached to a power head submersible pump which is immersed in the pool of water to be sampled. The instrument shows excellent response over the range o turbidity values (5NTU to 180 NTU). Linearity (R 2= 0.95) has been achieved using the device, working with 6 trials per particular NTU value. The NTU readings of the urbidity meter were calibrated against solutions of varying NTU's measured using a HORIBA multi-parameter probe. The other features of the device include: simplicity of operation, low-cost, rugged, handy and can be used in on-line and flow mode applications. (author)

Characterization behavior of some polymeric composite ion exchangers

International Nuclear Information System (INIS)

El-Zahhar, A.A; Ahdel-Aziz, H.M.; Siyam, T.

2005-01-01

Polymeric composite resins were prepared by template polymerization process in aqueous solution. Thermogravimetric analysis (TGA), differential thermal analysis (DTA) and The X-ray diffraction patterns (XRD) were performed to evaluate the physico chemical properties of the different polymeric composite resins. The TGA and DTA clarify high thermal stability of prepared polymeric composite resins. XRD of prepared polymeric composite shows that there is crystalline structure of some resins while other are amorphous one

Nanoparticles from a controlled polymerization process

International Nuclear Information System (INIS)

Tirumala, V.R.; Caneba, G.T.; Dar, Y.; Wang, H.-H.; Mancini, D.C.

2003-01-01

Free-radical retrograde precipitation polymerization process in the past has shown excellent control characteristics over reaction rate, molecular weight, and in the entrapment of live radicals for the generation of block copolymers. The same principle has now been extended to study the reaction confinement to a nanoscale region. Nanosized polymer particles have been reported to form from block copolymers, conventional precipitation polymerization methods, or through emulsion polymerization approaches. In this work, we present a new method of generating nanosized polymer particles by polymerizing the monomer in an environment that precipitates the polymer above the lower critical solution temperature. The nanoparticles have been characterized by both tapping-mode atomic force microscopy observations and in situ synchrotron time-resolved small-angle X-ray scattering analysis. The results from both the techniques showed the formation of nanoparticles in the size range of 15-30 nm, directly from the polymerization process.

Fabrication of ridge waveguide structure from photosensitive TiO2/ormosil hybrid films by using an ultraviolet soft imprint technique

International Nuclear Information System (INIS)

Zhang, Xuehua; Que, Wenxiu; Chen, Jing; Gao, Tianxi; Hu, Jiaxing; Liu, Weiguo

2013-01-01

Photosensitive TiO 2 /organically modified silane hybrid films were prepared by combining a low-temperature sol–gel process with a spin-coating technique. Optical properties and photochemical activities of the as-prepared hybrid sol–gel films under different UV irradiation time were characterized and monitored by prism coupling technique, UV–visible spectroscopy, and Fourier transform infrared spectroscopy. Surface morphology of the hybrid films was also observed by an atomic force microscopy. Advantages for fabrication of ridge waveguide structure based on the photosensitive hybrid films were demonstrated by an ultraviolet soft imprint technique. Effects of imprint force, imprint time, and UV irradiation time on high replication fidelity of the ridge waveguide structure were also investigated. An altitude replication fidelity of 99.7% can be obtained when the imprint force of 2 MPa, imprint time of 30 min and UV irradiation time of 45 min were chosen. Scanning electron microscopy and surface profiler were used to characterize the morphological and surface profile properties of the as fabricated ridge waveguide structure. Results indicate that the as-prepared photosensitive hybrid materials have great applicability for the fabrication of micro-optical elements and advantage as the imprint layer under the ultraviolet soft imprint technique. - Highlights: ► Photosensitive TiO 2 /ormosil hybrid film is prepared by a sol–gel process. ► Optical properties of the films change a little with UV exposure time. ► Photo-chemical property of the film changes a lot with UV exposure time. ► The imprint force and time, and the UV exposure time affect the imprint fidelity. ► A fidelity value of 99.7% is obtained under an optimized condition

Synthesis of imine bond containing insoluble polymeric ligand and its transition metal complexes, structural characterization and catalytic activity on esterification reaction.

Science.gov (United States)

Gönül, İlyas; Ay, Burak; Karaca, Serkan; Saribiyik, Oguz Yunus; Yildiz, Emel; Serin, Selahattin

2017-01-01

In this study, synthesis of insoluble polymeric ligand (L) and its transition metal complexes [Cu(L)Cl 2 ]·2H 2 O (1) , [Co(L)Cl 2 (H 2 O) 2 ] (2) and [Ni(L)Cl 2 (H 2 O) 2 ] (3) , having the azomethine groups, were synthesized by the condensation reactions of the diamines and dialdehydes. The structural properties were characterized by the analytical and spectroscopic methods using by elemental analysis, Fourier Transform Infrared, Thermo Gravimetric Analysis, Powder X-ray Diffraction, magnetic susceptibility and Inductively Coupled Plasma. The solubilities of the synthesized polymeric materials were also investigated and found as insoluble some organic and inorganic solvents. Additionally, their catalytic performance was carried out for the esterification reaction of acetic acid and butyl acetate. The highest conversion rate is 75.75% by using catalyst 1 . The esterification of butanol gave butyl acetate with 100% selectivity.

Peptide block copolymers by N-carboxyanhydride ring-opening polymerization and atom transfer radical polymerization: The effect of amide macroinitiators

NARCIS (Netherlands)

Habraken, G.J.M.; Koning, C.E.; Heise, A.

2009-01-01

The synthesis of polypeptide-containing block copolymers combining N-carboxyanhydride (NCA) ring-opening polymerization and atom transfer radical polymerization (ATRP) was investigated. An amide initiator comprising an amine function for the NCA polymerization and an activated bromide for ATRP was

Cell-specific and pH-sensitive nanostructure hydrogel based on chitosan as a photosensitizer carrier for selective photodynamic therapy.

Science.gov (United States)

Belali, Simin; Karimi, Ali Reza; Hadizadeh, Mahnaz

2018-04-15

The major problems of porphyrins as promising materials for photodynamic therapy (PDT) are their low solubility, subsequently aggregation in biological environments, and a lack of tumor selectivity. With this in mind, a chitosan-based hydrogel conjugated with tetrakis(4-aminophenyl)porphyrin (NH 2 -TPP) and 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine (TRIPOD) via Schiff base linkage, functionalized with folate was designed and synthesized as a pH-sensitive, self-healable and injectable targeted PS delivery system. This new hydrogel was characterized by FT-IR, 1 H NMR, SEM, UV-vis, fluorescence spectroscopy and zeta potential. Formation of imine bonds with the aldehyde group of TRIPOD and amine group of NH 2 -TPP and chitosan, as a dynamic connection, was approved by rheological analysis. Spectroscopic characterizations revealed that aggregation of porphyrin in aqueous media was eliminated due to diminished π stacking interaction of porphyrin in 3D cross-linked hydrogel structure. Hydrogel 3D microporous structure efficiently transfers the excitation energy to the porphyrin unit, yielding improvement singlet oxygen releases. Cytotoxicity and phototoxicity analysis of the CS/NH 2 -TPP/FA hydrogels indicating an excellent capability to kill cancer cells selectively and prevent damage to normal cells. This work presents a new and efficient model for the preparation of highly efficient and targeting photosensitizer delivery system. Copyright © 2018. Published by Elsevier B.V.

Cascading of molecular logic gates for advanced functions: a self-reporting, activatable photosensitizer.

Science.gov (United States)

Erbas-Cakmak, Sundus; Akkaya, Engin U

2013-10-18

Logical progress: Independent molecular logic gates have been designed and characterized. Then, the individual molecular logic gates were coerced to work together within a micelle. Information relay between the two logic gates was achieved through the intermediacy of singlet oxygen. Working together, these concatenated logic gates result in a self-reporting and activatable photosensitizer. GSH=glutathione. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Natural evolution from idiopathic photosensitive occipital lobe epilepsy to idiopathic generalized epilepsy in an untreated young patient.

Science.gov (United States)

Bonini, Francesca; Egeo, Gabriella; Fattouch, Jinan; Fanella, Martina; Morano, Alessandra; Giallonardo, Anna Teresa; di Bonaventura, Carlo

2014-04-01

Idiopathic photosensitive occipital lobe epilepsy (IPOE) is an idiopathic localization-related epilepsy characterized by age-related onset, specific mode of precipitation, occipital photic-induced seizures--frequently consisting of visual symptoms--and good prognosis. This uncommon epilepsy, which usually starts in childhood or adolescence, has rarely been observed in families in which idiopathic generalized epilepsy also affects other members. We describe a nuclear family in which the proband showed electro-clinical features of idiopathic photosensitive occipital lobe epilepsy in childhood, which subsequently evolved into absences and a single generalized tonico-clonic seizure in early adolescence. His mother had features suggestive of juvenile myoclonic epilepsy. This case illustrates a continuum between focal and generalized entities in the spectrum of the so-called idiopathic (genetically determined) epileptic syndromes. Copyright © 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Improvement of dissolution behavior of poorly water soluble drugs by biodegradable polymeric submicron carriers containing sparingly methylated β-cyclodextrin.

Science.gov (United States)

Singhavi, Dilesh J; Khan, Shagufta; Yeole, Pramod G

2013-04-01

The objective of this study was to develop submicron carriers of two drugs that are practically insoluble in water, i.e. meloxicam and aceclofenac, to improve their dissolution behavior. The phase solubility of the drugs was studied using different concentrations of sparingly methylated β-cyclodextrin, Kleptose(®) Crysmeβ (Crysmeb), in the presence and absence of 0.2 % w/v water-soluble chitosan. Drug-loaded submicron particles (SMPs) were prepared using chitosan chlorhydrate and Crysmeb by the ionotropic gelation method. The SMPs were characterized in terms of powder X-ray diffraction, Fourier transforms infrared spectroscopy, size determination, process yield, drug loading, encapsulation efficiency, surface morphology and in vitro release. The drug loading in the SMPs was enhanced in the presence of Crysmeb. The in vitro drug release was found to be enhanced with SMPs prepared using higher concentrations of Crysmeb. These results indicate that SMPs formed from chitosan chlorhydrate and Crysmeb are promising submicron carriers for enhancing the dissolution of meloxicam and aceclofenac.

Microcontainers - an oral drug delivery system for poorly soluble drugs

DEFF Research Database (Denmark)

Nielsen, Line Hagner; Petersen, Ritika Singh; Marizza, Paolo

In oral delivery, it can sometimes be necessary to employ drug delivery systems to achieve targeted delivery to the intestine. Microcontainers are polymeric, cylindrical devices in the micrometer size range (Figure 1), and are suggested as a promising oral drug delivery system [1],[2]. The purpose...... of these studies was to fabricate microcontainers in either SU-8 or biodegradable poly-L-lactic acid (PLLA), and fill the microcontainers with poorly soluble drugs. Furthermore, the application of the microcontainers as an oral drug delivery system was investigated in terms of release, in situ intestinal perfusion...... medium at pH 6.5 was observed. In situ intestinal perfusions were performed in rats of the Eudragit-coated ASSF-filled microcontainers and compared to a furosemide solution. At the end of the study, the small intestine was harvested from the rat and imaged under a light microscope. The absorption rate...

Polymeric Nanoparticles for Increasing Oral Bioavailability of Curcumin

Directory of Open Access Journals (Sweden)

Anita Umerska

2018-03-01

Full Text Available Despite the promising biological and antioxidant properties of curcumin, its medical applications are limited due to poor solubility in water and low bioavailability. Polymeric nanoparticles (NPs adapted to oral delivery may overcome these drawbacks. Properties such as particle size, zeta potential, morphology and encapsulation efficiency were assessed. Then, the possibility of storing these NPs in a solid-state form obtained by freeze-drying, in vitro curcumin dissolution and cytocompatibility towards intestinal cells were evaluated. Curcumin-loaded Eudragit® RLPO (ERL NPs showed smaller particle diameters (245 ± 2 nm and better redispersibility after freeze-drying than either poly(lactic-co-glycolic acid (PLGA or polycaprolactone (PCL NPs. The former NPs showed lower curcumin encapsulation efficiency (62% than either PLGA or PCL NPs (90% and 99%, respectively. Nevertheless, ERL NPs showed rapid curcumin release with 91 ± 5% released over 1 h. The three curcumin-loaded NPs proposed in this work were also compatible with intestinal cells. Overall, ERL NPs are the most promising vehicles for increasing the oral bioavailability of curcumin.

Synthesis and polymerization of vinyl triazolium ionic liquids

Science.gov (United States)

Luebke, David; Nulwala, Hunaid; Matyjaszewski, Krzysztof; Adzima, Brian

2018-05-15

Herein, we describe polymerized ionic liquids, demonstrate the synthesis of polymerized ionic liquids, and demonstrate the polymerization of triazolium monomers. One embodiment shows the polymeriazation of the triazolium monomers with bis(trifluoromethanesulfonyl)imide anions. In another embodiment we show the feasibility of copolymerizing with commodity monomers such as styrene using free radical polymerization techniques.

Progress in the development of photosensitive GEMs with resistive electrodes manufactured by a screen printing technology

International Nuclear Information System (INIS)

Peskov, V.; Martinengo, P.; Nappi, E.; Oliveira, R.; Paic, G.; Pietropaolo, F.; Picchi, P.

2009-01-01

An innovative photosensitive gaseous detector, consisting of a GEM-like amplification structure with double-layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen-printing technology on the top of the metallic strips's grid The inner metallic grid is used for 2-D position measurements whereas the resistive layer provides an efficient spark-protected operation at high gains close to the breakdown limit. Detectors with active areas of 10x10 and 10x20 cm 2 were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large-area detectors for UV visualization, as for example, in Cherenkov imaging devices.

Progress in the development of photosensitive GEMs with resistive electrodes manufactured by a screen printing technology

CERN Document Server

Peskov, V; Nappi, E; Oliveira, R; Paic, G; Pietropaolo, F; Picchi, P

2009-01-01

An innovative photosensitive gaseous detector, consisting of a GEM-like amplification structure with double-layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen-printing technology on the top of the metallic strips's grid The inner metallic grid is used for 2-D position measurements whereas the resistive layer provides an efficient spark-protected operation at high gains close to the breakdown limit. Detectors with active areas of 10×10 and 10×20 cm2 were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large-area detectors for UV visualization, as for example, in Cherenkov imaging devices.

Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

International Nuclear Information System (INIS)

Galhardo, Eduardo; Lona, Liliane M.F.

2009-01-01

Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

Folate-conjugated polymeric micelle HB-loaded on targeting effect by intraperitoneal to ovarian cancer in vitro and in vivo.

Science.gov (United States)

Li, Jie; Yao, Shu; Wang, Kai; Lu, Zaijun; Su, Xuantao; Li, Li; Yuan, Cunzhong; Feng, Jinbo; Yan, Shi; Kong, Beihua; Song, Kun

2018-04-04

Photodynamic therapy (PDT) is considered as an innovative and attractive modality to treat ovarian cancer. In this study, a biodegradable polymer poly (ethylene glycol)-poly (lactic acid)(PLA)-folate (FA-PEG-PLA) was prepared in order to synthesize an active targeting, water soluble and pharmacomodulated photosensitizer nano-carriers. The drug loading content, encapsulation efficiency, in vitro and in vivo release were characterized, in which HB/FA-PEG-PLA micelles had a high encapsulation efficiency and much slower control release for drugs compared to free drugs (pHB/FA-PEG-PLA micelles, the cellular uptake study in vitro were tested, which owned significantly enhanced uptake of HB/FA-PEG-PLA micelles in SKOV3 (FR+) compared to A2780 cancer cells (FR-). The enhanced uptake of HB/FA-PEG-PLA micelles to cancer cells resulted in a more effective post-PDT killing of SKOV3 cells compared to plain micelles and free drugs. Binding and uptake of HB/FA-PEG-PLA micelles by SKOV3 cells were also observed in vivo after intraperitoneal injection of folate targeted micelles in tumor-bearing ascitic ovarian cancer animals. The drug levels in ascitic tumor tissues were increased by 20-fold (pHB-loaded micelles were mainly distributed in kidney and liver (the main clearance organs) in biodistribution. These results demonstrated that our new developed PDT photosensitizer HB/FA-PEG-PLA micelles has a high drug-loading capacity, good biocompatibility, control drug release, and enhanced targeting and antitumor effect, which is a potential approach to future targeting ovarian cancer therapy. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Antioxidant Properties of Astaxanthin in Oil-in-Water Emulsions with Differently-Charged Emulsifiers Under Chlorophyll Photosensitization.

Science.gov (United States)

Yi, BoRa; Kim, Mi-Ja; Lee, JaeHwan

2018-03-01

The antioxidative or prooxidative properties of astaxanthin at the concentrations of 0, 10, and 100 μM were determined in oil-in-water (O/W) emulsions containing neutral, anionic, and cationic emulsifiers, which was Tween 20, sodium dodecyl sulfate, cetyltrimethylammonium bromide (CTAB), respectively, under chlorophyll photosensitization. The oxidative parameters and headspace volatiles were analyzed in O/W emulsions. In the 24 h period of visible light irradiation, 100 μM of astaxanthin acted as an antioxidant in O/W emulsions containing neutral and anionic emulsifiers. However, astaxanthin in O/W emulsions with a cationic emulsifier was neither an antioxidant nor a prooxidant. The profiles of volatile compounds showed that astaxanthin served as a singlet oxygen quencher in O/W emulsions containing neutral and anionic emulsifiers. However, in O/W emulsion with a cationic emulsifier, astaxanthin was neither a singlet oxygen quencher nor a free radical scavenger because prooxidant properties of CTAB overwhelmed the antioxidant effects of astaxanthin. Therefore, the antioxidant properties of astaxanthin were influenced by the emulsifier charges in O/W emulsions. Astaxanthin is a lipid-soluble pigment and has antioxidant, anticancer, and anti-inflammatory properties and beneficial effects on cardiovascular diseases. Many lipid-based foods are displayed on the shelves in the markets under fluorescent light. The addition of astaxanthin can extend the shelf life of O/W emulsion type foods such as beverage and dressing products under visible light irradiation. Also, oxidative stability in emulsion type foods containing astaxanthin rich natural ingredients can be predicted. © 2018 Institute of Food Technologists®.

Photochemical characterization of water samples from Minnesota and Vermont sites with malformed frogs: potential influence of photosensitization by singlet molecular oxygen (1O2) and free radicals on aquatic toxicity

International Nuclear Information System (INIS)

Bilski, P.; Burkhart, J.G.; Chignell, C.F.

2003-01-01

Environmental pollutants activated by UV sunlight may have contributed to the recent decline in frog populations and the concomitant increase in malformations in the USA and abroad. UV radiation is able to mutate DNA and to initiate photosensitization processes that generate mutagenic and biologically disruptive oxygen transients. We have examined water from selected sites in Minnesota and Vermont using singlet molecular oxygen ( 1 O 2 ), detected by its phosphorescence and free radicals detected by spin trapping, as markers for photosensitization. Water from a pond in Minnesota with malformed frogs, which also causes malformations in the laboratory, photosensitized more 1 O 2 , even though it absorbed less UV light compared to water from a site that did not cause malformations. This suggested that unknown natural or pollutant agents were present, and that photosensitization may be involved. Although UV irradiation of the two Minnesota water samples in the presence of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) revealed the presence of the DMPO/·OH, DMPO/·H(e aq - ) and DMPO/·C(unknown) adducts there were no qualitative or quantitative differences between them. We also examined water samples from several sites in Vermont, and compared them by measuring the quantum yield of 1 O 2 photosensitization. While all the Vermont samples produced a small amount of 1 O 2 , there was no clear correlation with the incidence of frog malformations. However, the samples differed strongly in absorption spectra and the ability to quench 1 O 2 . These factors may determine how much UV light is absorbed and converted into chemical reactions. Our results show that photochemical characterization of 1 O 2 photosensitization is possible in untreated natural water samples. Photosensitization falls into the category of global factors that may be closely associated with the effects of UV irradiation of the Earth's environments. Thus, photosensitization might be an important

The effects of photosensitizing antibiotics and ultraviolet irradiation on the biosynthesis of prostaglandins

International Nuclear Information System (INIS)

Lord, J.T.; Ziboh, V.A.; Blick, G.; Poitier, J.; Kursunoglu, I.; Penneys, N.S.

1978-01-01

Oxygenation of arachidonic acid in vitro by calf skin microsomal acetone powder was enhanced by UV-irradiation at wavelengths of 254 and 360 nm. Further enhancement of the oxygenation reaction was observed in the presence of two photosensitizing cyclic antibiotics, tetracycline and demethylchlortetracycline. To test whether or not the oxygenation of arachidonic acid was related to the biosynthesis of prostaglandins, [I- 14 C]-arachidonic acid was incubated with calf skin acetone powder in the presence of UV-irradiation and the cyclic antibiotics. Prostaglandin biosynthesis from arachidonic acid by the calf skin microsomal acetone powder was enhanced after exposure to UV-irradiation at 254 nm and moderately at 360 nm. Incubation in the presence of demethylchlortetra-cycline (0.2 mM) increased prostaglandin biosynthesis approximately 95% over control by UV-irradiation at 254 nm. No significant stimulation of prostaglandin biosynthesis was observed at 360 nm. Non-photosensitizing antibiotics had no effect either on the oxygenation of arachidonic acid or on the biosynthesis of prostaglandin with or without UV-irradiation. It is suggested that the inflammatory reactions associated with these photo-reactive antibiotics may in part, be via the biosynthesis and release of the prostaglandins which are known to produce cutaneous inflammatory reactions. (author)

Preparations of spherical polymeric particles from Tanzanian ...

African Journals Online (AJOL)

Spherical Polymeric Particles (SPP) have been prepared from Tanzanian Cashew Nut Shell Liquid (CNSL) by suspension polymerization technique involving either step-growth or chain- growth polymerization mechanisms. The sizes of the SPP, which ranged from 0.1 to 2.0 mm were strongly influenced by the amounts of ...

Synthesis of amphiphilic poly(ε-caprolactone)-b-poly( N-vinylcaprolactam) block copolymers via the combination of RAFT polymerization and click chemistry

International Nuclear Information System (INIS)

Assis, Paulo Henrique; Aguiar, Graziele Aparecida de Jesus; Moraes, Rodolfo Minto de; Medeiros, Simone de Fatima; Santos, Amilton Martins

2016-01-01

Full text: In recent years, well-defined block copolymers composed of a hydrophilic and hydrophobic segments have gained much interest as drug carriers, because of their enhanced solubility and sustained release of the drug in controlled delivery systems [1]. The development of strategies to obtain block copolymers has attracted considerable attention, due to the possibility to combine characteristic properties of the homopolymers. A wide variety of well-defined block copolymers have been successfully synthesized by combining the efficiency and selectivity of click chemistry with the powerful RAFT polymerization mechanism. In the present work, well-defined amphiphilic, biocompatible, partially biodegradable, and thermosensitive poly(ε-caprolactone)-b-poly(N-vinylcaprolactam) (PCL-b-PNVCL) block copolymers were synthesized by combining ring opening polymerization (ROP), reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequent click chemistry reaction. Alkyne-terminated poly(ε-caprolactone) (alkyne-PCL) was obtained by the ring opening polymerization of ε-caprolactone (ε-CL) using propargyl alcohol as initiator and stannous-2-ethylhexanoate [Sn(Oct) 2 ] as catalyst. The azide end-capped-poly(N-vinylcaprolactam) (PNVCL-N 3 ) was synthesized by reversible addition-fragmentation chain transfer/macromolecular design via interchange of xanthates (RAFT/MADIX) polymerization of the N-vinylcaprolactam (NVCL) mediated by a novel chain transfer agent comprising an azide function , 2-azidoethyl[(ethoxycarbonothioyl)thio](phenyl)acetate. These functionalized homopolymers, alkyne-PCL and PNVCL-N 3 , were coupled by the 1,3 dipolar cycloaddition reaction in order to obtain the corresponding block copolymers. These (co)polymers were characterized by FTIR, 1 H NMR and GPC measurements. Reference: 1. RAMESH, K., SINGH, S., MITRA, K., CHATTOPADHYAY, D., MISRA, N., & RAY, B. (2015). Colloid and Polymer Science, 1-9. (author)

Synthesis of Stable and Soluble One-Handed Helical Homopoly(substituted acetylenes without the Coexistence of Any Other Chiral Moieties via Two-Step Polymer Reactions in Membrane State: Molecular Design of the Starting Monomer

Directory of Open Access Journals (Sweden)

Takashi Kaneko

2012-01-01

Full Text Available A soluble and stable one-handed helical poly(substituted phenylacetylene without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1 removing the chiral groups (desubstitution; and (2 introduction of achiral long alkyl groups at the same position as the desubstitution to enhance the solubility of the resulting one-handed helical polymer (resubstitution. The starting chiral monomer should have four characteristic substituents: (i a chiral group bonded to an easily hydrolyzed spacer group; (ii two hydroxyl groups; (iii a long rigid hydrophobic spacer between the chiral group and the polymerizing group; (iv a long achiral group near the chiral group. As spacer group a carbonate ester was selected. The two hydroxyl groups formed intramolecular hydrogen bonds stabilizing a one-handed helical structure in solution before and after the two-step polymer reactions in membrane state. The rigid long hydrophobic spacer, a phenylethynylphenyl group, enhanced the solubility of the starting polymer, and realized effective chiral induction from the chiral side groups to the main chain in the asymmetric-induced polymerization. The long alkyl group near the chiral group avoided shrinkage of the membrane and kept the reactivity of resubstitution in membrane state after removing the chiral groups. The g value (g = ([θ]/3,300/ε for the CD signal assigned to the main chain in the obtained final polymer was almost the same as that of the starting polymer in spite of the absence of any other chiral moieties. Moreover, since the one-handed helical structure was maintained by the intramolecular hydrogen bonds in a solution, direct observation of the one-handed helicity of the final homopolymer has been realized in CD for the solution for the first time.

Photosensitized Oxygenations of Hexamethylbenzene in Phase Contact Enhanced Microreactor

International Nuclear Information System (INIS)

Park, Chan Yi; Park, Jeong Hyeon; Lim Hyo Jin; Hwang, Geumsook; Park, Chan Pil

2014-01-01

Activated singlet oxygen ( 1 O 2 ) has successfully been utilized in production of various compounds including fragrances, pharmaceuticals, and fine chemicals. However, the traditional reaction required a prolonged reaction time due to the difficulty of introducing adequate light and oxygen into the solution. Low contact probability between four species of oxygen, photosensitizer, light, and reagent is an inherent drawback of the traditional photoreaction. Molecular diffusion distance is the most important factor in the heterogeneous reactions including gas-liquid, gassolid, liquid-solid, and immiscible liquid-liquid. Therefore, rates of reaction are closely depended on the distance. Microreactor has provided a distinct advantage in the short molecular diffusion distance due to the high surface-to-volume ratio driven by narrow fluidic channels

Volumetric polymerization shrinkage of contemporary composite resins

Directory of Open Access Journals (Sweden)

Halim Nagem Filho

2007-10-01

Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

Multispectral confocal microscopy images and artificial neural nets to monitor the photosensitizer uptake and degradation in Candida albicans cells

Science.gov (United States)

Romano, Renan A.; Pratavieira, Sebastião.; da Silva, Ana P.; Kurachi, Cristina; Guimarães, Francisco E. G.

2017-07-01

This study clearly demonstrates that multispectral confocal microscopy images analyzed by artificial neural networks provides a powerful tool to real-time monitoring photosensitizer uptake, as well as photochemical transformations occurred.

Photodynamic efficacy of liposome-delivered hypocrellin B in microvascular endothelial cells in vitro and chicken combs in vivo: a potential photosensitizer for port wine stain

International Nuclear Information System (INIS)

Chen, H X; Zou, X B; Yang, Z F; Zhu, J G; Gu, Y; Deng, H; Zhao, J Q

2013-01-01

Photodynamic therapy (PDT) has been proved a successful method for port wine stain (PWS), but the prolonged skin photosensitivity induced by the photosensitizers used currently seriously limits the clinical application of PDT. In this study, we investigate the feasibility of hypocrellin B (HB), a promising second-generation photosensitizer for the treatment of PWS. The photodynamic effect of liposome-delivered HB was evaluated in vitro with microvascular endothelial cells (MEC) and in vivo with chicken combs. The dark cytotoxicity and photocytotoxicity of liposomal HB in MEC were evaluated using the MTT assay. Gross and histological examinations were performed to investigate the selective occlusion of the superficial dermal microvasculature in the chicken comb. The result showed that photocytotoxicity of liposomal HB was dependent on both light dose and drug concentration. PDT with HB (0.5–1 mg kg −1 ) and a light dose of 120 J cm −2 showed selective destruction of the superficial dermal microvasculature of the chicken comb, leaving the overlying epidermis intact. This is the first study to investigate the potential efficacy of HB-PDT as a novel modality for the treatment of PWS. These findings suggest that liposomal HB is a safe and effective photosensitizer for PWS. (paper)

Radiation-induced graft polymerization of amphiphilic monomers with different polymerization characteristics onto hydrophobic polysilane

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Hidenori; Iwasaki, Isao; Kunai, Yuichiro [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Sato, Nobuhiro, E-mail: sato-n@rri.kyoto-u.ac.j [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Matsuyama, Tomochika [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

2011-08-15

The structures of poly(methyl-n-propylsilane) (PMPrS) amphiphilically modified through {gamma}-ray-induced graft polymerization were investigated with {sup 1}H NMR measurement. By the use of methyl methacrylate (MMA) or diethyl fumarate (DEF) as monomers for the graft polymerization, grafting yield rose with increasing total absorption dose and monomer concentrations, but decreased with increasing dose rate. This result means that grafting yield of modified PMPrS can be controlled by changing irradiation conditions. However, the number of PMMA or PDEF graft chains per PMPrS chain was estimated to be less than 1.0 by analysis of {sup 1}H NMR spectra, and this value was lower than that we had expected. To improve graft density, maleic anhydride (MAH), which is known as a non-homopolymerizable monomer in radical polymerization, was used as a monomer for grafting. As a result, high density grafting (one MAH unit for 4.2 silicon atoms) was attained. It demonstrates that the structure of {gamma}-ray-modified polysilane strongly depends on the polymerization characteristics of grafted monomers.

Investigation of UV photocurable microcapsule inner crosslink extent

Science.gov (United States)

Li, Xiaowei; Meng, Shuangshuang; Lai, Weidong; Yu, Haiyang; Fu, Guangsheng

2008-11-01

UV photocuring technology has encountered increased applications in recent years, which finds a variety of applications on protective coating of the optical-fiber, ink and optical recording materials. Combined with techniques of photohardenable, microcapsule, heat-sensitive and interface-polymerization method, a novel photoheat sensitive recording material of non-silver salt is explored in this thesis. Microcapsules are particulate substance with a core and shell structure, where photopolymerizable composition, monofunctional/polyfunctional diluents, photopolymerization initiator, photosensitivity enhancing agent and dye precursor are encapsulated as the internal phase. In this paper introduced the characteristics and curing mechanism of photo-sensitive microcapsule materials. The photocuring process may be a complex-function with photopolymerizable compound and photopolymerization initiator. For the sake of high photocuring speed and degree, optimal photo-sensitive materials were selected. In order to match with the light source excitation wavelength and absorb more wider ultraviolet band, combined type of photo-polymerization initiators were employed. With the kinds and dosage of photopolymerization initiator changing, the photocuring speed and quality can be ameliorated. Through studying the UV-visible absorption spectrum and infra-red spectrum of the material , the optical response property of the inner compound can be obtained.

UV causation of melanoma in Xiphophorus is dominated by melanin photosensitized oxidant production

OpenAIRE

Wood, Simon R.; Berwick, Marianne; Ley, Ronald D.; Walter, Ronald B.; Setlow, Richard B.; Timmins, Graham S.

2006-01-01

Controversy continues both as to which wavelengths of sunlight cause melanoma and the mechanisms by which these different wavelengths act. Direct absorption of UVB by DNA is central in albino animal models, but melanin-pigmented models have shown major contributions by wavelengths longer than UVB that are thought to be mediated by photosensitized oxidant production. The only model for which the action spectrum of melanoma causation is known is a genetically melanoma-susceptible specific cross...

On the factors influencing the performance of solar reactors for water disinfection with photosensitized singlet oxygen.

Science.gov (United States)

Manjón, Francisco; Villén, Laura; García-Fresnadillo, David; Orellana, Guillermo

2008-01-01

Two solar reactors based on compound parabolic collectors (CPCs) were optimized for water disinfection by photosensitized singlet oxygen (1O2) production in the heterogeneous phase. Sensitizing materials containing Ru(II) complexes immobilized on porous silicone were produced, photochemically characterized, and successfully tested for the inactivation of up to 10(4) CFU mL(-1) of waterborne Escherichia coli (gram-negative) or Enterococcus faecalis (gram-positive) bacteria. The main factors determining the performance of the solar reactors are the type of photosensitizing material, the sensitizer loading, the CPC collector geometry (fin- vs coaxial-type), the fluid rheology, and the balance between concurrent photothermal--photolytic and 1O2 effects on the microorganisms' inactivation. In this way, at the 40 degrees N latitude of Spain, water can be disinfected on a sunny day (0.6-0.8 MJ m(-2) L(-1) accumulated solar radiation dose in the 360-700 nm range, typically 5-6 h of sunlight) with a fin-type reactor containing 0.6 m2 of photosensitizing material saturated with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (ca. 2.0 g m(-2)). The optimum rheological conditions require laminar-to-transitional water flow in both prototypes. The fin-type system showed better inactivation efficiency than the coaxial reactor due to a more important photolytic contribution. The durability of the sensitizing materials was tested and the operational lifetime of the photocatalyst is at least three months without any reduction in the bacteria inactivation efficiency. Solar water disinfection with 1O2-generating films is demonstrated to be an effective technique for use in isolated regions of developing countries with high yearly average sunshine.

Radiation-induced polymerization and radiation effect on polymers

International Nuclear Information System (INIS)

Seguchi, Tadao

1977-12-01

The processes of radiation-induced polymerization of monomers and also radiation effects on polymers have been studied by instrumental analyses of electron spin resonance (ESR), nuclear magnetic resonance (NMR) and electron microscopy. In radiation-induced polymerization, graft-copolymerization and absorbed state polymerization were taken up. For graft-copolymerization, monomers such as methylmethacrylate and butadiene were made to react with irradiated polyethylene, and behaviors of the initiating radicals and propagating radicals were followed under the reaction by ESR. For absorbed state polymerization, acrylonitrile/zeolite and methylmethacrylate/zeolite were chosen. Absorbed monomers were irradiated at 77 0 K and polymerized at room temperature. Active species and the concentrations were measured by ESR and the yields of polymer were observed by NMR. In radiation effect on polymers, polyvinylfluoride, polyvinylidenfluoride and polytetrafluoroethylene were taken up. Active species trapped in the polymer matrixes were identified and decay and reactivity of the species were also studied. On the basis of information from the electron microscopy and x-ray analysis, radiation effects on these polymers are described. In polytetrafluoroethylene produced by radiation polymerization, the relation between morphology and polymerization conditions and also the process of crystallization during polymerization were studied. (auth.)

Surface modification of nanodiamond through metal free atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

2016-12-30

Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by {sup 1}H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

Surface modification of nanodiamond through metal free atom transfer radical polymerization

International Nuclear Information System (INIS)

Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

2016-01-01

Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1 H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

Photodynamic therapy of early stage cancer of lung, esophagus, and stomach with two different photosensitizers

Science.gov (United States)

Chissov, Valery I.; Sokolov, Victor V.; Trakhtenberg, A. K.; Mamontov, A. S.; Vaschakmadze, L. A.; Frank, George A.; Filonenko, E. V.; Telegina, L. V.; Belous, T. A.; Gladunov, V. K.; Aristarkhova, E. I.; Zharkova, Natalia N.; Menenkov, V. D.

1996-01-01

The paper presents the results of photodynamic therapy (PDT) of early-stage cancer of lung (17 patients), esophagus (8 patients) and stomach (10 patients). Fifteen patients had second primary tumors. New drugs photoheme and photosens were used as photosensitizers. Complete remission was obtained in 87%. The patients are followed up without relapses to 2.5 years.

Fabrication of ridge waveguide structure from photosensitive TiO{sub 2}/ormosil hybrid films by using an ultraviolet soft imprint technique

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xuehua [Electronic Materials Research Laboratory, International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Chen, Jing; Gao, Tianxi; Hu, Jiaxing [Electronic Materials Research Laboratory, International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Liu, Weiguo [Micro-optoelectronic Systems Laboratories, Xi' an Technological University, Xi' an 710032, Shaanxi (China)

2013-03-01

Photosensitive TiO{sub 2}/organically modified silane hybrid films were prepared by combining a low-temperature sol–gel process with a spin-coating technique. Optical properties and photochemical activities of the as-prepared hybrid sol–gel films under different UV irradiation time were characterized and monitored by prism coupling technique, UV–visible spectroscopy, and Fourier transform infrared spectroscopy. Surface morphology of the hybrid films was also observed by an atomic force microscopy. Advantages for fabrication of ridge waveguide structure based on the photosensitive hybrid films were demonstrated by an ultraviolet soft imprint technique. Effects of imprint force, imprint time, and UV irradiation time on high replication fidelity of the ridge waveguide structure were also investigated. An altitude replication fidelity of 99.7% can be obtained when the imprint force of 2 MPa, imprint time of 30 min and UV irradiation time of 45 min were chosen. Scanning electron microscopy and surface profiler were used to characterize the morphological and surface profile properties of the as fabricated ridge waveguide structure. Results indicate that the as-prepared photosensitive hybrid materials have great applicability for the fabrication of micro-optical elements and advantage as the imprint layer under the ultraviolet soft imprint technique. - Highlights: ► Photosensitive TiO{sub 2}/ormosil hybrid film is prepared by a sol–gel process. ► Optical properties of the films change a little with UV exposure time. ► Photo-chemical property of the film changes a lot with UV exposure time. ► The imprint force and time, and the UV exposure time affect the imprint fidelity. ► A fidelity value of 99.7% is obtained under an optimized condition.

Copper-mediated homogeneous living radical polymerization of acrylamide with waxy potato starch-based macroinitiator.

Science.gov (United States)

Fan, Yifei; Cao, Huatang; van Mastrigt, Frank; Pei, Yutao; Picchioni, Francesco

2018-07-15

Cu 0 -mediated living radical polymerization (Cu 0 -mediated LRP) was employed in this research for the synthesis of starch-g-polyacrylamide (St-g-PAM). The use of a controlled radical grafting technique is necessary, as compared to the traditional free-radical polymerization methods, in order to obtain a well-defined structure of the final product. This is in turn essential for studying the relationship between such structure and the end-properties. Waxy potato starch-based water-soluble macroinitiator was first synthesized by esterification with 2-bromopropionyl bromide in the mixture of dimethylacetamide and lithium chloride. With the obtained macroinitiator, St-g-PAM was homogeneously synthesized by aqueous Cu 0 -mediated LRP using CuBr/hexamethylated tris(2-aminoethyl)amine (Me 6 Tren) as catalyst. The successful synthesis of the macroinitiator and St-g-PAM was proved by NMR, FT-IR, SEM, XRD and TGA analysis. The molecular weight and polydispersity of PAM chains were analyzed by gel permeation chromatography (GPC) after hydrolyzing the starch backbone. Monomer conversion was monitored by gas chromatography (GC), on the basis of which the kinetics were determined. A preliminarily rheological study was performed on aqueous solutions of the prepared materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Stability study of polyacrylic acid films plasma-polymerized on polypropylene substrates at medium pressure

Energy Technology Data Exchange (ETDEWEB)

Morent, Rino, E-mail: Rino.Morent@Ugent.be [Department of Applied Physics, Research Unit Plasma Technology, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); De Geyter, Nathalie [Department of Applied Physics, Research Unit Plasma Technology, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); Trentesaux, Martine; Gengembre, Leon [Unite de Catalyse et Chimie du Solide, UMR CNRS 8181, Universite des Sciences et Technologies de Lille, Bat. C3, Cite Scientifique, 59655 Villeneuve d' Ascq (France); Dubruel, Peter [Department of Organic Chemistry, Polymer Chemistry and Biomaterials Research Group, Faculty of Sciences, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium); Leys, Christophe [Department of Applied Physics, Research Unit Plasma Technology, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); Payen, Edmond [Unite de Catalyse et Chimie du Solide, UMR CNRS 8181, Universite des Sciences et Technologies de Lille, Bat. C3, Cite Scientifique, 59655 Villeneuve d' Ascq (France)

2010-11-01

Plasma polymerization of acrylic acid has become an interesting research subject, since these coatings are expected to be beneficial for biomedical applications due to their high surface density of carboxylic acid functional groups. However, the application of these monomers is counteracted by their low stability in humid environments, since a high stability is a required characteristic for almost any biological application. The present work investigates whether it is possible to obtain stable deposits with a high retention of carboxylic acid functions by performing plasma polymerization on polypropylene substrates with a dielectric barrier discharge operating at medium pressure. In order to obtain coatings with the desired properties, the plasma parameters need to be optimized. Therefore, in this paper, the influence of discharge power and location of the substrate in the discharge chamber is examined in detail. The properties of the deposited films are studied using contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy. Moreover, to determine whether the obtained deposits are soluble in water, the coatings are once again analyzed after rinsing in water. This paper will clearly show that stable COOH-rich surfaces can be obtained at high discharge power and close to the monomer inlet, which might open perspectives for future biomedical applications.

Polymerization of N-(fluoro phenyl) maleimides

International Nuclear Information System (INIS)

Barrales-Rienda, J.M.; Ramos, J.G.; Chaves, M.S.

1979-01-01

Poly(N-aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. The polymerization of N-(fluoro phenyl) maleimides by free-radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ-ray irradiation with that by free-radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x-ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free-radical polymerization initiated by azobisisobutyronitrile in bulk or in solution and by the self-initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N-(fluoro phenyl) maleimide]s have been analyzed by using a multiple-heating-rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. 6 figures, 8 tables

Plasma polymerization by Softplasma

DEFF Research Database (Denmark)

Jiang, J.; Wu, Zhenning; Benter, Maike

2008-01-01

, external electrode, and electrodeless microwave or high frequency reactors. [3] Softplasma™ is an internal electrode plasma setup powered by low frequenc~ gower supply. It was developed in late 90s for surface treatment of silicone rubber. [ ]- 5] It is a low pressure, low electron density, 3D homogenous......In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode...... plasma. In this study, we are presenting the surface modification"pf polymers by plasma polymerization using Softplasma™. Softplasma™ can be used for two major types of polymerization: polymerization of vinyl monomers, where plasma acts as initiator; chemical vapour deposition, where plasma acts...

High Vacuum Techniques for Anionic Polymerization

KAUST Repository

Ratkanthwar, Kedar; Hadjichristidis, Nikolaos; Mays, Jimmy

2015-01-01

Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization

Polymerization of phenol by using discharged plasma under hydrothermal state

Energy Technology Data Exchange (ETDEWEB)

Mitsugi, M; Yoshida, A; Watanabe, H; Kiyan, T; Takade, M; Miyaji, K; Kuwahara, Y; Akiyama, H; Hara, M; Sasaki, M [Graduate School of Science and Technology, Kumamoto University (Japan); Namihira, T; Goto, M, E-mail: mgoto@kumamoto-u.ac.j [Bioelectrics Research Center, Kumamoto University 2-39-1 Kurokami, Kumamoto 865-8555 Japan (Japan)

2010-03-01

Supercritical fluid with plasma is a type of green processing media because this technique does not use catalyst and toxic solvents. In this study, we carried out experiments of organic materials in the presence of discharged plasma in sub- and supercritical water to evaluate the possibility for new reactions. For this purpose, we used SUS316 reactor that generates plasma at temperature and pressure up to 573K and 30MPa, respectively. 100 mmol/L aqueous phenol solution was used as starting material. The reactions were carried out at temperature of 523K and under pressure of 25MPa. After a series of reactions, water-soluble, water-insoluble (oily products), solid residue and gaseous product were obtained. For the analysis of these products, HPLC, GC-MS, TOC, GC-TCD and TOF-MS were used. The highest phenol conversion was 16.96% obtained at 523K, 25MPa and with 4000 times discharged plasma. Polymerized phenol was obtained as a product.

Polymerization of phenol by using discharged plasma under hydrothermal state

International Nuclear Information System (INIS)

Mitsugi, M; Yoshida, A; Watanabe, H; Kiyan, T; Takade, M; Miyaji, K; Kuwahara, Y; Akiyama, H; Hara, M; Sasaki, M; Namihira, T; Goto, M

2010-01-01

Supercritical fluid with plasma is a type of green processing media because this technique does not use catalyst and toxic solvents. In this study, we carried out experiments of organic materials in the presence of discharged plasma in sub- and supercritical water to evaluate the possibility for new reactions. For this purpose, we used SUS316 reactor that generates plasma at temperature and pressure up to 573K and 30MPa, respectively. 100 mmol/L aqueous phenol solution was used as starting material. The reactions were carried out at temperature of 523K and under pressure of 25MPa. After a series of reactions, water-soluble, water-insoluble (oily products), solid residue and gaseous product were obtained. For the analysis of these products, HPLC, GC-MS, TOC, GC-TCD and TOF-MS were used. The highest phenol conversion was 16.96% obtained at 523K, 25MPa and with 4000 times discharged plasma. Polymerized phenol was obtained as a product.

Antibiotic polymeric nanoparticles for biofilm-associated infection therapy.

Science.gov (United States)

Cheow, Wean Sin; Hadinoto, Kunn

2014-01-01

Polymeric nanoparticles are highly attractive as drug delivery vehicles due to their high structural integrity, stability during storage, ease of preparation and functionalization, and controlled release capability. Similarly, lipid-polymer hybrid nanoparticles, which retain the benefits of polymeric nanoparticles plus the enhanced biocompatibility and prolonged circulation time owed to the lipids, have recently emerged as a superior alternative to polymeric nanoparticles. Drug nanoparticle complex prepared by electrostatic interaction of oppositely charged drug and polyelectrolytes represents another type of polymeric nanoparticle. This chapter details the preparation, characterization, and antibiofilm efficacy testing of antibiotic-loaded polymeric and hybrid nanoparticles and antibiotic nanoparticle complex.

Dissolution and Solubility Enhancement of the Highly Lipophilic Drug Phenytoin via Interaction with Poly(N-isopropylacrylamide-co-vinylpyrrolidone) Excipients.

Science.gov (United States)

Widanapathirana, Lakmini; Tale, Swapnil; Reineke, Theresa M

2015-07-06

Excipients of natural or synthetic origin play an important role in pharmaceutical performance to enhance the solubility, bioavailability, release, and stability of insoluble drugs. Herein, a series of seven excipient models was prepared by both homopolymerization and copolymerization of 1-vinyl-2-pyrrolidone (VP) and N-isopropylacrylamide (NIPAAm) by free radical polymerization yielding two homopolymers poly(VP) and poly(NIPAAm) and five copolymers of poly(NIPAAm-co-VP) at difference compositions. While the VP monomer provided aqueous solubility at a variety of conditions to the excipient, the incorporation of NIPAAm into the copolymer offered additional hydrogen bond donating sites to optimize the drug-polymer interactions in the system. Due to the presence of NIPAAm, the copolymers were sensitive to temperature as well. It was found that as the proportion of VP was increased (from 0 to 100%), the lower critical solution temperature (LCST) and the water solubility of the polymer models increased. To examine the role of specific drug-polymer interactions during dissolution on drug solubility and bioavailability, the polymers were formulated with the anticonvulsant drug phenytoin, which is a poorly water-soluble BCS class II drug where oral absorption is limited by the drug solubility. Amorphous solid dispersions (ASD) were prepared via spray drying of phenytoin with the polymer excipient models to contain 10% and 25% by weight drug loading. Physical characterization of the ASDs by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) revealed that the polymers held the drug in a high-energy amorphous phase in all the formulations prepared. All ASDs exhibited improved in vitro dissolution rates compared to drug only and physical mixtures of the polymers and the drug. Drug solubility was the highest with the ASDs containing poly(NIPAAm-co-VP) 60:40 and 50:50, which showed a solubility enhancement of near 14-fold increase compared to pure drug

The tempered polymerization of human neuroserpin.

Directory of Open Access Journals (Sweden)

Rosina Noto

Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

Measurement and Analysis of in vitro Actin Polymerization

Science.gov (United States)

Doolittle, Lynda K.; Rosen, Michael K.; Padrick, Shae B.

2014-01-01

Summary The polymerization of actin underlies force generation in numerous cellular processes. While actin polymerization can occur spontaneously, cells maintain control over this important process by preventing actin filament nucleation and then allowing stimulated polymerization and elongation by several regulated factors. Actin polymerization, regulated nucleation and controlled elongation activities can be reconstituted in vitro, and used to probe the signaling cascades cells use to control when and where actin polymerization occurs. Introducing a pyrene fluorophore allows detection of filament formation by an increase in pyrene fluorescence. This method has been used for many years and continues to be broadly used, owing to its simplicity and flexibility. Here we describe how to perform and analyze these in vitro actin polymerization assays, with an emphasis on extracting useful descriptive parameters from kinetic data. PMID:23868594

Polymeric Nanoparticles as a Metolachlor Carrier: Water-Based Formulation for Hydrophobic Pesticides and Absorption by Plants.

Science.gov (United States)

Tong, Yujia; Wu, Yan; Zhao, Caiyan; Xu, Yong; Lu, Jianqing; Xiang, Sheng; Zong, Fulin; Wu, Xuemin

2017-08-30

Pesticide formulation is highly desirable for effective utilization of pesticide and environmental pollution reduction. Studies of pesticide delivery system such as microcapsules are developing prosperously. In this work, we chose polymeric nanoparticles as a pesticide delivery system and metolachlor was used as a hydrophobic pesticide model to study water-based mPEG-PLGA nanoparticle formulation. Preparation, characterization results showed that the resulting nanoparticles enhanced "water solubility" of hydrophobic metolachlor and contained no organic solvent or surfactant, which represent one of the most important sources of pesticide pollution. After the release study, absorption of Cy5-labeled nanoparticles into rice roots suggested a possible transmitting pathway of this metolachlor formulation and increased utilization of metolachlor. Furthermore, the bioassay test demonstrated that this nanoparticle showed higher effect than non-nano forms under relatively low concentrations on Oryza sativa, Digitaria sanguinalis. In addition, a simple cytotoxicity test involving metolachlor and metolachlor-loaded nanoparticles was performed, indicating toxicity reduction of the latter to the preosteoblast cell line. All of these results showed that those polymeric nanoparticles could serve as a pesticide carrier with lower environmental impact, comparable effect, and effective delivery.

Imaging of Caenorhabditis elegans samples and sub-cellular localization of new generation photosensitizers for photodynamic therapy, using non-linear microscopy

Energy Technology Data Exchange (ETDEWEB)

Filippidis, G [Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, PO Box 1527, 71110 Heraklion (Greece); Kouloumentas, C [Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, PO Box 1527, 71110 Heraklion (Greece); Kapsokalyvas, D [Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, PO Box 1527, 71110 Heraklion (Greece); Voglis, G [Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, Heraklion 71110, Crete (Greece); Tavernarakis, N [Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, Heraklion 71110, Crete (Greece); Papazoglou, T G [Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, PO Box 1527, 71110 Heraklion (Greece)

2005-08-07

Two-photon excitation fluorescence (TPEF) and second-harmonic generation (SHG) are relatively new promising tools for the imaging and mapping of biological structures and processes at the microscopic level. The combination of the two image-contrast modes in a single instrument can provide unique and complementary information concerning the structure and the function of tissues and individual cells. The extended application of this novel, innovative technique by the biological community is limited due to the high price of commercial multiphoton microscopes. In this study, a compact, inexpensive and reliable setup utilizing femtosecond pulses for excitation was developed for the TPEF and SHG imaging of biological samples. Specific cell types of the nematode Caenorhabditis elegans were imaged. Detection of the endogenous structural proteins of the worm, which are responsible for observation of SHG signals, was achieved. Additionally, the binding of different photosensitizers in the HL-60 cell line was investigated, using non-linear microscopy. The sub-cellular localization of photosensitizers of a new generation, very promising for photodynamic therapy (PDT) (Hypericum perforatum L. extracts) was achieved. The sub-cellular localization of these novel photosensitizers was linked with their photodynamic action during PDT, and the possible mechanisms for cell killing have been elucidated.

Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

Science.gov (United States)

Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

2017-09-01

In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

Nucleotide Selectivity in Abiotic RNA Polymerization Reactions.

Science.gov (United States)

Coari, Kristin M; Martin, Rebecca C; Jain, Kopal; McGown, Linda B

2017-09-01

In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

Impact of polymer type on bioperformance and physical stability of hot melt extruded formulations of a poorly water soluble drug.

Science.gov (United States)

Mitra, Amitava; Li, Li; Marsac, Patrick; Marks, Brian; Liu, Zhen; Brown, Chad

2016-05-30

Amorphous solid dispersion formulations have been widely used to enhance bioavailability of poorly soluble drugs. In these formulations, polymer is included to physically stabilize the amorphous drug by dispersing it in the polymeric carrier and thus forming a solid solution. The polymer can also maintain supersaturation and promote speciation during dissolution, thus enabling better absorption as compared to crystalline drug substance. In this paper, we report the use of hot melt extrusion (HME) to develop amorphous formulations of a poorly soluble compound (FaSSIF solubility=1μg/mL). The poor solubility of the compound and high dose (300mg) necessitated the use of amorphous formulation to achieve adequate bioperformance. The effect of using three different polymers (HPMCAS-HF, HPMCAS-LF and copovidone), on the dissolution, physical stability, and bioperformance of the formulations was demonstrated. In this particular case, HPMCAS-HF containing HME provided the highest bioavailability and also had better physical stability as compared to extrudates using HPMCAS-LF and copovidone. The data demonstrated that the polymer type can have significant impact on the formulation bioperformance and physical stability. Thus a thorough understanding of the polymer choice is imperative when designing an amorphous solid dispersion formulation, such that the formulation provides robust bioperformance and has adequate shelf life. Copyright © 2016 Elsevier B.V. All rights reserved.

Dynamic Membrane Formation in Anaerobic Dynamic Membrane Bioreactors: Role of Extracellular Polymeric Substances.

Directory of Open Access Journals (Sweden)

Hongguang Yu

Full Text Available Dynamic membrane (DM formation in dynamic membrane bioreactors plays an important role in achieving efficient solid-liquid separation. In order to study the contribution of extracellular polymeric substances (EPS to DM formation in anaerobic dynamic membrane bioreactor (AnDMBR processes, EPS extraction from and re-addition to bulk sludge were carried out in short-term filtration tests. DM formation behaviors could be well simulated by cake filtration model, and sludge with EPS re-addition showed the highest resistance coefficient, followed by sludge after EPS extraction. The DM layers exhibited a higher resistance and a lower porosity for the sludge sample after EPS extraction and for the sludge with EPS re-addition. Particle size of sludge flocs decreased after EPS extraction, and changed little with EPS re-addition, which was confirmed by interaction energy analysis. Further investigations by confocal laser scanning microscopy (CLSM analysis and batch tests suggested that the removal of in-situ EPS stimulated release of soluble EPS, and re-added EPS were present as soluble EPS rather than bound EPS, which thus improved the formation of DM. The present work revealed the role of EPS in anaerobic DM formation, and could facilitate the operation of AnDMBR processes.

Neptunium (IV) oxalate solubility

International Nuclear Information System (INIS)

Luerkens, D.W.

1983-07-01

The equilibrium solubility of neptunium (IV) oxalate in nitric/oxalic acid solutions was determined at 22 0 C, 45 0 C, and 60 0 C. The concentrations of nitric/oxalic acid solutions represented a wide range of free oxalate ion concentration. A mathematical solubility model was developed which is based on the formation of the known complexes of neptunium (IV) oxalate. the solubility model uses a simplified concentration parameter which is proportional to the free oxalate ion concentration. The solubility model can be used to estimate the equilibrium solubility of neptunium (IV) oxalate over a wide range of oxalic and nitric acid concentrations at each temperature

Enhanced photosensitized degradation of rhodamine B on CdS/TiO{sub 2} nanocomposites under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Li, Wenjuan [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Sciences and Engineering, Nanjing 210044 (China); Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Shandong Province Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165 (China); Cui, Xiaoli [Shandong Province Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165 (China); Wang, Peixian; Shao, Yu [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Li, Danzhen, E-mail: dzli@fzu.edu.cn [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Teng, Fei [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Sciences and Engineering, Nanjing 210044 (China)

2013-09-01

Graphical abstract: The photosensitized degradation of RhB was largely enhanced by the synergistic effect of the RhB and CdS/TiO{sub 2} nanocomposite. The composite of the two inorganic semiconductors with appropriate oxidation reduction energy levels enhanced the charge separation and extended the absorption response to visible region. - Highlights: • CdS/TiO{sub 2} nanocomposites were synthesized by a simple hydrothermal method. • Samples prepared at 200 °C, 12 h, CdS/TiO{sub 2} = 12% possessed the best activity. • The photosensitized degradation of RhB was largely enhanced by the composite. • The better activity was due to the synergistic effect of the RhB and CdS/TiO{sub 2}. - Abstract: Visible-light-driven photocatalysts, CdS/TiO{sub 2} nanocomposites were synthesized by a simple hydrothermal method. Their formation and structures were characterized by X-ray diffractometer, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Taking rhodamine B (RhB) as a model, their photocatalytic activities in aqueous phase under visible light irradiation (420 < λ < 800 nm) were tested. The results showed that the composite of CdS and TiO{sub 2} with appropriate oxidation reduction energy levels enhanced the charge separation and extended the absorption response into visible light region. Thus, the photosensitized degradation of RhB was largely enhanced. The degradation mechanism was explored concretely.

ProTEK PSB as Biotechnology Photosensitive Protection Mask on 3C-SiC-on-Si in MEMS Sensor

Science.gov (United States)

Marsi, N.; Majlis, B. Y.; Mohd-Yasin, F.; Hamzah, A. A.; Mohd Rus, A. Z.

2016-11-01

This project presents the fabrication of MEMS employing a cubic silicon carbide (3C- SiC) on silicon wafer using newly developed ProTEK PSB as biotechnology photosensitive protection mask. This new biotechnology can reduce the number of processes and simplify the process flow with minimal impact on overall undercut performance. The 680 pm thick wafer is back-etched, leaving the 3C-SiC thin film with a thickness of 1.0 μm as the flexible diaphragm to detect pressure. The effect of the new coating of ProTEK PSB on different KOH solvents were investigated depending on various factors such as development time, final cure temperature and the thickness of the ProTEK PSB deposited layer. It is found that 6.174 μm thickness of ProTEK PSB offers some possibility of reducing the processing time compared to silicon nitride etch masks in KOH (55%wt, 80°C). The new ProTEK PSB biotechnology photosensitive protection mask indicates good stability and sustains its performance in different treatments under KOH and IPA for 8 hours. This work also revealed that the fabrication of MEMS sensors using the new biotechnology photosensitive protection mask provides a simple assembly approach and reduces manufacturing costs. The MEMS sensor can operate up to 500 °C as indicated under the sensitivity of 0.826 pF/MPa with nonlinearity and hysteresis of 0.61% and 3.13%, respectively.

Characterization and development of ZnO nanoparticles as a photosensitizer for diagnostic and treatment of cancer using lasers (abstract)

International Nuclear Information System (INIS)

Firdous, S.

2011-01-01

For over ongoing Biophotonics research we have characterized a cost expensive, and noninvasive Zinc Oxide (ZnO) nanoparticles (Np) and NRs of 11-15nm and nanorods (NRs) of 60-120nm diameter to use a photosensitizer in photodynamic therapy (PDT) of cancer. Confocal microscopy and light polarization techniques were employed to characterize the samples. Confocal microscopy of well known photosensitizer 5-Aminolavlonic acid (ALA) with ZnO and ALA without ZnO significant changes were seen and verified ZnO is tissue non toxic in dark, but enhances endogenous fluorescence in human cells. The fluorescence of ZnO with ALA is prominent if compared with other images. We observed that in dark ZnO is biosafe, biocompatible but cell toxic in the presence of 635nm laser light. ZnO conjugated photo-sensitizers being toxic under exposure of suitable light for malignant cells, and can be used as cancer cell killing drug. Mechanism of cytotoxicity appears to involve the generation of singlet oxygen inside the cell. The novel findings of cell-localized toxicity indicate a potential application of ZnO NRs with and without ALA can be used as efficient drug carrier, biomarker in diagnostic clinical applications, while ZnO NRs can be an appealing candidate for the PDT treatment of malignant diseases epically cancer. (author)

Composites with Photosensitive 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin Entrapped into Silica Gels

Czech Academy of Sciences Publication Activity Database

Rychtáriková, Renata; Šabata, Stanislav; Hetflejš, Jiří; Kuncová, Gabriela

2012-01-01

Roč. 61, č. 1 (2012), s. 119-125 ISSN 0928-0707 R&D Projects: GA MŠk ME 892 Institutional research plan: CEZ:AV0Z40720504 Keywords : sol-gel * photosensitizer * immobilization Subject RIV: CC - Organic Chemistry Impact factor: 1.660, year: 2012

Water-soluble resist for environmentally friendly lithography

Science.gov (United States)

Lin, Qinghuang; Simpson, Logan L.; Steinhaeusler, Thomas; Wilder, Michelle; Willson, C. Grant; Havard, Jennifer M.; Frechet, Jean M. J.

1996-05-01

This paper describes an 'environmentally friendly,' water castable, water developable photoresist system. The chemically amplified negative-tone resist system consists of three water-soluble components: a polymer, poly(methyl acrylamidoglycolate methyl ether), [poly(MAGME)]; a photoacid generator, dimethyl dihydroxyphenylsulfonium triflate and a crosslinker, butanediol. Poly(MAGME) was synthesized by solution free radical polymerization. In the three-component resist system, the acid generated by photolysis of the photoacid generator catalyzes the crosslinking of poly(MAGME) in the exposed regions during post-exposure baking, thus rendering the exposed regions insoluble in water. Negative tone relief images are obtained by developing with pure water. The resist is able to resolve 1 micrometer line/space features (1:1 aspect ratio) with an exposure dose of 100 mJ/cm2 at 248 nm. The resist can be used to generate etched copper relief images on printed circuit boards using aqueous sodium persulfate as the etchant. The crosslinking mechanism has been investigated by model compound studies using 13C NMR. These studies have revealed that the acid catalyzed reaction of the poly(MAGME) with butanediol proceeds via both transesterification and transacetalization (transaminalization) reactions at low temperatures, and also via transamidation at high temperatures.

Enhanced sensitivity to the lethal and mutagenic effects of photosensitizing action of chlorpromazine in ethylenediaminetetraacetate-treated Escherichia coli

International Nuclear Information System (INIS)

Yonei, S.; Todo, T.

1982-01-01

Ethylenediaminetetraacetate (EDTA) treatment of Escherichia coli H/r30 (Arg - ) enhanced cell sensitivity to the lethal and mutagenic effects of the photosensitizing action of chlorpromazine (CPZ). The most obvious effect of EDTA on the fluence-survival curve was an elimination of the shoulder. In the absence of EDTA, CPZ plus near-UV radiation did not induce the reversion from arginine-auxotroph to autotroph of E. coli H/r30. However, when EDTA (5 mM)-treated cells were subjected to CPZ plus near-UV radiation, the induced reversion frequency increased with time of irradiation. It is concluded that the enhanced penetration of CPZ into E. coli cells by EDTA facilitates the drug binding to DNA within the cells upon near-UV irradiation and that this is the cause for the enhanced photosensitized lethal and mutagenic effects of CPZ. (author)

Enhanced oral bioavailability of fenofibrate using polymeric nanoparticulated systems: physicochemical characterization and in vivo investigation

Directory of Open Access Journals (Sweden)

Yousaf AM

2015-03-01

other formulations, it existed in the crystalline state with a reduced intensity. The aqueous solubility and dissolution rates of the nanoparticles (after 30 minutes were not significantly different from one another. Among the nanoparticulated systems tested in this study, the initial dissolution rates (up to 10 minutes were higher with the PVP nanospheres and HP-β-CD nanocorpuscles; however, neither of them resulted in the highest oral bioavailability. Irrespective of relatively retarded dissolution rate, gelatin nanocapsules showed the highest apparent aqueous solubility and furnished the most improved oral bioavailability of the drug (~5.5-fold, owing to better wetting and diminution in crystallinity.Conclusion: Fenofibrate-loaded gelatin nanocapsules prepared using the solvent-evaporation method through the spray-drying technique could be a potential oral pharmaceutical product for administering the poorly water-soluble fenofibrate with an enhanced bioavailability.Keywords: gelatin nanocapsules, hydrophilic polymeric matrix, crystallinity, ameliorated oral bioavailability

Uranium solubility and solubility controls in selected Needle's Eye groundwaters

International Nuclear Information System (INIS)

Falck, W.E.; Hooker, P.J.

1991-01-01

The solubility control of uranium in selected groundwater samples from the cliff and sediments at the Needle's Eye natural analogue site is investigated using the speciation code PHREEQE and the CHEMVAL thermodynamic database (release 3). Alkali-earth bearing uranyl carbonate secondary minerals are likely to exert influence on the solubility . Other candidates are UO 2 and arsenates, depending on the prevailing redox conditions. In the absence of literature data, solubility products for important arsenates have been estimated from analogy with other arsenates and phosphates. Phosphates themselves are unlikely to exert control owing to their comparatively high solubilities. The influence of seawater flooding into the sediments is also discussed. The importance of uranyl arsenates in the retardation of uranium in shallow sediments has been demonstrated in theory, but there are some significant gaps in the thermodynamic databases used. (author)

Studies on Rate Enhancement of Polymerization in NMRP

Institute of Scientific and Technical Information of China (English)

HUANG Jian-ying; XU Miao-qing; YAN Ming-fa; CHEN Yi-hong; CHU Jia-yan; ZHUANG Jia-ming; DAI Li-zong; ZOU You-si

2005-01-01

In NMRP, the polymerization of MMA, the polymerization of St and the copolymerization of MMA with St were distinctly accelerated by the addition of a small amount of MN. The polymerization proceeds in a living fashion as indicated by the increase in molecular weight with the increase of time and conversion and a relatively low polydispersity. It has been found that the addition of MN results in a nearly one hundred times higher rate of the polymerization of MMA, a nearly twenty times higher rate of the polymerization of St and a nearly fifteen times higher rate of the copolymerization of St and MMA.

The Large-Scale Synthesis of Vinyl-Functionalized Silicon Quantum Dot and Its Application in Miniemulsion Polymerization

Directory of Open Access Journals (Sweden)

Xuan-Dung Mai

2016-01-01

Full Text Available Stable luminescence, size-tunability, and biocompatibility encourage the deployment of Cd-free NPs into diverse biological applications. Here we report one-pot synthesis of blue-emitting and polymerizable silicon quantum dots (Si QDs from which water-soluble Si QDs embedded polystyrene nanoparticles (SiQD@PS NPs were prepared using a miniemulsion polymerization approach. The hydrodynamic size of NPs was controlled by KOH to oleic acid molar ratio. Studies on the photoluminescence properties of SiQD@PS NPs in different conditions reveal that they exhibit two-photon luminescence property and high stability against pH and UV exposure. These NPs add new size regime to the Si QDs based luminescent makers for bioimaging and therapy applications.

Liquid crystal nanoparticles for delivery of photosensitizers for photodynamic therapy

Science.gov (United States)

Nag, Okhil K.; Naciri, Jawad; Delehanty, James B.

2018-02-01

The main principle of photodynamic therapy (PDT) is to kill malignant cells by generation of reactive oxygen species (ROS). PDT appeared highly effective when ROS can be produced in subcellular location such as plasma membrane. The plasma membrane maintains the structural integrity of the cell and regulates multiple important cellular processes, such as endocytosis, trafficking, and apoptotic pathways, could be one of the best points to kill the cancer cells. Previously, we have developed a plasma membrane-targeted liquid crystal nanoparticle (LCNP) formulation that can be loaded with dyes or drugs. Here we highlight the utility of this LCNP for membrane targeted delivery and imaging for a photosensitizer (PS) for PDT applications.

Quasi Two-Dimensional Dye-Sensitized In 2 O 3 Phototransistors for Ultrahigh Responsivity and Photosensitivity Photodetector Applications

KAUST Repository

Mottram, Alexander D.; Lin, Yen-Hung; Pattanasattayavong, Pichaya; Zhao, Kui; Amassian, Aram; Anthopoulos, Thomas D.

2016-01-01

of the light absorbing organic dye D102. The resulting transistors exhibit a preferential color photoresponse centered in the wavelength region of ∼500 nm with a maximum photosensitivity of ∼106 and a responsivity value of up to 2 × 103 A/W. The high

Photoexcited riboflavin induces oxidative damage to human serum albumin

Science.gov (United States)

Hirakawa, Kazutaka; Yoshioka, Takuto

2015-08-01

Photoexcited riboflavin induced damage of human serum albumin (HSA), a water soluble protein, resulting in the diminishment of fluorescence from the tryptophan residue. Because riboflavin hardly photosensitized singlet oxygen generation and sodium azide, a singlet oxygen quencher, did not inhibit protein damage, electron transfer-mediated oxidation of HSA was speculated. Fluorescence lifetime of riboflavin was not affected by HSA, suggesting that the excited triplet state of riboflavin is responsible for protein damage through electron transfer. In addition, the preventive effect of xanthone derivatives, triplet quenchers, on photosensitized protein damage could be evaluated using this photosensitized reaction system of riboflavin and HSA.

Nonperturbative Renormalization Group Approach to Polymerized Membranes

Science.gov (United States)

Essafi, Karim; Kownacki, Jean-Philippe; Mouhanna, Dominique

2014-03-01

Membranes or membrane-like materials play an important role in many fields ranging from biology to physics. These systems form a very rich domain in statistical physics. The interplay between geometry and thermal fluctuations lead to exciting phases such flat, tubular and disordered flat phases. Roughly speaking, membranes can be divided into two group: fluid membranes in which the molecules are free to diffuse and thus no shear modulus. On the other hand, in polymerized membranes the connectivity is fixed which leads to elastic forces. This difference between fluid and polymerized membranes leads to a difference in their critical behaviour. For instance, fluid membranes are always crumpled, whereas polymerized membranes exhibit a phase transition between a crumpled phase and a flat phase. In this talk, I will focus only on polymerized phantom, i.e. non-self-avoiding, membranes. The critical behaviour of both isotropic and anisotropic polymerized membranes are studied using a nonperturbative renormalization group approach (NPRG). This allows for the investigation of the phase transitions and the low temperature flat phase in any internal dimension D and embedding d. Interestingly, graphene behaves just as a polymerized membrane in its flat phase.

Diblock Terpolymers Are Tunable and pH Responsive Vehicles To Increase Hydrophobic Drug Solubility for Oral Administration.

Science.gov (United States)

Tale, Swapnil; Purchel, Anatolii A; Dalsin, Molly C; Reineke, Theresa M

2017-11-06

Synthetic polymers offer tunable platforms to create new oral drug delivery vehicles (excipients) to increase solubility, supersaturation maintenance, and bioavailability of poorly aqueous soluble pharmaceutical candidates. Five well-defined diblock terpolymers were synthesized via reversible addition-fragmentation chain transfer polymerization (RAFT) and consist of a first block of either poly(ethylene-alt-propylene) (PEP), poly(N-isopropylacrylamide) (PNIPAm), or poly(N,N-diethylaminoethyl methacrylate) (PDEAEMA) and a second hydrophilic block consisting of a gradient copolymer of N,N-dimethylacrylamide (DMA) and 2-methacrylamidotrehalose (MAT). This family of diblock terpolymers offers hydrophobic, hydrophilic, or H-bonding functionalities to serve as noncovalent sites of drug binding. Drug-polymer spray dried dispersions (SDDs) were created with a model drug, probucol, and characterized by differential scanning calorimetry (DSC). These studies revealed that probucol crystallinity decreased with increasing H-bonding sites available in the polymer. The PNIPAm-b-P(DMA-grad-MAT) systems revealed the best performance at pH 6.5, where immediate probucol release and effective maintenance of 100% supersaturation was found, which is important for facilitating drug solubility in more neutral conditions (intestinal environment). However, the PDEAEMA-b-P(DMA-grad-MAT) system revealed poor probucol dissolution at pH 6.5 and 5.1. Alternatively, at an acidic pH of 3.1, a rapid and high dissolution profile and effective supersaturation maintenance of up to 90% of the drug was found, which could be useful for triggering drug release in acidic environments (stomach). The PEP-b-P(DMA-grad-MAT) system showed poor performance (only ∼20% of drug solubility at pH 6.5), which was attributed to the low solubility of the polymers in the dissolution media. This work demonstrates the utility of diblock terpolymers as a potential new excipient platform to optimize design parameters for

AZIDE-ALKYNE CLICK POLYMERIZATION: AN UPDATE

Institute of Scientific and Technical Information of China (English)

Hong-kun Li; Jing-zhi Sun; An-jun Qin; Ben Zhong Tang

2012-01-01

The great achievements of click chemistry have encouraged polymer scientists to use this reaction in their field.This review assembles an update of the advances of using azide-alkyne click polymerization to prepare functional polytriazoles (PTAs) with linear and hyperbranched structures.The Cu(Ⅰ)-mediated click polymerization furnishes 1,4-regioregular PTAs,whereas,the metal-free click polymerization of propiolates and azides produces PTAs with 1,4-regioisomer contents up to 90％.The PTAs display advanced functions,such as aggregation-induced emission,thermal stability,biocompatibility and optical nonlinearity.

Photochemical characterization of water samples from Minnesota and Vermont sites with malformed frogs: potential influence of photosensitization by singlet molecular oxygen ({sup 1}O{sub 2}) and free radicals on aquatic toxicity

Energy Technology Data Exchange (ETDEWEB)

Bilski, P.; Burkhart, J.G.; Chignell, C.F

2003-11-19

Environmental pollutants activated by UV sunlight may have contributed to the recent decline in frog populations and the concomitant increase in malformations in the USA and abroad. UV radiation is able to mutate DNA and to initiate photosensitization processes that generate mutagenic and biologically disruptive oxygen transients. We have examined water from selected sites in Minnesota and Vermont using singlet molecular oxygen ({sup 1}O{sub 2}), detected by its phosphorescence and free radicals detected by spin trapping, as markers for photosensitization. Water from a pond in Minnesota with malformed frogs, which also causes malformations in the laboratory, photosensitized more {sup 1}O{sub 2}, even though it absorbed less UV light compared to water from a site that did not cause malformations. This suggested that unknown natural or pollutant agents were present, and that photosensitization may be involved. Although UV irradiation of the two Minnesota water samples in the presence of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) revealed the presence of the DMPO/{center_dot}OH, DMPO/{center_dot}H(e{sub aq}{sup -}) and DMPO/{center_dot}C(unknown) adducts there were no qualitative or quantitative differences between them. We also examined water samples from several sites in Vermont, and compared them by measuring the quantum yield of {sup 1}O{sub 2} photosensitization. While all the Vermont samples produced a small amount of {sup 1}O{sub 2}, there was no clear correlation with the incidence of frog malformations. However, the samples differed strongly in absorption spectra and the ability to quench {sup 1}O{sub 2}. These factors may determine how much UV light is absorbed and converted into chemical reactions. Our results show that photochemical characterization of {sup 1}O{sub 2} photosensitization is possible in untreated natural water samples. Photosensitization falls into the category of global factors that may be closely associated with the effects of