Search results for "PLASTICS"
showing 10 items of 2724 documents
Toward Anticancer Immunotherapeutics: Well-Defined Polymer-Antibody Conjugates for Selective Dendritic Cell Targeting
2014
This paper describes the synthesis of semitelechelic maleimide-modified N-(2-hydroxypropyl)methacrylamid) (HPMA) based polymers of narrow dispersity that can be conjugated e.g. to anti-DEC-205 antibodies affording "star-like" topologies (one antibody decorated with several polymer chains). FCS revealed a hydrodynamic diameter of R(h) = 7.9 nm and SEC narrow dispersity (1.45). Primary in vitro studies with bone marrow derived dendritic cells (DC) show higher cellular binding and uptake rates compared to control samples. Moreover, incubating these conjugates to primary splenocytes demonstrates a much higher affinity to the primary DCs than to any other immune cell population within the splee…
Evaluation of radiation stability of electron beam irradiated Nafion® and sulfonated poly(ether ether ketone) membranes
2022
Proton exchange membranes (PEM), which have been commonly used in fuel cells have raised interest for the application in harsh environments involving ionizing radiation. Therefore, radiation stability and ability to sustain their functionality under the radiation environment are of great interest. Within this study, electron beam irradiation in dose range from 50 to 500kGy was used to evaluate the effects of radiation on the physico-chemical and mechanical properties of two types of PEM: commercial Nafion®117 and sulfonated poly(ether-ether-ketone) (SPEEK) with high degree of sulfonation (DS = 0.75±0.5). SPEEK membrane presented higher mechanical and thermal stability compared to that of Na…
Caffeine analysis and extraction from a topical cream intended for UV-skin protection
2020
Made available in DSpace on 2021-06-25T10:16:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 This study aimed to develop and validate a method for the analysis of caffeine in complex cosmetic samples, such as sunscreens. Besides, an extraction method of caffeine from coffee oil and from creams, which contains both lipophilic and hydrophilic components, has been developed. The method to analyze caffeine was developed using an isocratic pump, Waters 1515 and an automatic injector Perkin-Elmer Series 200 and an UV detector Perkin-Elmer. As stationary phase, Kromasil C-18 (150 × 4.6 mm ID with particle size of 5 µm) column was used and a mixture of water (pH 4.00)/acetonitrile (…
In vitro evaluation of glycol chitosan based formulations as oral delivery systems for efflux pump inhibition.
2017
Recently, we have reported that glycol chitosan (GCS) was able to reverse the P- glycoprotein (P-gp) efflux pump. The objective of the present study was to evaluate the potential of two GCS-based dosage forms (aqueous solution or nanoparticle suspension) for oral administration of the P-gp substrate Rho-123. A further aim of the present study was to assess the effect of the glycol chitosan-4-thiobutylamidine thiomer (GCS-TBA) on P-gp activity considering that the corresponding thiomer of chitosan series is a well-known P-gp inhibitor. Pre-treatment of Caco-2 cell monolayer with a GCS solution or GCS-based nanoparticles increased the absorptive transport of Rho-123 across the monolayer of 1.…
Electrostatically Driven Complexation of Liposomes with a Star-Shaped Polyelectrolyte to Low-Toxicity Multi-Liposomal Assemblies
2013
Anionic liposomes are electrostatically complexed to a star-shaped cationic polyelectrolyte. Upon complexation, the liposomes retain their integrity and the resulting liposome-star complexes do not dissociate in a physiological solution with 0.15 M NaCl. This provides a multi-liposomal container for possible use as a high-capacity carrier.
External Versus Internal Metabolic Activation of Polycyclic Aromatic Compounds in Mutagenicity Tests: A Comparison Using Heterologous Expression Syst…
1996
Abstract Benzo[a]pyrene-trans-7,8-dihydrodiol was virtually non-mutagenic to Chinese hamster V79p cells, but was strongly mutagenic to a V79-derived cell line expressing cytochrome P450 1A1, when the cells were exposed separately. In mixed cultures of these two cell types, it showed about 50 % of the mutagenic activity in V79p cells, compared to that observed in the enzyme-proficient cell line, indicating an efficient intercellular transfer of the active metabolite. The benzylic alcohols 1-hydroxymethylpyrene and 6-hydroxymethylbenzo[a]-pyrene were weakly mutagenic to Salmonella typhimurium TA1538 in the absence of a metabolic activation system, but were potent mutagens to a TA1538-derived …
Dielectric properties of water/lecithin/cyclohexane gels
1993
Dielectric relaxation measurements in the frequency range 0.1–15 GHz have been carried out on water/lecithin/cyclohexane gels using a time domain reflectometry method (TDR). Dielectric dispersions describable in terms of a power law typical of percolated systems, but with exponents significantly different from those characterizing statically or dynamically percolated systems are observed. The dielectric dispersions, attributed to water and/or lecithin head group rotational motions, indicate that these motions are characterized by a wide spectrum of relaxation times.
Tailored electrospun nanofibrous polycaprolactone/gelatin scaffolds into an acid hydrolytic solvent system
2018
[EN] Blended nanofibrous scaffolds based on polycaprolactone (PCL) and gelatin (Ge) were successfully prepared. A formic/acetic acid (1:1) mixture was used to dissolve PCL/Ge blends from 100/0 to 20/80 %wt in steps of 10 %wt. The hydrolysis of the PCL diluted in the formic/acetic acid mixture was considered as a method for tailoring the surface morphology and physicochemical features of the nanofibrous PCL/Ge scaffolds as a function of the dissolution time. The fibre diameter remained in the nanoscale range for all the studied scaffolds, which is crucial to mimic the extra-cellular matrix size. The reduction of the intrinsic viscosity, molar mass and hydrodynamic radius found for the PCL mo…
Coupling tyrosol, quercetin or ferulic acid and electron beam irradiation to cross-link chitosan–gelatin films: A structure–function approach
2015
International audience; Marine industry by-products, chitosan and fish gelatin, entrapping natural antioxidants (ferulic acid, quercetin and tyrosol) were used to prepare edible active films by casting. The films were composed of chitosan and fish gelatin (1:1 w:w) and incorporating antioxidants (∼50 mg/g). After solvent evaporation (drying), the films were irradiated at 60 kGy by electron beam. This treatment aims at investigating the coupled effect of irradiation with the presence of active compound on the structure and functional properties of the films. Electron Spin Resonance (ESR) unravelled free radical formation during irradiation in films containing ferulic acid or tyrosol which fa…
Bionanocomposite films containing halloysite nanotubes and natural antioxidants with enhanced performance and durability as promising materials for c…
2020
In the last decade, the interest toward the formulation of polymer films for cultural heritage protection continuously grew, and these films must be imperatively transparent, removable, and should not react/interact with surface of the artworks. In this research, bionanocomposite films, based on chitosan (Ch) and pectin (P) and containing naturally occurring fillers and antioxidants, were formulated by solvent casting methods and were accurately characterized. The natural halloysite nanotubes (HNT) have a two-fold role, specifically, physical compatibilizer and antioxidant carrier. Therefore, the theoretical solubility between Ch and P was estimated considering Hoy&rsquo