Search results for "Light scatter"
showing 10 items of 465 documents
Heparin-Based Nanocapsules as Potential Drug Delivery Systems
2015
Herein, the synthesis and characterization of heparin-based nanocapsules (NCs) as potential drug delivery systems is described. For the synthesis of the heparin-based NCs, the versatile method of miniemulsion polymerization at the droplets interface was achieved resulting in narrowly distributed NCs with 180 nm in diameter. Scanning and transmission electron microscopy images showed clearly NC morphology. A highly negative charge density for the heparin-based NCs was determined by measuring the electro-kinetic potential. Measuring the activated clotting time demonstrated the biological intactness of the polymeric shell. The ability of heparin-based NCs to bind to antithrombin (AT III) was i…
Estimation of Number-Average Molecular Weights of Copolymers by Gel Permeation Chromatography−Light Scattering
1996
The true number-average molecular weight, Mn, of copolymers is obtained by GPC coupled with a light-scattering detector even if the composition and therefore the refractive index increment varies with elution volume, provided slices taken are monodisperse with respect to molecular weight and composition. In contrast, only an apparent weight-average molecular weight, can be obtained by the conventional GPC−light scattering combination, even for a perfect chromatographic resolution. The errors in Mn associated with nonhomogeneous slices are estimated. Experimental data with mixtures of linear polystyrene and poly(methyl methacrylate) confirm these estimations and indicate that the error in Mn…
Polyvinylferrocene-Based Amphiphilic Block Copolymers Featuring Functional Junction Points for Cross-Linked Micelles
2016
The synthesis of high-molecular-weight, well-defined poly(vinylferrocene)-block-poly(ethylene glycol) (PVFc-b-PEG) diblock copolymers (Mn = 13 000–44 000 g mol–1; Đ = 1.29–1.34) with precisely one allyl group at the junction point is introduced. Allyl glycidyl ether (AGE) was used to end-functionalize PVFc, resulting in hydroxyl functional macroinitiators for the oxyanionic polymerization of ethylene oxide. The self-assembly behavior of the amphiphilic PVFc-b-PEG copolymers in water has been investigated in a detailed manner, using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The redox activity of the PVFc block was confirmed by UV/vis spectroscopy, while cyclo…
Introduction into the study of translational diffusion by laser techniques
1988
Breve description de la technique du reseau holographique pour mesurer les coefficients de diffusion de traceurs dans des polymeres et de la technique de spectrometrie de correlation de photon pour la mesure des coefficients de diffusions mutuelle dans des melanges de polymeres
Characterization of Polyorganosiloxane Nanoparticles in Aqueous Dispersion by Asymmetrical Flow Field-Flow Fractionation
2001
The advantages of asymmetrical flow field-flow fractionation (AF-FFF) for the characterization of aqueous dispersions of spherical polyorganosiloxane nanoparticles are discussed. With AF-FFF it was possible to obtain information about the synthesis, which is based on the hydrolysis and condensation of alkylalkoxysilanes in aqueous dispersion, and the average size of the spherical nanoparticles in the complex mixture in the presence of excess surfactant. The results are compared to measurements performed with dynamic light scattering (DLS). The size of the nanoparticles increases as a function of the amount of added monomer. Particles with radii between 2 and 50 nm are observed. If only the …
Diffusion in concentrated colloidal suspensions and glasses
1998
The well established analogy between colloidal suspensions and atomic fluids has been extended to the glass transition problem in the past few years. Colloids have become the ideal test case for checking glass transition theories; this was due to the possibility of modeling hard spheres with colloidal dispersions. Significant progress has also been made in instrumentation, especially in the development of light-scattering techniques allowing moderately turbid and nonergodic samples to be analyzed. Mode coupling theory has become a paradigm not only for the glass transition, but also for the understanding of dynamics in highly concentrated colloidal dispersions where crystallization is suppr…
Novel hydrogels based on a polyasparthydrazide. Synthesis and characterization
2000
α,β-polyasparthydrazide (PAHy), a synthetic water-soluble biocompatible polymer, was chemically crosslinked with ethyleneglycol diglycidylether (EGDGE), in order to obtain water swellable microparticies. These were characterized by means of FT-IR spectrophotometry and by means of particle size distribution analysis. The mean pore size of the prepared gels as various crosslinking ratios and the fractal dimensions were determined by light scattering measurements. Swelling measurements gave evidence of the high affinity of PAHy-EGDGE microparticles towards aqueous media at different pH values. The physical state of the prepared networks was evaluated by means of X-rays diffractometry and therm…
Uptake of polymeric nanoparticles in a human induced pluripotent stem cell-based blood-brain barrier model: Impact of size, material, and protein cor…
2021
The blood–brain barrier (BBB) maintains the homeostasis of the central nervous system, which is one of the reasons for the treatments of brain disorders being challenging in nature. Nanoparticles (NPs) have been seen as potential drug delivery systems to the brain overcoming the tight barrier of endothelial cells. Using a BBB model system based on human induced pluripotent stem cells (iPSCs), the impact of polymeric nanoparticles has been studied in relation to nanoparticle size, material, and protein corona. PLGA [poly(lactic-co-glycolic acid)] and PLLA [poly(d,l-lactide)] nanoparticles stabilized with Tween® 80 were synthesized (50 and 100 nm). iPSCs were differentiated into human brain m…
SiRNA-mediated in vivo gene knockdown by acid-degradable cationic nanohydrogel particles
2017
Cationic nanohydrogel particles have become an attractive tool for systemic siRNA delivery, but improvement of their in vivo tolerance is desirable, especially to prevent potential long term side effects by tissue and cellular accumulation. Here, we designed novel ketal cross-linked cationic nanohydrogel particles that were assessed for reduced tissue accumulation and robust siRNA delivery in vitro and in vivo. An oligo-amine cross-linker equipped with a ketal moiety in its core was synthesized and applied to nanohydrogel cross-linking of self-assembled reactive ester block copolymers in DMSO. The resulting acid-sensitive cationic nanoparticles spontaneously disassembled over time in acidic…
Silver nanoparticles stabilized by a polyaminocyclodextrin as catalysts for the reduction of nitroaromatic compounds
2015
Abstract Silver nanoparticles stabilized by means of poly -(6- N , N -dimethyl-propylenediamino)-(6-deoxy)-β-cyclodextrin were synthesized, characterized by different techniques (UV–vis spectroscopy, Dynamic Light Scattering, High Resolution Transmission Electron Microscopy, Fourier-transform IR Spectroscopy) and used as catalysts for the reduction of various nitrobenzene derivatives with sodium borohydride. The nanocomposites obtained appear to have an organized structure, with a metal core surrounded by a layer-structured coating shell. Kinetic data, rationalized in terms of a modified Langmuir–Hinshelwood model, evidenced a non-linear dependence of the reaction rate on the concentration …