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Colloids of metal nanoparticles (NPs) of Au, Ag, Pd, and Pt protected by natural polymer arabinogalactan (ARB) extracted from Larix sibirica were studied. The nanocomposites were prepared by reduction of metal salts in the water solutions of ARB. We carried out dynamic (DLS) and static light scattering resonantly enhanced by the NP plasmons. The translational diffusion was examined via DLS and a polarized interferometer. The virgin ARB was shown to form aggregates in dilute aqueous solutions. The introduction of NPs reduced the size of the virgin ARB aggregates. The aggregate forms as viewed by the scanning electron microscopy support the light scattering results.

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A series of novel polysaccharide-based biocomposites was obtained by impregnation of bacterial cellulose produced by Komagataeibacter rhaeticus (BC) with the solutions of negatively charged polysaccharides—hyaluronan (HA), sodium alginate (ALG), or κ-carrageenan (CAR)—and subsequently with positively charged chitosan (CS). The penetration of the polysaccharide solutions into the BC network and their interaction to form a polyelectrolyte complex changed the architecture of the BC network. The structure, morphology, and properties of the biocomposites depended on the type of impregnated anionic polysaccharides, and those polysaccharides in turn determined the nature of the interaction with CS. The porosity and swelling of the composites increased in the order: BC–ALG–CS > BC–HA–CS > BC–CAR–CS. The composites show higher biocompatibility with mesenchymal stem cells than the original BC sample, with the BC–ALG–CS composite showing the best characteristics.

ABSTRACT:The separation properties in the dehydration of a water-ethanol mixture and the swelling behavior of interpenetrating polymer network (IPN) pervaporation membranes based on a cellulose or cellulose-hydroxyethyl cellulose (HEC) matrix and poly(acrylamide and/or acrylic acid) were investigated depending on the ionic acrylate groups content (␥) in synthetic polymer chains (0 -100 mol %), the HEC content in the matrix (0 -50 wt %), and the temperature (25-60°C). The separation factor (␣), permeation rate (P), and separation index (␣P) significantly improved with increasing ␥ values only for the separation of concentrated ethanol solutions (ϳ86 wt %). For more dilute solutions of ethanol (ϳ46 wt %), the P and ␣P values also increased but no considerable increase in ␣ was observed. All types of membranes based on the cellulose matrix were characterized by a drastic decrease in the values of P at [EtOH] Ն90 wt % and, as a result, a decrease in the separation index (kg m Ϫ2 h Ϫ1 ) from ϳ2000 (for 86 wt % EtOH, 50°C) to ϳ240 (for 95 wt % EtOH, 50°C), which correlates with a decrease in the degree of membrane swelling. The modification of the cellulose matrix by introducing HEC into it makes it possible to increase considerably the membrane swelling in concentrated EtOH solutions and, hence, the ␣P value to ϳ760 (95 wt % EtOH, 50°C). All types of IPN membranes exhibit a marked increase in both ␣ and P when the temperature increases from 25 to 60°C.

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