Synthesis of Silicon-Containing Chitosan Hydrogels in a Glycolic Acid Medium

Abstract

The present paper considers a “one-pot” green sol-gel synthesis of hybrid inorganic/organic hydrogels based on chitosan glycolate by using organically modified silica Si(OGly)4·2GlyOH as a precursor to form a network of ≡Si–O–Si≡ bonds at 4, 20, and 37°C. The gelation time of the multicomponent chitosan-containing system was estimated as a function of the composition (the polymer template and precursor concentrations, introduction of a low-molecular-weight accelerator NaCl) and gelation conditions (the pH and temperature of the sol-gel process). It has been shown that an increased polymeric salt concentration, the introduction of an accelerator, and increased pH and temperature accelerate the gel-forming process.

Influence of Chitosan Ascorbate Chirality on the Gelation Kinetics and Properties of Silicon-Chitosan-Containing Glycerohydrogels

“…The revealed differences in the chirality of l - and d -diastereomerically-enriched chitosan ascorbates exert a significant influence on the kinetics of the biomimetic sol–gel synthesis of silicon-chitosan-containing glycerohydrogels. Previously, it was shown that the gelation kinetics of the systems based on chitosan salts and silicon tetraglycerolate was controlled by the acidity of the medium, determined by the nature and acid-base properties of the acid used [ 19 , 26 , 27 ]. Taking into account the same pH values of the source gelling systems, we associate the retarding or accelerating effect of chitosan ascorbate with the stereoisomerism of the chiral ligand and, correspondingly, with features of the spatial structure of the corresponding polysalt.…”

“…We considered the biomimetic sol-gel synthesis of silicon-chitosan-containing glycerohydrogels using glycerol solutions of silicon tetraglycerolate and aqueous solutions of chitosan salts with organic (СН 3 СООН, HOOCCH 2 OH, and С 6 Н 8 О 6 ) and inorganic (HCl) acids [ 19 , 26 , 27 ]. The influence of the concentration of the precursor and chitosan salt, the pH of the medium and the temperature of the sol–gel process on the gelation time of the multicomponent chitosan-containing system was estimated.…”

“…It has been established that chitosan accelerates gelation in weakly-acidic media; in more acidic media, the kinetics of the process changes along a curve with a maximum, which may be due to various mechanisms of the reaction of silanol condensation before and after the isoelectric point. Electron microscopy has shown that biomimetic mineralization of the polysaccharide occurs in the formation of these hybrid hydrogels, and the hydrogel skeleton is a 3D network consisting of agglomerated supramolecular chitosan structures coated with a “shell” of amorphous SiO 2 [ 26 , 27 ]. It is shown that, in practical terms, the salts of chitosan with pharmacopeic organic acids, in particular, with ascorbic ones, are the most promising to synthesize pharmacologically-active hydrogels.…”

Physico-mechanical Properties of Silicon-chitosan-containing Glycerohydrogels Plates Based on Chitosan L- and D-ascorbates

“…Ранее нами рассмотрен биомиметический золь-гель синтез кремнийхитозансодержащих глицерогидрогелей с использованием глицериновых растворов тетраглицеролата кремния и умеренно концентрированных водных растворов солей хитозана с органическими и неорганическими кислотами: уксусной, гликолевой, аскорбиновой, соляной [20,26,27]. Оценено влияние концентрации предшественника и соли хитозана, рН среды и температуры проведения золь-гель процесса на время гелеобразования многокомпонентной хитозансодержащей системы.…”