Hybrid Polysaccharide−Silica Nanocomposites Prepared by the Sol−Gel Technique

Abstract

New monolithic nanocomposite silica biomaterials were synthesized on the basis of various natural polysaccharides and recently introduced completely water-soluble precursor tetrakis(2-hydroxyethyl) orthosilicate. The sol-gel processes were performed in aqueous solutions without the addition of organic solvents and catalysts. The silica polymerization was promoted by the polysaccharides through acceleration and catalytic effect on the processes. By introducing poly(vinyl alcohol) or poly(ethylene oxide) in the precursor solution, it was shown that the jellification took place in the case of the hydroxyl-containing polymer. Therefore, it was suggested that the catalysis was caused by a formation of hydrogen bonds between hydroxyl groups in macromolecules and products of precursor hydrolysis (silanols). It was also demonstrated that the polysaccharides radically changed the structure of biomaterials. In place of the cross-linked nanoparticles, there was a three-dimensional network from crossed or branched fibers and uncrossed spherical particles that filled the mesh space. The density of network, thickness of fibers, and properties of synthesized biomaterials depended on the polysaccharide type, charged degree of their macromolecule, and concentration. By varying these parameters, it was possible to manipulate the structural organization of hybrid polysaccharide-silica nanocomposites.

The dramatic effect of small pH changes on the properties of chitosan hydrogels crosslinked with genipin

“…Syneresis occurs due to thermodynamic imbalance at the gel point leading to reorganization of the chains within the hydrogel, thus causing solvent exclusion (Vachoud, Zydowicz, & Domard, 2000). It has been observed before for other polysaccharides such as alginate (Blanshard & Muhr, 1982;Draget et al, 2001;Ingar Draget, Østgaard, & Smidsrød, 1990;Mitchell & Blanshard, 1974), carrageenan (de Jong & van de Velde, 2007;Dunstan, Salvatore, Jonsson, & Liao, 2000;Shchipunov & Karpenko, 2004), agarose (Park, Shalaby, & Park, 1993), starch (Yook & Sosulski, 1994), laminaran, arabinogalactan and guar gum (Shchipunov, Karpenko, Krekoten, & Postnova, 2005). There have been several reports regarding syneresis displayed in physically crosslinked chitosan gels created by N-acetylation of the polysaccharide (Félix, Hernández, Argüelles, & Goycoolea, 2005;Hirano & Yamaguchi, 1976;Moore & Roberts, 1980;Vachoud & Domard, 2001).…”

Efficient conversion of CO2 to formic acid by formate dehydrogenase immobilized in a novel alginate–silica hybrid gel

“…Moreover, incorporating inorganic material into the alginate matrix might be an effective method to overcome its disadvantages. Many researchers have prepared the hybrid silica-polysaccharide composites for enzyme immobilization by physically mixing the silica with alginate or sol-gel process by using a certain precursor [12][13][14].…”

Bionanocomposites Assembled by “From Bottom to Top” Method

“…Usage of polysaccharides as templates in sol-gel processes allows control over organized hybrid nanocomposites [143][144][145]. Formation of 3D fiber net [143] of a composite is due to hydrogen bonds formed between hydroxyl of macromolecules and products of TEOS hydrolysis.…”