Immobilization Of Alcohol Dehydrogenases In Biomimetic Carrageenan-Silica Hybrid Gels

κ-carrageenan gel is one of the most commonly used carriers of the enzyme immobilization attributed to their significant advantages such as good biocompatibility, simplicity of preparation and easy availability. However, due to some disadvantages, such as loose network, large pore size, serious syneresis and swelling, high enzyme leakage, the lifetime of these immobilized enzymes and their further application are limited. To overcome these disadvantages, in the study inspired by diatoms in nature, a novel biomimetic carrageenan-silica hybrid gel microspheres with the structure of"core-shell"were prepared to immobilize enzyme.First, the chitosan molecules were adsorbed on the surface of carrageenan gel microspheres to catalyse the silanol in hydrolyzed TEOS polycondensation and prepare biomimetic carrageenan-silica hybrid gels. The structure and morphologies, chemical and physical properties of pure and hybrid carrageenan microspheres by scanning electron (SEM), BET nitrogen adsorption-desorption method, Fourier Transform IR spectrophotometer (FTIR), and so on. Meanwhile, the mechanism of chitosan-catalysed formation of silica was evaluated.Then by encapsulating the bovine serum albumin (BSA) in pure carrageenan gels and hybrid carrageenan gels, the enzyme leakage during the encapsulation and release was studied. During the encapsulation, first BSA was encapsulated in carrageenan gel microspheres and then coat these microspheres with silica films. It was found that the silica shell could prevent the BSA leakage during release process and the capabilities of anti-swelling was enhanced.At last, yeast alcohol dehydrogenase (YADH) was chosen for encapsulation in carrageenan-silica hybrid gel microspheres. The enzyme leakage, catalytic activity, optimum reaction conditions, kinetic parameters, and the operational and storage stability of immobilized YADH were investigated. The results showed that compared with the pure carrageenan gels, enzyme leakage from the hybrid carrageenan gel microspheres was remarkably reduced by about 60%. The activity retention, operational and storage stabilities of the enzyme immobilized in hybrid carrageenan gel microspheres were improved. In addition, after immobilization, the thermal stability of YADH enhanced and the protein secondary structure was retained well.