A HYDROGEL CAPABLE OF FACILITATING POLYMER DIFFUSION THROUGH THE GEL POROSITY AND ITS APPLICATION IN ENZYME IMMOBILIZATION

A hydrogel was designed and prepared which is capable of promoting the diffusion of soluble starches through its pores. The preparation was carried out via the iterative freezing-thawing of an aqueous poly(vinyl alcohol) solution containing concanavalin A, Con A, which had a binding affinity toward the starch to be diffused through the gel porosity. Gel permeation chromatographic analysis of the starch remaining in an aqueous solution after shaking with the Con A-loaded gel showed that the starch concentration of the gel phase was effectively enhanced. This strongly suggests that an attractive force (biochemical affinity) between the Con A within and the starch outside of the gel facilitated the diffusion of the starch through the gel porosity. The present Con A/gel system was applied in the immobilization of glucoamylase which was performed through the physical gel entrapment of both the enzyme and Con A. The gel with the entrapped enzyme hydrolyzed starch (as a polymeric substrate) into glucose in an aqueous system. Increased enzyme activity was observed due to the facilitated diffusion of the substrate induced by the Con A.