POLY(VINYL ALCOHOL) CRYOGELS EMPLOYED AS MATRICES FOR CELL IMMOBILIZATION .2. ENTRAPPED CELLS RESEMBLE POROUS FILLERS IN THEIR EFFECTS ON THE PROPERTIES OF PVA-CRYOGEL CARRIER

Poly(vinyl alcohol) cryogels which ale prepared by freeze-thawing of c oncentrated aqueous solutions of the polymer are used as carriers for cell immobilization. Biomass entrapment causes a variation in the mech anical properties of the composites obtained. With rheological testing and scanning electron microscopy, it was shown that cells which manif ested the reinforcing action in respect to the carrier resembled in th eir ''physical behavior'' simple model inorganic fillers of definite p orosity. This porosity allows macromolecules of gel forming polymer to penetrate into the inner legions of the particles and promote the for mation of tight contacts between the matrix and dispersed phase, such as entrapped cells in particular. The immobilized cultures and model f illers were as follows: Citrobacter intermedius, Zymomonas mobilis, an d Pseudomonas sp, bacteria, Saccharomyces cerevisiae native and modifi ed yeast cells, titanium dioxide, silica gels, and controlled pore gla ss. (C) 1997 by Elsevier Science Inc.