Gel Entrapment of Whole Cells in Cross-Linked Prepolymerized Polyacrylamide-Hydrazide Gels

Gel entrapment of cells is attained by suspending the cells in an aqueous solution of monomers or prepolymers, followed by inducing the gelation of the system through physical change (cooling), by the addition of an initiator or a cross-linking reagent. An efficient process for whole-cell immobilization should allow for high retention of envisaged immobilized activity, good controlled porosity to ensure a free exchange of substrates and products, use of reasonably priced gel components, and good mechanical, chemical, and biological stability. This chapter presents entrapment method to meet with most of these guidelines. This entrapment procedure is based on suspending the cells in an aqueous solution of a linear, water-soluble synthetic polymer, containing controlled amounts of functional groups. The chapter discusses several examples of cells successfully entrapped through this method. In most of these cases, the gel entrapment of the same cells in the corresponding polyacrylamide network, derived from the polymerization of acrylamide monomer and bisacrylamide, led to a significant loss of activity. Thus, these examples represent the superiority of employing prepolymerized backbone over carrying out the polymerization of low-molecular-weight and toxic monomers.