Development of enzyme-loaded PVA microspheres by membrane emulsification

Enzyme applications have a considerable role at the heart of biotechnological processes. A large number of these biotechnological processes require successful enzyme immobilization in terms of resistance to leaking, retention of enzyme activity over long-term storage, operational stability under adverse environmental conditions, accessibility to substrates, fast catalysis, and, in general, proper enzyme immobilization density with adequate orientation. Among the different methods of immobilization, enzyme encapsulation in a network matrix of polymeric materials in the form of particles is of particular interest. Polyvinyl alcohol (PVA) microspheres produced by a membrane emulsification/cross-linking method have been used as enzyme carriers. The enzyme was immobilized during particle formation (by entrapment) or after particle production (by adsorption and cross-linking). The entrapment during particle solidification from a water in oil (W/O) emulsion, allowed the enzyme to be distributed at the interface in its active form. The best operating conditions to control particle size, particle size distribution and particle structure for PVA microspheres production as well as the most suitable method for lipase immobilization on/in PVA microspheres have been identified. The immobilization method that does not affect enzyme intrinsic biocatalytic activity, whilst allowing at the same time confinement with balance between molecular mobility and heterogenization has been identified.