Immobilization of Enzymes By Spray-Drying Method in Core-Shell Structured Chitosan Carriers Cross-Linked By Novel “in-Situ” Method

This work deals with the encapsulation of model enzymes by a 3-fluid kinetic nozzle. This type of nozzle allows us to produce particles with a core-shell structure. In a case of 2-fluid nozzle chitosan-enzyme solution is cross-linked before spray-drying process (“ex-situ”) and thus enzymatic activity could be negatively affected by the cross-linker presence. In the case of 3-fluid nozzle the enzyme is in intimate contact with the cross-linker for a very short time during spray-drying formation and the range of possible chitosan and cross-linker concentration is higher that for “ex-situ” cross-linking. This could be very significant to prevent enzyme deactivation during long storage and reduce undesirable cross-linker content in the final product. Enzymatic activity, encapsulation efficiency and stability of the carriers in aqueous medium are compared with particles produced by 2-fluid nozzle. The next step is the production of structured particles by 3-fluid nozzle where a core of substrate is surrounded by enzyme in a cross-linked chitosan shell. This approach allows us to produce particles with substrate and immobilized enzyme in one carrier.