Abstract

The aim of the present study was to investigate the application of ‘Gellasan’ - chitosan crosslinked gellan gum as a
novel matrix for lipase immobilization. The biocatalyst used was Porcine Pancreas Lipase (triacylglycerol esterase) (EC
3.1.1.3). Gellan being heteroanionic and chitosan being cationic, the interaction between them resulted in the formation of
ionic crosslinked Gellasan beads. The hydrogel beads were prepared and optimized using a 32 factorial design by ionotropic
gelation technique. The beads were characterized by IR studies, Scanning Electron Microscopy. The lipase activity was
assayed using para-nitrophenylpalmitate as substrate with the highest activity of 261.1U/g of support. The average particle
size was found to be in the range of 192-226 μm. The beads showed a pH dependent swelling with a significantly higher
swelling index at pH 7.4 in phosphate buffer than in 0.1 N HCl. The percent release of the enzyme for the freeze-dried beads
was found to be 2.5-19% while of air-dried beads were 1.5-16% in 0.05 M Tris HCl buffer pH 7.4 within 8 hrs. Thus, the
two polymers gellan and chitosan were compatible for lipase immobilization and may become a potential delivery system to
control the release of drugs in future.

Key words: Chitosan; Factorial design; Gellan Gum; Gellasan; Ionotropic gelation; Lipase.