Quitosana aplicações

International Journal of Pharmaceutics 339 (2007) 148–156

Immobilization and bioactivity of glucose oxidase in hydrogel microspheres formulated by an emulsification–internal gelation–adsorption–polyelectrolyte coating method
Qun Liu a , Andrew Michael Rauth b , Xiao Yu Wu a,∗ a Leslie Dan Faculty of Pharmacy, University of Toronto,144 College Street, Toronto, Ont., Canada M5S 3M2 b Division of Experimental Therapeutics, Ontario Cancer Institute, Toronto, Ont., Canada M5G 2M9 Received 31 January 2007; received in revised form 20 February 2007; accepted 26 February 2007 Available online 1 March 2007

Abstract The purpose of this study was to develop a novel microsphere formulation of glucose oxidase (GOX) with high drug loading, encapsulation efficiency and bioactivity. GOX was encapsulated in alginate/chitosan microspheres (ACMS) using an emulsification–internal gelation, followed by GOX adsorption and polyelectrolyte coating method. The factors influencing GOX loading, encapsulation efficiency and activity of the loaded GOX were investigated. The resultant ACMS in wet state were spherical with a mean diameter of about 138 m. GOX loading was found to be pH dependent. High GOX loading and encapsulation efficiency were achieved when the pH of the adsorption medium was lower than the isoelectric point (pI) of GOX. GOX loading and encapsulation efficiency increased with increasing GOX concentration in the loading solution, but decreased with increasing chitosan concentration in the coating solution. The activity of loaded GOX increased and then decreased with increasing chitosan concentration. The activity of GOX in ACMS was maintained and showed sustained production of H2 O2 as compared to free GOX. Around 90% of the original activity of immobilized GOX remained after lyophilization and storage at −20 ◦ C for a month. These results suggest that the ACMS and the fabrication method are suitable for microencapsulation of proteins like GOX. © 2007 Elsevier B.V. All