Porous chitosan microsphere for controlling the antigen release of Newcastle disease vaccine: preparation of antigen-adsorbed microsphere and in vitro release

Porous chitosan microspheres suitable for the delivery of antigen were prep ared using a wet phase-inversion method. The pore structure of the chitosan microsphere could be modified by the change of pH value of the coagulation medium, which is the aqueous tripolyphosphate (TPP) solution. High porosit y of chitosan microsphere with an open porous structure on its surface was prepared by coagulation in TPP aq. solution of pH 8.9. The porous chitosan microspheres were modified chemically with reagents to introduce three type s of functional groups; carboxyl, hydrophobic acyl and quaternary ammonium groups. Antigen of ND vaccine was immobilized into the pores of porous chit osan microspheres and the adsorbed antigen was assayed by the Hemoglobin Ag gregation (HA) analytical method. Sustained-release of ND vaccine's antigen could be achieved through an adsorption-desorption release test. The chemi cal modifications of the porous chitosan microspheres have a strong large i nfluence on the adsorption efficiency or release rates of the antigen inves tigated. The porous microspheres have a higher adsorption efficiency and th e slower release rate of antigen when modified chemically with 3-chloro-2-h ydroypropyltrimethylamonium chloride. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.