Single dose vaccine delivery system of tetanus toxoid formulation based on chitosan microspheres

Background: Biodegradable polymers such as Chitosan or PLGA has been used for sustain release of vaccines for prolonged period. Purpose of the study: To develop single dose vaccine delivery system of tetanus toxoid using chitosan microspheres. Different batches, 1%, 2% and 3% of chitosan microspheres (CM) were prepared by emulsion cross-linking method using glutaradehyde saturated toluene (GST). The tetanus toxoid (TT) was loaded with 1%, 2% and 3% of CM by adsorption method. Percentage of TT absorbed in 1%, 2% and 3% CM were determined by Limes flocculation method. In vitro release of adsorbed TT from 1%, 2% and 3% CM were performed with PBS (pH 7.4) and evaluated by ELISA assay using purified guinea pig IgG by affinity chromatography. Results: The average particle size of 1%, 2% and 3% of CM were determined by optical microscopic method and particle size was found to be 30μm, 31μm, and 35μm respectively. Percentage of TT adsorbed in 1%, 2% and 3% CM were found to be 71%, 80% and 76% respectively by Limes flocculation method. In vitro studies showed that different batches (1%, 2% and 3%) of CM showed cumulative percentage release of TT 74.09%, 89.31%, and 80.23% respectively for 50 days. Among three batches of microspheres, 2% of chitosan microspheres showed better consistent and sustained release of TT for 50 days. Conclusions: This study suggested that 2% of chitosan microspheres could be useful for sustained release of tetanus toxoid to maintain the antibody titre for prolonged period.