Influence of various technological parameters on the preparation of spray-dried poly(epsilon-caprolactone) microparticles containing a model antigen

This work evaluates the efficacy of the spray-drying technique to prepare p oly(epsilon-caprolactone) (PCL) microparticles containing an entrapped mode l antigen (bovine albumin, BSA). The presence of a stabiliser was found to be an important parameter when preparing PCL microparticles containing a hy drophilic antigen. The effect of various technological parameters (concentr ation of the polymer and protein solutions, organic/aqueous phases ratio, n ature of solvents and emulsion parameters such as duration and speed of agi tation) on microparticle morphology and size, BSA entrapment and encapsulat ion efficiency was studied. Microparticles were characterized by a mean siz e from 9.56 +/- 0.25 to 24.31 +/- 2.87 mu m and a BSA entrapment from 0.80 +/- 0.02 to 24.21 +/- 0.23% (w/w). SDS-PAGE electrophoresis and isoelectric focusing (IEF) confirmed the conservation of the physicochemical character istics of the BSA entrapped within PCL microparticles produced by spray-dry ing. Together, these results showed that spray-drying is an efficient techn ique to overcome the key obstacle that represents the scaling-up of the man ufacturing process to produce sufficient quantities of vaccine for clinical trials and, ultimately, commercialization.