A one-step modified method to reduce the burst initial release from PLGA microspheres.

To decrease the initial burst release of protein entrapped in PLGA microspheres, bovine serum albumin was entrapped into microspheres and a one-step modified method was evaluated. Low level of alginate was added into the internal aqueous phase with protein together; meanwhile calcium chloride and chitosan were put into the external, and all the other processes kept unvaried. After modification, the initial release was inhibited markedly, and the entrapment efficiency was increased slightly, while the particle size remained unaltered. An attracting result is that almost all the little pores at the surface of microspheres had been closed with the modification one under SEM.