INVIVO EVALUATION OF PROTEIN ADSORPTION TO STERICALLY STABILIZED COLLOIDAL CARRIERS

A diffusion chamber implanted intraperitoneally in the rabbit was employed as an in vivo model to evaluate the interaction of peritoneal proteins with block copolymer (poloxamer and poloxamine)-coated polystyrene microspheres (PS). Using a desorption technique followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, six proteins of 94, 86, 66, 53, 40, and 20 kDa were desorbed from the carrier systems after incubation with peritoneal fluid in vitro. The 40- and 20-kDa proteins dominated the protein profile. A similar pattern was observed when proteins were desorbed from PS microspheres removed after 24-h implantation in chambers in the peritoneal cavity, although the protein profile was dominated by the 94- and 53-kDa proteins. In general, coating of PS with block copolymers reduced the amount of protein bound to the microspheres in vitro and in vivo but did not change the types of proteins bound.