INTERACTION BETWEEN SELF-ASSEMBLED PROTEIN VESICLES AND MICROPOROUS APATITE SURFACE

Self-assembled structures such as vesicles have generated immense inte rest in recent decades due to their potential in mimicking biological membranes and in acting as drug-delivery systems. Despite the importan ce of the interaction between these organized assemblies and the surfa ce of biomaterials, little is known about the mechanism involved. In t his study, the interaction between giant proline-rich mussel adhesive protein (MAP) vesicles and the microporous apatite surface was investi gated by scanning electron microscopy (SEM). We have found that MAP ve sicles incubated on the apatite surface similar to osteoclasts, induce site-specific resorption of the apatite surface. However, in contrast to the osteoclastic resorption, the vesicle-induced resorption proces s appears to be accompanied by an organic matrix-mediated remineraliza tion process. This results in the formation of a variety of complex th ree-dimensional site-specific ''remodelled zones'' on the apatite surf ace of micrometre scale. The mechanism of the formation of ''remodelle d zones'' is discussed in terms of surface phenomena, such as adsorpti on and deformation of vesicles, site-specific release of resorptive ag ents, organic matrix-directed remineralization, and Ca-induced fusion, collapse and reshaping of the vesicles on the apatite surface.