Silicone−Protein Interaction at the Interface between a Functional Silicone and a Protein/Starch Microparticle

Silicone-coated starch/protein (human serum albumin, HSA) microparticles were prepared by precipitation of a starch/HSA/DMSO/water (water-in-oil) emulsion into acetone containing a silicone polymer. Two silicones (poly(dimethylsiloxane)) were examined: unfunctionalized (trimethylsilyl-terminated, PDMS) or functionalized at the termini with Si(OEt)3 groups (PDMS-TES 7). Microparticles were not formed in the absence of protein. Instead, the phase containing starch separated after agglomeration. Thus, stabilization/hydrophobization of the starch surface by silicone alone was not possible. However, there is a strong affinity between the silicone and the protein particularly in the case of the PDMS-TES and, simultaneously, an affinity between the PDMS-TES and the starch that leads to a stabilization of the starch surface. This could most clearly be seen from immunological data that showed that antibodies were elicited by protein in the microparticles coated with PDMS-TES following oral administration.