Interaction between Polymeric Organosilane Monolayer and Plasma Protein

The n-octadecyltrichlorosilane (OTS) and the [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS) monolayers, and their mixed monolayer were used as the model systems for the study of protein adsorption behavior because of their remarkable surface stability. The attenuated total reflection infrared (ATR-FT-IR) flow cell studies revealed that the adsorption amount of bovine serum albumin (BSA) onto each OTS and FOETS monolayer steeply increased in an initial stage of adsorption experiment and attained an equilibrium within a few minutes at pH 7.5. In the case of the (OTS/ FOETS) (50/50 mol/mol) mixed monolayer, the amount of protein adsorption was suppressed. AFM observation in a BSA solution at pH 7.5 revealed that BSA was preferentially adsorbed onto the FOETS phase of the (OTS/FOETS) mixed monolayer, while selective adsorption of BSA onto the FOETS phase was not observed at the isoelectric point of BSA (pH 4.7). Furthermore, [(3-mercaptopropyl)trimethoxysilane (MTS)/FOETS] mixed monolayer with reactive -SH group in domain was prepared. Then, the BSA was selectively immobilized onto the MTS phase.