Mixed self-assembled monolayers(SAMs)consisting of methoxy-tri(ethylene glycol)-terminated and alkyl-terminated dimethylchlorosilanes control the non-specific adsorption of proteins at oxidic surfaces

摘要

Monolayers from the newly synthesized compound methoxy-tri(ethylene glycol)-undecenyldimethylchlorosilane(CH_3O(CH_2CH_2O)_3-(CH_2)_(11)Si(CH_3)_2Cl,MeO(EG)_3C_(11)DMS)and dodecyldimethylchlorosilane(DDMS),both pure and mixed,were prepared by self-assembly from organic solution in the presence of an organic base.The films obtained were characterized by advancing and receding contact angle measurements and ellipsometry to confirm the formation of self-assembled monolayers(SAMs).The resulting data on the covalently attached dimethylsilanes were compared to known oligo(ethylene glycol)(OEG)-terminated SAM systems based on terminal alkenes,thiolates or tri-hydrolyzable silanes.The composition of the mixed SAMs was found to depend directly and linearly on the composition of the silanization solution.Enhanced protein repellent properties were found for the SAMs using a variety of proteins,including the Ras Binding Domain(RBD),a protein with high relevance for cancer diagnostics.Roughly a RBD protein monolayer amount was adsorbed to silicon oxide surfaces silanized with DDMS or non-silanized silicon wafers,and in contrast,no RBD was adsorbed to surfaces silanized with MeO(EG)_3C_(11)DMS or to mixed monolayers consisting of DDMS and MeO(EG)3C_(11)DMS if the content of OEG-silane overcame a critical content of X_(EG)approx= 0.9.