Formation, Characterization, Protein Resistance, and Reactivity of Cl_3Si(CH_2)_(11)(OCH_2CH_2)_3OH Self- Assembled Monolayers

摘要

We report a method for generating tri(ethylene glycol)-terminated-n-alkyltrichlorosiloxane monolayers on SiO_2 surfaces. These chemisorbed films, with a thickess of ～2-3 nm, provide an oligo(ethylene glycol) surface that reduces the nonspecific adsorption of proteins and hydroxyl attachment sites for covalently immobilizing biomolecules to the substrate. These mono-molecular films were formed by adsorbing an acetoxy-tri(ethylene glycol)-terminated n-alkyl-trichlorosilane, CH_3(C=O)O(CH_2CH_2O)_3(CH_2)_(11)SiCl_3, onto glass and Si/SiO_2 substrates, where the terminal acetate provided a protecting group for the hydroxyl functionality during self-assembly of the film. After formation of the monolayer, the acetate functionality was reduced chemically to form films exposing a covalently attached -(OCH_2CH_2)_3OH terminus at a density of ～3xl0~(14) molecules/cm~2. Protein adsorption studies verified that the films exhibited notable resistances against the non-specific adsorption of various proteins. Chemical modification of the -(OCH_2CH_2)_3OH surface with protein A provided a non-adsorbing surface for selective immobilization of immunoglobulins.