Protein-Resistant Polymer Coatings on Silicon Oxide by Surface-Initiated Atom Transfer Radical Polymerization

Abstract

The modification of silicon oxide with poly(ethylene glycol) to effectively eliminate protein adsorption has proven to be technically challenging. In this paper, we demonstrate that surface-initiated atom transfer radical polymerization (SI-ATRP) of oligo(ethylene glycol) methyl methacrylate (OEGMA) successfully produces polymer coatings on silicon oxide that have excellent protein resistance in a biological milieu. The level of serum adsorption on these coatings is below the detection limit of ellipsometry. We also demonstrate a new soft lithography method via which SI-ATRP is integrated with microcontact printing to create micropatterns of poly(OEGMA) on glass that can spatially direct the adsorption of proteins on the bare regions of the substrate. This ensemble of methods will be useful in screening biological interactions where nonspecific binding must be suppressed to discern low probability binding events from a complex mixture and to pattern anchorage-dependent cells on glass and silicon oxide.

Polymer brushes and self-assembled monolayers: Versatile platforms to control cell adhesion to biomaterials (Review)

“…Adsorption of trichlorosilanes on a variety of oxide surfaces is irreversible, but traces of water lead to the deposition of ill-defined multilayers through formation of siloxane linkages ͑Si-O-Si͒. 84,85 Use of a monochlorosilane avoids this complication, Fig. 2͑B͒.…”

“…SAMs of adsorbates bearing a bromoisobutyryl group at the termini have been used to initiate ATRP of oligo͑eth-ylene glycol͒ methacrylate ͑OEGMA͒ monomer. 70,85,165 Similar to poly͑ethylene glycol͒ and SAMs of EG n on gold, the poly͑OEGMA͒ polymer brushes prevent protein adsorption. Extensive studies of the SI-ATRP of OEGMA polymer brushes on silicon and gold substrates indicate that the length 6.…”

“…6͑A͒. 85 A ''grafting from'' approach in which functional groups on the substrate are used to initiate chain growth polymerizations can be used to obtain a higher density of polymer chains on a substrate, Fig. 6͑B͒.…”

In situ growth of a stoichiometric PEG-like conjugate at a protein's N-terminus with significantly improved pharmacokinetics

“…We chose poly(oligo(ethylene glycol) methyl ether methacrylate) [poly(OEGMA)] for in situ polymer growth because we had previously shown that poly(OEGMA) brushes grown on a planar surface confer exceptional protein and cell resistance to the surface of diverse materials (25)(26)(27), and we hypothesized that the corollary to protein resistance on surfaces is a long circulation half-life when the same polymer is grown from the surface of a protein. Furthermore, poly(OEGMA) can be synthesized by atom transfer radical polymerization (ATRP)-a living radical polymerization methodology-in aqueous medium (25)(26)(27) with good control of the polymer chain length (28), attributes that we believed would be invaluable for the growth of stoichiometric and functionally active polymer conjugates from the surface of a protein.…”

“…Furthermore, poly(OEGMA) can be synthesized by atom transfer radical polymerization (ATRP)-a living radical polymerization methodology-in aqueous medium (25)(26)(27) with good control of the polymer chain length (28), attributes that we believed would be invaluable for the growth of stoichiometric and functionally active polymer conjugates from the surface of a protein. In addition, poly(OEGMA) is likely to be biodegradable due to the enzyme-degradable and hydrolyzable ester linker (Fig.…”