Effects of polymer grafting on a glass surface for protein chip applications

Glass surfaces were modified using several hydrophilic polymers for the fabrication of protein chips and biosensors. Surface activation was carried out by silanization, and polymer films were introduced to the glass substrates by using two methods. First, preformed amino group containing polymers, capable of reacting with appropriate surface sites, were coupled to the glass substrates. Second, polymer layers were formed by free radical chain polymerization using immobilized initiators. Covalent binding and non-specific antibody adsorption were examined by quantifying IgG-peroxidase conjugates immobilized to the polymer-grafted glass substrates. Polymer-grafted glass substrates showed that non-specific adsorption was reduced by 10-60% as compared with 3-aminopropyltriethoxysilane (APTS)-treated substrate. In particular, chitosan-grafted substrates exhibited very low non-specific protein adsorption. Despite this protein-rejecting phenomenon of the surface-bound polymer, the quantity of antibodies immobilized by covalent binding to the polymer-grafted glass substrates was comparable to that immobilized on the non-polymer-grafted surface. We also performed a protein patterning experiment on the polymer-grafted surface by using maskless photolithography. We found that the chitosan-grafted glass substrate, with good protein repellency, displayed a very clear streptavidin-patterned surface. (C) 2003 Elsevier B.V. All rights reserved.