Site-selective functionalization of indium tin oxide surface using electrochemically active polymeric layers

Abstract

The patterning of biomolecules at designated locations is essential for the fabrication of biologically multifunctional devices such as array-based biochips for diagnosis. It has been explored that biomolecules are spatially immobilized on electrochemically active layers. We prepared and characterized electrochemically active polymeric layers on ITO electrodes and found their applications to biomolecule patterning. Self-assembled polymeric layers on ITO coated glass were prepared in water from a series of random copolymers of 3-(trimethoxysilyl)propyl methacrylate (TMSMA), poly(ethylene glycol) methyl ether methacrylate (PEGMA) and p-aminophenol (p-Ap), denoted as poly(TMSMA-r-PEGMA-r-p-Ap). An electrochemical oxidation of the resulting polymeric layers enables thiol terminated molecules to be immobilized on the surface via 1,4-addition of thiols to p-Ap moieties. Analyses by cyclic voltammetry, x-ray photoelectron spectroscopy, silver enhancement, and 4-chloro-1-naphthol precipitation show that the resulting polymer modified ITO provide effective and selective surfaces for immobilizing alkanethiols, biotins and aptamers.