Formation of Biofunctional Thin Films on Gold Electrodes by Electrodeposition of Poly(acrylamide-co-tyrosineamide)

A new method was developed for modifying gold electrode surfaces through electrochemically triggered adsorption of acrylamide copolymers containing a low percentage of tyrosineamide side chains. The amount of copolymer adsorbed, as monitored by surface plasmon resonance (SPR), was proportional to the percent of tyrosineamide side chains in the polymer over the range 0-3 mol %. The modified gold surfaces were hydrophilic and resisted nonspecific adsorption of green fluorescent protein (GFP). Incorporation of nickel-binding nitrilotriacetic acid (NTA) side chains into the tyrosineamide copolymers allowed specific immobilization of His6-tagged GFP. The Ni(II)-dependent GFP binding was measured by SPR and verified by fluorescence microscopy. The method may find utility as a means to electrically address the immobilization of unique ligands in biosensors or other diagnostic devices based on arrayed ligands.