Use of polymethacryloyl chloride to immobilize proteins onto gold surfaces. Detection by surface plasmon resonance

We report the binding of rabbit immunoglobulin G to gold surfaces via reactive polymers derived from polymethacryloyl chloride (PMAC). The thicknesses of the polymer and the protein layers are measured by Surface Plasmon Resonance (SPR). Two methods have been used for the coating of gold with PMAC. In the first one, the covalent attachment of a monomer monolayer at the gold surface followed by the polymerization of PMAC in situ (grafting `fromʹ the surface) results in the formation of extended polymer chains. In another method, the preformed polymer is grafted `toʹ the surface, leading to more compact polymer layers. Due to the mobility of polymer chains obtained by the first method, a better contact between the immobilized polymer film and the protein is achieved; however, the amount of antibody bound to both sensing layers after modification by N-hydroxysuccinimide is comparable (5.0 nm). The accessibility of the reactive functions to the antibody can also be improved by grafting spacer arms to the immobilized polymer. This method leads to antibody layers between 4.5 and 6.7 nm with better recognition properties than without a spacer arm.