Aryl diazonium salt surface chemistry and graft photopolymerization for the preparation of molecularly imprinted polymer biomimetic sensor layers

A novel strategy is described for the preparation of sensitive molecularly imprinted (MIPs) sensing layers based on the combination of diazonium salts as photoinitiators and graft photopolymerization on gold electrode. The MIPs were synthesized using methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker in co-polymerization process, and dopamine (DA) as a template. The gold-grafted MIP (Au-MIP) electrodes were found to be specific and selective toward dopamine with a detection limit of 0.9 nmol L−1 as determined by square wave voltammetry (SWV). Selectivity was interrogated with l-DOPA which gave a flat response of Au-MIP. In the case of DA and ascorbic acid (AA) mixture (0.1/0.8 mmol L−1), the electrochemical detection gave an oxidation peak of same shape and quasi the same intensity for pure DA and DA/AA mixtures, therefore confirming the high selectivity of the MIP grafts. The same strategy can be extended to a broad range of templates, monomers and surfaces.The significance of this work lies in the originality of the process, its simplicity, speed of detection protocol, and especially stable adhesion of the sensing layers. These important characteristics rely on the versatile interfacial chemistry of aryl diazonium coupling agents.