Aryl diazonium salt surface chemistry and ATRP for the preparation of molecularly imprinted polymer grafts on gold substrates

Quercetin-imprinted poly(vinyl pyridine-co-ethylene glycol dimethacrylate) cross-linked grafts were prepared by atom transfer radical polymerization (ATRP) using aryl modified gold substrates as macroinitiators. The aryl layers were first attached to Au by electrochemical reduction of the diazonium salt BF4-, N-+(2)-C6H4-CH2CH2-OH. The resulting Au-C6H4-CH2CH2-OH plates (Au-OH) were further treated with 2-bromopropionyl bromide (Br-C(O)C(CH3)(2)-Br) in order to attach ATRP initiator sites to Au-OH, thus yieldingAu-C6H4-CH2CH2-OC(O)C(CH3)(2)-Br(Au-Br). 4-Vinylpyridine (4VP, functional monomer) and ethylene glycol dimethacrylate (EGDMA, cross-linking monomer) were co-polymerized in acetonitrile at room temperature in the presence of quercetin as a template molecule. Quercetin was then solvent-extracted to obtain Au-grafted molecularly imprinted polymer (Au-MIP). The gold-grafted nonimprinted polymer film (Au-NIP) was prepared as a control substrate. The changes in the surface chemical composition, from the neat Au to Au-MIP and Au-NIP, were monitored by XPS and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). Cyclic voltammetry (CV) was used to assess the specificity and selectivity of Au-MIP to detect quercetin. The detection limit was found to be better than 10(-6) mol/l with CV. Using square wave stripping voltammetry (SWSV), the detection limit was found to be as low as 10(-9) mol/l. Copyright (C) 2010 John Wiley & Sons, Ltd.