A Novel Mass-Sensitive Sensor Based on beta-Cyclodextrin-Anchored Bisphenol A-Imprinted TiO2 Ultrathin Layers

A novel approach to fabricating artificial receptors based on the synergic effect of molecular imprinting and host (beta-cyclodextrin)-guest (bisphenol A, BPA.) interaction in TiO2 ultrathin films prepared by the gas-phase surface sol-gel process was reported. Quartz crystal microbalance (QCM) electrodes were used to confirm the mass-sensitive change due to BPA incorporation and guest binding into the film with the aim of developing a BPA sensor. The concentration of 1 mu M (272 ppb) BPA was successfully measured and the limit of detection was estimated to be 0.1 mu M (27.2 ppb) BPA. The affinity of the imprinted film to BPA, which was calculated using a Benesi-Hildebrand plot, was ca. 8 times higher than that of the nonimprinted film. This selective binding feature in principle can be applied to more complex organic compounds.