Fabrication of a Novel and Simple Microcystin-LR Photoelectrochemical Sensor with High Sensitivity and Selectivity

摘要

Microcystin-LR (MC-LR), an inert electrochemical species, is difficult to be detected by a simple and direct electrochemical method. In the present work, a novel photoelectrochemical sensor is developed on highly ordered and vertically aligned TiO_2 nanotubes (TiO_2 NTs) with convenient surface modification of molecularly imprinted polymer (MIP) (denoted as MIP@TiO_2 NTs) for highly sensitive and selective determination of MC-LR in solutions. Molecularly imprinted polypyrrole (PPy) of MC-LR is chosen as the recognition element. The designed MIP@TiO_2 NTs photoelectrochemical sensor presents excellent applicability in MC-LR determination, with linear range from 0.5 to 100 μg L~(-1) and limit of detection of 0.1 μg L~(-1). Moreover, the sensor exhibits outstanding selectivity while used in coexisting systems containing 2,4-dichorophenoxyacetic acid, atrazine, paraquat, or monosultap with high concentration, 100 times that of MC-LR. The sensor presents good photoelectric conversion efficiency and detection sensitivity, as well as broad linear detection range, mainly because of the high specific surface area and photoelectric activity of TiO_2 NTs and the n bond delocalized electron system of PPy that promotes the separation of electron-holes. The prominent selectivity is from the MIP by forming multiple hydrogen bonds between PPy and MC-LR. Mechanisms for photoelectrochemical analysis and selective recognition are also discussed.