A highly sensitive biosensor with (Con A/HRP)(n) multilayer films based on layer-by-layer technique for the detection of reduced thiols

摘要

The bilayer of Con A/HRP through the biospecific affinity of concanavalin A (Con A) and glycoprotein horseradish peroxidase (HRP) was prepared on the surface of an Au electrode modified by the precursor film consisted of poly(allylamine hydrochloride) poly(sodium-p-styrenesulfonate). Atomic force microscopy and electrochemical impedance spectroscopy were adopted to monitor the uniform layer-by-layer assembly of the Con A/HRP bilayers. The amperometric measurement was based on the inhibition of reduced thiols and performed in the presence of the electron mediator hydroquinone in 0.2 M phosphate buffer of pH 6.5 at an applied potential of -0.15 V versus Ag/AgCl. Under the optimal conditions, the biosensor presented a linear response for cysteine from 0.1 to 23.5 mu M, with a detection limit of 0.02 mu M. The biosensor demonstrated high stability and repeatability. A series of reduced thiols were detected by this inhibition biosensor and oxidized thiols showed no effect on the current response of the biosensor. (c) 2007 Elsevier B.V. All rights reserved.