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摘要
A thiolated catechol (CA) consisting of 1,6-Hexanedithiol (HDT) and CA was modified on a gold (Au) electrode to obtain an amperometric L-cysteine sensor with detection limit of 60.6 nM. The preparation of thiolated CA was conducted via a thiol addition between HDT and electro-oxidized CA (EOCA). Briefly, the thiol addition reaction was accomplished by potential cycling of HDT/Au electrode in 0.1M phosphate buffer (PB, pH7.2) containing CA, and an EOCA-HDT/Au electrode was produced. The obtained EOCA-HDT/Au electrode exhibits a pair of well-defined redox peaks (at 0.22/0.10V) of o-quinone moiety, which effectively mediates the oxidation of L-cysteine in a 0.1M PB (pH7.2), with an over-potential decrease by ca. 0.12V (versus bare Au electrode). Electrochemical quartz crystal microbalance, cyclic voltammetry and surface-enhanced Raman spectra were used to study relevant processes and/or film properties. The amperometric L-cysteine sensor has good anti-interferent ability and reproducibility. It also has acceptable recovery for detection of L-cysteine in urine samples.
