Electrochemical determination of melamine using oligonucleotides modified gold electrodes

A novel and simple electrochemical method for determination of melamine is developed based on oligonucleotides film modified gold electrodes. The electrochemical probe of ferricyanide was used to investigate the interactions between oligonucleotides and melamine. Results of cyclic voltammetries, differential pulse stripping voltammetries, electrochemical impedance spectrometry and atomic force microscope, proved that melamine might interact with oligonucleotides mainly through electrostatic and hydrogen-bonding interactions. The interactions between oligonucleotides and melamine lead to the increase in the peak currents of ferricyanide, which could be used for electrochemical sensing of melamine. The redox peak currents of ferricyanide were linear with the concentration of melamine in the range from 3.9 x 10(-8) to 3.3 x 10(-6) M with a linear coefficiency of 0.990. The detection limit was 9.6 x 10(-9) M. The proposed electrochemical biosensor is rapid, convenient and low-cost for effective sensing of melamine. Particularly, the proposed method was applied successfully to the determination of melamine in milk products, and the recovery was 95%. (C) 2009 Elsevier B.V. All rights reserved.