Development of aptamer-modified SERS nano sensor and oligonucleotide chip to quantitatively detect melamine in milk with high sensitivity

Herein, we developed a novel nanosenor to detect trace amount of melamine (M) in the milk using aptamer-modified surface-enhanced Raman scattering (SERS) nanosensor and oligonucleotide chip. The SERS nanosensor was prepared by attaching Raman tag and ploy-thymine (T) aptamer to the gold nanoparticles, respectively. SERS nanosensor can be absorbed to the oligonucleotide chip with a high specificity where a "T-M-T" structure via multi-hydrogen-bond could be formed between the melamine molecule and the thymine molecule. In the measurement, the Raman signal intensities obtained from the chip increase when the concentrations of melamine in solutions increase. The proposed method allows us to detect melamine with a limit of 1.0 ppt (1.0 pg mL(-1)), which is fall far below the strictest safety limit. Compared with the previous methods, the sensitivity of this sensor shows about 100-fold improvement. The advantages of the present sensor are its low detection cost and the simplified sample pretreatment. Furthermore, the reliable and enough accurate results have been obtained by the using of the proposed nanosensor in the assay of trace melamine in real milk sample. (C) 2015 Elsevier B.V. All rights reserved.