Abstract:A highly sensitive biosensor based on surface enhanced Raman scattering (SERS) for detecting trace amounts of mercury (II) in seafood was designed by cycle amplification based on hybridization chain reaction of DNA hairpins and the stable structure formed between the nucleotide base thymine (T) and mercury (II). Firstly, the nano-Au bio-barcode with numerous Raman signal DNA molecules was prepared as the Raman signal probe, and then the captured DNA was immobilized on magnetic beads by amide bonds. The nano-Au particles containing numerous Raman signal DNA molecules were combined specifically on the magnetic beads by the stable structure formed by T-mercury (II)-T and the cycle amplification based on hybridization chain reaction. Finally, the detection of mercury (II) in the solution was achieved by the SERS technique. The optimum experimental conditions were also investigated. When the concentration of DNA captured by magnetic beads was 1.0×10-7 mol/L and the hybridization reaction proceeded for three hours at 37 ℃ in pH 7.4 Tris-HCl buffer solution, the mercury (II) concentration and the Raman signal intensity had good linear relationship, with a linear range of 1.0×10-7~1.0×10-13 mol/L and a detection limit of 1.0×10-13 mol/L (S/N=3). The biosensor was applied to determine the mercury (II) content in the seafood samples, and the measured results were consistent with those obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES).
