A Novel Electrochemical Biosensor Based on DNA for Rapid and Selective Detection of Cadmium

A sensitive platform for the rapid detection of cadmium basing on single-stranded DNA modified Au electrode (ssDNA/Au) was presented. The ssDNA/Au biosensor screened 6 kinds of chemicals including cadmium salts, sodium salts, copper salts, magnesium salts, plumbum salts and zinc salts. The results demonstrated that the detection signal of the ssDNA/Au biosensor for cadmium was related to the concentration. Linear responses were gotten in the range from 1 to 20 ng L-1 with a detection limit (S/N=3) of 0.3 ng L-1 for cadmium under the optimized conditions. It also showed that the ssDNA/Au biosensor could successfully differentiate cadmium salts from the interferent (magnesium salts and zinc salts, etc.). The interaction mechanism between ssDNA and cadmium ions was deduced from the electrochemical method and ultraviolet-visible spectrophotometer. The ssDNA/Au biosensor proved to be a potential alternative tool for the rapid detection of cadmium ions, and can be used for rapid detecting of cadmium in real water samples, evaluation of food safety and the status of environmental contamination.