The invention discloses an electrochemical sensor capable of detecting trace mercury in a
water body. The electrochemical sensor comprises a gold
electrode, wherein gold
nanoclusters are deposited on the surface of the reaction end of the gold
electrode; and sulfhydryl-modified mercury-specific
oligonucleotide probes are self-assembled on the gold
nanoclusters. The preparation method for the electrochemical sensor comprises the following steps of: first, preparing the gold
electrode; then, electrodepositing the gold
nanoclusters on the surface of the reaction end of the gold electrode; and finally, self-assembling the sulfhydryl-modified mercury-specific
oligonucleotide probes on the end surfaces of the gold nanoclusters so as to finish the manufacturing of the sensor. By using the sensor provided by the invention, the trace mercury in the
water body can be detected; and the specific operation comprises the following steps of: first, placing the reaction end of the sensor in a
water sample for reacting; then, immersing the reaction end into an anion double-stranded deoxyribonucleic acid (
DNA)
signal embedded agent for complete treatment; later on, connecting the sensor into an
electrolytic cell of a three-electrode
system and measuring the change of a response
peak current by using
square wave voltammetry; and finally, judging whether the
water sample contains mercury ions on the basis of the change. The electrochemical sensor has the advantages of simple and practical structure, convenience in manufacturing, high sensitivity, high selection specificity and the like.