A quartz crystal microbalance(QCM)-systematic evolution of ligands by the exponential en-richment(SELEX)technique was developed to screen out aptamers with high affinity for arsenic(Ⅲ).A random single strand DNA library was designed and fixed on the mercaptoethylamine-modified crystal plate with arsenic(Ⅲ)as the target,and the free aptamer was captured in the solution,and the QCM-SELEX screening method was constructed.After 6 rounds of screening,the secondary library was se-quenced with high throughput method,and the 6S1 dissociation coefficient Kd value was 0.36 μmol/L based on QCM resonance frequency.Using 6S1 as a probe,the QCM biosensor was constructed for the detection of arsenic(Ⅲ).The sensor has a good linear relationship in the range of 0.01 μmol/L～0.2μmol/L,and the detection limit of arsenic(Ⅲ)is 5.2 nmol/L(3σ),indicatinggood selectivity.
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