Method for ultra-sensitively detecting dopamine based on aptamer

The invention provides a method for ultra-sensitively detecting dopamine based on an aptamer. An ssDNA1 is combined with a dopamine aptamer and an ssDNA2 through utilization of a base complementary pairing principle, thereby forming a double-stranded DNA1 with two 3' protruding terminuses. The base number of the ssDNA2 is less than that of that of the ssDNA1. The ssDNA2 and the ssDNA1 are complemented and paired. The dopamine aptamer is complemented and paired with part of the ssDNA1 starting from a 3' terminus of the ssDNA2. A to-be-tested sample, a hairpin DNA, fluorochrome SYBR Green I andexonuclease III are added. The base number of the hairpin DNA is less than that of the ssDNA1. The hairpin DNA and the free ssDNA1 form a double-stranded DNA 2 of which hairpin DNA 3 3' terminus is sunken, through utilization of the base complementary pairing principle. According to the method, the dopamine is identified through utilization of the dopamine aptamer and the aptamer is separated wayfrom the double-stranded D