Nucleic acid colorimetric sensor with Y-shaped structure and application of sensor

The invention discloses a nucleic acid colorimetric sensor with a Y-shaped structure and an application of the sensor. The sensor comprises two parts, namely nanogold A asymmetrically modified by a probe DNA1 and nanogold B asymmetrically modified by a probe DNA2, wherein a target DNA can be respectively combined with a probe DNA1 and a probe DNA2 under the condition of existence of the target DNA, so as to form a DNA complex with the Y-shaped structure. Thus, independently dispersed nanogolds in a solution are close together. An absorption spectrum of a system greatly displaces due to an LSPR coupling effect, so that the existence of the target DNA can be judged by visual inspection. The nanogolds are subjected to asymmetric modification, so that a nanogold dimer is mainly formed in the solution under the existence of the target DNA while a plurality of nanogold aggregates are not formed. Compared with a conventional colloidal gold colorimetric method, for the sensor disclosed by the invention, the sensitivity of the sensor for detecting the target DNA can be improved by four orders of magnitudes, the linear range can be amplified by two orders of magnitudes, and meanwhile, the stability of the sensor is also greatly improved.