Method for detecting heavy metal ions based on ratio-type SERS (surface enhanced Raman scattering) sensing principle

The invention provides a method for detecting heavy metal ions based on a ratio-type SERS (surface enhanced Raman scattering) sensing principle. The method comprises the following steps: by taking silver coated with gold nano-particles as an SERS substrate, modifying T-rich sequences of Raman beacon molecules as target molecule identification probes, functionally modifying the target molecule identification probes on the surface of the SERS substrate by Au-S keys, modifying complementary DNA sequences of another Raman beacon molecules and performing complementary hybridization on the identification probes to form a rigid duplex DNA structure used for constructing a ratio-type SERS sensing platform; mediating the identification probes to realize transformation of configuration based on target molecules, so that signals are changed and taking a specific value of SERS signal intensity of two types of beacon molecules as a quantitative criterion, so that the sensitivity of detecting the heavy metal ions is improv