HIGHLY STABLE SURFACE-ENHANCED RAMAN SCATTERING NANOTAG AND PREPARATION METHOD THEREFOR

A highly stable surface-enhanced Raman scattering nanotag and a preparation method therefor. The nanotag comprises a gold core (1); the gold core (1) is sequentially covered with a silver shell (2) and a gold shell (3); a Raman dye (4) is disposed between the silver shell (2) and the gold shell (3). The preparation method comprises the following steps: a. adding chloroauric acid into ultrapure water, boiling, adding trisodium citrate, boiling, stopping heating, and cooling; b. adding CTAC to the product obtained in step a and stirring, adding ascorbic acid and AgNO3, centrifuging, and resuspending in CTAC; and c. adding CTAC to the product obtained in step b, stirring, adding Raman dye, ascorbic acid, and sodium hydroxide, injecting a mixture of chloroauric acid and potassium iodide, centrifuging, and resuspending in CTAC. The silver shell (2) of the nanotag is protected by the dense gold shell (3) to prevent the silver shell (2) from being oxidized, the label can be stored for a long time, and the Raman sign