| CPC G01N 21/658 (2013.01) | 9 Claims |

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1. A method for preparing a high-stability SERS nanotag, comprising the following steps:
(a) adding tetratetrachloroauric acid into ultrapure water, quickly adding a reducing agent with a mass to volume ratio of 1% to 2% after boiling, continuously carrying out boiling, stopping heating, and carrying out cooling to 24° C. to 37° C.;
(b) adding CTAC with a concentration of 0.01 mM to 1 mM into a substance obtained in the step (a), carrying out stirring, adding ascorbic acid, injecting AgNO3, and carrying out centrifugation after reaction and resuspending in CTAC with a concentration of 1 mM to 10 mM; and
(c) adding CTAC with a concentration of 20 mM to 100 mM into a substance obtained in the step (b), carrying out stirring, sequentially adding
a Raman dye, ascorbic acid and sodium hydroxide, injecting a mixture of tetratetrachloroauric acid and potassium iodide, and carrying out centrifugation after reaction and resuspending in CTAC with a concentration of 1 mM to 10 mM;
wherein the high-stability SERS nanotag comprises a gold core (1), wherein the gold core (1) is sequentially coated with a silver shell (2) and a gold shell (3), and a Raman dye (4) is arranged between the silver shell (2) and the gold shell (3).
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