The invention discloses a double-
ion response type SERS (Surface Enhanced
Raman Scattering) probe and a preparation method thereof. The probe comprises two nano particles with independent core-shell structures, wherein a carrier nano particle comprises four
layers of core-shell structures; the four
layers of core-shell structures are as follows: the innermost layer is made of Fe3O4 magnetic nano balls, a layer of
silicon dioxide is coated outside the innermost layer, the second-outer layer is a
gold foil shell layer, and the outermost layer is an
oligonucleotide coating layer; an object nano particle comprises two
layers of core-shell structure; the two layers of core-shell structure are as follows: the inner core is made of Raman molecule marked gold nano-balls, and a shell is an
oligonucleotide coating layer. Due to the adoption of a specific
base sequence in the
oligonucleotide coating layer, the identify and SERS trace detection on two
metal ions, namely silver / mercury, in an environment solution can be performed at the same time; furthermore, under the action of an external
magnetic field, the probe and the obtained silver / mercury ions can be rapidly separated from an initial environment
solution system, and therefore, the function of purifying the environment is realized.