step (1) mixing an enzyme-linked upconversion nanoparticle solution with an aptamer-bound magnetized polydopamine solution to obtain a fluorescence-ultraviolet dual-signal detection system;

step (2) establishing a fluorescence standard curve and a colorimetric standard curve for ciprofloxacin content determination through the fluorescence-ultraviolet dual-signal detection system in combination with potassium titanium oxalate and hydrogen peroxide; and

step (3) subjecting a meat sample to homogenization, dissolution by an organic solvent, centrifugation and filtration to obtain a solution of the meat sample; determining a fluorescence intensity signal characteristic value and an ultraviolet absorbance signal characteristic value of the solution of the meat sample; and calculating a ciprofloxacin content in the meat sample according to the fluorescence standard curve and the colorimetric standard curve;

wherein the enzyme-linked upconversion nanoparticle solution is prepared through steps of:

mixing an upconversion nanoparticle, a polyacrylic acid aqueous solution, chloroform and toluene followed by stirring and centrifugal drying to obtain a carboxylated upconversion nanomaterial; and

binding a complementary chain of a ciprofloxacin aptamer and horseradish peroxidase to a surface of the carboxylated upconversion nanomaterial to obtain the enzyme-linked upconversion nanoparticle solution;

the aptamer-bound magnetized polydopamine solution is prepared through steps of:

ultrasonically dispersing Fe₃O₄ in a Tris-HCl buffer followed by addition of dopamine hydrochloride and stirring at room temperature to obtain magnetized polydopamine; and

adding the magnetized polydopamine to a buffer E followed by ultrasonic dispersion, addition of the ciprofloxacin aptamer and NaCl and shaking, collecting a precipitate by means of an external magnetic field, and dissolving the precipitate in a buffer F to obtain the aptamer-bound magnetized polydopamine solution;

wherein the buffer E and the buffer F are independently a phosphate-buffered saline (PBS).