Molecularly imprinted “on-off” ratiometric fluorescence paper-based sensor for rapid and visual detection of sulfamethoxazole

The overuse of sulfonamide drugs has led to serious ecological problems. A “on-off” ratiometric fluorescence paper-based sensor was developed based on molecularly imprinted polymers (MIPs).This sensor integrates the high specificity of the MIP with the high sensitivity and visual detection capabilities of ratiometric fluorescence and has significant advantages in terms of detection limit and anti-interference ability for the detection of sulfamethoxazole (SMZ) residues in animal-derived foods. A visual detection system was established by coupling the sensor with a smartphone. The results showed that a linear relationship was observed between the SMZ concentration in the range of 0.01–20.00 μM and the fluorescence intensity ratio (F 630 /F 550 ) (R 2  = 0.9970). The detection limit was determined to be 67.9 nM. The spiked recovery rates ranged from 94.30% to 101.06%, with a relative standard deviation of less than 3.02%. The developed method has the advantages of simple operation and low cost, providing a feasible solution for the rapid detection of sulfonamide drug residues and having a promising practical application prospect.