A sulfamethoxazole molecularly imprinted two-dimensional photonic crystal hydrogel sensor

In this paper, a molecularly imprinted two-dimensional photonic crystal hydrogel sensor (SMZ-MIPCH) for the sensitive and label-free recognition of sulfamethoxazole (SMZ) was prepared. The SMZ-MIPCH sensor response performance was investigated via measuring the diameter of the Debye ring (D). When the SMZ-MIPCH sensor recognized SMZ, the diameter of the Debye ring gradually decreased and the particle spacing (d) of the photonic crystals gradually increased. As the SMZ concentration increased from 0 to 10-4 mol L-1, the diameter decreased by 15.2 mm and the corresponding particle spacing increased by 131 nm. As the diffraction peak wavelength of the sensor gradually red-shifted, the color changed from blue to green and finally to orange-red. A good linear relationship was found between the variation of the particle spacing (Δd) and the value of the logarithm of the SMZ concentration (lg c) in the range from 10-16 mol L-1 to 10-10 mol L-1. The limit of detection of the SMZ-MIPCH sensor is 10-16 mol L-1. In the presence of analogues of SMZ, such as sulfisoxazole, sulfadiazine, and sulfamethazine, the diameter changed only slightly, indicating that the SMZ-MIPCH sensor had specific recognition abilities for SMZ. The SMZ-MIPCH sensor has the advantages of high sensitivity, specific recognition, and naked eye detection, and it can be used for the detection of SMZ in water samples.