Molecularly imprinted polymer integrated into paper-based analytical device for smartphone-based detection: Application for sulfamethoxazole

In this work, we developed a paper-based analytical device (PAD) that utilizes molecularly imprinted polymer (MIP) as the biomimetic receptor and a very simple colorimetric assay combined with a smartphone readout. Sulfamethoxazole was used as a model analyte to evaluate the feasibility of the developed MIP-PAD. After the synthesis of MIP, its adsorption properties (isotherm, kinetic and thermodynamic) were scrutinized. Thereafter, The MIP- PAD was fabricated through the vacuum-assisted deposition of MIP suspension onto porous paper forming a 7 mm diameter of MIP layer. The MIP-PAD was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. The sulfamethoxazole transforms into azo dye through a colorimetric reaction. The smartphone was utilized for the read-out of results. The LOD was 0.21 ppm. The proposed MIP-PAD showed high long-term stability. The determination of SMX was carried out in spiked tap and river water samples to evaluate the applicability of the proposed analytical strategy in real-world applications. The developed MIP-PAD would provide a new platform for real-time, selective, rapid, user-friendly, low-cost, portable, and straightforward colorimetric assays in environmental monitoring, public health, and food control.