Antifouling Molecularly Imprinted Photoelectrochemical Sensors for Ultrasensitive and Selective Detection of the Sulfamethoxazole Antibiotic

Sulfamethoxazole (SMX) is a widely used antibiotic with toxic and persistent residues, which poses potential health risks in aquatic environments. However, reliable and accurate detection is impeded by the nonspecific adsorption of interfering biomolecules in complex matrices. This study develops a molecularly imprinted photoelectrochemical (PEC) sensor based on Bi₂O₂S/Bi₂WO₆ with excellent selectivity and antifouling properties. Specifically, a molecularly imprinted polymer is formed by using dopamine (DA) as a functional monomer and zwitterionic sulfobetaine methacrylate (SBMA) as an antifouling moiety, respectively. The results demonstrated that the fabricated sensors exhibited high selectivity and sensitivity to SMX in water, with a limit of detection (LOD) as low as 0.3 nM (within the detection range of 0.005 ∼400 μM). This LOD is significantly lower than that of the molecularly imprinted sensors without SBMA (7.5 nM), which can be attributed to the abundant π-π bonding and neutral charge of SBMA facilitating electron transfer. Additionally, the hydrophilicity and electroneutrality of SBMA endowed the sensors with excellent antifouling properties, achieving inhibition rates of 96.1% and 94.09% against <i>E. coli</i> and <i>S. aureus</i>, respectively. These attributes ensured that the sensors can reliably and selectively detect SMX even in complex water environments with an RSD of ≤4.9% and a recovery rate of 99%-110%. This combination of zwitterionic antifouling and molecular imprinting technology provides a promising strategy for enhancing the accuracy and antifouling capabilities of PEC sensors.