Detection\nof Sulfonamide Antibiotics Using an Elastic\nHydrogel Microparticles-Based Optical Biosensor

Sulfonamide antibiotics\nwere the first synthetic antibiotics on\nthe market and still have a broad field of application. Their extensive\nusage, wrong disposal, and limited degradation technologies in wastewater\ntreatment plants lead to high concentrations in the environment, resulting\nin a negative impact on ecosystems and an acceleration of antibiotic\nresistance. Although lab-based analytical methods allow for sulfonamide\ndetection, comprehensive monitoring is hampered by the nonavailability\nof on-site, inexpensive sensing technologies. In this work, we exploit\nfunctionalized elastic hydrogel microparticles and their ability to\neasily deform upon specific binding with enzyme-coated surfaces to\nestablish the groundwork of a biosensing assay for the fast and straightforward\ndetection of sulfonamide antibiotics. The detection assay is based\non sulfamethoxazole-functionalized hydrogel microparticles as sensor\nprobes and the biomimetic interaction of sulfonamide analytes with\ntheir natural target enzyme, dihydropteroate synthase (DHPS). DHPS\nfrom <i>S. pneumoniae</i> was recombinantly produced by <i>E. coli</i> and covalently coupled on a glass biochip using\na reactive maleic anhydride copolymer coating. Monodisperse poly(ethylene\nglycol) hydrogel microparticles of 50 μm in diameter were synthesized\nwithin a microfluidic setup, followed by the oriented coupling of\na sulfamethoxazole derivative to the microparticle surface. In proof-of-concept\nexperiments, sulfamethoxazole, as the most used sulfonamide antibiotic\nin medical applications, was demonstrated to be specifically detectable\nabove a concentration of 10 μM. With its straightforward detection\nprinciple, this assay has the potential to be used for point-of-use\nmonitoring of sulfonamide antibiotic contaminants in the environment.