A magnetic SERS aptasensor integrated with Fe3O4@SiO2-Au nanocomposites for high-throughput, sensitive, and selective detection of sulfonamides.

An innovative magnetic SERS aptasensor is presented that integrates Fe3O4@SiO2-Au nanocomposites with aptamers, leveraging advancements in nanotechnology to overcome existing challenges. The aptasensor utilizes the magnetic Fe3O4 core for efficient separation from complex samples and the Au-decorated SiO2 shell for signal enhancement via localized surface plasmon resonance. Moreover, aptamers with specificity for sulaquinoxaline (SQ), sulfamethoxypyridazine (SMP), and sulfamethoxydiazine (SMD) were used to enable selective recognition. Under optimized conditions, the detection limits of the aptasensor achieved were LODSQ = 33.26 pM, LODSMD = 63.11 pM, and LODSMP = 46.42 pM, with corresponding linear detection ranges of 0.1 nM to 50 μM, 0.1 nM to 50 μM, and 1 nM to 50 μM, respectively. It showed excellent selectivity against 11 interfering antibiotics and achieved recoveries  of 91.4%-119.0% in real water samples (tap water, lake water, drinking water, seawater, effluent, river aquaculture water bodies, water bodies in lake poultry breeding areas, and milk). Moreover, the aptasensor demonstrates reliable performance in detecting sulfonamides in actual water samples, indicating its potential for applications in food safety and environmental monitoring.