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

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 LOD_SQ = 33.26 pM, LOD_SMD = 63.11 pM, and LOD_SMP = 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.