Colorimetric aptasensor based on GO-SELEX screened aptamers for detecting norfloxacin antibiotic residues in fish and shrimp

Norfloxacin (NOR) has been widely applied in animal husbandry and aquaculture because of its potent antibacterial activity, broad-spectrum efficacy and cost-efficient. Nevertheless, its inappropriate use may result in teratogenic and carcinogenic risks to humans, making the accurate and rapid detection of NOR residues in food critically important. In this study, a strong affinity (Kd = 84 nM) and high selectivity anti-NOR aptamer was obtained by screening with Graphene Oxide Systematic Evolution of Ligands by Exponential Enrichment (GO-SELEX), and a colorimetric aptasensor was fabricated. The limit of detection of the aptasensor was 1.04 ng/mL, and the linear range was 1.56-100 ng/mL. Average recoveries of the aptasensor in shrimp and fish sample analyses ranged from 89.33% to 103.24%, accompanied by coefficients of variation from 3.63% to 9.43%, indicating good analytical precision and accuracy. The aptasensor constructed in this study showed high consistency with the High-Performance Liquid Chromatography (HPLC) for NOR detection, indicating that it is an efficient and promising sustainable strategy for monitoring NOR.