A novel aptamer based effective fluorescence detection method coupled to qPCR for ultra sensitive detection of oxytetracycline in water and food samples

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Oxytetracycline (OTC), a potent antibiotic extensively used in human and veterinary medicine, has raised growing concerns over environmental pollution and food contamination due to misuse. To achieve precise OTC residue detection, this study developed a novel aptamer-based sensing technology by integrating real-time fluorescence quantitative PCR (qPCR) signal amplification with indirect competitive assay principle. Key experimental parameters were optimized. Under optimal conditions, a significant linear correlation was observed between Ct value and the log OTC concentration (0.001–1000 ng/mL) with ultra-low detection limit (LOD). The method exhibited outstanding performance for detecting OTC residues in water, honey, and milk samples with spiked recoveries of 99.47%–106.51%. The results present high consistency with classical enzyme-linked immunosorbent assay (ELISA) method. Owing to its aptamer-based sensitivity and selectivity, this technology is ideal for effectively screening of OTC in food and environmental samples.