Fluoroquinolones (FQs) are veterinary drug residues in the food chain that threaten global food safety and human health and there is a great need for a rapid, sensitive and reliable monitoring method to better safeguard our food systems. In this study, we developed a high-performance aptamer via a recognition-mechanism-oriented truncation strategy, enabling rapid and sensitive detection of multiple FQs. The recognition mechanism between the aptamer and FQs were studied by the combination of computer-aided molecular simulation and experimental verifications. It was revealed that hydrophobicity of FQs critically governs aptamer-target interactions. Guided by these insights, the original sequence was truncated to a 40-nt aptamer, named as W-G1, which preserved key binding sites and structural stability. W-G1 with the characteristic G-quadruplex (G4) conformation demonstrated excellent affinity and stability for FQs. Exploiting the function of this conformation, a label-free fluorescent G4/thioflavine T biosensor was fabricated to detect FQs in chicken ham sausage within 30 minutes. The results showed that detection limits ranged from 1.32 ng/kg to 17.30 ng/kg that are lower than food safety regulation defined limits of 1.0 μg/kg (the lowest LOD of standard method for lomefloxacin), with recoveries of 81.17~115.94%. This mechanism-driven strategy enhances aptamer-based detection of FQs, offering improved performance, design flexibility, and reduced cost.
Xu et al. (2026) studied this question.