Design of label-free electrochemical aptasensors for enrofloxacin detection in mutton

A label-free electrochemical aptasensor was developed using a 3D porous chitosan-reduced graphene oxide nanocomposite matrix for rapid and ultrasensitive quantification of enrofloxacin residues in mutton samples. The high conductivity nanoscaffold allowed enhanced aptamer loading yielding improved dynamic range of 0.01-10 ng/mL and low detection limit of 0.005 ng/mL. The biosensor demonstrated good precision (RSD 2.7%) between measurements and selectivity against potentially interfering species. It also showed excellent accuracy with 92.7–97.5% recovery of spiked enrofloxacin in meat extracts. A storage stability of 91% was retained over 4 weeks without noticeable performance loss. Further, analysis of actual mutton samples using the aptasensor revealed enrofloxacin levels of 6.8 ng/g and 15.2 ng/g, validated by HPLC-UV reference technique. Thus, the proposed label-free impedimetric aptasensor provides a viable analytical platform for rapid on-site screening of trace enrofloxacin residues in complex food matrices within minutes, without requiring extensive sample processing steps or expensive instrumentation. The biosensor fabrication methodology exploiting advanced nanomaterials to tune sensitivity shows promise for enabling rapid detection of diverse targets.