Ultrasensitive optical fiber LSPR biosensor functionalized with gold nanorods, KMO nanoflowers, and ZnCdS/ZnS quantum dots for maduramicin detection.

Maduramicin (MD) is a widely used anticoccidial agent whose residues in animal-derived foods pose potential risks to food safety and public health. In this work, a localized surface plasmon resonance (LSPR) biosensor based on a nested tapered optical fiber was developed for rapid and sensitive MD detection. The sensing platform integrates gold nanorods, KMO nanoflowers, and ZnCdS/ZnS quantum dots to enhance plasmonic coupling and interfacial signal transduction. The sensor exhibited a linear response from 0.1 to 40 ng/mL with R2 > 0.981 and a limit of detection of 0.087 ng/mL. Excellent selectivity, reproducibility, and reusability were achieved. Real-sample analyses of egg, pork, and chicken breast yielded recoveries of 106%, 100%, and 100%, respectively, with RSD values below 1%, confirming the reliability of the proposed biosensor for accurate determination of MD residues in food matrices. These findings demonstrate the potential of the proposed platform for portable and cost-effective monitoring of veterinary drug residues.