Rapid detection of enrofloxacin using a localized surface plasmon resonance sensor based on polydopamine molecular imprinted recognition polymer

Abstract

Due to concerns of antibiotic-resistant bacterial strains from animal-derived food products, different countries or organizations have established their maximum residue limits for antibiotics. Current HPLC and ELISA methods are commonly used in testing antibiotic residues, but have their limitations for in-field rapid detections. Localized surface plasmon resonance (LSPR) sensors have shown great potential in biodetection, due to its sensitive, label-free and real-time features. Therefore, the objective of this project was to develop an LSPR biosensing method for rapid, sensitive and specific detection of enrofloxacin (ENRO), using polydopamine molecular imprinted polymer (PDA-MIP) as the recognition element. The PDA-MIP film was fabricated by polymerization of dopamine and ENRO in Tris buffer on the surface of LSPR sensor chip. After blocking with bovine serum albumin and removal with sodium dodecyl sulphate, the modified sensor chip was used to selectively capture ENRO in a sample. To amplify LSPR detection signals of ENRO, conjugates with protein molecules were synthesized, served as competitors, and reacted with the residual binding sites on the PDA-MIP film. The detection could be done within 20 min, with a detection range of 25–1000 ng/mL and a limit of detection of 61.1 ng/mL. The PDA-MIP film demonstrated a higher binding capacity to ENRO than the corresponding non-imprinted polymer film, and discriminated ENRO among structural analogues. Good reusability was achieved within seven binding-regeneration cycles, with a low relative standard deviation. With high sensitivity, specificity and stability, the developed LSPR/PDA-MIP sensor showed its potential for in-field rapid detection of ENRO residues.