Integrated magneto-optical strategy for substantial sensitivity enhancement in rapid detection of trace ciprofloxacin.

Accurate determination of ciprofloxacin (CIP) exposure levels in aquaculture demands ultrasensitive quantification. An integrated magneto-optical platform was developed for trace ciprofloxacin detection in water, synergizing immunomagnetic separation with polarization analysis. Immunomagnetic microspheres (MBs@Ab) were synthesized and distinguished via ResNet34 image recognition. Systematic optimization of multi-proportion MBs@Ab conjugation yielded a deviation coefficient (λ) of 0.14, with optimal conditions at 10 μg Ab per 1 mg MBs, achieving a maximum conjugation efficiency of 92.74 %. MBs@Ab displayed specific CIP adsorption: 1 mg MBs@Ab selectively bound 1.5 ng CIP, validated in mixed antibiotic matrices. Magnetic separation reduced pretreatment to < 2 min, and Mueller matrix microscopy acquired polarization images of MBs, MBs@Ab, and MBs@Ab@CIP. Polarization parameter analysis integrated with classification counting, validated by a confusion matrix, revealed high classification accuracy, with prediction rates of 88 % (MBs@Ab) and 89 % (MBs@Ab@CIP) and an overall accuracy exceeding 85 %. A CIP quantification curve (y = 0.01 + 1.08x, R² = 0.90) enables rapid detection with an LOD of 0.07 μg/L in < 30 min and recovery rates of 88 %-117.18 %. The proposed strategy provides a practical detection method for trace CIP in aquatic environments, enables rapid and accurate quantification, offering a reliable solution for monitoring trace antibiotic residues.