An IFE-based molecularly imprinted nanosensor for highly sensitive and rapid ratiometric fluorescence-visualization...

A versatile fluorescent molecularly imprinted nanosensor (MIPs@O-CDs) for profiling ciprofloxacin (CIP) was innovatively developed using a controllable post-imprinting modification strategy. High-affinity molecularly imprinted polymers (MIPs) as recognition elements granted nanosensor favorable anti-interference. Bright orange-emission carbon dots (O-CDs) as signal transducers demonstrated prominent reverse fluorescence response to CIP due to inner filter effect, ameliorating detection sensitivity and accuracy. Benefiting from inherent advantages, MIPs@O-CDs accomplished selectivity and ultrasensitive ratiometric fluorescence detection of CIP with a linear range of 0.025-6.000 μg mL^-1, a detection line (6.858 ng mL^-1), a rapid response time (1.5 min) and a distinguishable color transformation (orange-pink-purple). Additionally, a portable optosensing platform has been triumphantly established by integrating MIPs@O-CDs and smartphone-assisted detectors, which achieved precise on-site determination of CIP in milk with satisfactory recoveries (88.185-93.267 %) and a relative standard deviation below 3.960 %. Accordingly, MIPs@O-CDs-based platform demonstrated portability, feasibility, selectivity, and sensitivity, presenting a powerful tool for real-time food safety assessment.