Aggregation-induced electrochemiluminescence and molecularly imprinted polymer based sensor with Fe3O4@Pt nanoparticle amplification for ultrasensitive ciprofloxacin detection

To broaden the applicability of electrochemiluminescence (ECL) sensors toward the sensitive and selective detection of trace antibiotic residues, new ECL reagents are required. Herein, a novel molecularly imprinted sensor based on an aggregation-induced ECL reagent was fabricated for the sensitive detection of ciprofloxacin (CFX). A covalent organic framework with aggregation-induced ECL (COF-AIECL) was synthesised using a boric acid condensation dehydration reaction. Then, an electrode surface was modified with COF-AIECL as a signal element and nanozymatic ferriferrous oxide@platinum nanoparticles (Fe3O4@Pt NPs) as a signal amplification element. Subsequently, using CFX as a template molecule, a molecularly imprinted polymer (MIP) was fabricated on the modified electrode. The ECL signal of COF-AIECL was catalytically amplified by the Fe3O4@Pt NPs, whereas CFX effectively quenched this signal. Consequently, the ECL signal was controlled by CFX elution from and adsorption by the MIP, thus establishing a new method for CFX detection. The sensitivity of the sensor was greatly enhanced by the aggregation-induced luminescence effect and nanozyme amplification, whereas the MIP effectively improved the selectivity for CFX. Under optimal conditions, the electrochemical sensor exhibited a linear detection range of 2 × 10−12 to 3 × 10−9 mol L−1, with a detection limit of 5.98 × 10−13 mol L−1. Furthermore, in untreated milk samples, CFX recoveries of 92.0%–111% were achieved. Thus, the developed sensor exhibited good reproducibility, stability, and selectivity for CFX detection.