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

Abstract

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.