Covalent organic framework@metal-organic framework nanohybrid as ratiometric fluorescence sensor for ciprofloxacin determination.

Ciprofloxacin (CIP) is an effective and widely used antibiotic against various bacterial infections. However, its excessive presence in the environment and animal-derived food products poses significant risks to human health and ecological systems. Therefore, the development of sensitive, selective, and reliable detection methods for CIP determination is essential. In this work, the feasibility of fabricating a ratiometric fluorescence probe based on Schiff network-1 (SNW-1) and MIL-101-NH2 nanohybrid was investigated. The formation of covalent organic framework@metal-organic framework (COF@MOF) mesoporous nanohybrid effectively suppressed the aggregation-induced quenching (ACQ) of SNW-1, resulting in strong dual emission peaks at 465  and 537 nm. The SNW-1@MIL-101-NH2 nanohybrid with a large number of functional groups, high porosity and specific surface area can improve the sensitivity and selectivity of probe for CIP determination. The sensor provides excellent analytical performance for the determination of CIP, with low limits of detection of 0.0020  and 0.092 μM across two linear ranges. SNW-1@MIL-101-NH2 enhances the fluorescence intensity for CIP determination through ratiometric strategy and provides higher sensitivity than SNW-1 or MIL-101-NH2. The probe can successfully determine CIP in human blood samples and achieved satisfactory recovery with low relative standard deviation (RSD), highlighting its potential for practical biomedical and environmental applications.