11 / 2021-05-14 16:34:47

“Turn on” coordination polymer@nanocellulose composite film for detecting ciprofloxacin

Coordination polymer,Nanocellulose,Composite film,Ciprofloxacin,Fluorescence enhancement

In recent years, along with the extensive application of ciprofloxacin (CIP), it has also been detected by variety of technologies in rivers and groundwater, which may pose a certain risk to the ecosystem. Among the analytical methods, fluorescence analysis has the advantages of probe diversity, high sensitivity, fast response, simple operation and good selectivity, and is more suitable for the quantitative analysis of CIP. On account of the unique optical properties of rare earth metals, the lanthanide coordination polymers have attracted much attention, which are ideal fluorescent probe materials. The fluorescent responsive nanocellulose composite film was fabricated by combining TEMPO-oxidized cellulose nanofibrils (TOCNF) and coordination polymer (Tb-AMP), in aqueous medium at room temperature via in-situ synthesis to detect CIP. There are high density of carboxyl groups on TOCNF surface, and metal−carboxylate complexes are easily formed because of the strong affinity between carboxylates and metal ions. Terbium ions complexed with carboxyl groups on TOCNF were immobilized on the surface of TOCNF. The biomolecule AMP was added to coordinate with terbium ions forming a coating layer of Tb-AMP on the surface of TOCNF. Due to the small size and abundant carboxyl groups of TOCNF, the coordination polymer was induced to change its original morphology and polymerize on the fiber surface to form a coating layer. CIP supplied terbium ion energy through antenna effect, which was emitted green light under ultraviolet irradiation. The influence of several different antibiotics on film fluorescence performance was investigated, and the results showed that the film had a good selectivity to CIP in solutions. When a certain concentration of the metal ions or biological small molecules were added into CIP solution, the film still worked normally, demonstrating the strong anti-interference ability of Tb-AMP@TOCNF film. As CIP concentration increased, the fluorescence intensity of Tb-AMP@TOCNF increased, and fluorescence intensity had a good linear relationship with CIP concentration (y=4.57+3.17x, R²=0.999, LOD=0.0392 μM). The fluorescence, selectivity, transparency and other characteristics of Tb-AMP@TOCNF made it have a great application prospect in CIP specific rapid detection. As its pH adaptability was similar to the human environment, it had potential application value in the detection of antibiotics in urine and blood.