Synthesis of naphthylimide-quinoline fluorescent probe for the detection of Fe3+ and its application to Hela cells imaging

In this work, a novel ratiometric fluorescent probe, CL-LF, specifically designed for the detection of iron ions (Fe³⁺), was synthesized through the Click reaction using naphthylimine and quinoline as fluorophores. The structure of CL-LF was characterized and analyzed using Fourier transform infrared absorption spectroscopy (FTIR), nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS) and Single-crystal XRD, and the detection mechanism of CL-LF was verified by density functional theory (DFT) calculations. In addition, the photophysical properties of CL-LF were analyzed by fluorescence emission spectroscopy. The results indicated that CL-LF exhibits significant sensitivity toward Fe³⁺, with a calculated limit of detection (LOD) of 0.18 μM and a rapid response time of 1 min. The addition of Fe³⁺ to the CL-LF system causes the fluorescence colour to change from weak blue to bright green under the irradiation of a 365 nm UV lamp. This change provided an intuitive basis for the visual detection of Fe³⁺. At the same time, CL-LF demonstrated excellent selectivity and anti-interference ability, effectively distinguishing Fe³⁺ from other interfering ions. Based on the favorable fluorescence properties of CL-LF, this study further explored its potential application in cells through cell imaging experiments. The experiments showed that CL-LF has low toxicity and good cytocompatibility with Hela cells. With its exceptional cell imaging capabilities, CL-LF holds promise as a novel tool for investigating Fe³⁺-related biological processes and diseases.