Ultrafast, Sensitive and Visual Sensing of Copper Ions by a Dual-Fluorescent Film Based on Quantum Dots
Abstract: Fluorescent sensors are one of the most promising approach for meeting the growing demand of sensitive, convenient and cost-effective detection of metal ions. However, visual sensing based on fluorescent materials remain a challenge due to the hard-to-see changes of fluorescence intensity, long response time and poor stability. Here, a simple and effective film sensor is developed for visual detection of Cu2+ using quantum dots (QDs) modified by polyethylenimine(PEI) and poly (vinylidene fluoride) (PVDF) by electrospinning and dip-coating methods. QDsr-PEI on surface of nanofibers were used as responsive red fluorescent signal while QDsg dispersed in nanofibers were used as green background signal. As the high Cu2+ binding capacity of PEI and the contrast-color sensitivity of two kind of QDs, it realizes an obvious fluorescent change from red to green toward Cu2+ in liquid phase with a short response time of 30s and low detection limit of 2 µM by observation. What’s more, the film exhibits excellent fluorescent stabilities to high temperature and UV light, which is beneficial for satisfying much more possible applications. These results demonstrate that the dual fluorescent film sensor has great potential for real-time and visual detection of Cu2+.