Highly sensitive red-emitting carbon dot-based fluorescence sensor for simultaneous detection of copper ions and L-histidine in environmental and biomedical samples

The detection of Cu 2+ ions and L-histidine (L-His), which are crucial trace elements and amino acids in biological systems, is of paramount importance for environmental health, food safety, and clinical diagnosis. However, conventional detection methods often suffer from drawbacks such as complexity, time-consuming procedures, and high costs. To address these challenges, we have developed an efficient, sensitive, and straightforward detection techniques. In this study, we successfully synthesized red-emitting carbon dots (R-CDs) with a remarkable quantum yield of 26.6 % and devised an R-CDs-based fluorescence sensor that operates via an “on-off-on” mode for the simultaneous detection of Cu 2+ ions and L-His. The sensor's working principle involves the static quenching of R-CDs fluorescence upon the addition of Cu 2+ ions, followed by the restoration of fluorescence through the competitive binding of L-His to Cu 2+ ions. This approach enables the ultrasensitive detection of Cu 2+ ions and L-His, with detection limits as low as 0.58 μM and 0.45 μM, respectively. The sensor has been effectively applied to detect Cu 2+ ions in environmental water samples and L-His in human blood, food additives, and health-care products. It demonstrates excellent selectivity, strong anti-interference ability, and high accuracy, with recovery rates ranging from 95.0 % to 105.0 %. Owing to its simplicity, rapidity, cost-effectiveness, and high sensitivity, the proposed R-CDs-based fluorescence sensor holds great promise as a valuable tool for environmental monitoring, food safety assessment, and clinical diagnosis. Future efforts will focus on further optimizing the sensor's performance and exploring its applications in a broader range of real-world samples, thereby providing substantial support for scientific research and technological advancements in related fields.