Development of a novel label-free NIR aptasensor based on triphenylmethane dyes for rapid and sensitive detection of copper ions.

Heavy metal pollution, particularly from copper ions (Cu), poses a significant threat to both the ecological environment and human health. However, traditional copper ion analysis techniques are often hindered by the need for expensive equipment, labor-intensive sample preparation and skilled operation, which limits their effectiveness for field and real-time applications. In this work, we report a novel near-infrared aptamer sensor (NIRApt) that originates from the binding reaction between the DNA aptamer Apt and the fluorescent small molecule crystal violet (CV), enabling rapid detection of Cu through the competitive effect of Cu with Apt. This sensor shows a significant enhancement in NIR fluorescence after aptamer binding. NIRApt exhibits superior performance, requiring only three core components to achieve a fast response time and operational simplicity in less than a minute. The sensor shows high sensitivity with a detection limit as low as 61 nM, making it suitable for the detection of trace amounts of Cu in diverse samples. The efficacy of NIRApt has been validated through successful applications in real water samples, highlighting its promising potential for environmental monitoring.