A novel colorimetric/fluorescent dual-signal probe based on silver nanoparticles functionalized with -cysteine and rhodamine 6G derivatives for copper ion detection and cell imaging.

The dual-signal probe utilizing functionalized silver nanoparticles (AgNPs) is a promising sensing tool. Herein, a novel colorimetric/fluorescent dual-signal probe (AgNPs--Cys-Rh6G2) was fabricated for copper ion (Cu) detection and cell imaging by using -cysteine as a "bridge" to connect AgNPs and rhodamine 6G derivatives. The AgNPs--Cys-Rh6G2 probe exhibits a dual-signal response to Cu due to Rh6G2 hydrolysis, resulting in a high fluorescence response and a significant change in color from light yellow to pink under sunlight. The linear detection ranges of the AgNPs--Cys-Rh6G2 probe for Cu were 100-450 μM and 150-650 μM using fluorescent and colorimetry methods, respectively. The detection limits were as low as 0.169 μM and 1.36 μM, respectively. Meanwhile, the proposed probe was applied to detect Cu in the actual sediment with satisfactory recovery and low relative standard deviation. Furthermore, the probe was further employed for fluorescence imaging in HeLa cells. In brief, the developed AgNPs--Cys-Rh6G2 sensing platform can be used for simultaneous Cu determination and cell imaging.