One-pot synthesis of Cys-functionalized CuS quantum dots via microwave-assisted for silver ions detection in real...

Convenient synthesis of functionalized CuS quantum dots (CuS QDs) with good biocompatibility in aqueous solution remains a significant obstacle. To overcome these limitations, a microwave-assisted one-pot method was developed to synthesize ultrasmall, cysteine-capped CuS QDs in aqueous phase. These CuS QDs exhibit outstanding optical properties, as well as excellent water dispersibility and stability. Based on these advantages, CuS QDs can be employed as a simple, rapid, and efficient fluorescent nanosensing platform for the selective detection of Ag⁺ across a wide concentration range (1-250 µM). Notably, the sensing system features a rapid response time (60 s) and a large Stokes shift (115 nm), which contribute to improved detection efficiency and sensitivity. Moreover, the system exhibits exceptional selectivity for Ag⁺ against a range of common metal ions via a fluorescence quenching mechanism. The underlying detection mechanism involves an Ag⁺-induced cation exchange process, resulting in the release of Cu²⁺ from the CuS QDs. Importantly, this sensing strategy has been successfully applied to the detection of Ag⁺ in real water samples, demonstrating high recovery rates. Additionally, the low toxicity and superior biocompatibility of the CuS QDs enable their further application in Ag⁺ detection within living cells. In summary, the CuS QD-based fluorescent probe offers a promising platform for environmental monitoring and biological diagnostics.