Fluorescence Turn-On Sensing of Leucine Using Bimetallic Cu–Ag Nanoclusters: A Potential Non-Invasive Biomarker for Cancer Detection

This study investigates the use of bimetallic copper–silver nanoclusters (Cu-AgNCs) for fluorescence turn-on sensing of leucine, a potential biomarker for cancer detection. These nanoclusters exhibit high fluorescence tunability and specificity, with Fe³⁺ serving as a quencher to facilitate leucine detection. The fluorescence recovery mechanism is attributed to the interaction of leucine with Fe³⁺, alleviating the quenching effect on the metal nanoclusters. This bimetallic nanocluster is a promising platform for biomarker identification in cancer diagnosis. The fluorescence enhancement upon leucine binding provides a measurable signal, confirming the feasibility of these nanoclusters as noninvasive sensors for cancer biomarkers. The sensor achieves a detection limit of 0.58 μM and demonstrates a linear response within the range of 110–657 μM. This approach offers a promising method for noninvasive cancer diagnostics using saliva and urine samples. Additionally, the method’s reproducibility and robustness further support its potential in clinical applications, providing a cost-effective and accessible technique for early cancer detection.