Sensitive detection and prostate cancer cellular evaluation of sarcosine via a fluorescence turn-on assay using an N-CQDs/Ag ⁺ nanosensor

to Ag nanoparticles, thereby restoring the fluorescence of N-CQDs. The sensor demonstrated a linear response to sarcosine in the range of 10-60 µM with a detection limit of 2.1 µM, and exhibited high selectivity against common interfering substances. Furthermore, the platform was successfully applied to detect sarcosine in lysates of prostate cell lines, revealing significantly elevated sarcosine levels in androgen-independent PC-3 cells compared to benign (BPH-1) and androgen-sensitive (LNCaP) cells. This work presents a cost-effective, and cell-compatible fluorescence strategy for sarcosine detection, holding potential for PCa early screening and metabolic profiling.