Fluorescence sensing platform for sarcosine analysis based on nitrogen-doping copper nanosheets and gold nanoclusters

Herein, nitrogen-doped copper nanosheet ([email protected] NS) was obtained by pyrolysis of the tryptophan‐based Cu‐containing nanosheet (CuT NS) and graphitic carbon nitride (g-C3N4). The high Cu loading (8.62 wt%) on the nitrogen-doped carbon-nanosheets endowed [email protected] NS with prominent peroxidase-mimicking activity. A fluorometric sensing platform comprising [email protected] NS with exceptional catalytic performance and 5-methyl-2-thiouracil capped gold nanoclusters (AuNCs) was successfully constructed for the determination of sarcosine. Under appropriate conditions, sarcosine oxidase (SOx) recognized and oxidized the sarcosine substrate to generate H2O2. The as-obtained [email protected] NS then decomposed H2O2 into superoxide radicals (O2•−) and further promoted the reaction between 4-aminoantipyrine (AAP) and phenol to form pink-red quinone-imine dye (p-QID, absorbance at 508 nm). When excited at 380 nm, the orange-emitting AuNCs peak at 560 nm was quenched by the produced p-QID via inner filter effect (IFE). Thus, a [email protected] NS/AuNCs-based fluorometric sensing strategy for sarcosine analysis was constructed. Impressively, the outputting fluorometric signal revealed a wide linear range of 7.5–1100 μmol L−1 with the detection limit of 4.69 μmol L−1. These findings not only expanded the applications of nanozyme in bioanalysis, but also provided a sensitive and effective approach for monitoring the levels of sarcosine.