Biomineralized gold nanoparticle-based colorimetric sensing platform for ascorbic acid detection.

Ascorbic acid (AA), a critical regulator of redox homeostasis, plays a vital role in disease prevention. Thus, the development of a rapid and precise detection method is urgently needed. In this work, a colorimetric sensing platform based on bioinspired mineralization-synthesized gold nanoparticles (AuNPs) was proposed for the visual and rapid detection of AA. The as-prepared AuNPs exhibited uniform morphology and excellent oxidase-like activity, efficiently catalyzing 3,3',5,5'-tetramethylbenzidine (TMB) oxidation to produce a characteristic 650 nm absorption peak. However, in the presence of AA, TMB oxidation was significantly inhibited due to the reducing property of AA. The color change was visually detectable within 5 min. The absorbance at 650 nm linearly decreased with the AA concentration in the range of 1-60 μM (R² = 0.999). The detection limit was estimated to 0.27 μM. Besides, the selectivity was excellent against common interfering species. The detection of AA in complex fruit samples was realized, and the recovery rate was 98.5-106.1%. Owing to the simplicity, cost-effectiveness, high sensitivity, and rapid response, this colorimetric sensing strategy provides new insights into the on-site monitoring of antioxidants in biological samples.