A novel gold nanoparticle-based colorimetric assay for highly sensitive detection of ascorbic acid

In this study, a novel approach for colorimetric detection of ascorbic acid (AA) was proposed based on the peroxidase-like activity of gold nanoparticles, which were synthesized using Oldenlandia corymbosa leaves extract (OC-AuNPs). The OC-AuNPs synthesis was optimized at 0.5 mM Au3+, a reaction time of 20 min, and a temperature of 60 °C. The results showed that the biogenic OC-AuNPs presented as highly-efficient peroxidase mimics for catalyzing H2O2 to oxidize 3,3′,5,5′-tetramethylbenzidine forming a typical blue product with the characteristic absorption at 654 nm. The developed colorimetric method exhibited high sensitivity for AA with a detection limit of 0.26 μM in the linear range of 0 – 100 μM. The proposed assay can be serviced as a sensitive biosensor for the determination of AA in aqueous solutions due to its simple detection procedure, fast operation, and high sensitivity.