Colorimetric detection of tyrosinase during the synthesis of kojic acid/silver nanoparticles under illumination

•A green, reliable and one-step colorimetric assay for tyrosinase (Tyr) is developed during the synthesis of silver nanoparticles (AgNPs).•The assay was based on specific binding between Tyr and kojic acid which prevented the formation of AgNPs.•The use of light makes the assay rapid, economical, and environmentally friendly.•The assay was applied to detect Tyr in human serum samples.

We report a green, reliable and single-step colorimetric assay for tyrosinase (Tyr) using the silver nanoparticles (AgNPs) as the signal readout. With the aid of light as the catalyst, kojic acid can rapidly reduce Ag+ ions and stablize the produced AgNPs. While uopn addition of Tyr during the synthesis of AgNPs, Tyr can effectively interrupt the formation of AgNPs due to its preferential combination with kojic acid, eventually leading to color fading and signal decrease of AgNPs solution. The presented method shows a good linear response toward Tyr over the range 0.5-4 u/mL with low detection limit of 0.117 u/mL. Common coexisting substances including metal ions, amino acids and biomacromolecules exert no effect on the determination of Tyr. This colorimetric sensor was successfully employed to quantify Tyr in human serum samples.