Rapid synthesis of protein conjugated gold nanoclusters and their application in tea polyphenol sensing

In this report, a rapid approach for the synthesis of protein conjugated gold nanoclusters under heating condition (AuNCs-protein(p)-heating(h)) was proposed. These AuNCs-p-h were synthesized within 3   min at approximately 100   °C and contain remarkable peroxidase-like activity. Notably, in the presence of tea polyphenols (TPs), the peroxidase-like activity of AuNCs-p-h is restrained, which is likely due to the TP-induced aggregation. A facile approach for TP sensing based on the inhibition effect of TPs towards the peroxidase mimic activity of AuNCs-p-h has been developed. Tea is one of the most popular and health beneficial beverages, the favourable effect of which attributes greatly to its key component, TPs. TP detection thus becomes an important task for various food and beverage companies. This novel TP colorimetric detecting method exhibits a linear response in the concentration range of 10   nM to 10   μM with detection limit of 10   nM as well as prominent selectivity towards various TP related molecules including tyrosol, protocatechuate, chlorogenic acid, theophylline, l -theanine, and l -norepinephrine hydrochloride. Comparing with the traditional tartaric acid colorimetric approach (Tac), this new system shows basically identical experimental results but with much higher sensitivity. AuNCs-p-h can be readily used for TP quantification from real tea samples.