Facile and green synthesis of Au nanoparticles decorated Epigallocatechin-3-Gallate nanospheres with enhanced performance in stability, photothermal conversion and nanozymatic activity.

In this study, epigallocatechin-3-gallate nanospheres (EGCG NSs) are employed as an innovative alternative to traditional reducing agents for the in-situ growth of AuNPs on the EGCG NS surface to produce the Au nanoparticles decorated EGCG nanospheres (EGCG NS@AuNPs). This eco-friendly approach avoids toxic chemicals and simplifies the synthesis process, enhancing biocompatibility and functional properties of the resulting EGCG NS@AuNPs nanocomposite. The nanocomposite exhibits remarkable stability, photothermal properties, and peroxidase-like enzymatic activity. Taking advantage of the enhanced photothermal properties, the application of EGCG NS@AuNPs in the antibacterial field was investigated, and the antibacterial activity was greatly improved against both Gram-negative and Gram-positive bacteria comparing to bare AuNPs or EGCG NS. Additionally, based on the excellent enzymatic activity, the sensing application of EGCG NS@AuNPs was explored by developing a colorimetric method for detecting ascorbic acid (AA). A remarkably low detection limit of 0.076 μM was achieved. This method has been successfully applied to measure the AA content in vitamin C tablets, demonstrating the practicality and accuracy of this approach. Therefore, the synthesis for EGCG NS@AuNPs is not only rapid, and cost-effective, but also eco-friendly and not harmful to biological systems, which is potential in biosensing, clinical diagnosis, and therapeutics. Future research could explore further applications of EGCG NS@AuNPs in biomedicine field, revealing even more of its remarkable potential.