One-Step Synthesis of Tea Polyphenol–Iron Nanoparticles for Enhanced Antioxidant and Antibacterial Properties

Tea polyphenols (TPs) are promising natural bioactive compounds; however, their practical application is hindered by poor stability and low bioavailability. To address this challenge, we synthesized TP–iron nanoparticles (TP-Fe NPs) through coordination-driven self-assembly. Comprehensive characterization (SEM, TEM, FTIR, and XRD) confirmed the successful formation of stable TP-Fe NPs, primarily mediated by phenolic hydroxyl and carbonyl groups. Among TP-Fe NPs, the TP3-Fe1 NPs exhibited superior performance, achieving DPPH and ABTS radical scavenging rates of 65.71% and 89.64%, respectively, and inhibition rates of 91.44% against E. coli and 88.67% against S. aureus . Furthermore, TP3-Fe1 NPs demonstrated excellent biocompatibility, showing no significant cytotoxicity to L929 cells at 0.01–0.1 mg/mL. These findings highlight the potential of TP3-Fe1 NPs as a safe and effective material with dual functionality for antioxidant and antibacterial applications.