Ferric Ions as a Catalytic Mediator in Metal‐EGCG Network for Bactericidal Effect and Pathogenic Biofilm Eradication at Physiological pH

Pathogenic bacteria and biofilm formation have become the urgent threats to global public health. Herein, metal‐epigallocatechin gallate (EGCG) network with improved bactericidal effect and pathogenic biofilm eradication ability via trivalent cationic Fe3+ catalyzed hydrogen peroxide (H2O2) decomposition is developed. EGCG, the predominant catechin from tea, is predicted to be a good chelator for eight metal ions (i.e., Al3+, Cr3+, Cu2+, Co2+, Zn2+, Mn2+, Ni2+, Fe3+). 3,3',5,5'‐tetramethylbenzidine oxidation experiment using UV–vis spectrometer demonstrated that Zn2+, Mn2+, Ni2+ are the potential candidates to accelerate the generation of H2O2 by EGCG. Compared with the other two metal‐EGCG network (Zn2+‐EGCG or Mn2+‐EGCG), only Ni2+‐EGCG network has better bactericidal property and plays a synergistic role in the network system. Furthermore, by introducing Fe3+ to Ni2+‐EGCG network, the complex exhibits the best bactericidal property for gram‐negative bacteria Escherichia coli (E. coli) and Pseudomonas aeruginosa (PAO1), which can be explained by the rapid H2O2 decomposition and associated production of hydroxyl radicals. With SYTO 9/PI staining assay, Fe3+ as a catalytic mediator in Ni2+‐EGCG network shows the most significant bactericidal effect and pathogenic biofilm eradication ability. According to the above analysis, Ni2+‐EGCG network presents a promising nanoplatform as an alternative to antibiotics for eradication of pathogenic bacteria and biofilms.