Intelligent Metal-Phenolic Metallogels as Dressings for Infected Wounds

Ha Thi Phuong Anh, Chun Ming Huang, Chun Jen Huang

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45 Scopus citations


In this study, we report a metallogel developed based on metal-phenolic coordination of natural low-cost polyphenolic molecule and metal ions. Gelation occurs by mixing tannic acid (TA) and group (IV) titanium ions (TiIV) to form TA-TiIV gel. The TA-TiIV gel exhibits good capability to incorporate diverse metal ions by in situ co-gelation. Herein, five antimicrobial metal ions, i.e. ferric (FeIII), copper (CuII), zinc (ZnII), cobalt (CoII) and nickel (NiII) ions, were employed to include in TA-TiIV gels for developing intelligent dressings for infected wounds. The chemical and coordinative structures of TA-TiIV metallogels were characterized by UV-Vis and Fourier-transform infrared (FT-IR) spectroscopies. Cytotoxicity of antimicrobial metallogels was explored by MTT assay with NIH 3T3 fibroblasts. The release of metal ions was evaluated by inductively coupled plasma mass spectrometry (ICP-MS), indicating the different releasing profiles upon the coordinative interactions of metal ions with TA. The formation and disassembly of metallogels are sensitive to the presence of acid and an oxidizer, H2O2, which are substances spontaneously generated in infected wounds due to the metabolic activity of bacteria and the intrinsic immune response. The CuII releasing rates of TA-TiIV-CuII metallogels at different pH values of 5.5, 7.4 and 8.5 have been studied. In addition, addition of H2O2 trigger fast release of CuII as a result of oxidation of galloyl groups in TA. Consequently, the antimicrobial potency of TA-TiIV-CuII metallogels can be simultaneously activated while the wounds are infected and healing. The antimicrobial property of metallogels against Gram-negative Escherichia coli, and Gram-positive Methicillin-Resistant Staphylococcus aureus (USA300) and Staphylococcus epidermidis has been investigated by agar diffusion test. In an animal model, the TA-TiIV-CuII metallogels were applied as dressings for infected wounds, indicating faster recovery in the wound area and extremely lower amount of bacteria around the wounds, compared to TA-TiIV gels and gauze. Accordingly, the intelligent nature derived metallogels is a promising and potential materials for medical applications.

Original languageEnglish
Article number11562
JournalScientific Reports
Issue number1
StatePublished - 1 Dec 2019


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