Nanoclay-Mediated Crystal-Phase Engineering in Biofunctions to Balance Antibacteriality and Cytotoxicity

The crystalline phase of metal oxides is a key determinant of the properties and functions of the nanomaterials. Traditional approaches have focused on replicating bulk-phase structures, with limited exploration of phase diversity due to challenges in controlling the crystal morphology. Here, we introduce a nanoclay-mediated strategy for crystal-phase engineering, using talc to modulate the morphology and phase of manganese oxide (MnOx) nanoparticles. This approach enhances the oxidase activity of the MnOx composite (M/T), optimizing the antimicrobial efficacy while minimizing cytotoxicity. M/T-190 demonstrated 99% bactericidal activity against Escherichia coli and Staphylococcus aureus, coupled with 84% cytocompatibility. Theory calculations suggest that talc modulates the charge distribution and d-band center tuning at the Mn₃O₄/MnOOH interface, enhancing oxygen activation. When integrated into gauze, M/T exhibits strong antimicrobial activity, low toxicity, and promotes wound healing in both in vitro and in vivo studies. These findings highlight the potential of natural minerals for crystal-phase engineering in biomedical applications.