Enhanced photon energy conversion of iron oxide nanomaterials via ligand-to-metal charge transfer process for photothermal antibacterial activity and combined phototherapy

Abstract

The photon absorption enhancement inducing photothermal conversion via interfacial ligand-to-metal charge transfer (LMCT) was first proposed in this study Through a wet-chemistry hydrothermal process of tannic acid (TNA) and commercial iron oxide (γ-Fe2O3) nanoparticles (γ-IONP(c)) the phase transformation from γ-Fe2O3 to form Fe3O4 material UV-visible FT-IR and TGA measurements determined 6 1 % TNA molecules immobilized onto the surface of IONPs (IONP-TNA) Such ligand-assisted complex effect showed an absorption enhancement in the wide visible-NIR wavelengths via interfacial LMCT effect between TNA and IONPs The different TNA concentrations and reaction temperatures were further studied for demonstrating the preferred co-precipitation and self-assembly of TNA with Fe3+ ions on the NPs surface IONP-TNA was further modified with d-mannose (IONP-TNA@Man) to increase binding affinity toward the membrane molecules of Escherichia coli (E coli) IONP-TNA@Man could efficiently accumulate on the different strains of E coli and produce the localized hyperthermia to destroy the bacteria surface directly upon an excitation with a NIR laser It also sterilized well against Gram-positive bacteria as the model of Staphylococcus aureus (S aureus) Considering of eco-friendly concept IONP-TNA@Man could recycle via external magnetic field-integrated PTA treatment We prepared methylene blue (MB)-immobilized IONP-TNA (IONP-TNA@MB) for executing combined photothermal-photodynamic therapy (PDT) IONP-TNA@MB was stable in different environment and could deplete the glutathione (GSH) a natural PDT physiological barrier As an employment of 660 nm light IONP-TNA@MB acted as a therapeutic nano-mediator for inducing cancer cell death via the iron oxide-mediated phototherapy

Date of Award	2018 Jul 19
Original language	English
Supervisor	Chih-Chia Huang (Supervisor)