Gold‑nanorod coated titanium heats under NIR light and reduces Staphylococcus aureus biofilms in FDA lab tests
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Summary
WEAC researchers reported that titanium surfaces functionalized with gold nanorods via thiol‑silane chemistry (MPTMS) produced stronger coating, a ~15°C photothermal rise under 808 nm illumination and over a 1‑log reduction in S. aureus biofilms after 20 minutes, while ISO 10993‑5 cytotoxicity tests showed no significant cell‑viability loss in vitro.
Dr. Jelika Amarsingh presented WEAC's development and testing of gold‑nanorod (GNR) coatings on titanium intended for targeted photothermal ablation of bacterial biofilms. The project compared two silane chemistries to affix GNRs to titanium — amine‑terminated APTES and thiol‑terminated MPTMS — and assessed coating stability, photothermal conversion, antimicrobial performance, and in‑vitro biocompatibility.
Amarsingh said SEM, EDS and XPS characterization confirmed GNR attachment for both chemistries but showed stronger and more uniform gold signal on MPTMS‑treated titanium. ‘‘MPTMS led to greater gold nanorod deposition than APTES,’’ she reported.
Under 808‑nm near‑infrared illumination for 20 minutes, MPTMS‑coated samples exhibited a temperature rise of about 15°C and produced ‘‘over a 1 log reduction in viable bacteria after 20 minutes of irradiation,’’ Amarsingh said, a significantly larger effect than observed on APTES‑coated surfaces.
Biocompatibility testing followed ISO 10993‑5 in‑vitro cytotoxicity procedures. Direct‑contact MTS assays on macrophages, fibroblasts and osteoblasts showed high viability comparable to control titanium. Extract tests (21‑day incubations of coated samples in medium) did not reduce cell viability, and cytokine assays (IL‑6 and TGF‑β) showed no significant inflammatory response compared with lipopolysaccharide positive controls.
Amarsingh framed the findings as encouraging for surface‑targeted, on‑demand photothermal cleaning of device surfaces but cautioned that further optimization and broader testing are needed to assess tissue safety, robustness under realistic contamination and long‑term stability.
She said ongoing work will refine fabrication strategies and expand testing to more species and realistic device geometries; regulatory translation would require performance standards and safety validation in clinically relevant contexts.
