Photodynamic effect of light emitting diodes on E. coli and human skin cells induced by a graphene-based ternary composite

In this paper, the photodynamic effect of a ternary nanocomposite (TiO2-Ag/graphene) on Escherichia coli bacteria and two human cell lines: A375 (melanoma) and HaCaT (keratinocyte) after exposure to different wavelength domains (blue, green or red-Light Emitting Diode, LED) was analyzed. The results obtained through bioassays were correlated with the morphological, structural and spectral data obtained through FT-IR, XPS and UV–Vis spectroscopy, powder X-Ray diffractometry (XRD) and STEM/EDX techniques, leading to conclusions that showed different photodynamic activation mechanisms and effects on bacteria and human cells, depending on the wavelength. The nanocomposite proved a therapeutic potential for blue light-activated antibacterial treatment and revealed a keratinocyte cytotoxic effect under blue and green LEDs. The red light–nanocomposite duo gave a metabolic boost to normal keratinocytes and induced stasis to melanoma cells. The light and nanocomposite combination could be a potential therapy for bacterial keratosis or for skin tumors. •The Ag-TiO2/TRGO was prepared via impregnation/thermal procedures avoiding toxic reagents.•The TiO2-Ag/TRGO nanocomposite had clear effects on E. coli under blue light LED irradiation•Skin cells are responsive to 24 h continuous lighting in all three LEDs, as opposed to E. coli.•The cytotoxic effect is a synergetic result of photodynamic effect and surface plasmon resonance of Ag NPs.