Effects Of Near-infrared Irradiation Research Articles

Near-infrared-emitting nanoparticles activate collagen synthesis via TGF\u03b2 signaling

Research efforts towards developing near-infrared (NIR) therapeutics to activate the proliferation of human keratinocytes and collagen synthesis in the skin microenvironment have been minimal, and the subject has not been fully explored. Herein, we describe the novel synthesis Ag2S nanoparticles (NPs) by using a sonochemical method and reveal the effects of NIR irradiation on the enhancement of the production of collagen through NIR-emitting Ag2S NPs. We also synthesized Li-doped Ag2S NPs that exhibited significantly increased emission intensity because of their enhanced absorption ability in the UV–NIR region. Both Ag2S and Li-doped Ag2S NPs activated the proliferation of HaCaT (human keratinocyte) and HDF (human dermal fibroblast) cells with no effect on cell morphology. While Ag2S NPs upregulated TIMP1 by only twofold in HaCaT cells and TGF-β1 by only fourfold in HDF cells, Li-doped Ag2S NPs upregulated TGF-β1 by tenfold, TIMP1 by 26-fold, and COL1A1 by 18-fold in HaCaT cells and upregulated TGF-β1 by fivefold and COL1A1 by fourfold in HDF cells. Furthermore, Ag2S NPs activated TGF-β1 signaling by increasing the phosphorylation of Smad2 and Smad3. The degree of activation was notably higher in cells treated with Li-doped Ag2S NPs, mainly caused by the higher PL intensity from Li-doped Ag2S NPs. Ag2S NPs NIR activates cell proliferation and collagen synthesis in skin keratinocytes and HDF cells, which can be applied to clinical light therapy and the development of anti-wrinkle agents for cosmetics.

New insight into singlet oxygen generation at surface modified nanocrystalline TiO2 – the effect of near-infrared irradiation

The generation of singlet oxygen in aqueous colloids of nanocrystalline TiO2 (anatase) modified by organic chelating ligands forming surface Ti(IV) complexes was studied. Detailed studies revealed a plausible and to date unappreciated influence of near-infrared irradiation on singlet oxygen generation at the surface of TiO2. To detect (1)O2, direct and indirect methods have been applied: a photon counting technique enabling time-resolved measurements of (1)O2 phosphorescence, and fluorescence measurements of a product of singlet oxygen interaction with Singlet Oxygen Sensor Green (SOSG). Both methods proved the generation of (1)O2. Nanocrystalline TiO2 modified with salicylic acid appeared to be the most efficient photosensitizer among the tested materials. The measured quantum yield reached the value of 0.012 upon irradiation at 355 nm, while unmodified TiO2 colloids appeared to be substantially less efficient generators of singlet oxygen with the corresponding quantum yield of ca. 0.003. A photocatalytic degradation of 4-chlorophenol, proceeding through oxidation by OH˙, was also monitored. The influence of irradiation conditions (UV, vis, NIR or any combination of these spectral ranges) on the generation of both singlet oxygen and hydroxyl radicals has been tested and discussed. Simultaneous irradiation with visible and NIR light did not accelerate OH˙ formation; however, for TiO2 modified with catechol it influenced (1)O2 generation. Singlet oxygen is presumably formed according to Nosaka's mechanism comprising O2˙(-) oxidation with a strong oxidant (hole, an oxidized ligand); however, the energy transfer from NIR-excited titanium(iii) centers (trapped electrons) plays also a plausible role.