Study of the Effect of Photobiomodulation on a Skin Repair Model in SKH-1 Mice.

Background and objective: Laser applied at low power (400-1100 nm), currently named photobiomodulation (PBM), is a noninvasive therapy to speed up wound healing. The purpose of this study was whether two different laser PBM delivery protocols would impact the skin wound healing in a mouse model. Materials and methods: A total of 24 SKH-1 mice were divided into three groups: Group 1 (control: untreated ulcers), Group 2 (a single postsurgical laser application), and Group 3 (laser each other day for 10 days; total five applications). Laser parameters were 940 nm, 0.4 W, 10 mm spot size, 0.008 J/cm2, 300 sec/wound. Each animal received two skin wounds which were photographed on days 0, 5, and 10 to determine wound closure (ImageJ). Half of the animals in each group were sacrificed on day 5 and the other half on day 10. Samples were routinely processed for histological analysis (re-epithelization, angiogenesis, granulation tissue formation, inflammation, and collagen deposition). Results: The closure of the wounds at the end of the experiment in the animals photobiostimulated each other day was more advanced than in the controls and in those treated only once, in both the macroscopic and microscopic studies. Angiogenesis was higher in both treated groups than in the control in the first study time (day 5). However, inflammation, maturation of the granulation tissue, and collagen deposition only improved when the laser was applied each other day. Conclusions: In our study, with the parameters used, PBM improved the healing of skin wounds when applied every other day and not in a single dose.

Infrared-Emitting Multimodal Nanostructures for Controlled In Vivo Magnetic Hyperthermia.

Deliberate and local increase of the temperature within solid tumors represents an effective therapeutic approach. Thermal therapies embrace this concept leveraging the capability of some species to convert the absorbed energy into heat. To that end, magnetic hyperthermia (MHT) uses magnetic nanoparticles (MNPs) that can effectively dissipate the energy absorbed under alternating magnetic fields. However, MNPs fail to provide real-time thermal feedback with the risk of unwanted overheating and impeding on-the-fly adjustment of the therapeutic parameters. Localization of MNPs within a tissue in an accurate, rapid, and cost-effective way represents another challenge for increasing the efficacy of MHT. In this work, MNPs are combined with state-of-the-art infrared luminescent nanothermometers (LNTh; Ag2 S nanoparticles) in a nanocapsule that simultaneously overcomes these limitations. The novel optomagnetic nanocapsule acts as multimodal contrast agents for different imaging techniques (magnetic resonance, photoacoustic and near-infrared fluorescence imaging, optical and X-ray computed tomography). Most crucially, these nanocapsules provide accurate (0.2 °C resolution) and real-time subcutaneous thermal feedback during in vivo MHT, also enabling the attainment of thermal maps of the area of interest. These findings are a milestone on the road toward controlled magnetothermal therapies with minimal side effects.