Low-energy laser irradiance at certain wavelengths is able to stimulate the tissue bio-reaction and enhance the healing process. Collagen deposition is one of the important aspects in healing process because it can increase the strength of the skin. This study was designed to examine the biophotonic effect of irradiance on collagen production of diabetic wound in rat model. The tensile strength of skin was employed as a parameter to describe the wound. Diabetic rat models were induced by streptozotocin via intravenous injection. Skin-breaking strength was measured using an Instron tensile test machine. The experimental animals were treated with 808-nm diode laser at two different powers-0.1 and 0.5 W/cm(2)-and 30, 60, and 120 s for each session. The tensile strength was optimized after treated with high-power diode laser. The photostimulation effect was revealed by accelerated healing process and enhanced tensile strength of wound. Laser photostimulation on tensile strength in diabetic wound suggests that such therapy facilitates collagen production in diabetic wound healing.

Q-switched Nd: YAG laser is the most effective laser for tattoo removal. Photobiomodulation (PBM) therapy is an alternative method applied to accelerate the wound healing. This paper investigated the effects of PBM therapy using 808 nm diode laser on tattooed skin after laser tattoo removal. Forty-five rats were selected and tattooed with black ink on their dorsal, and then distributed into three groups. G0 was received non-laser irradiation. G1 was treated by laser tattoo removal using 1064 nm with energy density of 3.4 J/cm without PBM therapy, while G2 was treated daily with PBM therapy using 808 nm diode laser of 5 J/cm after a single session of laser tattoo removal. The effects of tattoo removal and healing progress of the wound were analyzed using histological studies. Findings showed 808 nm laser promotes the healing process through enhancing epithelialization and collagen deposition. Moreover, PBM therapy stimulated immune cells to improve phagocytosis process for removing the tattoo ink fragments effectively. The PBM therapy treated group was capable of improving the healing process and increasing the quality of skin following the laser tattoo removal. It was also found that stimulation of cellular function by PBM therapy increased tattoo clearance efficiency.

This paper presents a study on the effect of laser irradiation on wound healing. 808 nm diode laser was employed to facilitate the healing of impaired wounds in experimental diabetes using a rat model. Diabetes was induced in male rats by a streptozotocin injection with a dose of 60 mg kg −1 . The disease was verified via measurement of the blood glucose level, which was set having 20 mmol L −1 stability. The rats were randomly distributed into two groups; one served as a control group and the other group was treated with the laser. The power density of the laser used was 0.5 W cm −2 and the wounds were treated for 8 d with the contact time of one second daily. The energy density used was 0.5 J cm −2 . The healing progress was recorded via a digital camera. The recorded images were then transferred into Inspector Matrox and image J programs for the accurate measurement of the healing area. The tissue details of the wound were studied through histology. The wound contraction rate of laser therapy group was found to be two times faster than control group. This indicates that the 808 nm diode laser can accelerate the wound healing process.

Photobiomodulation therapy (PBMT) is used for wound healing at two different power densities, i.e. 0.2 W cm −2 and 0.4 W cm −2 , while maintaining the same fluence of 5 J cm −2 . Forty-five streptozotocin (STZ)-induced diabetic rats were allocated into three groups: the untreated laser group (G0), 0.2 W cm −2 laser treated group (GL1), and 0.4 W cm −2 laser treated group (GL2). Six mm full thickness cutaneous wounds are created on the dorsal side of rats. A 808 nm diode laser irradiates the wound in GL1 and GL2 daily for 9 consecutive days. Groups GL1 and GL2 have the same total fluence but different power densities, 0.2 W cm −2 and 0.4 W cm −2 , which results in stimulatory and inhibitory effects in wound healing, respectively. In group GL1, enhanced wound contraction and inflammation has been triggered at an earlier stage compared to the untreated laser group G0. Meanwhile, the laser treated group GL2 exhibits an escalated volume of inflammatory cells, and collagen synthesis is inhibited. Therefore, it can be concluded that PBMT has potential in promoting wound healing under the low power density (0.2 W cm −2 ) condition.

Photobiomodulation therapy (PBMT) is the use of near infrared light to stimulate tissue repair in the healing process. The aim of this study was to evaluate the wavelength-and dosedependent effects of PBMT on wound healing.Thirty-six Sprague Dawley rats with four circular full thickness 6 mm diameter cutaneous wounds each were distributed into experimental part 1 for optimization of wavelengths on wound treatment and experimental part 2 for dose-dependent studies. In part 1, various near infrared laser wavelengths (808, 880 and 1064 nm) were used as PBMT light source to optimize the wound treatment under the same fluence of 5 J cm −2 . Furthermore, the optimal wavelength was selected as treatment source in part 2 with various power densities in the range of 20-100 mW cm −2 . All wounds were treated immediately except for the control group and the experiment was conducted for nine consecutive days.The result in part 1 showed that 808 nm was the optimal wavelength to give the highest wound closure percentage at 94.08% ± 6.5%, meanwhile power density of 40-60 mW cm −2 better accelerated the healing rate than other groups in part 2.Therefore, PBMT using 808 nm at the range of 40-60 mW cm −2 has beneficial effects on the wound healing process.