In-vitro Investigations of Skin Closure using Diode Laser and Protein Solder Containing Gold Nanoshells

Introduction: Laser tissue soldering is a new technique for repair of various tissues including the skin, liver, articular cartilage and nerves and is a promising alternative to suture. To overcome the problems of thermal damage to surrounding tissues and low laser penetration depth, some exogenous chromophores such as gold nanoshells, a new class of nanoparticles consisting of a dielectric core surrounded by a thin metal shell, are used. The aims of this study were to use two different concentrations of gold nanoshells as the exogenous material for skin tissue soldering and also to examine the effects of laser soldering parameters on the properties of the repaired skin. Material and Methods: Two mixtures of albumin solder and different concentrations of gold nanoshells were prepared. A full thickness incision of 2×20 mm2 was made on the surface and after placing 50 μl of the solder mixture on the incision, an 810 nm diode laser was used to irradiate it at different power densities. The changes of tensile strength, σt, due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. Results: The results showed that the tensile strength of the repaired skin increased with increasing irradiance for both gold nanoshell concentrations. In addition, at constant laser irradiance (I), the tensile strength of the repaired incision increased with increasing Ns and decreasing Vs. In our case, this corresponded to st = 1610 g/cm2 at I ~ 60 Wcm-2, T ~ 65ºC, Ns = 10 and Vs = 0.2 mms-1. Discussion and Conclusion: Gold nanoshells can be used as an indocyanine green dye (ICG) alterative for laser tissue soldering.  Although by increasing the laser power density, the tensile strength of the repaired skin increases, an optimum power density must be considered due to the resulting increase in tissue temperature

Preliminary Results of Treating Cancerous Cells of Lung (QU-DB) by Hyperthermia using Diode Laser and Gold Coated Fe3O4/SiO2 Nano-Shells: An in-Vitro Assay

Introduction In this study, we describe the results of controlled synthesis and application of gold coated Fe3O4/SiO2 nano-shells combined with the optical property of gold for enhancement of selective photothermal interaction with cancerous cells based on the surface plasmon resonance (SPR) Phenomena. Materials and Methods Magnetite Nano-Particles (MNPs) were prepared by means of co-precipitation. MNPs were modified with a thin layer of Silica using the Stober method. The amino-modified Fe3O4/SiO2 nano-shells were covered with gold colloids as a self-assembeled process. In-vitro assays were performed to determine the effect of apoptosis of the cells based on the cells morphological changes. Results The biologically inert nano-shells (85 nm) with a Magnetite/Silica core and a gold shell were optically activated. A successful laser-hyperthermia based on the thermal effect of surface plasmon resonance was performed using different gold concentrations. The thermal profile effects of laser power are presented as ideal cases of nanoshell-assisted photo-thermal therapy. The thermally-induced cell death has been shown to be dependent on NPs concentration and laser power density. The power densities of 157 and 184 W/cm2 caused complete cell death at the focal point of the laser beam.Cell damage was reduced by decreasing the power density of laser. Also, a larger area of damage on cell culture plates was observed at longer intervals of laser irradiation. Conclusion An optimized laser-(SPR) hyperthermia was obtained using a concentration of gold coated Fe3O4/SiO2 nano-shells concentration=0.1 mg/ml at intensity=157 W/cm2 at 60s

Laser Soldering of Rat Skin Using a Controlled Feedback System

Introduction: Laser tissue soldering using albumin and indocyanine green dye (ICG) is an effective technique utilized in various surgical procedures. The purpose of this study was to perform laser soldering of rat skin under a feedback control system and compare the results with those obtained using standard sutures. Material and Methods: Skin incisions were made over eight rats’ dorsa, which were subsequently closed using different wound closure interventions in two groups: (a) using a temperature controlled infrared detector or (b) by suture. Tensile strengths were measured at 2, 5, 7 and 10 days post-incision. Histological examination was performed at the time of sacrifice. Results: Tensile strength results showed that during the initial days following the incisions, the tensile strengths of the sutured samples were greater than the laser samples. However, 10 days after the incisions, the tensile strengths of the laser soldered incisions were higher than the sutured cuts. Histopathological examination showed a preferred wound healing response in the soldered skin compared with the control samples. The healing indices of the laser soldered repairs (426) were significantly better than the control samples (340.5). Conclusion: Tissue feedback control of temperature and optical changes in laser soldering of skin leads to a higher tensile strength and better histological results and hence this method may be considered as an alternative to standard suturing

Effect of Argon Laser on Enamel Demineralization around Orthodontic Brackets: An In Vitro Study.

This study was designed to evaluate the effect of argon laser irradiation on development and progress of enamel demineralization around orthodontic brackets.Fifty caries-free, intact human premolars were randomly assigned to one of the following five equal groups: Groups 1 (control) and 2: The brackets were bonded using conventional halogen light for 40s and argon laser for 10s, respectively. Teeth in group 3 were lased with argon laser for 10s before bracket bonding with halogen light. Group 4 was the same as group 3 except that brackets were also bonded with argon laser. In group 5 samples were bonded conventionally, immersed in an artificial caries solution for two days and then irradiated for 10s with argon laser. All samples were subjected to demineralization by artificial caries solution for 10 days. After bracket removal, samples were buccolingually sectioned and evaluated by polarized light microscopy. Decalcified lesion depth in each section was measured by a trained examiner in a blind fashion. Data were analyzed in SPSS 14 using one-way ANOVA and Tukey's HSD post hoc test.The control group showed the greatest mean lesion depth while group 5 revealed the lowest. The laser-treated groups had significantly lower mean lesion depth compared with the control group (