Experimental study on the mechanical properties and thermal damage of laser welding the ruptured flexor digitorum longus tendons

To investigate the influence of laser parameters on the performance of tendon tissue, experiments were conducted and the process of laser-assisted tendon welding was studied. Several conclusions were drawn by analyzing the effects of laser parameters on the tensile strength, microstructure, and collagen content of tendon tissue incisions. The optimal parameters for laser welding tendon tissue were found to be a laser power of 5 W, a scanning speed of 150 mm/s, and a defocus amount of 0 mm, resulting in a laser energy density of 32.164 J/cm2 . At these parameters, the percentage of inactivated cells due to thermal damage was only 23.78%, and the tensile strength of the tendon tissue incisions reached 0.61 MPa. Additionally, the collagen content around the incision was measured to be 33.679%, composed of type I and type III collagens, with the latter accounting for 50.714% of the total collagen content.

Research on evolution process of full-layer incision of skin tissue under different laser incidences

Considering difficulties of achieving vertical incidence of beam in different positions of skin, it is significant to study potential effects of incidence angles of laser on incisions. Surgical platform with a 1064 nm continuous fiber laser was established. Incident angle was adopted and real-time temperature fluctuations in laser operating area could be monitored. The rats were treated with laser at day 0 and day 3 after incision modeling, and H&E, Masson, Sirius Red, and Immuno-histochemical staining and enzyme-linked immunosorbent assay were adopted at day 3, 7, 14 to analyze the performance of healing. Laser with energy density of 67.54 J/mm2 can effectively accelerate wound healing in vivo, in which a laser with incident angle around 60° can effectively avoid scar hyperplasia. Therefore, the use of low energy laser with a small deflection angle has a good clinical application prospect in promoting wound healing.

Evaluation of Laser Tissue Welding and Laser-Tissue Soldering for Mucosal and Vascular Repair

Context

Laser tissue bonding (LTB) is believed to have certain advantages over conventional sutures such as fluid-tight closure and minimal scarring and fibrosis.

Aim

The aim of the present study was to evaluate the bond strength of laser tissue welding and laser tissue soldering in mucosal and vascular repair.

Materials and Methods

A total of 85 samples of bovine oral mucosa and 85 bovine aortas were bonded using a CO₂ laser and different laser powers. Human serum albumin was used as solder. The breaking load for mucosal samples and the bursting pressure for aorta samples were evaluated. Few specimens were evaluated histologically for thermal damage and other microscopic changes.

Statistical Methods

Two-way ANOVA was performed as the data were normally distributed and analyzed for significant differences between the groups. This was followed by Simple Main effects (Tuckey's post hoc test) to determine the individual variation between groups and also the significant differences within the groups.

Results

Significantly higher values of breaking load (44.2 ± 3.03 g) and bursting pressure (70.8 ± 12.33 mmHg) were noted when 50% albumin was used. When reinforcing sutures were given the bond strength was further increased (68.0 ± 4.0 g for breaking load) (108.0 ± 12.56 mmHg for bursting pressure). Microscopically, a bridge of solder coagulum formed across the wound. Thermal damage was restricted to the top layers only although it did extend much more laterally adjacent to the wound edges. Few areas of vacuolization and carbonization were seen.

Conclusion

LTB seems to be a promising new method of wound closure and warrants further evaluation in the form of in vivo and clinical studies.

Guidable Thermophoretic Janus Micromotors Containing Gold Nanocolorifiers for Infrared Laser Assisted Tissue Welding

Current wound sealing systems such as nanoparticle-based gluing of tissues allow almost immediate wound sealing. The assistance of a laser beam allows the wound sealing with higher controllability due to the collagen fiber melting which is defined by loss of tertiary protein structure and restoration upon cooling. Usually one employs dyes to paint onto the wound, if water absorption bands are absent. In case of strong bleeding or internal wounds such applications are not feasible due to low welding depth in case of water absorption bands, dyes washing off, or the dyes becoming diluted within the wound. One possible solution of these drawbacks is to use autonomously movable particles composing of biocompatible gold and magnetite nanoparticles and biocompatible polyelectrolyte complexes. In this paper a proof of principle study is presented on the utilization of thermophoretic Janus particles and capsules employed as dyes for infrared laser-assisted tissue welding. This approach proves to be efficient in sealing the wound on the mouse in vivo. The temperature measurement of single particle level proves successful photothermal heating, while the mechanical characterizations of welded liver, skin, and meat confirm mechanical restoration of the welded biological samples.