Spatiotemporal modeling of laser tissue soldering using photothermal nanocomposites

Abstract

Objective Laser tissue soldering using photothermal solders is a technology that facilitates rapid sealing using heat-induced changes in the tissue and the solder material. The solder material is made of gold nanorods embedded in a protein matrix patch that can be placed over the tissue rupture site and heated with a laser. Although laser tissue soldering is an attractive approach for surgical repair, potential photothermal damage can limit the success of this approach. Development of predictive mathematical models of photothermal effects including cell death, can lead to more efficient approaches in laser-based tissue repair. Methods We describe an experimental and modeling investigation into photothermal solder patches for sealing porcine and mouse cadaver intestine sections using near-infrared laser irradiation. Spatiotemporal changes in temperature were determined at the surface as well as various depths below the patch. A mathematical model, based on the finite element method, predicts the spatiotemporal temperature distribution in the patch and surrounding tissue, as well as concomitant cell death in the tissue is described. Results For both the porcine and mouse intestine systems, the model predicts temperatures that are quantitatively similar to the experimental measurements with the model predictions of temperature increase often being within a just a few degrees of experimental measurements. Conclusion This mathematical model can be employed to identify optimal conditions for minimizing healthy cell death while still achieving a strong seal of the ruptured tissue using laser soldering.

Light‐Activated Tissue‐Integrating Sutures as Surgical Nanodevices

“…Surface temperatures of LATIS fibers irradiated with continuous wave (CW) laser at 800 nm increased with increasing laser power densities, which ranged from 1.6 to 4.8 W cm −2 . Typically, temperatures in the range of 55–70 °C are necessary for laser‐activated tissue sealing, and temperatures of 60–65 °C are considered optimal . These sealing temperatures were easily attained by modulating the laser power intensity.…”

“…Studies on second‐harmonic generation microscopy for visualizing laser‐welded corneal stroma indicated three related processes: breakdown of interfibrillar proteoglycan bridges at 45–50 °C, unfolding of proteins and contraction of fibrils at 55–60 °C and loss of protein network at temperatures higher than 80 °C . Spatiotemporal modeling enabled prediction of temperature profiles in tissues followed laser irradiation of the nanosealant; associated sealing strengths and potential tissue damage were also studied . A wide variety of sealant biomaterials including elastin‐like polypeptides (ELPs), silk, and collagen can be interfaced with photothermal convertors, including gold nanorods (GNRs), for rapid sealing of soft tissues following laser activation.…”

“…A wide variety of sealant biomaterials including elastin‐like polypeptides (ELPs), silk, and collagen can be interfaced with photothermal convertors, including gold nanorods (GNRs), for rapid sealing of soft tissues following laser activation. This approach can reduce operation and healing times, infection, and scarring compared to conventional modes of tissue repair and can protect the tissue from desiccation and peripheral heat damage …”

Robot-assisted laser tissue soldering system

“…In other cases, a coloring agent (Indocyanine Green) is mixed with the solder and the wavelength of the laser is chosen to be absorbed by the coloring agent [24]. A recent development involves incorporation of nano-particles within the solder allowing absorption at specific wavelengths [25,26]. The LTS technique has been attempted by several groups, mostly in ex-vivo experiments [27].…”

Gold nanospheres enhanced photothermal therapy in a rat model

“…Histological results indicated that GNPs combined with PBMT group was more effective in stimulating angiogenesis and triggered inflammatory response at early stage, suggesting that GNPs combined with PBMT has potential to accelerate wound healing. Mushaben et al established a spatiotemporal modeling to identify optimal conditions for achieving a strong seal of the ruptured tissue while minimizing healthy cell death in laser soldering combined with photothermal nanocomposites, which can be used to overcome the limit of this technology resulted from the potential photothermal damage. Giving their strong absorption coefficients and unique photothermal effect, selective photothermolysis with GNPs (known as selective nanophotothermolysis) may provide more localized heat to destroy aberrant blood vessels after intravenous injection of GNPs.…”