Gold Nanorod-Collagen Nanocomposites as Photothermal Nanosolders for Laser Welding of Ruptured Porcine Intestines

Abstract

Surgical site infection and postoperative leakage are complications that may develop following colorectal surgery and result in fatal consequences. Rapid, fluid-tight wound closure through laser tissue welding (LTW) can reduce postoperative leakage and thus decrease infection. Laser tissue welding involves generation of localized heat by exposing an exogenous chromophore to near-infrared (NIR) irradiation in order to seal wounds. In this study, we generated gold nanorod (GNR)-collagen nanocomposites (NCs) for laser-facilitated welding of ruptured intestinal tissue. The fluid content, stiffness, elasticity, and laser-induced temperature response of these nanocomposites were modulated to optimize laser-induced tissue fusion and minimize tissue damage. In addition, the effect of laser operating parameters including power density, femtosecond pulsed wave (PW) or continuous wave (CW) laser, and exposure duration were all studied. Laser power density and treatment duration significantly affected the temperatures reached during welding, as well as tissue weld strength and burst pressure. CW laser was found to induce significantly higher temperatures of the nanocomposites during treatment than PW laser, but the differences in weld strength and burst pressure for the two laser types were insignificant. This suggests that PW lasers can result in robust welds while minimizing potential thermal damage compared to CW lasers. The ultimate tensile strength of welded ruptured tissue was returned to as high as 68% of the native tissue strength through laser treatment, and laser treatment with these nanocomposites restored up to 64% of native tissue leak pressure and 42% of burst pressure. To the best of our knowledge, the laser power densities used (≤2.50 W/cm 2 ) are among the lowest reported for laser tissue welding, and the laser configuration and use require very little surgical skill. Our results indicate that GNR-collagen nanocomposites are promising photothermal biomaterials in laser tissue welding applications.

Spatiotemporal modeling of laser tissue soldering using photothermal nanocomposites

“…The solid lines (upper and lower) represent the model temperature prediction at two different locations (surface temperatures and inside the primary lumen) corresponding to the same locations as the experimental measurements. Experimental data are representative of n = 3 independent experiments used from .…”

“…To overcome these challenges, exogenous chromophore formulations have been used as stains , pastes , or patches in concert with lasers tuned to near infrared wavelengths, at which laser absorbance in the tissue is higher compared to light at visible wavelengths. Tissue stains using aqueous solutions of the organic dye indocyanine green (ICG), and tissue solders largely composed of albumin‐ICG viscous liquids or semi‐solids have been used .…”

“…The LTS approach of interest here is based on nanocomposite solders composed of gold nanorods (GNRs) cross‐linked or embedded within a polypeptide matrix. In the former case, elastin‐like polypeptides (ELP) were crosslinked with GNRs, resulting in the formation of thin film patches , and, in the latter case, collagen hydrogels were physically embedded within GNRs and compressed plastically to form thin film hydrogel patches . ELP‐GNR nanocomposites successfully soldered ex vivo porcine intestine in a 47% return in tensile strength and a 45% return in burst pressure compared to intact intestine, and collagen‐GNR nanocomposites similarly resulted in a 68% return in tensile strength and a 42% return in burst pressure compared to intact intestine.…”

Light‐Activated Tissue‐Integrating Sutures as Surgical Nanodevices

“…The supernatant was discarded, and the pellet was dispersed in nanopure water to the desired concentration (optical density or OD was used as a surrogate for concentration of GNRs). The GNRs were centrifuged and redispersed in nanopure water two additional times, bringing the concentration of free CTAB in the solution to less than 0.15 × 10 −3 m …”

“…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. 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 …”