Sutures and staples are generally adequate for closing the majority of wounds.
However, in some cases, traditional suturing methods may face challenges in precisely sealing wounds, particularly in soft tissues where the needle and thread approach might be ineffective and potentially cause additional harm.
This is where tissue soldering comes in. It entails applying a gelatinous paste to the delicate wound tissue or in the hard-to-reach areas, followed by the application of heat using a laser.
Researchers have now created a smart wound soldering paste called iSolder (intelligent solder).
This allows for the careful fusion of tissues, offering an alternative approach to effectively seal wounds.
Developed by the research institute Empa, and ETH Zurich, this laser soldering technique holds the potential to “prevent wound healing disorders and life-threatening complications from leaking sutures.”
Nanoparticle-based paste
In a conventional tissue soldering method, the application of heat causes the paste to polymerize, resulting in bonding with the underlying tissue. This efficiently closes the wound and promotes rapid healing.
This laser-based smart wound closure paste was created using the bonding agent containing metallic and ceramic nanoparticles.
Interestingly, the temperature of laser soldering may be accurately regulated in real time using nanothermometry. It is essentially a measurement and monitoring of temperature at the nanoscale.
The bonding protein-gelatin paste contains two kinds of nanoparticles.
“While the paste is irradiated by laser, titanium nitride nanoparticles convert the light into heat. The specially synthesized bismuth vanadate particles in the paste, on the other hand, act as tiny fluorescent nano thermometers,” explained the release.
Overall, this novel technique allows the laser soldering process to be regulated precisely and efficiently.

Lab testing of this composite material
In collaboration with surgeons from the University Hospital Zurich, the Cleveland Clinic (USA), and Charles University in the Czech Republic, the team evaluated the overall performance of this composite.
Through laboratory studies, they were able to establish “fast, stable, and biocompatible bonding of wounds” in numerous tissue samples. They also effectively sealed complicated regions of tissue, such as the urethra, fallopian tube, and intestine.
In subsequent stages, the team managed to substitute the laser light source with a milder infrared (IR) light, bringing this soldering method one step closer to practical usage in hospitals.
“If medically approved IR lamps were applied, the innovative soldering technology could be used in conventional operating rooms without additional laser protection measures,” concluded Inge Herrmann, who was part of this development.
The team has also applied for a patent.
The results were reported in the journal Small Methods.
Study abstract:
While often life-saving, surgical resectioning of diseased tissues puts patients at risk for post-operative complications. Sutures and staples are well-accepted and routinely used to reconnect tissues, however, their mechanical mismatch with biological soft tissue and invasiveness contribute to wound healing complications, infections, and post-operative fluid leakage. In principle, laser tissue soldering offers an attractive, minimally-invasive alternative for seamless soft tissue fusion. However, despite encouraging experimental observations, including accelerated healing and lowered infection risk, critical issues related to temperature monitoring and control during soldering and associated complications have prevented their clinical exploitation to date. Here, intelligent laser tissue soldering (iSoldering) with integrated nanothermometry is introduced as a promising yet unexplored approach to overcome the critical shortcomings of laser tissue soldering. It demonstrates that adding thermoplasmonic and nanothermometry nanoparticles to proteinaceous solders enables heat confinement and non-invasive temperature monitoring and control, offering a route to high-performance, leak-tight tissue sealing even at deep tissue sites. The resulting tissue seals exhibit excellent mechanical properties and resistance to chemically-aggressive digestive fluids, including gastrointestinal juice. The iSolder can be readily cut and shaped by surgeons to optimally fit the tissue defect and can even be applied using infrared light from a medically approved light source, hence fulfilling key prerequisites for application in the operating theatre.
Source: IE