Albumin-genipin solder for laser tissue-welding

Background. Laser tissue soldering (LTS) is an alternative technique to suturing for tissue repair. One of the major drawbacks of LTS is the weak tensile strength of the solder welds when compared to sutures. In this study, the possibility was investigated for a low cytotoxic crosslinker, acting on amino groups, to enhance the bond strength of albumin solders. Materials and Methods. Solder strips were welded onto rectangular sections of sheep small intestine by a diode laser. The laser delivered in continuous mode mode a power of 170 ±10 m W at λ=808 nm, through a multimode optical fiber (core size=200 μm) to achieve a dose of 10.8 ±0.5 J/mg. The solder thickness and surface area were kept constant throughout the experiment (thickness = 0.15 ±1mm, area = 12±1.2 mm²). The solder incorporated 62% bovine serum albumin, 0.38% genipin, 0.25% indocyanin green dye (IG) and water. Tissue welding was also performed with a similar solder, which did not incorporate genipin, as a control group. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Results. The tensile strength of the genipin solder was twice as high as the strength of the BSA solder (0.21 ±0.04 N and 0.11 ±0.04 N respectively; p∼10^-15 unpaired t-test, N=30). Discussion. Addition of a chemical crosslinking agent, such as genipin, significantly increased the tensile strength of adhesive-tissue bonds. A proposed mechanism for this enhanced bond strength is the synergistic action of mechanical adhesion with chemical crosslinking by genipin.