Photochemical tissue bonding with chitosan adhesive films

Background: Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Methods: Adhesive films, based on chitosan and containing similar to 0.1 wt% RB were manufactured and bonded to calf intestine by a solid state laser (lambda = 532 nm, Fluence similar to 110 J/cm(2), spot size similar to 0.5 cm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results: The RB-chitosan adhesive bonded firmly to the intestine with adhesion strength of 15 +/- 2 kPa, (n = 31). The adhesion strength dropped to 0.5 +/- 0.1 (n = 8) kPa when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26 degrees C to 32 degrees C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. Conclusion: A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.