title: Chitosan adhesive for laser tissue repair: in vitro characterization.
abstract: OBJECTIVE
  Laser tissue repair usually relies on hemoderivate protein solders, based on serum albumin. These solders have intrinsic limitations that impair their widespread use, such as limited tensile strength of repaired tissue, poor solder solubility, and brittleness prior to laser denaturation. Furthermore, the required activation temperature of albumin solders (between 65 and 70 degrees C) can induce significant thermal damage to tissue. In this study, we report on the design of a new polysaccharide adhesive for tissue repair that overcomes some of the shortcomings of traditional solders.
  
  
  METHODS
  Flexible and insoluble strips of chitosan adhesive (elastic modulus approximately 6.8 Mpa, surface area approximately 34 mm2, thickness approximately 20 microm) were bonded onto rectangular sections of sheep intestine using a diode laser (continuous mode, 120 +/- 10 mW, lambda = 808 nm) through a multimode optical fiber with an irradiance of approximately 15 W/cm2. The adhesive was based on chitosan and also included indocyanin green dye (IG). The temperature between tissue and adhesive was measured using a small thermocouple (diameter approximately 0.25 mm) during laser irradiation. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Murine fibroblasts were cultured in extracted media from chitosan adhesive to assess cytotoxicity via cell growth inhibition in a 48 hours period.
  
  
  RESULTS
  Chitosan adhesive successfully repaired intestine tissue, achieving a tensile strength of 14.7 +/- 4.7 kPa (mean +/- SD, n = 30) at a temperature of 60-65 degrees C. Media extracted from chitosan adhesive showed negligible toxicity to fibroblast cells under the culture conditions examined here.
  
  
  CONCLUSIONS
  A novel chitosan-based adhesive has been developed, which is insoluble, flexible, and adheres firmly to tissue upon infrared laser activation.
authors.affiliation: School of Chemistry, The University of New South Wales, 2052 New South Wales, Sydney, Australia. antonio1@gsbme.unsw.edu.au
authors.forename: Antonio
authors.initials: A
authors.lastname: Lauto
authors.forename: J
authors.initials: J
authors.lastname: Hook
authors.forename: M
authors.initials: M
authors.lastname: Doran
authors.forename: F
authors.initials: F
authors.lastname: Camacho
authors.forename: L A
authors.initials: LA
authors.lastname: Poole-Warren
authors.forename: A
authors.initials: A
authors.lastname: Avolio
authors.forename: L J R
authors.initials: LJ
authors.lastname: Foster
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D002478:Cells, Cultured; D048271:Chitosan / Q000494:pharmacology*; D005347:Fibroblasts / Q000502:physiology; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000601:surgery*; D053685:Laser Therapy; D008422:Materials Testing; D012756:Sheep; D013053:Spectrophotometry; D013696:Temperature; D013718:Tensile Strength / Q000502:physiology; D014014:Tissue Adhesives / Q000494:pharmacology*
chemical_list: D001672:Biocompatible Materials; D014014:Tissue Adhesives; D048271:Chitosan