The Development of Gelatin Based Tissue Adhesives for Use in Soft Tissue Biomedical Applications
Experiments were performed to characterize the pH, gelation time, diffusion processes, material properties, adhesive properties, and the drying variables on the material and adhesive properties of Gelatin Resorcinol Dialdehyde (GR-DIAL) tissue adhesives by varying formulation. Three adhesive formulations with altered weight content of water and glyoxal (a dialdehyde) were utilized. The adhesive formulations were characterized by pH and gelation time in situ, and absorption/desorption of water in the formed resin. Thermal analysis, mechanical testing, and lap shear adhesive bond testing were utilized to characterize fresh GR-DIAL adhesive formulations and formulations dried at 370C. From the results, the diffusion processes, material and adhesive properties of the adhesive formulations were primarily affected by hydrogen bonding, chemical cross-linking, and the existence of bound water within the bulk adhesive. Formulations with increased glyoxal content had both a higher degree of cross-linking and proportion of bound water within the bulk adhesive. The increased number of chemical cross-links greatly increased the swelling resistance of the adhesives, while, the existence of bound water within the adhesive increased the resistance to drying, and plasticized the resin by depressing the resin glass transition temperature, and increased the adhesive ductility. Hydrogen bonding increased with increased gelatin content or decreased water content, resulting in increased strength and modulus of the adhesives as well as increased adhesive strength.