Bio-adhesion evaluation of a chitosan-based bone bio-adhesive

Abstract Conventional treatment of complex fractures includes the use of plates and nails, which may compromise the affected limb's functionality. Previous studies have demonstrated promising results through chemical, mechanical, and cytotoxicity tests of a chitosan-based adhesive—proposed as a new method to bond high energy fractures—in dry environments with adequate adhesion, malleability, and biocompatibility. In this study, we focused on performing an evaluation of bio-adhesives’ mechanical properties and bone-adhesive joint using two chitosan-based formulations (with and without a cross-linking agent). The texture profile analysis determined adhesive properties, such as cohesiveness, adhesiveness, hardness, and resilience at different cure times. Bone-adhesive joint was evaluated according to the tensile bond strength test and shear bond strength test. Fracture toughness and cohesive strength were calculated through a rigid double cantilever beam test at mode I failure. Bone-adhesive joints were tested in two environments: dry and submersed in water at 37 °C for 1, 6, and 24 h (curing time), an approximation of surgery conditions. The experimental results showed an incremental of adhesiveness and hardness of the cross-linked adhesive during the first 15 min, which was determined as the usage time to spread on the bone fracture. The joint interaction between the adhesive and bone surfaces was studied; chitosan-based formulations showed an adhesive joint failure under dry conditions in most of the cases. However, this behavior changed under aqueous conditions, presenting cohesive failures. Under aqueous conditions, cross-linked bone-adhesive presented an augmented tensile bond strength up to 0.024 ± 0.0036 MPa, a shear bond strength up to 0.031 ± 0.0069 MPa, and fracture toughness of 2.38 ± 0.54 J/m2 was observed with a cure time of 24 h. Finally, the presence of the cross-linking agent in the cross-linked bio-adhesive reduced the sensitivity of the adhesive to water; a promising finding that should be explored in future studies.