Mechanically Competent Chitosan‐Based Bioadhesive for Tendon‐to‐Bone Repair

Current suture-based surgical techniques used to repair torn rotator cuff tendons do not result in mechanically competent tendon-to-bone attachments, leading to high postoperative failure rates. Although adhesives have been proposed to protect against sutures tearing through tendon during healing, no currently available adhesive meets the clinical needs of adhesive strength, biocompatibility, and promotion of healing. Here, a biocompatible, graded, 3,4-dihydroxy phenyl chitosan (BGC) bioadhesive designed to meet these needs is presented. Although 3,4-dihydroxy phenyl chitosan (DP-chitosan) bioadhesives are biocompatible, their adhesion strength is low; soluble oxidants or cross-linking agents can be added for higher bonding strength, but this sacrifices biocompatibility. These challenges are overcome by developing a periodate-modified ion exchange resin-bead filtration system that oxidizes catechol moieties to quinones and filters off the activating agent and resin. The resulting BGC bioadhesive exhibited sixfold higher strength compared to commercially available tissue adhesives, with strength in the range necessary to improve tendon-to-bone repair (≈1MPa, ≈20% of current suture repair strength). The bioadhesive is biocompatible and promoted tenogenesis; cells exposed to the bioadhesive demonstrated enhanced expression of collagen I and the tenogenic marker Scx. Results demonstrated that the bioadhesive has the potential to improve the strength of a tendon-to-bone repair and promote healing.