(178o) Protein-Polyphenol Adhesives for Bone Fracture Repair.

Bone adhesives are a promising alternative to traditional fixation and reduction methods, particularly for complicated comminuted fractures. There are no clinically active candidates due to developmental challenges because the bone tissue is highly intricate, and the adhesive needs to meet a host of characteristics, especially adhesion stability in a wet environment. Drawing inspiration from nature, especially the marine environment, the use of biomaterials as adhesive components has gained momentum. Further, sacrificial bonding involving temporary, weak bonds (i.e., ionic, metal co-ordination, hydrogen, hydrophobic interactions, and Vander Waals forces) is known to enhance adhesion and has been observed to exist in natural physiological environments (i.e., bone and underwater).

We performed a thorough literature review and made a few key conclusions: there are many stand-alone formulations whose synthesis is complicated, only a few have follow-up studies, and there is non-uniformity in testing methods. We further identified composites of proteins and polyphenols with fillers, such as nano-hydroxyapatite, as bankable candidates. In particular, we examined mixtures of silk fibroin and tannic acid. The concentration, composition, amount, and pH were varied. We further examined the hypothesis that adding metal cations can enhance cohesion and adhesion due to chelation by tannic acid. We included salts of calcium, iron, and magnesium in the study. We tested adhesion performance with two wooden blocks glued together and weights suspended to check endurance. We obtained sticky macroscopic gels as adhesives by mixing the above components. They could hold the blocks together for a maximum of approximately 50 gm/cm² for a minimum testing time of five minutes. This changed based on changes in the composition and testing conditions. This study will provide more insights into the optimal parameters, chemistry, and adhesion mechanisms in order to fabricate an ideal adhesive.