Biomimetic Adhesives for Bone Fractures Inspired by Marine Adhesion

Treatment of complex bone fractures poses significant clinical challenges, where the fixation devices often hinder the bone healing process. Biocompatible and biodegradable bone adhesives offer a promising solution by effectively bonding the bone fragments together, eliminating the need for secondary surgeries. Marine organisms, known for their ability to adhere to surfaces underwater, have long served as a source of inspiration for developing biomimetic adhesives. The key to their adhesion lies in the unique adhesive protein sequences and microscopic structures. This review first discusses the adhesion mechanisms and characteristics of mussels, barnacles, and sandcastle worms, where the key chemical components of protein sequences include DOPA, hydrophobic amino acids, and acidic phosphoserine. Microscopic structures such as complex coacervates of sandcastle worms formed by polyanions/polycations contribute to their strong adhesion. Next, the design strategies for biomimetic bone adhesives and methods to enhance adhesion strength are introduced, including adhesion based on DOPA and phosphate components, and cohesion enhanced by introducing multifunctional polymers, inorganic fillers, and complex coacervate structures. This review also highlights the potential of mineral-organic adhesives that mimic natural bone tissue. Finally, the challenges and future perspectives are addressed on the clinical development of biomimetic bone adhesives.