Microencapsulation of Octylcyanoacrylate for Applications as a Healing Agent in a Self-healing Bone Cement

Total joint replacement surgeries are performed on thousands of patients every year, yet these implants are subject to failure following prolonged exposure to the harsh environment of the body as well as the complex loading patterns seen in biological joints. The generation of wear debris from both the articulating surfaces and the poly(methyl methacrylate) (PMMA) bone cement used to anchor the replacements in place serves to accelerate wear and subsequent failure of the device. Self-healing approaches that employ an encapsulated healing agent embedded in a catalyst-containing matrix have been developed to restore mechanical function to materials that undergo crack damage; following capsule rupture, and healing agent release and polymerization serves to halt microcrack propagation. However, existing encapsulated systems do not adhere to biomaterials constraints. In this work, interfacial polymerization of polyurethane (PUR) in an oil-in-water emulsion was used to achieve encapsulation of octylcyanoacrylate (OCA), a medical grade adhesive used in sutureless surgeries. The optimized encapsulation procedure was determined by studying the effects of solvent, surfactant, and temperature on the final product. The average size and size distribution, capsule shell thickness, percent fill and reactivity of encapsulated agent, and shelf life of these capsules were studied and are now suitable for incorporation into PMMA and assessment as potential healing agent systems.