Photo-Curable Triazinetrione Composites With Tunable Degradation for Fracture Stabilization and Flexible Thin-Film Applications

The standard-of-care for treating complex bone fractures includes metal screws and plates. However, their rigid, pre-shaped geometry, coupled with a lack of patient-specific customization and degradability, often results in post-surgical complications and the need for secondary surgeries. Alternatives that are adaptable, biodegradable, and versatile enough to address these limitations have become a priority for the surgical community. Injectable viscous mixtures that harden on demand into composites present a compelling solution, as they can mimic the mechanical properties of bone and conform to any fracture geometry. One promising example evaluated in preclinical trials is clickable composites based on triazine-2,4,6-trione (TATO)-based allyl and thiol monomers combined with hydroxyapatite fillers. These materials cure via visible light-induced thiol-ene coupling chemistry, providing adequate stiffness and strength for bone healing. However, the lack of degradability in these composites has limited their broader application. To overcome this limitation, we developed a new generation of TATO composites with hydrolytically degradable ester linkages and bioresorbable fillers. Offering exceptional versatility, these advanced materials can be cast into twistable films or injected to form high-strength composites. Hydrolysis testing revealed a 41%-64% increase in mass loss compared to the non-degradable TATO composites, while maintaining a high flexural modulus up to 6.4 GPa and a softening temperature above 45 degrees C, well above body temperature. When evaluated as fracture fixation patches, the degradable composites demonstrated superior performance, including greater load capacity and flexibility, compared to their non-degradable counterparts. By delivering strong mechanical support throughout the bone healing process and seamlessly degrading over time, these composites can indeed pave the way for a new era in orthopedic care, where versatile, biodegradable materials not only address critical clinical challenges but also set a visionary standard for the future of patient-centered surgical solutions.