Polymer Surface-Modified Bioceramics for Osseous Tissue Engineering

Skeletal defects require surgery via using bone grafts. Autografts are the gold standard for bone grafting; however donor site morbidity limits the application. Allografts have the risk of disease transmission. These disadvantages of natural bone grafts have given rise to the development of various synthetic materials for bone substitutes. Ideal bone substitutes should be characterized with biocompatibility and osteoconductivity. Biodegradable synthetic polymers, such as polyanhydrides, polycaprolactones (PCL), polylactide, polyglycolide, and associated copolymers express different degradation times, mechanical strengths and byproducts. Bioceramics, such as SiO2, TiO2, SrO, tricalcium phosphate and hydroxyapatite (HAP) have been researched for osteogenesis. But inorganic compounds and ceramics tend to break because of their brittle nature. The combination of bioceramics and polymers as composites increases their bioactivity and. However, defects and cracks can form at the polymer/ceramic interface, resulting in uneven distribution of stress and subsequent inferior mechanical strength. This research project fabricates composite scaffolds as bone substitutes. Using ring opening polymerization, caprolactone is grafted onto the surface of the ceramic nanoparticles (SiO2, TiO2, SrO and HAP) by chemical binding. A stable (–O–C–) covalent bound is formed between nanoparticles and PCL. The PCL-grafted nanoparticles mixed with PCL polymer matrix as composite materials. The hydrophobic-hydrophobic interactions between the short chain PCL-grafted nanoparticles and the long-chain PCL polymer matrix will make the composites more stable. In vitro experiments include basic properties (mechanical strength, degradation rate, pH changes, surface morphology), and biochemical tests (cell viability, cell affinity, alkaline phosphatase activity, calcium deposition, osteogenic activity). We will finally select the preferred composition for in vivo animal experiments (biocompatibility, critical bone defect model). This project combines the advantage of polymers and bioceramic nanoparticles to fabricate composite scaffolds as bone substitutes. The specific aim is to achieve a stable mechanical strength, slow degradation rate, good biocompatibility and osteoconductivity. The method is innovated and the result is promising for clinical application.

Project ID:PC10401-0615
External Project ID:MOST103-2314-B182-036-MY3