Nanostructured Polymers for Bone Repair

1. CNMS User Project Highlight Nanostructured Polymers for Bone Repair • Scientific Achievement • Synthesis of a series of novel, injectable and photo-crosslinkable PPF-co-POSS copolymers via a two-step polycondensation. These copolymers exhibit improved stiffness, toughness and biological performance as bone-tissue engineering scaffolds, specifically when 10% wt. POSS is incorporated. • (PPF-co-POSS = poly(propylene fumarate)-co-polyhedral oligomericsilsesquioxane) • Significance • Understanding copolymer microstructure yields a better understanding of how it functions as scaffold for bone implants • Research Details • CNMS Capability: Oxygen mapping in energy-filtered TEM (EFTEM) revealed polydispersity and structure at the nanoscale that cannot be seen with regular bright field TEM; thereby providing a structural understanding of this 10% threshold. • Tensile and compressive moduli and facture toughness are enhanced for crosslinked PPF-co-POSS when POSS wt% is 10%, which results in POSS nanocages that are small and well-distributed. The mechanical properties are correlated with in vitro mouse pre-osteoblasticcell functions including cell attachment, spreading, proliferation, differentiation, and gene expression, which all maximize at POSS wt% of 10%. Fracture Toughness KIC (Mpa*m1/2) Weight% Fraction of POSS Oxygen map Bright Field 100 nm 100 nm Toughness as a function of POSS wt% (Top) and EFTEM images of 5 wt% POSS copolymer (Bottom). POSS crystals are small and well dispersed only for wt% less than 10% L. Cai , J. Chen, A. J. Rondinone, S. Wang, Advanced Functional Materials, Early View, DOI: 10.1002/adfm.201200457(2012).