Crosslinked polyanhydrides for use in orthopedic applications: Degradation behavior and mechanics

Abstract

High-strength, surface-eroding polymers were synthesized from methacrylated anhydride monomers of sebacic acid (MSA) and 1,6-bis(carboxyphenoxy) hexane (MCPH). These multifunctional monomers were photopolymerized using ultraviolet light to produce highly crosslinked polyanhydride networks. Through this approach, the crosslinking density of the resulting polymer network was used to control the final mechanical properties, while the degradation time scale was controlled by the chemical composition of the network. The combined hydrophobicity of the polymer backbone with the hydrolytically labile anhydride linkages led to surface-eroding networks, as confirmed by linear cumulative mass loss profiles as a function of degradation time for crosslinked polymer disks. By copolymerizing varying amounts of MSA and MCPH, the degradation rate of the final network was controlled from 2 days to 1 year. The tensile modulus of crosslinked poly(MSA) (1.4 GPa) was nearly an order of magnitude larger than that of linear poly(sebacic acid). In general, the mechanical properties of the crosslinked polyanhydrides networks were within ranges of those reported for cortical and trabecular bone. However, unlike bulk degrading polyesters such as poly(lactic acid), these surface eroding networks maintained >70% of their tensile modulus with 50% mass degradation.

Immobilization of poly(ɛ-caprolactone)–poly(ethylene oxide)–poly(ɛ-caprolactone) triblock copolymer on poly(lactide-co-glycolide) surface and dual biofunctional effects

“…Anseth and coworkers have investigated the degradation of cross-linked diacrylated PLA-b-PEO-b-PLA hydrogels [27,28]. They also studied dimethacrylated anhydride monomers, which reacted to form highly cross-linked degradable networks using various photoinitiation schemes [29]. To our knowledge, the application of PCL-PEG-PCL diacrylates as the surface modification precursor to enhance the biocompatibility of PLGA was not yet investigated.…”

Biodegradable injectable polyurethanes: Synthesis and evaluation for orthopaedic applications

“…Mikos et al [1] and Anseth et al [2,5] have reported in situ polymerisable systems based on polypropylene fumarate and polyanhydride chemistry, respectively. These systems can be cured in situ with low reaction exotherm and encourage cell attachment, proliferation, and differentiation of osteoblastic function in vivo [6][7][8]. However, such polymer systems have limited mechanical properties and as such may have limitation in orthopaedic applications.…”

Achieving Interconnected Pore Architecture in Injectable PolyHIPEs for Bone Tissue Engineering

“…Average values recorded at 2 weeks for compressive modulus and strength were 43 -12 MPa and 3 -0.2 MPa, respectively. These values approach those of human cancellous bone of 20-500 MPa 40,41 for modulus and 2-30 MPa 42,43 for strength. These data suggest that the compressive strength may continue to increase as indicated by the lack of a plateau in values.…”