In vivo bone biocompatibility and degradation of porous fumarate-based polymer/alumoxane nanocomposites for bone tissue engineering.

The objective of this study was to determine how the incorporation of surface-modified alumoxane nanoparticles into a biodegradable fumarate-based polymer affects in vivo bone biocompatibility (characterized by direct bone contact and bone ingrowth) and in vivo degradability. Porous scaffolds were fabricated from four materials: poly(propylene fumarate)/propylene fumarate-diacrylate (PPF/PF-DA) polymer alone; a macrocomposite consisting of PPF/PF-DA polymer with boehmite microparticles; a nanocomposite composed of PPF/PF-DA polymer and mechanically reinforcing surface-modified alumoxane nanoparticles; and a low-molecular weight PPF polymer alone (tested as a degradation control). Scaffolds were implanted in the lateral femoral condyle of adult goats for 12 weeks and evaluated by micro-computed tomography and histological analysis.

Biodegradable fumarate-based polyHIPEs as tissue engineering scaffolds.

PolyHIPEs show great promise as tissue engineering scaffolds due to the tremendous control of pore size and interconnectivity afforded by this technique. Highly porous, fully biodegradable scaffolds were prepared by polymerization of the continuous phase of high internal phase emulsions (HIPEs) containing the macromer poly(propylene fumarate) (PPF) and the cross-linker propylene fumarate diacrylate (PFDA). Toluene was used as a diluent to reduce the viscosity of the organic phase to enable HIPE formation.

Nanobiomaterial applications in orthopedics.

Advancements in nanobiotechnology are revolutionizing our capability to understand biological intricacies and resolve biological and medical problems by developing subtle biomimetic techniques. Nanocomposites and nanostructured materials are believed to play a pivotal role in orthopedic research since bone itself is a typical example of a nanocomposite. This article reviews current strategies using nanobiomaterials to improve current orthopedic materials and examines their applications in bone tissue engineering.

Enzymatic degradation of poly(ether urethane) and poly(carbonate urethane) by cholesterol esterase.

This study examined the effect of cholesterol esterase (CE) on the degradation of commercial poly(ether urethane) (PEU) and poly(carbonate urethane) (PCU). Unstrained PEU and PCU films were incubated in 400 U/mL CE solution or a buffer control for 36 days. The study used a concentration of cholesterol esterase that was considerably higher than the estimated physiological level in order to accelerate degradation.

Antioxidant inhibition of poly(carbonate urethane) in vivo biodegradation.

This study compared the effect of an antioxidant on the in vivo biodegradation of a poly(carbonate urethane) (PCU) and a poly(ether urethane) (PEU). Unstrained PEU and PCU films with and without Santowhite were implanted subcutaneously into 3-month-old Sprague-Dawley rats for 3, 6, and 12 months. Characterization of unstabilized PEU and PCU with ATR-FTIR and SEM showed soft-segment and hard-segment degradation consistent with previous studies.

Biostability and macrophage-mediated foreign body reaction of silicone-modified polyurethanes.

In this study, the effect of soft segment chemistry on the phase morphology and in vivo response of commercial-grade poly(ether urethane) (PEU), silicone-modified PEU (PEU-S), poly(carbonate urethane) (PCU), and silicone-modified PCU (PCU-S) elastomers were examined. Silicone-modified polyurethanes were developed to combine the biostability of silicone with the mechanical properties of PEUs. Results from the infrared spectroscopy confirmed the presence of silicone at the surface of the PEU-S and PCU-S films.

Surface modification of poly(ether urethane urea) with modified dehydroepiandrosterone for improved in vivo biostability.

In this study, a fatty acid urethane derivative of dehydroepiandrosterone (DHEA) was synthesized and evaluated as a polyurethane additive to increase long-term biostability. The modification was hypothesized to reduce the water solubility of the DHEA and physically anchor the additive in the polyurethane during implantation. Polyurethane film weight loss in water as a function of time was studied to determine the polymer retention of the modified DHEA.

Oxidative mechanisms of poly(carbonate urethane) and poly(ether urethane) biodegradation: in vivo and in vitro correlations.

This study used an in vitro environment that simulated the microenvironment at the adherent cell-material interface to reproduce and accelerate the biodegradation of poly(ether urethane) (PEU) and poly(carbonate urethane) (PCU). Polyurethane films were treated in vitro for 24 days in 20% hydrogen peroxide/0.1 M cobalt chloride solution at 37 degrees C.

Poly(carbonate urethane) and poly(ether urethane) biodegradation: in vivo studies.

Several strategies have been used to increase the biostability of medical-grade polyurethanes while maintaining biocompatibility and mechanical properties. One approach is to chemically modify or replace the susceptible soft segment. Currently, poly(carbonate urethanes) (PCUs) are being evaluated as a replacement of poly(ether urethanes) (PEUs) in medical devices because of the increased oxidative stability of the polycarbonate soft segment.