Injectable in situ cross-linkable nanocomposites of biodegradable polymers and carbon nanostructures for bone tissue engineering

Abstract

This study investigates the effects of nanostructure size and surface area on the rheological properties of un-cross-linked poly(propylene fumarate) (PPF) nanocomposites and the mechanical properties of cross-linked nanocomposites as a function of the nanostructure loading. Three model carbon nanostructures were examined, C(60) fullerenes, ultra-short single-walled carbon nanotubes (US-tubes) and single-walled carbon nanotubes (SWNTs). Rheological measurements showed that C60 and US-tube un-cross-linked nanocomposites exhibited viscous-like characteristics with the complex viscosity independent of frequency for nanostructure concentrations up to 1 wt%. Compressive and flexural mechanical testing demonstrated significant mechanical reinforcement of US-tube and SWNT nanocomposites as compared to cross-linked polymer alone, with an up to twofold increase in the mechanical properties. Scanning electron microscopy examination of the fracture surface of cross-linked US-tube nanocomposite revealed lack of aggregation of US-tubes. Although sol fraction studies did not provide any evidence of additional cross-linking, due to the presence of US-tubes in the nanocomposites, transmission electron microscopy studies suggested the crystallization of PPF on the surface of US-tubes which can contribute to the mechanical reinforcement of the US-tube nanocomposites. These results demonstrate that the rheological properties of un-cross-linked nanocomposites depend mainly on the carbon nanostructure size, whereas the mechanical properties of the cross-linked nanocomposites are dependent on the carbon nanostructure surface area. The data also suggest that US-tube nanocomposites are suitable for further consideration as injectable scaffolds for bone tissue engineering applications.

Polymeric composites containing carbon nanotubes for bone tissue engineering

“…Since carbon nanotubes are not biodegradable, they behave like an inert matrix on which cells can proliferate and deposit new living material, which becomes functional, normal bone. The ultra-short single-walled carbon nanotubes (US-tube) nanocomposites have been shown to be suitable for consideration as injectable scaffolds for bone tissue engineering applications [24]. The use of carbon nanotubes (CNTs) as suitable scaffold materials for osteoblast proliferation and bone formation was determined with osteoblastic osteosarcoma cell line ROS 17/2.8.…”

Multimodal Ultrasound-Photoacoustic Imaging of Tissue Engineering Scaffolds and Blood Oxygen Saturation In and Around the Scaffolds

“…SWCNTs within the polymer matrix are seen bridging the microcracks within the scaffold and protruding out from the polymer matrix. 54,55 Furthermore, microCT image of the scaffold shows a porous structure with interconnecting pores. Analysis shows porosity of about 89% with 145 mm as the average size of the pores.…”

A Novel Nanoparticle-Enhanced Photoacoustic Stimulus for Bone Tissue Engineering

“…[34][35][36] Further, studies show that SWCNT-incorporated biodegradable polymer scaffolds are osteoconductive and allow noninvasive magnetic resonance imaging to evaluate nanotube release during the polymer degradation process and their biodistribution on release from the polymer matrix. 37,38 Our results indicate that PA stimulation of SWCNT-incorporated bone tissue engineering polymer scaffolds should assist the process of osteoinduction.…”