Single-walled carbon nanotube/ultrahigh-molecular-weight polyethylene composites with percolation at low nanotube contents

UHMWPE-MWCNT-nHA based hybrid trilayer nanobiocomposite: Processing approach, physical properties, stem/bone cell functionality, and blood compatibility

The development of polymeric nanocomposites for biomedical applications remains a major challenge in terms of tailored addition of nanoparticles to realize the simultaneous enhancement of fracture resistance and cell/blood compatibility. To address this, the present work has been planned to determine whether small addition of surface functionalized multiwalled-carbon-nanotube, MWCNT (<1.5 wt%) and egg-shell derived nanosized hydroxyapatite, nHA (<10 wt%) to ultrahigh-molecular-weight-polyethylene (UHMWPE) can significantly improve the physical properties as well as biocompatibility. The difference in mouse osteoblast and human mesenchymal stem cell (hMSc) proliferation has been validated using both the monolithic composite and a trilayered composite with two different UHMWPE nanocomposites on either face with pure polymer at the middle. The combination of rheology and micro-CT with fractography reveals the homogeneous dispersion of nanofillers, leading to mechanical property enhancement. The quantitative analysis of cell viability and cell spreading by immunocytochemistry method, using vinculin and vimentin expression, establish significant cytocompatibility with hMSc and osteoblast cells onto the trilayer hybrid nanobiocomposite substrates. The hemocompatibility of the investigated composites under the controlled flow of rabbit blood in a microfluidic device reveals the signature of reduced thrombogenesis with reduction of platelet activation on UHMWPE nanocomposite w.r.t. unreinforced UHMWPE. An attempt has been made to discuss the blood compatibility results in the backdrop of the bovine serum albumin adsorption kinetics. Summarizing, the present study establishes that the twin requirement of mechanical property and cyto/hemo-compatibility can be potentially realized in developing trilayer composites in UHMWPE-nHA-MWCNT system.

Geobacter sulfurreducenspili support ohmic electronic conduction in aqueous solution

Solid-state and electrochemical observations of ohmic conductivity in purifiedGeobacter sulfurreducenspili.

Electrical and dielectric behaviors of dry-mixed CNT/UHMWPE nanocomposites

Carbon nanotube (CNT)/ultrahigh-molecular weight polyethylene (UHMWPE) nanocomposite with an electrical percolation threshold of only 0.1 wt% was prepared by simple dry mixing followed by compression molding. The nanocomposite microstructure, direct current and alternating current (AC) electrical conductivities, conduction mechanisms, and dielectric properties in the 101–105 Hz frequency range have been investigated. Due to the localization of the nanofiller at the surface of UHMWPE powder particles, a segregated microstructure within the polymer matrix was created. Nanocomposites filled with 0.125–0.5 wt% CNT were found to follow the typical universal dynamic response behavior, and the characteristic frequency was found to increase with the increase in CNT concentration. At CNT concentration ≥ 0.5 wt%, the AC conductivity was found to be frequency independent over the entire frequency range studied.