A nanobursa mesh: a graded electrospun nanofiber mesh with metal nanoparticles on carbon nanotubes.

A new type of material, a "nanobursa" mesh (from "bursa" meaning "sac or pouch"), is introduced. This material consists of sequential layers of porous polymeric nanofibers encapsulating carbon nanotubes, which are functionalized with different metal nanoparticles in each layer. The nanobursa mesh is fabricated via a novel combination of twin-screw extrusion and electrospinning. Use of this hybrid process at industrially-relevant rates is demonstrated by producing a nanobursa mesh with graded layers of Pd, Co, Ag, and Pt nanoparticles. The potential use of the fabricated nanobursa mesh is illustrated by modeling of catalytic hydrocarbon oxidation.

Surface patterning of poly(L-lactide) upon melt processing: in vitro culturing of fibroblasts and osteoblasts on surfaces ranging from highly crystalline with spherulitic protrusions to amorphous with nanoscale indentations.

Large-scale and reproducible manufacturing of scaffolds for tissue engineering applications will necessitate the adoption of methods relying on the processing of the biodegradable polymers directly from the melt. Such solventless processing will give rise to bulk and surface properties that will differ significantly from those generated upon processing from solution-based methods. Thus, detailed understanding of the microstructures that are developed during melt processing and the resulting surface/cell interactions is needed. Here, surfaces of melt-cast poly(L-lactide) (PLLA) were patterned to furnish membrane samples with a wide range of crystallinity and significant differences in surface topographies, ranging from highly crystalline (60%) with spherulitic protrusions at the surface to amorphous with nanoscale indentations. The PLLA membranes were used to culture in vitro mouse 3T3-Swiss albino fibroblast cells and osteoblast-like MC3T3-E1 cells. The growth rates of 3T3 fibroblasts were significantly lower on highly crystalline PLLA membranes with spherulitic protrusions in comparison to crystalline PLLA without spherulitic protrusions and amorphous surfaces with 5-10-nm-deep indentations. However, the differences in the growth rates of osteoblast-like cells cultured on the PLLA membranes with different surface patterns were only marginally different.

Biocomposites of nanohydroxyapatite with collagen and poly(vinyl alcohol).

Biocomposites of hydroxyapatite, HAp, in conjunction with various binders including poly(vinyl alcohol), PVA, and collagen have the potential of serving in various tissue engineering applications, such as in bone repair and reconstruction tasks, especially if the nanoparticles of hydroxyapatite are used. Here, hydroxyapatite nanoparticles (n-HAp) were synthesized at the ultimate size range of 10-50 nm and then incorporated into PVA or in situ synthesized in collagen/PVA. The biocomposites of HAp with PVA exhibited relatively high elasticity (as revealed by the linear viscoelastic material functions, characterized upon small-amplitude oscillatory shear) especially upon cryogenic treatment. The incorporation of the collagen into the PVA/HAp biocomposite provided internal porosity to the biocomposite with the pores in the 50-100 nm range for collagen/HAp and 50-500 nm for the collagen/HAp/PVA.