Electrospinning: a fascinating fiber fabrication technique.

Electrospinning is a highly versatile method to process solutions or melts, mainly of polymers, into continuous fibers with diameters ranging from a few micrometers to a few nanometers. This technique is applicable to virtually every soluble or fusible polymer. The polymers can be chemically modified and can also be tailored with additives ranging from simple carbon-black particles to complex species such as enzymes, viruses, and bacteria. Electrospinning appears to be straightforward, but is a rather intricate process that depends on a multitude of molecular, process, and technical parameters. The method provides access to entirely new materials, which may have complex chemical structures. Electrospinning is not only a focus of intense academic investigation; the technique is already being applied in many technological areas.

Electrospinning: A Fascinating Method for the Preparation of Ultrathin Fibers

The return of a forgotten polymer—Polycaprolactone in the 21st century

Electrospinning: Applications in drug delivery and tissue engineering

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the con- centration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immu- nologically tolerated "tissue" for wound hea ing and as a model for studying fibroblast function are discussed.

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative

Preparation and characterization of highly porous, biodegradable polyurethane scaffolds for soft tissue applications

Design and analysis of tissue engineering scaffolds that mimic soft tissue mechanical anisotropy.

Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix.

The engineering of tissue for mechanically demanding applications in the cardiovascular system is likely to require mechanical conditioning of cell-scaffold constructs prior to their implantation. Scaffold properties amenable to such an application include high elasticity and strength coupled with controllable biodegradative and cell-adhesive properties. To fulfill such design criteria, we have synthesized a family of poly(ester-urethane)ureas (PEUUs) from polycaprolactone and 1,4-diisocyanatobutane. Lysine ethyl ester (Lys) or putrescine was used as chain extenders. To encourage cell adhesion, PEUUs were surface modified with radio-frequency glow discharge followed by coupling of Arg-Gly-Asp-Ser (RGDS). The synthesized PEUUs were highly flexible, with breaking strains of 660-895% and tensile strengths from 9.2-29 MPa. Incubation in aqueous buffer for 8 weeks resulted in mass loss, from >50% (Lys chain extender) to 10% (putrescine chain extender). Human endothelial cells cultured for 4 days with medium containing the degradation products from PEUUs with either the Lys or putrescine chain extender showed no toxic effects. Cell adhesion was 85% of that measured on tissue-culture polystyrene for unmodified PEUU surfaces (p 160% (p < 0.001) of polystyrene on RGDS-modified PEUUs. These biodegradable PEUUs demonstrate potential for future application as cell scaffolds in cardiovascular tissue-engineering or other soft-tissue applications.

Jianjun Guan

Papers

Preparation and characterization of highly porous, biodegradable polyurethane scaffolds for soft tissue applications

Design and analysis of tissue engineering scaffolds that mimic soft tissue mechanical anisotropy.

Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix.

Synthesis, characterization, and cytocompatibility of elastomeric, biodegradable poly(ester-urethane)ureas based on poly(caprolactone) and putrescine

A bilayered elastomeric scaffold for tissue engineering of small diameter vascular grafts.