Co-electrospun poly(lactide-co-glycolide), gelatin, and elastin blends for tissue engineering scaffolds

In this study, we describe composite scaffolds composed of synthetic and natural materials with physicochemical properties suitable for tissue engineering applications. Fibrous scaffolds were co-electrospun from a blend of a synthetic biodegradable polymer (poly(lactic-co-glycolic acid), PLGA, 10% solution) and two natural proteins, gelatin (denatured collagen, 8% solution) and (x-elastin (20% solution) at ratios of 3:1:2 and 2:2:2 (v/v/v). The resulting PLGA-gelatin-elastin (PGE) fibers were homogeneous in appearance with an average diameter of 380 80 mn, which was considerably smaller than fibers made under identical conditions from the starting materials (PLGA, 780 +/- 200 nm; gelatin, 447 +/- 1.23 nm; elastin, 1060 170 nm). Upon hydration, PGE fibers swelled to an average fiber diameter of 963 +/- 132 nm, but did not disintegrate. Importantly, PGE scaffolds were stable in an aqueous environment without crosslinking, and were more elastic than those made of pure elastin fibers. To investigate the cytocompatibility of PGE, we cultured H9c2 rat cardiac myoblasts and rat bone marrow stromal cells (BMSCs) on fibrous PGE scaffolds. We found that myoblasts grew equally as well or slightly better on the scaffolds than on tissue-culture plastic. Microscopic evaluation confirmed that myoblasts reached confluence on the scaffold surfaces while simultaneously growing into the scaffolds.

Biodegradable electrospun poly(L-lactide) fibers containing antibacterial silver nanoparticles

Biodegradable poly(L-lactide) (PLA) ultrafine fibers containing nanosilver particles were prepared via electrospinning. Morphology of the Ag/PLA fibers and distribution of the silver nanoparticles were characterized. The release of silver ions from the Ag/PLA fibers and their antibacterial activities were investigated. These fibers showed antibacterial activities (microorganism reduction) of 98.5% and 94.2% against Staphylococcus aureus and Escherichia coli, respectively, because of the presence of the silver nanoparticles.

Biodegradable electrospun fibers for drug delivery

The influences of surfactants and medical drugs on the diameter size and uniformity of electrospun poly(L-lactic acid) (PLLA) fibers were examined by adding various surfactants (cationic, anionic, and nonionic) and typical drugs into the PLLA solution. Significant diameter reduction and uniformity improvement were observed. It was shown that the drugs were capsulated inside of the fibers and the drug release in the presence of proteinase K followed nearly zero-order kinetics due to the degradation of the PLLA fibers. Such ultrafine fiber mats containing drugs may find clinical applications in the future.

Ultrafine fibers electrospun from biodegradable polymers

Biodegradable poly(I-lactide) (PLLA) and poly(e-caprolactone) (PCL) were electrospun into ultrafine fibers. The technological parameters influencing the spinning process and morphology of the fibers obtained were examined. These parameters included solvent composition, addition of certain organic salts, molecular weight and concentration of the polymers, capillary diameter, air ventilation, and pressure imposed on the surface of the solution as well as electrostatic field. By properly choosing and adjusting these parameters, submicron PLLA and PCL fibers with a narrow diameter distribution were prepared. Scanning electronic microscopy was used to observe the morphology and diameter size of the fibers.

Preparation and properties of conductive polyaniline/poly-omega-aminoundecanoyle fibers

Historically, polyaniline (PANI) had been considered an intractable material, but it can be dissolved in some solvents. Therefore, it could be processed into films or fibers. A process of preparing a blend of conductive fibers of PANI/poly-omega-aminoun-decanoyle (PA11) is described in this paper. PANI in the emeraldine base was blended with PA11 in concentrated sulfuric acid (c-H,SO,) to form a spinning dope solution. This solution was used to spin conductive PANI/PA11 fibers by wet-spinning technology. As-spun fibers were obtained by spinning the dopes into coagulation bath water or diluted acid and drawn fibers were obtained by drawing the as-spun fibers in warm drawing bath water. A scanning electron microscope was employed to study the effect of the acid concentration in the coagulation bath on the microstructure of as-spun fibers. The results showed that the coagulating rate of as-spun fibers was reduced and the size of pore shrank with an increase in the acid concentration in the coagulation bath. The weight fraction of PANI in the dope solution also had an influence on the microstructure of as-spun fibers. The microstructure of as-spun fibers had an influence on the drawing process and on the mechanical properties of the drawn fibers. Meanwhile, the electrically conductive property of the drawn fibers with different percentage of PANI was measured.

Morphology of conductive blend fibers of polyaniline and polyamide-11

Polyaniline (PANI), a member of the intrinsically conducting polymer (ICPs) family, was blended with polyamide-11 (polyco-aminoundecanoyle) in concentrated sulfuric acid. The above solution was used to spin conductive PANI/polyamide-11 fibers by wet-spinning technology. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were employed to study the two-phase morphology of the conductive PANI/polyamide-11 fibers. The micrographs of the cross-section, the axial section and the surface of the monofilament demonstrated that the two blend components were incompatible. The morphology of PANI in the fibers was of fibrillar form, which was valuable for producing conducting channels. The electrical conductivity of the fibers was from 10(-6) to 10(-1) S/cm with the different PANI fraction and the percolation threshold was about 5 wt.%. By comparing the two blend systems of PANI/Polyamide-11 fibers and carbon black filled poly(ethylene terephthalate) (PET) fibers, it was shown that the morphology of the conductive component had an influence on electrical conductivity, The former had higher conductivity and lower percolation threshold than the latter. (C) 2001 Elsevier Science B.V. All rights reserved.

Studies on biodegradable poly(hexano-6-lactone) fibers 1. Structure and properties of drawn poly(hexano-6-lactone) fibers

Using high molecular weight (M-n=80,000) Poly(hexano-6-lactone) (PCL'), tough and high tenacity PCL monofilaments with various draw ratios (undrawn to 9 times drawn) were prepared by melt-spinning. The relationship between microstructure and properties of the PCL fibers is described in this current IUPAC Technical Report. Analysis of microstructure of the drawn PCL fibers by wide-angle X-ray diffraction revealed typical c-axis orientation with an increase in crystallinity. It was also supported by sonic velocity measurements. The thermal, mechanical, and dynamic mechanical properties of the PCL fibers were affected significantly by draw ratio. DSC thermograms showed that the melting temperature and the enthalpy of fusion increased with draw ratio. The temperature dependence curves of dynamic viscoelasticity showed that the temperature at tan delta peak of alpha dispersion corresponding to the glass transition temperature shifted toward higher temperature and the peak value of tan delta decreased with draw ratio. The dynamic storage modulus and the sonic modulus increased with draw ratio. These results are due to the increase in crystallinity and molecular orientation with drawing, and are responsible for an increase in tensile tenacity as well as knot tenacity of the PCL fibers.