No abstract

Cellulose derivatives of carboxymethyl cellulose sodium salt (CMC), hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and enzymatically treated cellulose have been electrospun, and the microstructure of the resulting nanofibers has been analyzed by scanning electron microscopy (SEM). Before electrospinning, the solutions were characterized by viscometry and surface tension measurements, and the results were correlated with spinnability. Four different CMC derivatives, varying in molecular weight (M w ), degree of substitution (DS), and substitution pattern, have been electrospun in mixtures with poly(ethylene oxide) (PEO), and nanofibers of various characteristics have formed. The CMC-based nanostructures, i.e., the nonwoven sheet and individual nanofibers, proved to be independent of M w and DS but largely dependent on the substitution pattern. The nonwoven sheets varied in homogeneity, and beads appeared on the individual fibers. Depending on the chemical nature of the CMC, the extraction of PEO resulted in pure CMC nanostructures of varying appearance, indicating that the distribution of PEO and CMC in the nanofibers also varied. Two different HPMC derivatives, varying in DS, were electrospun into nanofibers. Homogeneous nonwoven sheets based on nanofibers of similar appearance are formed, independent of the substitution content of the HPMC sample. Preliminary fibers were obtained from enzymatically treated cellulose in a solvent system based on lithium chloride dissolved in dimethyl acetamide (LiCl : DMAc).

Artelon 1 (degradable poly(urethane urea) elastomer) was electrospun into scaffolds for tissue engineering. The diameter of the electrospun fibers, studied by scanning electron microscopy, ranged from 100 nm to a few lm, with an average diameter of 750 nm. The molar mass of the polymer had a major influence on the morphology of the scaffold. Furthermore, aging of the polymer solution caused changes in viscosity, as measured by stress sweeps between 13.5-942 Pa that affected the morphology. The electrospun Artelon mats exhibited about the same elongations to break, both exceeding 200%, measured by tensile tests. The degradation study showed similar degradation behavior in electrospun mats and solids. In vitro study showed that human fibroblasts not only adhere to the surface but also migrate, proliferate, and produce components of an extracellular matrix. These results strongly support the use of electrospun Artelon as a scaffold in tissue engineering.