A series of polylactic acid (PLA) nonwovens were prepared by the melt blowing process using micro and nano dies. The nonwovens were characterized for structural, thermal, and mechanical properties. These properties varied with the type of die, airflow, and die to collector distance (DCD). The mean pore size for PLA microfiber ranged between 1.82 and 10.48 micrometers, and nanofiber nonwovens ranged between 452 and 818 nanometers. The tensile modulus and strength of PLA nonwovens increased with airflow at a given DCD, but decreased with increased DCD for a given airflow. Thermograms from calorimetry showed microfiber mats had a larger composition of beta-form crystals than the nanofiber mats. The results showed that a wide range of nonwovens can easily be generated with properties tailored to the specific application.
Polylactic acid (PLA) nanofiber nonwovens have recently come under more vigorous investigation for their use as tissue engineering scaffolds owing to its ability to mimic the physical properties of naturally occurring human extracellular matrix in a variety of host tissues. Currently, the majority of available research on PLA nanowebs has focused on their creation through electrospinning. The goal of this study was to evaluate meltblown nonwoven webs made of nanodiameter PLA fibers for their application as a tissue engineering scaffold. Meltblown PLA fabrics were produced with a variety of different crystallinities, tensile moduli, and pore diameters. One fabric with mechanical properties similar to human dermis was selected as a scaffold to study attachment, proliferation, and migration of human dermal fibroblasts over 1, 3, 7, and 14 days without the use of additional cell adhesion molecules. The 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide assay showed good proliferation from day 1 to 3 (P = 0.026) and up to 7 days of culture (P = 0.005) but without increase from day 7 to 14. Electron microscopy demonstrated adequate cellular attachment and surface migration at 1, 3, 7, and 14 days. Finally, confocal microscopy was used to investigate cellular penetration into the scaffolds. The investigation found that cells were able to penetrate fully through the thickness of the scaffold. The successes of this initial experiment are promising and confirm that meltblown nanofiber nonwovens are a viable avenue for tissue engineering scaffolds. Hopefully, these conclusions will open the door for others to pursue research in this exciting field.
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