Tuning electrospinning parameters for production of 3D-fiber-fleeces with increased porosity for soft tissue engineering applications.

Degrapol® and PLGA electrospun fiber fleeces were characterized with regard to fiber diameter, alignment, mechanical properties as well as scaffold porosity. The study showed that electrospinning parameters affect fiber diameter and alignment in an inverse relation: fiber diameter was increased with increased flow rate, with decrease in working distance and collector velocity, whereas fiber alignment increased with the working distance and collector velocity but decreased with increased flow rate. When Degrapol® or PLGA-polymers were co-spun with increasing ratios of a water-soluble polymer that was subsequently removed; fibrous scaffolds with increased porosities were obtained. Mechanical properties correlated with fiber alignment rather than fiber diameter as aligned fiber scaffolds demonstrated strong mechanical anisotropy. For co-spun fibers the Young's modulus correlated inversely with the amount of co-spun polymer. Cell proliferation was independent of the porosity of the scaffold, but different between the two polymers. Furthermore, fibrous scaffolds with different porosities were analyzed for cell infiltration suggesting that cell infiltration was enhanced with increased porosity and increasing time. These experiments indicate that 3D-fiber fleeces can be produced with controlled properties, being prerequisites for successful scaffolds in tissue engineering applications.