Structural characterization of electrospun micro/nanofibrous scaffolds by liquid extrusion porosimetry: A comparison with other techniques

Poly(ε-caprolactone) micro/nanofibrous scaffolds obtained by electrospinning technique from polymer solutions were characterized in terms of fiber diameter (as measured by scanning electron microscopy-SEM), pore size and its distribution (as measured by liquid extrusion porosimetry), and porosity (as determined by gravimetric measurement, liquid intrusion method, SEM image analysis and liquid extrusion porosimetry — LEP). Nonwoven micro/nanofibrous scaffolds were formed by uniform bead-free fibers with mean diameters in the range of 0.4 to 7 μm. The results indicate that pore size and pore size distribution are strongly associated to fiber diameter. Porosity results were analyzed taking into account the accuracy and limitations of each method. LEP resulted as the most suitable technique for measuring through-pore diameter and porosity. In order to compare empirical data of pore size from LEP, a theoretical multiplanar model for stochastic fiber networks was applied. The results predicted by the model were in good agreement with the experimental data provided by LEP for mean diameters higher than 1 μm. The present study shows the potential of LEP as a valuable instrumental technique for characterizing the porous structure of electrospun fibrous scaffolds.