The crystalline morphologies of electrospun random and aligned poly(ε-caprolactone) (PCL) nanofibers, obtained by a plate collector and a two-parallel-conductive-plate collector, respectively, were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), two-dimensional wide-angle X-ray diffraction (2D WAXD), and polarized Fourier transform infrared (polarized FTIR) spectroscopy. The fiber orientations and diameters of the aligned nanofibers were found to depend on the gap size of the collector, which was much larger than those previously reported, thus easing and improving sample handling and characterization. The degree of crystallinity of the aligned nanofibers was higher than that of their randomly aligned counterparts. The crystallites in the nanofibers were highly oriented along the nanofiber axis, as were the molecular chains. The estimated crystallite size suggested that a single nanofiber was composed of dozens of nanofibrils and that each nanofibril was further composed of crystallites along the nanofiber axis with an amorphous region of extended PCL molecular chains between neighboring crystallites.

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Particulate matter (PM) pollution poses a significant threat to human health. Air filtration is an effective way to eliminate PM pollution. In this study, nanofibers of polycarbonate (PC), a polymer that has been widely used in engineering due to its favorable properties, were obtained using the electrospinning technique and applied to filter PM. The results revealed that the PM is either intercepted by the nanofibers or captured on the surfaces of the fibers by inertial impaction or diffusion. The filtration efficiency of this PC membrane was higher than those of both polyvinyl alcohol (PVA) and polystyrene (PS) membranes with similar fibrous morphologies, suggesting that polarity is the most influential factor shaping the interaction of particles and fiber surfaces. Moreover, fiber diameter and membrane thickness also influence filtration efficiency by varying the odds that particles and fiber surfaces will meet.

Regulating cell migration dynamics is of significance in tissue engineering and regenerative medicine. A 3D scaffold was created to provide various topographies based on a poly­(ε-caprolactone) (PCL) self-induced nanohybrid shish-kebab structure, which consisted of aligned PCL nanofibers and spaced PCL crystal lamellae grown on the fibers. Electrospinning was applied followed by self-induced crystallization. The results resembled natural collagen fibrils in an extracellular matrix. This variable microstructure enabled control of cell adhesion and migration. The kebab size was controlled by initial PCL concentrations. The geometry of cells seeded on the fibers was less elongated, but the adhesion was more polarized with a higher nuclear shape index and faster migration speed. These results could aid in rapid endothelialization in tissue engineering.

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