Characterization of dielectrophoresis-aligned nanofibrous silk fibroin–chitosan scaffold and its interactions with endothelial cells for tissue engineering applications

Abstract

Aligned three-dimensional nanofibrous silk fibroin-chitosan (eSFCS) scaffolds were fabricated using dielectrophoresis (DEP) by investigating the effects of alternating current frequency, the presence of ions, SF:CS ratio, and post-DEP freezing temperature. Scaffolds were characterized with polarized light microscopy (PLM) to analyze SF polymer chain alignment, atomic force microscopy (AFM) to measure the apparent elastic modulus, and scanning electron microscopy and AFM to analyze scaffold topography. The interaction of human umbilical vein endothelial cells (HUVECs) with eSFCS scaffolds was assessed using immunostaining to assess cell patterning and AFM to measure the apparent elastic modulus of the cells. The eSFCS (50:50) samples prepared at 10 MHz with NaCl had the highest percentage of aligned area as compared to other conditions. As DEP frequency increased from 100 kHz to 10 MHz fibril sizes decreased significantly. eSFCS (50:50) scaffolds fabricated at 10 MHz in the presence of 5 mM NaCl had a fibril size of 77.96 ± 4.69 nm and an apparent elastic modulus of 39.9 ± 22.4 kPa. HUVECs on eSFCS scaffolds formed aligned and branched capillary-like vascular structures. The elastic modulus of HUVEC cultured on eSFCS was 6.36 ± 2.37 kPa. DEP is a potential tool for fabrication of SFCS scaffolds with aligned nanofibrous structures that can guide vasculature in tissue engineering and repair.

Nanomaterials, Scaffolds, and Skin Tissue Regeneration

“…These mats were useful in wound healing since they promoted attachment and proliferation of murine fi broblasts [ 25 ]. The same type of mats but with aligned nanofi brous structures were recommended for guiding vessels in tissue engineering and repair applications [ 26 ]. When composite nanofi bers were prepared from carboxyethyl chitosan-fi broin, to favor formation of polyelectrolyte complexes, the electrospinning properties of the resulting aqueous solutions were very poor.…”

Incorporation of aligned PCL–PEG nanofibers into porous chitosan scaffolds improved the orientation of collagen fibers in regenerated periodontium

“…Therefore, it may be hypothesized that a scaffold which provides a more precise topographic guidance for each individual cell could be better utilized in the functionally oriented regeneration of periodontium. Meanwhile, it is widely understood that aligned nanostructure can induce aligned morphologies in most cell types through contact guidance [20][21][22][23], which are especially important in designing tissue engineering environments that mimic aligned tissues such as ligament and tendon. In addition, aligned cell morphology generally correspond to changes in cytoskeletal arrangement that can further trigger variations in other cell behaviors such as elongation, proliferation, migration, ECM production, and differentiation into cellular phenotypes that exhibit an elongated morphology [24,25].…”

Simulation of ECM with silk and chitosan nanocomposite materials

“…1–4 SF has a complex hierarchical microstructure and different compositions which depend on the source and processing. These features mean that it is feasible for silk-based materials to form various material types and shapes with tunable performance, (e.g., mechanical properties, degradation lifetime in vivo ), thus satisfying the prerequisites for the regeneration of different tissues.…”

“…15–18 Because of its superior and tunable mechanical properties, controllable degradation and relatively low inflammatory response, SF has been used to replace collagen, and blended with chitosan (CS), a biocompatible natural biomaterial with some similarities with glycosaminoglycan, to mimic the ECM composition. 4 Although many previous studies suggested better biocompatibility with silk rather than CS materials, 19,20 better biocompatibility and cell growth in vitro and in vivo than pure silk and CS were achieved using SF-CS composite scaffolds, by tuning the ratio of SF and CS, suggesting that they have promising applications as matrices. 21–23 …”

“…4 Therefore, it is reasonable to assume that simultaneously modifying the composition and microstructure in the SF-CS system, ECM-like niches will be generated. Although several studies have confirmed the feasibility, 7, 36–40 the challenge remains to prepare SF-CS scaffolds with multiple ECM-mimetic cues, in part because of the difficulties in forming three-dimensional nanofibrous structures with SF and CS.…”