Effect of Electrospun Fiber Mat Thickness and Support Method on Cell Morphology

Abstract

Electrospun fiber mats (EFMs) are highly versatile biomaterials used in a myriad of biomedical applications. Whereas some facets of EFMs are well studied and can be highly tuned (e.g., pore size, fiber diameter, etc.), other features are under characterized. For example, although substrate mechanics have been explored by several groups, most studies rely on Young’s modulus alone as a characterization variable. The influence of fiber mat thickness and the effect of supports are variables that are often not considered when evaluating cell-mechanical response. To assay the role of these features in EFM scaffold design and to improve understanding of scaffold mechanical properties, we designed EFM scaffolds with varying thickness (50–200 µm) and supporting methodologies. EFM scaffolds were comprised of polycaprolactone and were either electrospun directly onto a support, suspended across an annulus (3 or 10 mm inner diameter), or “tension-released” and then suspended across an annulus. Then, single cell spreading (i.e., Feret diameter) was measured in the presence of these different features. Cells were sensitive to EFM thickness and suspended gap diameter. Overall, cell spreading was greatest for 50 µm thick EFMs suspended over a 3 mm gap, which was the smallest thickness and gap investigated. These results are counterintuitive to conventional understanding in mechanobiology, which suggests that stiffer materials, such as thicker, supported EFMs, should elicit greater cell polarization. Additional experiments with 50 µm thick EFMs on polystyrene and polydimethylsiloxane (PDMS) supports demonstrated that cells can “feel” the support underlying the EFM if it is rigid, similar to previous results in hydrogels. These results also suggest that EFM curvature may play a role in cell response, separate from Young’s modulus, possibly because of internal tension generated. These parameters are not often considered in EFM design and could improve scaffold performance and ultimately patient outcomes.

Electrospun Poly(ethylene Terephthalate)/Silk Fibroin Composite for Filtration Application

“…Young’s modulus (E) of the electrospun pure r-PET, r-PSF mats, containing different SF amounts is shown in Figure 4 . Young´s modulus is attributed to the strength of the interaction between fibers within the material that does not significantly depend on its thickness [ 89 ]. It was observed that increasing SF content in r-PSF samples increases the E. Similar behavior was reported by Gobin et al [ 90 ], which attributed these changes to more numerous interactions of SF, with presented chitosan in the form of strong molecular hydrogen bonding.…”

“…The published results, as well as opinions on this topic, seem clear. Silk is not considered a polymer with antibacterial activity [ 89 , 103 ]. On the other side, there have been published studies that have shown that the antibacterial activity of polymers in different forms is influenced by many factors related to its preparation, processing [ 104 ], possibly mixing with other polymers [ 50 , 105 ] or active molecules, drugs, and biocides [ 106 , 107 , 108 ].…”

MicroRNA-mRNA Interactions at Low Levels of Compressive Solid Stress Implicate mir-548 in Increased Glioblastoma Cell Motility

“…GBM cells display high sensitivity to their mechanical microenvironment. For example, we have shown that U87 GBM cells grown on 50 µm thick electrospun fiber mats 35 or patient-derived GBM cells cultured in <25 µm thick hydrogels 36 are sensitive to the mechanics of their underlying supports. GBM cells also increase migration in response to low linear flow rates (<1 µm/s) 37 .…”

Effects of Fiber Density and Strain Rate on the Mechanical Properties of Electrospun Polycaprolactone Nanofiber Mats

“…Packing density of an electrospun material has been shown to play a large role on the properties of electrospun materials in comparison to mat thickness (Leung et al, 2010 ). One study observed the effects of electrospun polycaprolactone fiber mat thickness on indentation modulus, and found that an increase in mat thickness resulted in an increase in indentation modulus in supported mats (Calhoun et al, 2019 ). Additionally, a 1.5x increase in Young's modulus was observed in unsupported polycaprolactone mats when comparing a 50 um thick mat to a 200 um thick mat.…”