Measuring the Poisson’s Ratio of Fibronectin Using Engineered Nanofibers

Abstract

The extracellular matrix (ECM) is a fibrillar protein-based network, the physical and chemical properties of which can influence a multitude of cellular processes. Despite having an important role in cell and tissue signaling, a complete chemo-mechanical characterization of ECM proteins such as fibronectin (FN) is lacking. In this study, we engineered monodisperse FN nanofibers using a surface-initiated assembly technique in order to provide new insight into the elastic behavior of this material over large deformations. FN nanofibers were patterned on surfaces in a pre-stressed state and when released from the surface underwent rapid contraction. We found that the FN nanofibers underwent 3.3-fold and 9-fold changes in length and width, respectively, and that the nanofiber volume was conserved. Volume was also conserved following uniaxial extension of the FN nanofibers of ~2-fold relative to the patterned state. This data suggests that the FN networks we engineered formed an incompressible material with a Poisson’s ratio of ~0.5. While the Poisson’s ratio of cells and other biological materials are widely estimated as 0.5, our experimental results demonstrate that for FN networks this is a reasonable approximation.

Fabrication of a Tailored, Hybrid Extracellular Matrix Composite

“…When pFN was deposited on the FN micropattern, a FRET efficiency of 0.54 ± 0.09 was measured, which is thought to be that the pFNs were partially opened by the extended FN molecules mechanically by µCP. [ 44 ] However, when pFNs are deposited on cell‐induced FNfs (as shown in Figure 1g), the FRET efficiency drops sharply to 0.17 ± 0.01 (** p < 0.001). These results show that pFN molecules induced by cFN fibrils were denatured into a form similar to cell‐derived fibrils, and as a result, the hybrid FN network was implemented with a molecular structure similar to that of FN constituting the native ECM of cells.…”

“…The increase of donor intensity after acceptor photobleaching indicated higher FRET efficiency. When pFN was deposited on the FN micropattern, a FRET efficiency of 0.54 ± 0.09 was measured, which is thought to be that the pFNs were partially opened by the extended FN molecules mechanically by μCP [44]. However, when pFNs are deposited on cell-induced FNfs (as shown in Figure1g), the FRET efficiency drops sharply to 0.17 ± 0.01 (**p < 0.001).…”

Mechanotransduction through adhesion molecules: Emerging roles in regulating the stem cell niche

“…Mechanically regulated interaction between FN and collagen drives the deposition of collagen over FN matrices at the wound bed, which protects the FN matrix from the microenvironmental forces ( Patten and Wang, 2021 ). Although it is known that the interaction between FN and collagen is mechanically regulated, the mechanism for the unfolding of the FN fibrils is less well understood ( Gee et al, 2008 ; Ponmurugan and Vemparala, 2012 ; Früh et al, 2015 ; Szymanski et al, 2017a ; Szymanski et al, 2017b ).…”

Mechanical regulation of tissues that reproduces wrinkle patterns of gastrointestinal tracts

“…The thickness ratio between the substrate and the epithelial layer H/h = 10 is set referring to the general histology of the gastrointestinal tracts. We also use the Poisson's ratios relatively low ν xy = 0.2 for the epithelial layer and relatively incompressible ν m = 0.45 for the substrate based on the experimental studies [32,33]. Lastly, the time increment Δt/τ = 50, with τ = η/ C11 a time scale, is selected to ensure numerical stability.…”