Stimulus-Responsive, Gelatin-Containing Supramolecular Nanofibers as Switchable 3D Microenvironments for Cells

Abstract

Polymer- and/or protein-based nanofibers that promote stable cell adhesion have drawn increasing attention as well-defined models of the extracellular matrix. In this study, we fabricated two classes of stimulus-responsive fibers containing gelatin and supramolecular crosslinks to emulate the dynamic cellular microenvironment in vivo. Gelatin enabled cells to adhere without additional surface functionalization, while supramolecular crosslinks allowed for the reversible switching of the Young’s modulus through changes in the concentration of guest molecules in culture media. The first class of nanofibers was prepared by coupling the host–guest inclusion complex to gelatin before electrospinning (pre-conjugation), while the second class of nanofibers was fabricated by coupling gelatin to polyacrylamide functionalized with host or guest moieties, followed by conjugation in the electrospinning solution (post-conjugation). In situ AFM nano-indentation demonstrated the reversible switching of the Young’s modulus between 2–3 kPa and 0.2–0.3 kPa under physiological conditions by adding/removing soluble guest molecules. As the concentration of additives does not affect cell viability, the supramolecular fibers established in this study are a promising candidate for various biomedical applications, such as standardized three-dimensional culture matrices for somatic cells and the regulation of stem cell differentiation.

Discreteness of cell–surface contacts affects spatio-temporal dynamics, adhesion, and proliferation of mouse embryonic stem cells

“…Prior to the indentation, we scanned to obtain the topographic profile near one single fiber and ensured that the probe indented the middle point. In this study, we used a particle-attached cantilever, because the indentation of nanofibers with a sharp, pyramidal tip resulted in an overestimation of Young's modulus with a broader distribution (Supplementary Figure S4), as reported previously [38] Although the exact origin of the broad distribution was not conclusively identified, each fiber likely contained both densely and loosely crosslinked regions. A representative force curve (symbols) is shown in Figure 1C.…”

“…The thickness and width of the fibers in the aqueous medium were 400-900 nm (thickness) and 300-800 nm (width), suggesting that electrospinning and successive crosslinking reproducibly resulted in uniform fibers that were stable in the aqueous buffer. Note that the width of GNFs, W, was determined from the full width at half maximum (FWHM) of the AFM image by taking the radius of the AFM cantilever, r = 20 nm, into account [38,39],…”

Cell Shape and Forces in Elastic and Structured Environments: From Single Cells to Organoids

“…To model dynamic changes in fiber elasticity accompanied with ECM remodeling, Hayashi and colleagues developed a gelatin‐based nanofiber system that can modulate the Young's modulus by using reversible host‐guest crosslinkers. [ 144 ] Methods to fabricate 2D meshes can also be used to manufacture 3D structures, for example, by combining electrospinning with 3D printing [ 145 ] or by placing the syringe on a freely moveable platform. [ 146 ] 3D scaffolds produced with electrospinning are used to increase cell growth and viability for tissue engineering applications.…”

Design and Application of Hybrid Polymer-Protein Systems in Cancer Therapy

“…Kentaro et al fabricated two types of stimulus-responsive gelatincontaining supramolecular nanofibers that can be utilized as well-defined, switchable 3D microenvironments for cells. The first type of nanofibers was prepared by coupling the host-guest inclusion complex to gelatin before electrospinning, while the second type of nanofibers was fabricated by coupling gelatin to polyacrylamide functionalized with the host (βCD) and guest (Ad) moieties followed by conjugation in the electrospinning solution (Figure 4) [67]. The stimulus responsive was achieved by elasticity switching under physiological conditions by adding/removing soluble guest molecules.…”

“…Table 1 shows some examples of different types of polymers. [64] Gelatin-containing supramolecular nanofibers [67] These are the main types of polymers above-mentioned. Table 1 shows some examples of different types of polymers.…”