Dynamic Responsive Formation of Nanostructured Fibers in a Hydrogel Network: A Molecular Dynamics Study

Abstract

In an effort to study natural fiber formation, such as, e.g., spider silk, we present a model, which is capable of forming biomimetic fibrillar nanostructure from a hydrogel micellar network. The latter consists of interacting atomic groups which form cores of micelles, and of flexible chains forming the shells of the micelles. Micelles are connected in a compact network by linearly stretched chains. The structural elements of the network can be transformed during deformation from micellar into fibrillary type and their evolution is found to depend significantly on strain rate. Our model suggests a set of conditions suitable for the formation of nanostructured fibrillar network. It demonstrates that a fibrillar structure is only formed upon sufficiently fast stretching while, in contrast, the micellar gel structure is preserved, if the material is pulled slowly. We illustrate this key aspect by a minimalistic model of only four chains as part of the whole network, which provides a detailed view on the mechanism of fibril formation. We conclude that such a simplified structure has similar functionality and is probably responsible for the formation of nano-structured molecular fibrils in natural materials.

Micro and nano-scale compartments guide the structural transition of silk protein monomers into silk fibers

“…During the spinning process, the protein is transformed from a soluble, largely disordered random coil structure into solid fibers containing ordered intermolecular hydrogen-bonded, β-sheet-rich conformations 14,15 . Interestingly, the generation of the fiber from a soluble silk protein feedstock is based solely on the underlying structural (secondary structure) transformations, while the final fiber structure requires external processing (spinning in the duct) [16][17][18][19][20][21][22][23] . The final composition of the natural silkworm silk fiber comprises a silk fibroin core and a sericin (glycoprotein gum) coating.…”

“…The coating layer, which is added at the final stages of the spinning process, glues two fibroin fibers to form the final composite material 16 . The structural transformations involve the formation of multiple supramolecular phase states of silk fibroin, from soluble monomers, through microscale spherical assemblies, to liquid crystals and nanofibrils 4,[17][18][19][20][21] .…”

Polyvinyl alcohol: a high-resolution hydrogel resist for humidity-sensitive micro-/nanostructure

“…Due to porous cross-linked networks and hydrophilic functional groups, hydrogel materials present significant hygroscopicity and swelling behavior [1][2][3]. This dynamic deformability can be triggered with the stimuli from an aqueous medium, e.g.…”