The construction of multilength scaled hierarchical nanostructures from diverse natural components is critical in the progress toward all-natural nanocomposites with structural robustness and versatile added functionalities. Here, we report a spontaneous formation of peculiar "shish kebab" nanostructures with the periodic arrangement of silk fibroin domains along straight segments of cellulose nanofibers. We suggest that the formation of these shish kebab nanostructures is facilitated by the preferential organization of heterogeneous (β-sheets and amorphous silk) domains along the cellulose nanofiber driven by modulated axial distribution of crystalline planes, hydrogen bonding, and hydrophobic interactions as suggested by all-atom molecular dynamic simulations. Such shish kebab nanostructures enable the ultrathin membrane to possess open, transparent, mechanically robust interlocked networks with high mechanical performance with up to 30 GPa in stiffness and 260 MPa in strength. These nanoporous robust membranes allow for the extremely high water flux, up to 3.5 × 10 L h m bar combined with high rejection rate for various organic molecules, capability of capturing heavy metal ions and their further reduction into metal nanoparticles for added SERS detection capability and catalytic functionalities.
Silk fibroin adsorption at the heterogeneous hydrophobic–hydrophilic surface of graphene oxide (GO) with different degrees of oxidation is addressed experimentally and theoretically. Samples are prepared using various spin‐assisted deposition conditions relevant to assembly of laminated nanocomposites from graphene‐based components, and compared with silicon dioxide (SiO2) as a benchmark substrate. Secondary structure of silk backbones changes as a function of silk fibroin concentration, substrate chemical composition, and deposition dynamics are assessed and compared with molecular dynamic simulations. It is observed that protofibrils form at low concentrations while variance in the deposition speed has little effect on silk secondary structure and morphology. However, balance of nonbonded interactions between electrostatic and van der Waals contributions can lead to silk secondary structure retention on the GO surface. Molecular dynamics simulations of silk fibroin at different surfaces show that strong van der Waals interactions play a pivotal role in losing and disrupting secondary structure on graphene and SiO2 surfaces. Fine tuning silk fibroin structure on heterogeneous graphene‐based surfaces paves the way toward development of biomolecular reinforcement for biopolymer–graphene laminated nanocomposites.
Constructing advanced functional nanomaterials with pre-designed organized morphologies from low-dimension synthetic and biological components is challenging. Herein, we report an efficient and universal amphiphilicity-driven assembly strategy to construct "hairy" flexible hybrid nanosheets with a 1D cellulose nanofibers (CNFs) net conformally wrapped around 2D graphene oxide (GO) monolayers. This interface-driven bio-synthetic assembly is facilitated by tailoring the surface chemistry of flexible GO sheets, resulting in individual sheets tightly surrounded by dense conformal nanocellulose network. The mechanical stability of the products far exceeds the compressive instability limits of both individual components. Additionally, the CNF network significantly enhances the wetting ability of initial hydrophobic reduced GO nanosheets, allowing fast water transport combined with high filtration efficiency.
Candida antarctica lipase B (CALB) is an efficient biocatalyst for hydrolysis, esterification, and polymerization reactions. In order to understand how to control enzyme activity and stability we performed a combined experimental and molecular dynamics simulation study of CALB in organic solvents and ionic liquids (ILs). Our results demonstrate that the conformational changes of the active site cavity are directly related to enzyme activity and decrease in the following order: [Bmim][TfO] > tert-butanol > [Bmim][Cl]. The entrance to the cavity is modulated by two isoleucines, ILE-189 and ILE-285, one of which is located on the α-10 helix. The α-10 helix can substantially change its conformation due to specific interactions with solvent molecules. This change is acutely evident in [Bmim][Cl] where interactions of LYS-290 with chlorine anions caused a conformational switch between α-helix and turn. Disruption of the α-10 helix structure results in a narrow cavity entrance and, thus, reduced the activity of CALB in [Bmim][Cl]. Finally, our results show that the electrostatic energy between solvents in this study and CALB is correlated with the structural changes leading to differences in enzyme activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.