Two dimensional materials are non-nanotoxic and biocompatible towards cyclotides: evidence from classical molecular dynamics simulations

Antifungal mechanism and application to phytopathogenic fungi after anaerobic fermentation of Gracilaria agar wastewater

Agar production is accompanied by a large amount of wastewater, which threatens the ecological environment and wastes biomass resources. The high-value utilization of biomass resources in wastewater is one of the key factors in wastewater treatment. We investigated the conversion process and antifungal mechanism of large molecule polysaccharides in wastewater into small molecule substances with antifungal activity through anaerobic fermentation. The results indicated that anaerobic fermentation of GAW achieved inhibition rates of 91.06 % and 88.94 % against Alternaria alternata and Alternaria spp. 16S rDNA sequencing and metabolomics revealed that dominant species such as Blautia, Agathobacter and Sphingomonas converted polysaccharide into phenolic acids like procyanidin C and columbidin. These substances disrupted the integrity of fungal cells, leading to their death. The preparation of composite antifungal agents using fermentation products effectively inhibited cherry tomato spoilage and toxin production. This study provided reliable technical support for the reuse of seaweed waste resources.

Screening 2D Materials for Their Nanotoxicity toward Nucleic Acids and Proteins: An In Silico Outlook

Since the discovery of graphene, two-dimensional (2D) materials have been anticipated to demonstrate enormous potential in bionanomedicine. Unfortunately, the majority of 2D materials induce nanotoxicity via disruption of the structure of biomolecules. Consequently, there has been an urge to synthesize and identify biocompatible 2D materials. Before the cytotoxicity of 2D nanomaterials is experimentally tested, computational studies can rapidly screen them. Additionally, computational analyses can provide invaluable insights into molecular-level interactions. Recently, various "in silico" techniques have identified these interactions and helped to develop a comprehensive understanding of nanotoxicity of 2D materials. In this article, we discuss the key recent advances in the application of computational methods for the screening of 2D materials for their nanotoxicity toward two important categories of abundant biomolecules, namely, nucleic acids and proteins. We believe the present article would help to develop newer computational protocols for the identification of novel biocompatible materials, thereby paving the way for next-generation biomedical and therapeutic applications based on 2D materials.

Computational Assessment of the Biocompatibility of Two-Dimensional g-C3N3 Toward Lipid Membranes

One of the most recent additions to the family of two-dimensional (2D) materials, graphitic C3N3 (g-C3N3), has been considered a viable contender for biomedical applications, although its potential toxicity remains elusive. We perform all-atom molecular dynamics simulations to decipher the interactions between model lipid membranes and g-C3N3 as a first step toward exploring the cytotoxicity induced at the nanoscale. We show that g-C3N3 can easily insert into the cellular membranes following a multistage mechanism consisting of simultaneous desolvation of the 2D material along with enrichment of nanomaterial-lipid interactions. Free energy calculations indicate that g-C3N3 is more stable in a membrane-bound state compared to an aqueous solution; however, the insertion of the material does not disturb the structural integrity of lipid membranes. After being inserted into a membrane, g-C3N3 is unlikely to be released into the cellular environment and is incapable of extracting lipid molecules from the membrane. The nature of interaction between the 2D material and membranes is found to be independent of the nanomaterial size. Also, the performance of g-C3N3 toward biomolecular delivery is shown to be significantly improved compared to the state-of-the-art 2D materials graphene and hexagonal boron nitride (h-BN). It is revealed that, the affinity of g-C3N3 toward lipid membranes is weaker compared to the nanotoxic graphene and h-BN, while being marginally higher than h2D-C2N, which in turn, increases the biocompatibility of the material, thereby brightening its future as a noncytotoxic material for forthcoming biomedical applications.

Villin headpiece unfolding upon binding to boridene mediated by the "anchoring-perturbation" mechanism

We employ molecular dynamics (MD) simulations to investigate the influence of boridene on the behavior of a protein model, HP35, with the aim of assessing the potential biotoxicity of boridene. Our MD results reveal that HP35 can undergo unfolding via an "anchoring-perturbation" mechanism upon adsorption onto the boridene surface. Specifically, the third helix of HP35 becomes tightly anchored to the boridene surface through strong electrostatic interactions between the abundant molybdenum atoms on the boridene surface and the oxygen atoms on the HP35 backbone. Meanwhile, the first helix, experiencing continuous perturbation from the surrounding water solution over an extended period, suffers from potential breakage of hydrogen bonds, ultimately resulting in its unfolding. Our findings not only propose, for the first time to our knowledge, the "anchoring-perturbation" mechanism as a guiding principle for protein unfolding but also reveal the potential toxicity of boridene on protein structures.

First-principles Calculations Reveal Frictional Advantage for C2 N/C6 N6 van der Waals Heterostructures

Friction at the atomic scale is determined for three different carbon nitride structures namely C2 N/C2 N, C6 N6 /C6 N6 and C6 N6 /C2 N employing ab-initio density functional theory (DFT). The sliding path along the lowest energy corrugations determines the static frictional forces. Both the homo-layer structures (C2 N/C2 N and C6 N6 /C6 N6 ) have higher corrugation energy and correspondingly higher static lateral forces with respect to the hetero-layer structure (C2 N/C6 N6 ). The corrugation energy for the C2 N/C6 N6 heterostructure (δ c o r r ${{\delta }_{corr}}$ =0.29 meV/atom) is one-order lower than C2 N/C2 N (δ c o r r ${{\delta }_{corr}}$ =2.08 meV/atom) and C6 N6 /C6 N6 (δ c o r r ${{\delta }_{corr}}$ =4.37 meV/atom). Such a significantly lower corrugation energy for the heterostructure arises due to the reduced fluctuation in the interfacial charge density along the sliding pathway. Moreover, the change in the interlayer distance along the sliding pathway is only 0.2 Å for the heterostructure while its 0.3 Å and 0.4 Å for C2 N and C6 N6 homo-layers respectively. The friction coefficients (FL /FN , FL =static lateral force; FN =normal force) decrease with increasing load for all the systems with the lowest value (0.04) for C2 N/C6 N6 at 2 GPa. The van der Waals heterostructures are, therefore, predicted to be highly efficient lubricant materials for reducing friction at the atomic scale.