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.

Remarkable enhancement of the adsorption and diffusion performance of alkali ions in two-dimensional (2D) transition metal oxide monolayers via Ru-doping

Transition metal oxides (TMO) are the preferred materials for metal ion battery cathodes because of their high redox potentials and good metal-ion intercalation capacity, which serve as an outstanding replacement for layered sulphide. In this work, using first-principles calculations based on Density functional theory approach, we explored the structural and electronic properties which comprise of adsorption and diffusion behaviour along with the analysis of voltage profile and storage capacity of Ru doped two-dimensional transition metal oxide [Formula: see text], [Formula: see text], and [Formula: see text] monolayers. The adsorption of alkali ions (Li, Na) to the surface of TMOs is strengthened by Ru-atom doping. Ru doping enhanced the adsorption energy of Li/Na-ion by 25%/11% for [Formula: see text], 8%/13% for [Formula: see text], and 10%/11% [Formula: see text] respectively. The open circuit voltage (OCV) also increases due to the high adsorption capacity of doped Monolayers. Ru doping makes the semiconducting TMOs conduct, which is suitable for battery application. As alkali ion moves closer to the dopant site, the adsorption energy increases. When alkali ions are close to the vicinity of doping site, their diffusion barrier decrease and rises as they go further away. Our current findings will be useful in finding ways to improve the storage performance of 2D oxide materials for application in energy harvesting and green energy architecture.

Twistronics in two-dimensional transition metal dichalcogenide (TMD)-based van der Waals interface

Transition metal dichalcogenides (TMD) based heterostructures have gained significant attention lately because of their distinct physical properties and potential uses in electronics and optoelectronics. In the present work, the effects of twist on the structural, electronic, and optical properties (such as the static dielectric constant, refractive index, extinction coefficient, and absorption coefficient) of vertically stacked TMD heterostructures, namely MoSe2/WSe2, WS2/WSe2, MoSe2/WS2 and MoS2/WSe2, have been systematically studied and a thorough comparison is done among these heterostructures. In addition, the absence of negative frequency in the phonon dispersion curve and a low formation energy confirm the structural and thermodynamical stability of all the proposed TMD heterostructures. The calculations are performed using first-principles-based density functional theory (DFT) method. Beautiful Moiré patterns are formed due to the relative rotation of the layers as a consequence of the superposition of the periodic structures of the TMDs on each other. Twist engineering allows the modulation of bandgaps and a phase change from direct to indirect band gap semiconductors as well. The high optical absorption in the visible range of spectrum makes these twisted heterostructures very promising candidates in photovoltaic applications.

A numerical model for water hydration on nanosurfaces: from friction to hydrophilicity and hydrophobicity

Fluidic transport down to the nanometer scale is of great importance for a wide range of applications such as energy harvesting, seawater desalination, and water treatment and may help to understand many biological processes. In this work, we studied the interfacial friction of liquid water on a series of nanostructures through molecular dynamics (MD) simulations. Our results reveal that the friction coefficient of the water-solid interface cannot be described using a previously reported simple function of the free energy corrugation. Considering that the water-solid friction is firmly correlated with the microscopic water motion, we proposed a probability parameter P(d, t) to classify water motion modes on a surface. We demonstrate that this parameter can be used to accurately predict the water-solid friction by simply monitoring the water binding time on a nanosurface. More importantly, according to the relationship between P(d, t) and friction, we found that the friction coefficient can be used as an indicative criterion for quantitatively assessing hydrophobic or hydrophilic materials, where the borderline is roughly 2 × 10⁵ N s m^-3. That is if the water-solid friction is less than 2 × 10⁵ N s m^-3, the surface is considered hydrophobic. But if the friction is larger than this value, the surface is hydrophilic. The present findings could help to better understand fluidic transport at the nanoscale and guide the future design of functional materials, such as super-hydrophobic and super-hydrophilic surfaces by structure engineering.

Electric Field-Controlled Peptide Self-Assembly through Funnel-Shaped Two-Dimensional Nanopores

Self-assembly of biomolecules is critical for the realization of biological functions. Thus, the precise control of self-assembly has great significance in the design of biochips and biomedical agents. In this report, we design a Y-shaped funnel on a two-dimensional (2D) heterostructure, called 2D funnel, based on monolayered polyaniline carbon nitride (C₃N) and boron carbide (BC₃), and study its application in the self-assembly state regulation of the peptide oligomer, using Aβ_16-21 as the representative model. Structurally, the 2D funnel is composed of three regions: channel area, triangle area, and barrier area. The channel and triangle areas show higher binding affinity to the peptide than that of the barrier area, which leads to the confinement of the peptide in the 2D funnel. Our results show that when an external electric field is applied along the 2D funnel, the oligomer is driven to migrate across the funnel. Its trajectory is confined inside the narrow channel area, which effectively causes peptide dissociation into the individual peptide chains. Then, when the external electric field is turned off, the separated peptide chains spontaneously assemble in the triangle area and tend to reunite. Our present findings propose a novel heterostructure platform, which enables the manipulation of the self-assembly state of peptides by switching the electric field, which could guide the design and fabrication of nanodevices for sensing and sequencing applications.

Potential Unwinding of Double-Stranded DNA upon Binding to a Carbon Nitride Polyaniline (C3N) Nanosheet

Recently, carbon nitride polyaniline (C₃N) had attracted considerable attention from many scientific fields after its successful synthesis. However, thus far, limited efforts were devoted to reveal its potential effect to biomolecules, which correlated intimately with its further utilization. In this study, by using a molecular dynamics (MD) simulation approach, we investigated in detail the interaction between C₃N and a double-stranded DNA (dsDNA) segment to expose the underlying biological effect of C₃N to dsDNA and the corresponding molecular basis. MD simulation results demonstrated that dsDNA presented serious damages upon adsorption onto a C₃N nanosheet with the terminal base pairs denaturized, unwound, and directly packing on the C₃N surface, which implied that C₃N was potentially deleterious to biomolecules. This binding/unwinding process was mainly guided by a combination of van der Waals and π-π stacking interactions together with a continuous lateral migration of dsDNA. Moreover, the nanoscale dewetting also played an important role during the adsorption. These findings revealed the potential bio-effect of the C₃N nanomaterial and its molecular mechanism, which might benefit the future applications of C₃N-based nanostructures.

Electronic phase-crossover and room temperature ferromagnetism in a two-dimensional (2D) spin lattice

Tuning of system properties such as electronic and magnetic behaviour through various engineering techniques is necessary for optoelectronic and spintronic applications. In our current work, we employ first-principles methodologies along with Monte-Carlo simulations to comprehensively study the electronic and magnetic behaviour of 2-dimensional (2D) Cr₂Ge₂Te₆ (T_c = 61 K), uncovering the impact of strain and electric field on the material. In the presence of strain, we were able to achieve high temperature magnetic ordering in the layer along with observable phase crossover in the electronic state of the system, where the system exhibited transference from semiconducting to half-metallic state. Finally, on coupling strain and electric field remarkable increase in Curie temperature (T_c) ∼ 331 K (above 5-fold enhancement from pristine configuration) was observed, which is very well above room temperature. Our inferences have shed light on a relatively new type of coupling method involving strain and electric field which may have tremendous implications in the development of 2D spintronic architecture.

In the presence of strain, high temperature magnetic ordering in Cr₂Ge₂Te₆ was observed with electronic phase crossover from semiconducting to half-metallic state. On coupling strain and electric field, the Curie temperature reaches 331 K.

Bi-stimuli assisted engineering and control of magnetic phase in monolayer CrOCl

Magnetic phase control and room temperature magnetic stability in two-dimensional (2D) materials are indispensable for realising advanced spintronic and magneto-electronic functions. Our current work employs first-principles calculations to comprehensively study the magnetic behaviour of 2D CrOCl, uncovering the impact of strain and electric field on the material. Our studies have revealed that uniaxial strain leads to the feasibility of room temperature ferromagnetism in the layer and also detected the occurrence of a ferromagnetic → antiferromagnetic phase transition in the system, which is anisotropic along the armchair and zigzag directions. Beyond such a strain effect, the coupling of strain and electric field leads to a remarkable enhancement of the Curie temperature (T_c) ∼ 450 K in CrOCl. These predictions based on our detailed simulations show the prospect of multi-stimuli magnetic phase control, which could have great significance for realizing magneto-mechanical sensors.