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An analog of graphene, graphitic carbon nitride (g-C3N4), is a promising metal-free conjugated polymer, owing to its excellent performance in biosensing and photocatalysis. We have demonstrated the adsorption of twenty-five amino acids (AA) employing DFT-D3 correction method of Grimme's dispersion and the non-equilibrium Green's function (NEGF) for describing the coherent transport in molecular devices coupled with adsorption energies, substrate-adsorbate distances, the density of states, charge transfer mechanism, molecular dynamics, work function, and bonding patterns. We have also depicted the current-voltage (I-V) characteristics where the curves of current vs. bias voltage (I-V-b) display a distinct response for each AA. Furthermore, we have illustrated the anti-bacterial mechanism of g-C3N4 utilizing bioinformatics study and compared it with DFT studies. We found evidence of a difference in transport, electronic as well as molecular mechanisms reinforcing the possibility of g-C3N4 applications based on sensors for AA sequencing of proteins, water-disinfection technique, and microbial control.

In the present study, we systematically investigated the adsorption mechanism of canonical DNA nucleobases and their two nucleobase pairs on a single-layer gallium sulfide (GaS) substrate using DFT+D3 methods. The GaS substrate has chemical interactions with molecules 0.02 |e| 0.11 |e| from molecules to the monolayer GaS surface. Due to the chemical interactions of adenine, cytosine, guanine, and thymine on the monolayer GaS surface, the work function is decreased by 0.69, 0.60, 0.97, and 0.20 eV, respectively. It is displayed that the bandgap of the monolayer GaS sheet can be significantly affected as induced molecular electronic states tend to appear near the Fermi level region due to chemical and physisorption mechanism. We have also investigated the transport properties of DNA nucleobases, namely, AT and GC pair molecules on the GaS surface, which shows significant reduction in the zero-bias transmission spectra. Moreover, with and without DNA nucleobases, namely, AT and GC pair molecules' absorptions on the GaS surface, clearly expressed in terms of distinct current signals, can be observed as ON and OFF states for this device. The distinctive nucleobase adsorption energies and different I-V responses may serve as potential probes for the selective detection of nucleobase molecules in imminent DNA sequencing applications based on a monolayer GaS surface.

An in-depth understanding of the practical sensing mechanism of two-dimensional (2D) materials is critically important for the design of efficient nanosensors toward environmentally toxic gases. Here, we have performed van der Waals-corrected density functional theory (DFT) simulations along with nonequilibrium Green’s function (NEGF) to investigate the structural, electronic, transport, thermodynamic, and gas-sensing properties of pristine and defect-crafted bismuthene (bBi) sheets toward sulfur- (H₂S, SO₂) and nitrogen-rich (NH₃, NO₂) toxic gases. It is revealed that the electrical conductivities of pristine and defective bBi sheets are altered upon the adsorption of incident gases, which have been verified through transport calculation coupled with the work function and electronic density of states. Our calculations disclose that bBi sheets show superior and selective gas-sensing performance toward NO₂ molecules among the studied gases due to a significant charge redistribution and more potent adsorption energies. We find that the mono- and divacancy-induced bBi sheets have enhanced sensitivity because the adsorption behavior is driven by a considerable change in the electrostatic potential difference between the sheets and the gas molecules. We further performed statistical thermodynamic analysis to quantify the gas adsorption abilities at the practical temperature and pressures for the studied gas samples. This work divulges the higher sensitivity and selectivity of bBi sheets toward hazard toxins such as NO₂ under practical sensing conditions of temperature and pressure.

When nano-molecular electronics devices (nanoMoED) are developed as gas sensors, single molecules are utilized as sensing units. In this work, we expose two different types of such nanoscale hybrid devices to sense NO2, NH3, and ethanol gases. The nanoMoED devices differ in the molecule with which they are functionalized, and here, we have available a vast library of conductive, organic molecules. We chose the phenyl-based molecules of 4,4’-biphenyldithiol (BPDT) and p-ter-phenyl-4,4''-dithiol (TPDT) to functionalised the devices. The molecules showed a change in electronic structure when the analyte gas was introduced in gas sensing cham-ber which resulted in change in the electron transport across the devices. A selective response is observed to NO2, NH3 and ethanol gases. Both BPDT and TPDT devices are sensitive to NO2 gas with differences in the sensor response. The sensor results for NO2, NH3 and ethanol are undermined by density functional theory calculations.

Contact electrification (triboelectrification) has been a long-standing phenomenon for 2600 years. The scientific understanding of contact electrification (triboelectrification) remains un-unified as the term itself implies complex phenomena involving mechanical contact/sliding of two materials involving many physico-chemical processes. Recent experimental evidence suggests that electron transfer occurs in contact electrification between solids and liquids besides the traditional belief of ion adsorption. Here, we have illustrated the Density Functional Theory (DFT) formalism based on a first-principles theory coupled with temperature-dependent ab initio molecular dynamics to describe the phenomenon of interfacial charge transfer. The model captures charge transfer dynamics upon adsorption of different ions and molecules on AlN (001), GaN (001), and Si (001) surfaces, which reveals the influence of interfacial charge transfer and can predict charge transfer differences between materials. We have depicted the substantial difference in charge transfer between fluids and solids when different ions (ions that contribute to physiological pH variations in aqueous solutions, e.g., HCl for acidic pH, and NaOH for alkaline pH) are adsorbed on the surfaces. Moreover, a clear picture has been provided based on the electron localization function as conclusive evidence of contact electrification, which may shed light on solid-liquid interfaces.

The developmental rapidity of nanotechnology poses higher risks of exposure to humans and the environment through manufactured nanomaterials. The multitude of biological interfaces, such as DNA, proteins, membranes, and cell organelles, which come in contact with nanoparticles, is influenced by colloidal and dynamic forces. Consequently, the ensued nano-bio interface depends on dynamic forces, encompasses many cellular absorption mechanisms along with various biocatalytic activities, and biocompatibility that needs to be investigated in detail. Addressing the issue, the study offers a novel green synthesis strategy for antibacterial AgNPs with higher biocompatibility and elucidates the mechanistic in vivo biocompatibility of silver nanoparticles (AgNPs) at the cellular and molecular levels. The analysis ascertained the biosynthesis of G-AgNPs with the size of 25 +/- 10 nm and zeta potential of -29.2 +/- 3.0 mV exhibiting LC50 of 47.2 mu g mL(-1) in embryonic zebrafish. It revealed the mechanism as a consequence of abnormal physiological metabolism in oxidative stress and neutral lipid metabolism due to dose-dependent interaction with proteins such as he1a, sod1, PEX protein family, and tp53 involving amino acids such as arginine, glutamine and leucine leading to improper apoptosis. The research gave a detailed insight into the role of diverse AgNPs-protein interactions with a unique combinatorial approach from first-principles density functional theory and in silico analyses, thus paving a new pathway to comprehending their intrinsic properties and usage.

Nanoparticles have been well studied for controlling viral infections. However, very little knowledge exists on their potential use as an adjuvant for enhancing antiviral drug efficacy and reducing toxicity. Herein, we describe gold nanoparticle decorated zinc oxide tetrapods (ANZOT) that electrostatically neutralize viral infections. Given their negative charge distribution caused by engineered oxygen vacancies, ANZOT can prevent herpes simplex virus-1 and the novel human coronavirus, SARS-CoV-2 from infecting cells. More notably, when ANZOT was used as an adjuvant, several fold lower than normally used concentrations of a nucleoside analog, acyclovir or a preclinical antiviral compound, BX795, were enough to inhibit infection and eliminate drug toxicity. BX795 was found to exert its antiviral benefits through inhibition of cellular protein kinase C (α and ζ). Cumulatively our findings highlight an innovative use of ANZOT as a drug adjuvant for superior broad-spectrum effects against viral infections.