Computational Study on the Inhibitory Effect of Natural Compounds against the SARS-CoV-2 Proteins

COVID-19 is more virulent and challenging to human life. In India, the Ministry of AYUSH recommended some strategies through Siddha, homeopathy, and other methods to effectively manage COVID-19 (Guidelines for AYUSH Clinical Studies in COVID-19, 2020). Kabasura Kudineer and homeopathy medicines are in use for the prevention and treatment of COVID-19 infection; however, the mechanism of action is less explored. This study aims to understand the antagonist activity of natural compounds found in Kabasura Kudineer and homeopathy medicines against the SARS-CoV-2 using computational methods. Potential compounds were screened against NSP-12, NSP-13, NSP-14, NSP-15, main protease, and spike proteins. Structure-based virtual screening results shows that, out of 14,682 Kabasura Kudineer compounds, the 250395, 129677029, 44259583, 44259584, and 88583189 compounds and, out of 3,112 homeopathy compounds, the 3802778, 320361, 5315832, 14590080, and 74029795 compounds have good scoring function against the SARS-CoV-2 structural and nonstructural proteins. As a result of docking, homeopathy compounds have a docking score ranging from −5.636 to 13.631 kcal/mol, while Kabasura Kudineer compounds have a docking score varying from −8.290 to −13.759 kcal/mol. It has been found that the selected compounds bind well to the active site of SARS-CoV-2 proteins and form hydrogen bonds. The molecular dynamics simulation study shows that the selected compounds have maintained stable conformation in the simulation period and interact with the target. This study supports the antagonist activity of natural compounds from Kabasura Kudineer and homeopathy against SARS-CoV-2’s structural and nonstructural proteins.</p

Copper coordination polymer with lattice water molecules and strong electrocatalytic OER activity

The versatility of organic ligand and metal coordination geometry produced coordination polymer with intriguing network structure and exciting functional properties. Herein, we have synthesized a copper coordination polymer (Cu-HS) using an amino acid based multidentate ligand and explored its electrocatalytic OER activity in alkaline condition. Single crystal structural studies showed the formation of 1D coordination network structure and inclusion of lattice water. Copper ions in Cu-HS displayed octahedral and square pyramidal coordination geometry. Electrocatalytic OER studies in alkaline medium showed strongly enhanced activity for Cu-HS polymer that required an overpotential of 273 mV to achieve the benchmark current density of 10 mA/cm2. Tafel slope analysis and electrochemical impedance studies suggested faster reaction kinetics at the electrode surface modified using Cu-HS. After catalysis, XPS and FTIR spectra of Cu-HS suggested the conversion to metal oxide during the electrocatalysis

Excited state absorption of Cu-doped barium borate nanostructures under nanopulsed laser excitation

Intensity- and concentration-dependent nonlinear absorption of Cu-doped ($$\gamma$$ and $$\beta )$$-$$\hbox {BaB}_{2}\hbox {O}_{4}$$ nanostructures was measured by a standard open aperture Z-scan setup under nanopulsed (9 ns, 10 Hz) laser excitation (532 nm) at various peak intensities (1.26–2.52 GW/$$\hbox {cm}^{2})$$. Intensity-dependent 2PA coefficient exposes the involvement of accumulative 2PA process rather than genuine 2PA. From ground state absorption studies, existence of new energy states due to Cu incorporation has availed a near-resonant state favoring excited state absorption leading to sequential 2PA. Among the samples, 0.05 M Cu-doped $$\gamma$$-$$\hbox {BaB}_{2}$$$$\hbox {O}_{4}$$$$(2.6\times 10^{-10}$$ m/W, $$0.78\times 10^{12}$$$$\hbox {W}/\hbox {m}^{2})$$ and 0.03 M Cu-doped $$\beta$$-$$\hbox {BaB}_{2} \hbox {O}_{4}$$$$(2.5\times 10^{-10}$$ m/W, $$1.21\times 10^{12}\hbox {W}/\hbox {m}^{2})$$ exhibit higher 2PA coefficient and lower onset limiting threshold. The presence of CT and intragap states of $$\hbox {Cu}^{2+}$$ ions-induced strain in visible region transformed genuine 2PA in pristine ($$\gamma$$ and $$\beta )$$-$$\hbox {BaB}_{2}$$$$\hbox {O}_{4}$$ nanorods into sequential 2PA (1PA$$+$$2PA) in Cu-doped ($$\gamma$$ and $$\beta )$$-$$\hbox {BaB}_{2}$$$$\hbox {O}_{4}$$. By simple hydrothermal process, concentration-dependent Cu-doped ($$\gamma$$ and $$\beta )$$-$$\hbox {BaB}_{2}$$$$\hbox {O}_{4}$$ nanostructures were prepared and their structural and optical properties were studied. Thus, Cu-doped ($$\gamma$$ and $$\beta )$$-$$\hbox {BaB}_{2}$$$$\hbox {O}_{4}$$ exhibit sequential 2PA (1PA$$+$$ESA)-based optical limiting with enhanced 2PA coefficient than its pristine ($$\gamma$$ and $$\beta )$$-$$\hbox {BaB}_{2}$$$$\hbox {O}_{4}$$ nanorods

Quaternary Cu2FeSnS4/PVP/rGO Composite for Supercapacitor Applications

Electrochemical energy storage is a current research area to address energy challenges of the modern world. The Cu2FeSnS4/PVP/rGO-decorated nanocomposite using PVP as the surface ligand was explored in a simple one-step solvothermal route, for studying their electrochemical behavior by designing asymmetric hybrid supercapacitor devices. The full cell three-electrode arrangements delivered 748 C/g (62.36 mA h/g) at 5 mV/s employing CV and 328 F/g (45.55 mA h/g) at 0.5 A/g employing GCD for the Cu2FeSnS4/PVP/rGO electrode. The half-cell two-electrode device can endow with 73 W h/kg and 749 W/kg at 1 A/g energy and power density. Furthermore, two Cu2FeSnS4/PVP/rGO//AC asymmetric devices connected in series for illuminating a commercial red LED more than 1 min were explored. This work focuses the potential use of transition-metal chalcogenide composite and introduces a new material for designing high-performance supercapacitor applications

Colorimetric optical chemosensor of toxic metal ion (Hg2+) and biological activity using green synthesized AgNPs

In this paper, we have reported the green synthesis of silver nanoparticles (AgNPs) using silver nitrate and Ficus carica (fig) stem extract at room temperature. We have also explored the effect of volume of extract (1–3 ml) on the formation of AgNPs using various analytical techniques such as Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), and energy-dispersive X-ray analyzer (EDX). The formations of AgNPs were monitored by ultraviolet–visible spectrophotometer as well as from color change through the naked eye. The absorption peaks appear between 442 and 455 nm, confirming to surface plasmon resonance (SPR) of AgNPs. It is clear from the FTIR results that the biologically active compounds present in the extract act as capping and reducing agents for AgNPs creation. Electron microscopy results show that by increasing the concentration of extract, the morphology and size of AgNPs changed due to the presence of more phenolic group. The green synthesized AgNPs have been sequentially employed for the selective and sensitive detection of toxic metal ion (Hg2+) in aqueous medium and antimicrobial activity against all tested microbes including five gram negative and two gram positive. Furthermore, the brown color of green synthesized AgNPs turned into colorless with Hg2+ ion by naked eye response and the limit of detection was 1.06 µM. Figure (A) represents the UV–visible spectra of AgNPs with different concentrations of Hg2+ (0.1–10 µM) in aqueous solution and inset shows the variation of the absorbance of AgNPs solution as a function of Hg2+ ion concentration. Figure (B) represents the images of color variations of AgNPs with different concentrations of Hg2+ (10−1–10−7 M) in aqueous solution

Ruthenium oxide/tungsten oxide composite nanofibers as anode catalysts for the green energy generation of Chlorella vulgaris mediated biophotovoltaic cells

The development of electrochemically active and stable anode catalysts for the photoelectrochemical splitting of water molecules via biophotovoltaic cells (BPVs) utilizing microalgae receives a prime importance in green energy sector. Herein, we report the ruthenium oxide (RuO2)/tungsten oxide (WO3) composite nanofibers based photoanode for the application of high performance and durable BPV. The sequential arrangement of 6 nm sized RuO2/WO3 spherical particles constitutes the nanofibrous morphology and a number of surface active sites and structural integrity of nanofibers demonstrate the excellent and stable photo-oxidation currents. Under the light regime, RuO2/WO3/carbon cloth photoanode exhibits the substantial BPV power and current densities with an excellent durability. Thus this systematic study evokes the fundamental understanding on the electron generation and transference mechanisms, which offers new dimensions in the development of high performance and durable BPVs. © 2019 American Institute of Chemical Engineer