Showing papers by "University of Madras published in 2020"

Andrographolide as a potential inhibitor of SARS-CoV-2 main protease: an in silico approach.

Abstract: SARS-CoV-2 virus which caused the global pandemic the Coronavirus Disease- 2019 (COVID-2019) has infected about 1,203,959 patients and brought forth death rate about 64,788 among 206 countries as m...

Facile synthesis of paper based graphene electrodes for point of care devices: A double stranded DNA (dsDNA) biosensor

Abstract: The demand for high-quality graphene for electronic applications is increasing due to its high carrier mobility and electrical conductivity. In this connection, printing technology is a reliable method towards the fabrication of conductive, disposable graphene-based electrode for low-cost sensor application. Herein, we aimed to report the synthesis of high-quality graphene nanosheets obtained by electrochemical exfoliation of biomass-derived from corn cob. The conductive ink was prepared from this exfoliated graphene and was utilized for the preparation of paper-based graphene electrode towards double stranded DNA (dsDNA) sensor application. This paper, based graphene electrode opens the possibility of direct electrochemical analysis of analyte without any sample preparation. In this study, two irreversible oxide peaks were obtained from paper-based printed graphene electrode, corresponds to oxidation of guanine (G) and adenine (A) of dsDNA in the linear range of 0.2 pg mL−1 to 5 pg mL−1 with the detection limit of 0.68 pg mL−1 and the sensitivity of 0.00656 mA pg−1 cm−2. Further, a small-scale printable circuit is fabricated using this graphene shows good conductivity of 1.145x103(S/m).

Green-Synthesized Rice-Shaped Copper Oxide Nanoparticles Using Caesalpinia bonducella Seed Extract and Their Applications.

Abstract: Copper oxide nanoparticles (CuO Nps) were synthesized using Caesalpinia bonducella seed extract via a green synthetic pathway and were evaluated for electrocatalytic properties by carrying out electrochemical detection of riboflavin [vitamin B2 (VB2)]. The seeds of C. bonducella are known to have strong antioxidant properties arising due to the presence of various components, including citrulline, phytosterinin, β-carotene, and flavonoids, which serve as reducing, stabilizing, and capping agents. The synthesized CuO Nps were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy, thermogravimetrc analysis-differential thermal analysis, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy and further used as a modifier for a graphite electrode surface. The modified electrode was electrochemically characterized by cyclic voltammetry, square-wave voltammetry, and chronoamperometry techniques and then assessed for electrocatalysis by carrying out the detection of VB2. The electrochemical sensor could be used for nanomolar detection of VB2 with an observed linear range of 3.13-56.3 nM with a limit of detection of 1.04 nM. The electrode showed good stability and reproducibility over a period of 120 days. The CuO Nps were further analyzed for antibacterial effect with Gram-positive and Gram-negative bacteria, and in both cases, high antibacterial activity was clearly observed. The newly synthesized nanoparticles, thus, proved to be an interesting material for electrochemical and biological studies.

Effect of Various Deep Eutectic Solvents on the Sustainable Synthesis of MgFe2O4 Nanoparticles for Simultaneous Electrochemical Determination of Nitrofurantoin and 4-Nitrophenol

Abstract: The innovations in the field of green chemistry have expedited the pace of advances in varied research areas ranging from the development of diverse routes for the material synthesis to designer so...

Structure, Function, Regulation and Phylogenetic Relationship of ZIP Family Transporters of Plants.

Abstract: Zinc (Zn) is an essential micronutrient for plants and humans. Nearly 50% of the agriculture soils of world are Zn-deficient. The low availability of Zn reduces the yield and quality of the crops. The zinc-regulated, iron-regulated transporter-like proteins (ZIP) family and iron-regulated transporters (IRTs) are involved in cellular uptake of Zn, its intracellular trafficking and detoxification in plants. In addition to Zn, ZIP family transporters also transport other divalent metal cations (such as Cd2+, Fe2+, and Cu2+). ZIP transporters play a crucial role in biofortification of grains with Zn. Only a very limited information is available on structural features and mechanism of Zn transport of plant ZIP family transporters. In this article, we present a detailed account on structure, function, regulations and phylogenetic relationships of plant ZIP transporters. We give an insight to structure of plant ZIPs through homology modeling and multiple sequence alignment with Bordetella bronchiseptica ZIP (BbZIP) protein whose crystal structure has been solved recently. We also provide details on ZIP transporter genes identified and characterized in rice and other plants till date. Functional characterization of plant ZIP transporters will help for the better crop yield and human health in future.

Leptospirosis: a neglected tropical zoonotic infection of public health importance—an updated review

Abstract: Leptospirosis is a zoonotic and waterborne disease worldwide. It is a neglected, reemerging disease of global public health importance with respect to morbidity and mortality both in humans and animals. Due to negligence, rapid, unplanned urbanization, and poor sanitation, leptospirosis emerges as a leading cause of acute febrile illness in many of the developing countries. Every individual has a risk of getting infected as domestic and wild animals carry leptospires; the at-risk population varies from the healthcare professionals, animal caretakers, farmers and agricultural workers, fishermen, rodent catchers, water sports people, National Disaster Response Force (NDRF) personnel, people who volunteer rescue operations in flood-affected areas, sanitary workers, sewage workers, etc. The clinical manifestations of leptospirosis range from flu-like illness to acute kidney failure (AKF), pneumonia, jaundice, pulmonary hemorrhages, etc. But many rare and uncommon clinical manifestations are being reported worldwide. This review will cover all possible updates in leptospirosis from occurrence, transmission, rare clinical manifestations, diagnosis, treatment, and prophylactic measures that are currently available, their advantages and the future perspectives, elaborately. There are less or very few reviews on leptospirosis in recent years. Thus, this work will serve as background knowledge for the current understanding of leptospirosis for researchers. This will provide a detailed analysis of leptospirosis and also help in finding research gaps and areas to focus on regarding future research perspectives.

Quantification of microplastic in Red Hills Lake of Chennai city, Tamil Nadu, India.

Abstract: Inevitable use of plastic materials in our day-to-day life has led to the entry of microplastic into aquatic environments, which are plastics less that than 5 mm. Microplastic is of great concern in recent years due to its impact on humans and aquatic organisms since they absorb organic contaminants and pathogens from the surrounding media due to higher surface and volume ratio. This is the first study attempted to study the distribution and source of microplastic contamination in Red Hills Lake which is one of the freshwater systems supplying water to the North of Chennai city. Thirty-two sediment samples and six water samples were collected covering an area 18.21 km2. The presence of microplastic was analyzed in water and sediment as per the National Oceanic and Atmospheric Administration (NOAA) protocol. The mean concentration of microplastic in water samples was 5.9 particles/L and 27 particles/kg in sediment. In both sediments and water, the most commonly found microplastic types are as follows: fibers (37.9%), fragments (27%), films (24%), and pellets (11.1%). Based on the FTIR, the common types of microplastic were of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene. Further samples were evaluated for surface elemental composition in order to understand whether heavy metals get adhered to the surface of microplastic using energy-dispersive X-ray. Our results indicated the presence of microplastic in water and sediments which will lead to further study of microplastic presence in biota and microplastic pollution in freshwater systems.

Therapeutic potential of Mucuna pruriens (Linn.) on ageing induced damage in dorsal nerve of the penis and its implication on erectile function: an experimental study using albino rats.

Abstract: Objective: To study the effect of ethanolic seed extract of Mucuna pruriens on damaged dorsal nerve of the penis (DNP) in aged rat in relation to penile erection.Methods: The rats were divided into...

Eutectic Solvent-Mediated Synthesis of NiFe-LDH/Sulfur-Doped Carbon Nitride Arrays: Investigation of Electrocatalytic Activity for the Dimetridazole Sensor in Human Sustenance

Abstract: Pharmaceutical contamination is an emerging environmental concern that threatens global health and impacts every hemisphere of existence. The extensive exploitation and unregulated release of these...

5-Fluorouracil and curcumin co-encapsulated chitosan/reduced graphene oxide nanocomposites against human colon cancer cell lines

Abstract: Recent attention on chemotherapy against cancer is to explore the effective therapy through targeted delivery of anticancer agents to the tumor site by manipulating pharmacokinetic properties of nanocarriers. 5-Fluorouracil (5-FU) and curcumin (CUR) loaded chitosan/reduced graphene oxide (CS/rGO) nanocomposite has been prepared via simple chemical method. The polymer matrix-type chitosan/rGO nanocomposite, before and after encapsulation, has been analyzed by various characterizations. Entrapment and loading efficiencies were estimated. The results that demonstrated higher entrapment efficiency (> 90%) were achieved by CS/rGO nanocarrier. Various kinetic models were used to analyze the release model and to elucidate the release mechanism of the drug from CS/rGO nanocomposite. The synergistic cytotoxicity was observed on addition of 5-FU + CUR-loaded CS/rGO nanocomposite which shows the effectiveness of the system toward the inhibition of growth of HT-29 colon cancer cells. The better cytotoxicity with an IC50 of 23.8 μg/mL was observed for dual-drug-loaded nanocomposite.

Synthesis of Palladium(II) Complexes via Michael Addition: Antiproliferative Effects through ROS-Mediated Mitochondrial Apoptosis and Docking with SARS-CoV-2.

Abstract: Metal complexes have numerous applications in the current era, particularly in the field of pharmaceutical chemistry and catalysis. A novel synthetic approach for the same is always a beneficial addition to the literature. Henceforth, for the first time, we report the formation of three new Pd(II) complexes through the Michael addition pathway. Three chromone-based thiosemicarbazone ligands (SVSL1-SVSL3) and Pd(II) complexes (1-3) were synthesized and characterized by analytical and spectroscopic tools. The Michael addition pathway for the formation of complexes was confirmed by spectroscopic studies. Distorted square planar structure of complex 2 was confirmed by single-crystal X-ray diffraction. Complexes 1-3 were subjected to DNA- and BSA-binding studies. The complex with cyclohexyl substituent on the terminal N of thiosemicarbazone (3) showed the highest binding efficacy toward these biomolecules, which was further understood through molecular docking studies. The anticancer potential of these complexes was studied preliminarily by using MTT assay in cancer and normal cell lines along with the benchmark drugs (cisplatin, carboplatin, and gemcitabine). It was found that complex 3 was highly toxic toward MDA-MB-231 and AsPC-1 cancer cells with IC50 values of 0.5 and 0.9 μM, respectively, and was more efficient than the standard drugs. The programmed cell death mechanism of the complexes in MDA-MB-231 cancer cells was confirmed. Furthermore, the complexes induced apoptosis via ROS-mediated mitochondrial signaling pathway. Conveniently, all the complexes showed less toxicity (≥50 μM) against MCF-10a normal cell line. Molecular docking studies were performed with VEGFR2, EGFR, and SARS-CoV-2 main protease to illustrate the binding efficiency of the complexes with these receptors. To our surprise, binding potential of the complexes with SARS-CoV-2 main protease was higher than that with chloroquine and hydroxychloroquine.

Reduced graphene oxide-wrapped micro-rod like Ni/Co organic-inorganic hybrid nanocomposite as an electrode material for high-performance supercapacitor

Abstract: A Ni/Co metal-organic frameworks (MOFs) and its reduced graphene oxide (rGO) composite has been fabricated through a room-temperature route using simple 3D linker as trimesic acid. The crystalline nature, morphology, functional groups and thermal stability of the prepared materials are characterized via XRD, SEM, Raman and TGA studies. The synthesized Ni/Co-MOF/rGO reveals spherical particles decorated rod-like morphology with a length of ~3–10 μm. The incorporation of rGO into the Ni/Co-MOF enhances conductivity and electrochemical performance. The electrochemical properties of Ni/Co-MOF and its rGO composite are evaluated in 1 M KOH. The produced Ni/Co-MOF/rGO composite (1162 F g−1) exhibits higher specific capacitance than bare Ni/Co-MOF (978 F g−1). The Ni/Co-MOF/rGO composite exposes excellent stability even after 5000 cycles and maintains 109% of its initial capacitance. This result suggests that the fabricated Ni/Co-MOF/rGO composite may be employed as an electrode material for supercapacitor applications.

Enhanced mechanical and biocompatible properties of strontium ions doped mesoporous bioactive glass

Abstract: Very low (≤0.2%) strontium (Sr) ion doped mesoporous (45S5) bioactive glasses (BG) were synthesized by sol-gel technique and calcination without using polymers (porogens), mould or other additives. The phases and their functional groups were confirmed by the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) and FT-Raman spectroscopy respectively. Sodium calcium phosphate silicate [(Na0.11Ca0.89) (P0.11Si0.89O3)] which is essential for assisting the self-repair process of enamel was formed along with sodium calcium silicate (Na2Ca2Si3O9) phase. Doping of Sr ions (0.2 wt %) enhances the pore volume (96%) and surface area (108%) compared to pristine. Further, interconnected network structures are created exhibiting controlled and sustained drug release (58% in 720 h). The mechanical strength of the Sr doped BG samples was increased significantly. The compressive strength of sample (Sr = 0.2 and 0.5 wt %) were 8.1 ± 0.5 and 11.2 ± 0.5 MPa with respective percentage increase of 440 and 647% compared to BG. The thermal stability and zeta potential increases on the Sr doped BG samples with considerable variation in the particle size when compared to the pristine. The cell viability and proliferation were also significantly enhanced by doping of Sr ions which tailor the surface properties as well. The overall results robustly demonstrate for the first time that the very low doping of Sr ions (≤0.2%) in BG, play a major role in engineering the properties viz., mechanical, surface, drug release and cell proliferation making them suitable for multifunctional biomedical applications.

Human occupation of northern India spans the Toba super-eruption ~74,000 years ago.

Abstract: India is located at a critical geographic crossroads for understanding the dispersal of Homo sapiens out of Africa and into Asia and Oceania. Here we report evidence for long-term human occupation, spanning the last ~80 thousand years, at the site of Dhaba in the Middle Son River Valley of Central India. An unchanging stone tool industry is found at Dhaba spanning the Toba eruption of ~74 ka (i.e., the Youngest Toba Tuff, YTT) bracketed between ages of 79.6 ± 3.2 and 65.2 ± 3.1 ka, with the introduction of microlithic technology ~48 ka. The lithic industry from Dhaba strongly resembles stone tool assemblages from the African Middle Stone Age (MSA) and Arabia, and the earliest artefacts from Australia, suggesting that it is likely the product of Homo sapiens as they dispersed eastward out of Africa. When modern humans colonized India is debated. Here, Clarkson and colleagues report an archaeological site in India that has been occupied for approximately 80,000 years and contains a stone tool assemblage attributed to Homo sapiens that matches artefacts from Africa, Arabia, and Australia.

Synthesis and Characterization of Amorphous Iron Oxide Nanoparticles by the Sonochemical Method and Their Application for the Remediation of Heavy Metals from Wastewater.

Abstract: Nanoparticles have gained huge attention in the last decade due to their applications in electronics, medicine, and environmental clean-up. Iron oxide nanoparticles (IONPs) are widely used for the wastewater treatment due to their recyclable nature and easy manipulation by an external magnetic field. Here, in the present research work, iron oxide nanoparticles were synthesized by the sonochemical method by using precursors of ferrous sulfate and ferric chloride at 70 °C for one hour in an ultrasonicator. The synthesized iron oxide nanoparticles were characterized by diffraction light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), electron diffraction spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The FTIR analysis exhibits characteristic absorption bands of IONPs at 400–800 cm−1, while the Raman spectra showed three characteristic bands at 273, 675, and 1379 cm−1 for the synthesized IONPs. The XRD data revealed three major intensity peaks at two theta, 33°, 35°, and 64° which indicated the presence of maghemite and magnetite phase. The size of the spherical shaped IONPs was varying from 9–70 nm with an average size of 38.9 nm while the size of cuboidal shaped particle size was in microns. The purity of the synthesized IONPs was confirmed by the EDS attached to the FESEM, which clearly show sharp peaks for Fe and O, while the magnetic behavior of the IONPs was confirmed by the VSM measurement and the magnetization was 2.43 emu/g. The batch adsorption study of lead (Pb) and chromium (Cr) from 20% fly ash aqueous solutions was carried out by using 0.6 mg/100 mL IONPs, which exhibited maximum removal efficiency i.e., 97.96% and 82.8% for Pb2+ and Cr ions, respectively. The fly ash are being used in making cements, tiles, bricks, bio fertilizers etc., where the presence of fly ash is undesired property which has to be either removed or will be brought up to the value of acceptable level in the fly ash. Therefore, the synthesized IONPs, can be applied in the elimination of heavy metals and other undesired elements from fly ash with a short period of time. Moreover, the IONPs that have been used as a nanoadsorbent can be recovered from the reaction mixture by applying an external magnetic field that can be recycled and reused. Therefore, this study can be effective in all the fly ash-based industries for elimination of the undesired elements, while recyclability and reusable nature of IONPs will make the whole adsorption or elimination process much economical.

Room temperature operatable high sensitive toluene gas sensor using chemiresistive Ag/Bi2O3 nanocomposite

Abstract: Toluene gas is known to cause severe acute respiratory effects on human health and thereby its detection at trace levels is most essential. Herein, we demonstrate a room temperature operatable Ag/Bi2O3 nanocomposite based chemiresistive toluene gas sensor that detects minimal concentration range of 10−100 ppm. Further, Ag/Bi2O3 showed the highest sensitivity as for sensing of toluene gas in the presence of 50 ppm concentration of six different gases namely methanol, ethanol, formaldehyde, acetone, benzene, and toluene. The present sensor displays the highest sensor response of 89.2 % for detecting the very low concentration of toluene gas at 50 ppm under the relative humidity value of below 60 %. As achieved sensor exhibits a high and quick response, good repeatability and excellent stability for toluene gas, which promising and interesting as well.

Cobalt molybdate nanorods decorated on boron-doped graphitic carbon nitride sheets for electrochemical sensing of furazolidone

Abstract: A nanorod-like structured CoMoO4 embedded on boron doped-graphitic carbon nitride composite (CoMoO4/BCN) has been developed by a simple sonochemical method for electrochemical detection of furazolidone (FUZ). Interestingly, the impedance of CoMoO4/BCN fabricated screen-printed carbon electrode (SPCE) possesses a lower resistance charge transfer (Rct), which favors superior electrochemical detection of FUZ. Such CoMoO4/BCN/SPCE exhibits an ultralow detection limit of 1.6 nM with a concentration range of 0.04–408.9 μM, and high sensitivity of 11.6 μA μM−1 cm−2 by DPV method. In addition, biological and water samples were used for demonstration of practical application of CoMoO4/BCN/SPCE towards electrochemical detection of FUZ, and the result exhibits a satisfactory recovery. Graphical abstract

Deep eutectic solvent-based manganese molybdate nanosheets for sensitive and simultaneous detection of human lethal compounds: Comparing the electrochemical performances of M-molybdate (M= Mg, Fe, and Mn) electrocatalysts

Abstract: Potentially hazardous chemical contaminants endanger the environment and human well-being, challenging scientists and policy makers to develop holistic alternative approaches for remediation. The addition or accumulation of these chemicals can have a series of far-reaching consequences and have direct and indirect effects at multiple levels of ecological organization. Therefore, the development of a sensitive tool for the comprehensive evaluation of chemical concentrations is highly relevant. Herein, we thus report the simultaneous electrochemical detection of highly toxic hydroquinone (HQ), Hg2+, and nitrite (NO2-) compounds using nanostructured metal molybdate (M = Mg, Fe and Mn) catalysts. These functional nanomaterials are synthesized using a deep eutectic solvent (DES) modified hydrothermal method that provides sustainable aspects and energy efficient synthesis strategies. Choline chloride (ChCl)-urea DES used in this study exhibits an all-in-one behaviour by simultaneously acting as a template, reducing agent, and homogeneous means for stabilizing metal ions. This stimulates the fabrication of hierarchical structures of metal molybdates with high surface activities that cause their remarkable properties with minimal waste generation. The structural, morphological, catalytic, and electrochemical capacities of the as-synthesized MgMoO4, Fe2(MoO4)3, and MnMoO4 materials are explored through various techniques and comparatively, MnMoO4 presents superior characterization features such as a reduced particle size, increased surface area and hierarchical architectures. Owing to the exceptional physicochemical attributes, the MnMoO4 modified glassy carbon electrode (GCE) demonstrates superior electrochemical activities towards the individual and simultaneous detection of HQ, Hg2+, and NO2-. Well-defined and separate peaks are observed for the simultaneous detection of HQ, Hg2+, and NO2- which is influenced by the binding energies of these pollutants. Furthermore, the modified electrode exhibits a high sensitivity of 23.8, 17.7 and 10.2 μA μM-1 cm-2 with a limit of detection (LOD) of 0.026, 0.05, and 0.01 μM for HQ, Hg2+, and NO2- respectively under ideal conditions. Also, the reproducibility and anti-interference ability reinforce the application potential of the MnMoO4 modified electrode for the simultaneous electrochemical detection of HQ, Hg2+, and NO2- in real samples with better recoveries, thus assessing the effect of these hazardous chemicals on humanity.

Weighted Mostar indices as measures of molecular peripheral shapes with applications to graphene, graphyne and graphdiyne nanoribbons.

Abstract: In this study we consider relatively new bond-additive Mostar indices that appear to provide quantitative measures of peripheral shapes of molecules. We have computed weighted Mostar, edge-Mostar and total-Mostar indices of graphene, [Formula: see text]-types of graphyne and graphdiyne, which are of considerable interest owing to their novel properties and thus find applications in a number of areas such as sensors, catalysis, chemisorption and nanomedicine. We have implemented the results to analyse the weighted Mostar indices and have obtained exact analytical expressions for the title molecules. We propose that Mostar indices together with frontier molecular orbitals, and HOMO-LUMO gaps can provide measures of chemical reactivity and analysis of peripheral molecular shapes.

Low cost and quick time absorption of organic dye pollutants under ambient condition using partially exfoliated graphite

Abstract: Worldwide, the removal of organic effluent dyes from domestic water is of high need due to the lesser availability of drinking water. In the present work, we reported on the synthesis of partially exfoliated graphite from corn cob and its ability to adsorb halogenated organic dyes. The synthesis of partially exfoliated graphene (PEG) showed the ability to adsorb the organic dyes at a quick time of about 5 s, even without any additional mechanical and radiation requirements. The adsorptive behavior of partially exfoliated graphite was conducted in an ambient condition, in the presence of halogenated organic dyes such as Methylene blue (MB) and Rhodamine B (RhB) as the adsorbate model. From the UV–vis absorption studies, it was observed that 1 mg of this sample had the efficiency to adsorb 0.1 mg/mL of MB and 0.01 mg/mL of RhB with the adsorption efficacy of 45 % and 75 %, respectively. The adsorption performance was well fitted with non-linear Gaussian regression plot for MB (R2 = 0.9841) and RhB (R2 = 0.7781).The photoluminescence studies also show that decreases in the intensity from the initial concentration of the MB and RhB dyes. The deconvoluted photoluminescence spectrum for both MB and Rh B showed peak broadening with peak shift for MB and the merged peaks for Rh B. The results suggested that, the partially exfoliated graphite can be utilized as an efficient low cost recyclable adsorbate for organic dye domestic effluent at low cost and also at a sustainable way. The partially exfoliated graphite also observed the possibility of hydrogen evolution reaction and opens the option of metal doping for futuristic applications.