K. Lingaraju

Green synthesis of CuO nanoparticles using Gloriosa superba L. extract and their antibacterial activity

Abstract The investigation aims at the synthesis of copper oxide nanoparticles (CuO Nps) using Gloriosa superba L. plant extract as fuel by solution combustion synthesis, their characterization and studies on antibacterial activities against selected pathogenic bacteria. X-ray diffraction studies showed that the particles are monoclinic in nature. The UV–visible absorption spectrum of CuO Nps indicates the blue shift with increase of concentration of plant extract. SEM images reveal that the particles are spherical in nature. TEM image indicates that as-formed CuO Nps are spherical in shape, and the size is found to be in the range 5–10 nm. Further, as-formed CuO Nps exhibit significant antibacterial activity against pathogenic bacterial strains namely Gram −ve Klebsiella aerogenes, Pseudomonas desmolyticum, and Escherichia coli, Gram +ve bacteria Staphylococcus aureus. The current study demonstrates convenient utilization of Gloriosa superba L. extract as a fuel for the efficient synthesis of CuO nanoparticles through a green synthesis method to obtain significantly active antibacterial material.

EGCG assisted green synthesis of ZnO nanopowders: Photodegradative, antimicrobial and antioxidant activities

Zinc oxide nanopowders were synthesized by solution combustion method using Epigallocatechin gallate (EGCG) a tea catechin as fuel. The structure and morphology of the product was characterized by Powder X-ray Diffraction, Scanning Electron Microscopy, photoluminescence and UV-Visible spectroscopy. The nanopowders (Nps) were subjected to photocatalytic and biological activities such as antimicrobial and antioxidant studies. PXRD patterns demonstrate that the formed product belongs to hexagonal wurtzite system. SEM images show that the particles are agglomerated to form sponge like structure and the average crystallite sizes were found to be ∼10-20nm. PL spectra exhibit broad and strong peak at 590nm due to the Zn-vacancies, and O-vacancies. The prepared ZnO Nps exhibit excellent photocatalytic activity for the photodegradation of malachite green (MG) and methylene blue (MB) indicating that the ZnO NPs are potential photocatalytic semiconductor materials. ZnO NPs exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus using the agar well diffusion method. Furthermore, the ZnO nano powders show good antioxidant activity by potentially scavenging DPPH radicals. The study successfully demonstrates synthesis of ZnO NPs by simple ecofriendly route employing EGCG as fuel that exhibit superior photodegradative, antibacterial and antioxidant activities.

Leucas aspera mediated multifunctional CeO2 nanoparticles: Structural, photoluminescent, photocatalytic and antibacterial properties.

Spherical shaped cerium dioxide (CeO2) nanoparticles (NPs) were synthesized via bio mediated route using Leucas aspera (LA) leaf extract. The NPs were characterized by PXRD, SEM, UV-Visible techniques. Photoluminescence (PL), photocatalysis and antibacterial properties of NPs were studied. PXRD patterns and Rietveld analysis confirm cubic fluorite structure with space group Fm-3m. SEM results evident that morphology of the NPs was greatly influenced by the concentration of LA leaf extract in the reaction mixture. The band gap energy of the NPs was found to be in the range of 2.98-3.4 eV. The photocatalytic activity of NPs was evaluated by decolorization of Rhodamine-B (RhB) under UVA and Sun light irradiation. CeO2 NPs show intense blue emission with CIE coordinates (0.14, 0.22) and average color coordinated temperature value ∼148,953 K. Therefore the present NPs quite useful for cool LEDs. The superior photocatalytic activity was observed for CeO2 NPs with 20 ml LA under both UVA and Sunlight irradiation. The enhanced photocatalytic activity and photoluminescent properties were attributed to defect induced band gap engineered CeO2 NPs. Further, CeO2 with 20 ml LA exhibit significant antibacterial activity against Escherichia coli (EC) and Staphylococcus aureus (SA). These findings show great promise of CeO2 NPs as multifunctional material for various applications.

Synthesis, characterizations, antibacterial and photoluminescence studies of solution combustion-derived α-Al2O3 nanoparticles

Abstract In this work, we report a novel, economical, low temperature solution combustion synthesis (SCS) method to prepare α-Al2O3 (Corundum) nanoparticles. Powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), BET surface area and ultraviolet visible spectroscopy (UV–vis) measurements were used to characterize the product. Antibacterial studies were examined against gram −ve Klebsiella aerogenes, Escherichia coli, Pseudomonas desmolyticum and gram +ve Staphylococcus aureus bacteria by agar well diffusion method. The α-Al2O3 nanoparticles showed substantial effect on all the four bacterial strains. Photoluminescence (PL) measurements under excitation at about 255 nm show that the alumina nanoparticles have emission peaks at 394 and 392 nm.

Bio-mediated route for the synthesis of shape tunable Y2O3: Tb3+ nanoparticles: Photoluminescence and antibacterial properties

The study reports green mediated combustion route for the synthesis of Tb(3+) ion activated Y2O3 nanophosphors using Aloe Vera gel as fuel. The concentration of Tb(3+) plays a key role in controlling the morphology of Y2O3 nanostructures. The formation of different morphologies of Y2O3: Tb(3+) nanophosphors were characterized by PXRD, SEM, TEM and HRTEM. PXRD data and Rietveld analysis evident the formation of single phase Y2O3 with cubic crystal structure. The influence of Tb(3+) ion concentration on structural morphology, UV-visible absorption and PL emission were investigated systematically. The PL emission of Y2O3: Tb(3+) (1-11 mol%) nanophosphors were studied in detail under 271 and 304nm excitation wavelengths. The CIE coordinates lies well within green region and correlated color temperature values were found to be 6221 and 5562K under different excitations. Thus, the present phosphor can serve as an excellent candidate for LEDs. Further, prismatic Y2O3: Tb(3+) (3 mol%) nanophosphor showed significant antibacterial activity against Pseudomonas desmolyticum and Staphylococcus aureus. The present study successfully demonstrates Y2O3: Tb(3+) nanophosphors can be used for display applications as well as in medical applications for controlling pathogenic bacteria.

Synthesis, structural characterization of nano ZnTiO3 ceramic: An effective azo dye adsorbent and antibacterial agent

Abstract Nanocrystalline meta-zinc titanate (ZnTiO3) ceramic was prepared using a self-propagating solution combustion synthesis (SCS) for the first time using urea as fuel. The product was calcined at 800 °C for 2 h to improve the crystallinity. Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), high resolution transmission electron microscopy (HR-TEM) and UV–vis absorption spectroscopy were used to characterize the final product. PXRD results show that the ilmenite type rhombohedral structure was formed when the sample was calcined at 800 °C for 2 h. Adsorption experiments were performed with cationic malachite green (MG) dye. ∼96% dye was adsorbed onto nanocrystalline ZnTiO3 ceramic at pH 9 for 30 min of the contact time. The optimum adsorbent dose was found to be 0.45 g/L of dye. Langmuir–Hinshelwood model was used to study adsorption kinetics and first order kinetic model best describes the MG adsorption on ZnTiO3. Antibacterial activity was investigated against gram negative Klebsiella aerogenes, Pseudomonas desmolyticum, Escherichia coli, and gram positive Staphylococcus aureus bacteria by agar well diffusion method. Nanocrystalline ZnTiO3 ceramic showed significant effect on all the four bacterial strains at the concentration of 1000 and 1500 μg per well.

Citrus maxima (Pomelo) juice mediated eco-friendly synthesis of ZnO nanoparticles: Applications to photocatalytic, electrochemical sensor and antibacterial activities ☆

In the present work, Zinc oxide nanoparticles (ZnO Nps) have been successfully prepared through a simple, effective and low cost solution combustion method using Zn (NO3)2·6H2O as an oxidizer, chakkota (Common name=Pomelo) fruit juice as novel fuel. X-ray diffraction pattern indicates the hexagonal wurtzite structure with average crystallite size of ~22nm. ZnO Nps were characterized with the aid of different spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Photoluminescence and UV-Visible spectroscopy. FTIR shows characteristic ZnO vibrational mode at 393cm-1. SEM images show that the particles are agglomerated. TEM image shows the size of the particles are about 10-20nm. Further, in order to establish practical applicability of the synthesized ZnO Nps, photocatalytic degradation of methylene blue (MB) dye as a model system was studied in presence of UV (665nm) light. In addition to this, the antibacterial activity was screen against 3 bacterial strains and electrochemical sensor performance towards the quantification of dopamine at nano molar concentrations was also explored.

Electrochemical Sensing, Photocatalytic and Biological Activities of ZnO Nanoparticles: Synthesis via Green Chemistry Route

In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

Molecular docking and dynamic studies of bioactive compounds from Naravelia zeylanica (L.) DC against glycogen synthase kinase-3β protein

Abstract Bioactive phytochemicals are a rich source of chemopreventive substances. The bioactive constituents of Naravelia zeylanica (L.) DC were extracted and isolated from the leaves, and two sterol compounds, taraxerol and β-sitosterol, were characterized spectroscopically. The compounds were screened for inhibition of glycogen synthase kinase-3β (GSK-3β) protein, a wound-healing biomarker, by molecular docking and dynamic studies. Taraxerol may be a potent inhibitor of GSK-3β because it exhibited minimum binding (−12.59 kJ mol−1) and docking (−11.25 kJ mol−1) energy. Molecular dynamics studies revealed that taraxerol had minimum potential energy with the target protein. Wound-healing was studied in experimental rats in vivo. Taraxerol was efficient, with a mean time of epithelialization of 18.28 ± 1.17 days in the excision wound model. In the incision wound model, it had significant activity, with a skin-breaking strength of 562.36 ± 7.60. The hydroxyproline content of granulation tissue was found to be 1455.93 ± 0.60. Taraxerol was confirmed to have potent wound-healing activity in silico and in vivo.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm−1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.