Green Synthesis of NiO-SnO2 Nanocomposite and Effect of Calcination Temperature on Its Physicochemical Properties: Impact on the Photocatalytic Degradation of Methyl Orange.

Background: Nickel stannate nanocomposites could be useful for removing organic and toxic water pollutants, such as methyl orange (MO). Aim: The synthesis of a nickel oxide-tin oxide nanocomposite (NiO-SnO2 NC) via a facile and economically viable approach using a leaf extract from Ficus elastica for the photocatalytic degradation of MO. Methods: The phase composition, crystallinity, and purity were examined by X-ray diffraction (XRD). The particles' morphology was studied using scanning electron microscopy (SEM). The elemental analysis and colored mapping were carried out via energy dispersive X-ray (EDX). The functional groups were identified by Fourier transform infrared spectroscopy (FTIR). UV-visible diffuse reflectance spectroscopy (UV-vis DRS) was used to study the optical properties such as the absorption edges and energy band gap, an important feature of semiconductors to determine photocatalytic applications. The photocatalytic activity of the NiO-SnO2 NC was evaluated by monitoring the degradation of MO in aqueous solution under irradiation with full light spectrum. The effects of calcination temperature, pH, initial MO concentration, and catalyst dose were all assessed to understand and optimize the physicochemical and photocatalytic properties of NiO-SnO2 NC. Results: NiO-SnO2 NC was successfully synthesized via a biological route using F. elastica leaf extract. XRD showed rhombohedral NiO and tetragonal SnO2 nanostructures and the amorphous nature of NiO-SnO2 NC. Its degree of crystallinity, crystallite size, and stability increased with increased calcination temperature. SEM depicted significant morphological changes with elevating calcination temperatures, which are attributed to the phase conversion from amorphous to crystalline. The elemental analysis and colored mapping show the formation of highly pure NiO-SnO2 NC. FTIR revealed a decrease in OH, and the ratio of oxygen vacancies at the surface of the NC can be explained by a loss of its hydrophilicity at increased temperatures. All the NC samples displayed significant absorption in the visible region, and a blue shift is seen and the energy band gap decreases when increasing the calcination temperatures due to the dehydration and formation of compacted large particles. NiO-SnO2 NC degrades MO, and the photocatalytic performance decreased with increasing calcination temperature due to an increase in the crystallite size of the NC. The optimal conditions for the efficient NC-mediated photocatalysis of MO are 100 °C, 20 mg catalyst, 50 ppm MO, and pH 6. Conclusions: The auspicious performance of the NiO-SnO2 NCs may open a new avenue for the development of semiconducting p-n heterojunction catalysts as promising structures for removing undesirable organic pollutants from the environment.

In-vivo toxicity and therapeutic efficacy of Paeonia emodi-mediated zinc oxide nanoparticles: In-vitro study.

This study was planned to explore the in-vitro and in-vivo therapeutic significance of Paeonia emodi-mediated zinc oxide nanoparticles (ZnO NPs) against the Staphylococcus aureus and Escherichia coli. The texture parameters were derived from nitrogen adsorption-desorption data using Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, and the surface area (SBET ) was found to be 214 m2 /g with a pore size of 2.3 nm. The crystallographic parameters were investigated through X-ray diffraction analysis, and the calculated crystallite size is 29.13 nm. The microstructure was examined through transmission and scanning electron microscopies (TEM and SEM, respectively), and the average particle size estimated from a TEM image is 44.40 nm. The chemical composition and attached function groups were identified through energy-dispersive X-ray and Fourier transform infrared spectroscopies. The in-vitro minimum inhibitory concentration (MIC) for both bacterial species results was found less than 2 µg/ml. The tolerance limit of mouse models was evaluated by the inoculation of different concentrations of ZnO suspension where the concentration above 23 ppm was proved lethal. The maximum infection was caused in mouse models by inoculation of 3 × 107 CFUs (Colony forming unit) of the both bacterial species. The concentration higher than 3 × 107 CFUs led to the ultimate death of the mice. The histopathological and hematological studies reveal that the after simultaneous inoculation of both ZnO NPs and bacterial suspensions (tolerated amount), no/negligible infection was found in the mice model.

In-Vitro and In-Vivo Tolerance and Therapeutic Investigations of Phyto-Fabricated Iron Oxide Nanoparticles against Selected Pathogens.

The Paeonia emodi (P. emodi)-mediated iron oxide nanoparticles (Fe2O3 NPs) were screened for in-vitro and in-vivo antibacterial activity against the Staphylococcus aureus (S. aureus) (ATCC #: 6538) and Escherichia coli (E. coli) (ATCC #:15224). The synthesized Fe2O3 NPs were characterized via nitrogen adsorption-desorption process, X-ray diffractometer (XRD), transmission and scanning electron microscopies (TEM and SEM), energy dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopies. The SBET was found to be 94.65 m2/g with pore size of 2.99 nm, whereas the average crystallite and particles size are 23 and 27.64 nm, respectively. The 4 µg/mL is the MIC that inhibits the growth of E. coli, whereas those for S. aureus are below the detection limit (<1.76 µg/mL). The tolerance limit of the mice model was inspected by injecting different concentration of Fe2O3 NPs and bacteria suspensions. The 14 ppm suspension was the tolerated dose and the concentration above were proved lethal. The most severe infection was induced in mice with injection of 3 × 107 CFUs of both bacteria, while the inoculation of higher concentrations of bacterial suspensions resulted in the mice's death. The histopathological and hematological studies reveals that the no/negligible infection was found in the mice exposed to the simultaneous inoculation of Fe2O3 NPs (14 ppm) and bacterial suspensions (3 × 107 CFUs).

Structural and biological investigation of biogenically synthesized titanium dioxide nanoparticles: Calcination and characterization.

The antimicrobial drug resistance is increasing with the passage of time due to wide and improper use of broad spectrum drugs and the demand of the new drug increases day by day. The present study was planned to encounter this problem by synthesizing titanium dioxide nanoparticles (TiO2 NPs) by an eco-friendly route using Cannabis sativa leaves extract. The synthesized TiO2 NPs were calcined at 100, 300, 600, and 900°C in a muffle furnace. The crystallographic parameters were studied by X-ray diffraction and the phase transition occurred above 600°C. The surface morphology of the synthesized samples was studied by transmission electron microscopy (TEM), and scanning electron microscopy (SEM) and the particle size was measured through the ImageJ software. The elemental composition and purity of all the samples were studied by performing energy dispersive X-ray (EDX). All the synthesized TiO2 NPs were tested for their antimicrobial effect against Gram-positive and Gram-negative bacteria using the agar well diffusion method. The activity was found higher against Gram-negative bacteria and compared to Gram-positive bacteria.

Populus ciliata mediated synthesis of silver nanoparticles and their antibacterial activity.

Design and synthesis of bactericidal and fungicidal agents is very important to protect human beings from different diseases. Silver nanoparticles (AgNPs) possess good bactericidal properties. Synthesis of these nanoparticles (NPs) via green route is cost-effective and environmentally harmonious as compared to the chemical and physical approaches. In this work, AgNPs were synthesized through green synthesis method using Populus ciliata leaf extract. The synthesized AgNPs were characterized by x-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray (EDX) techniques. The XRD pattern depicted the characteristic Bragg's peaks of (111), (200), (220), and (311) planes which are the features of face centered cubic (FCC) geometry of the synthesized AgNPs. TEM micrographs revealed the spherical shaped particles having average size of 4 nm. The AgNPs showed inhibitory effects against selected gram positive (Staphylococcus epidermidis and Streptococcus pyogenes) and gram negative bacteria (Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas pseudoalcaligenes). The maximum zone of inhibition (26 mm) was observed for gram negative bacterium (Serratia marcescens) when 25 mg/ml solution of AgNPs was used and for similar concentration of these NPs, the maximum zone of inhibition (25 mm) was observed against gram positive bacteria (S. pyogenes). The results indicated good bactericidal potential of the synthesized AgNPs. RESEARCH HIGHLIGHTS: Populus ciliata leaf extract mediated synthesis of AgNPs. Transmission electron microscopy analysis revealed very small size of the synthesized AgNPs (4 nm). The synthesized AgNPs were found very effective against various bacterial pathogens.

Synthesis of enriched boron nitride nanocrystals: A potential element for biomedical applications.

The shortcomings in Boron neutron capture therapy (BNCT) and Hyperthermia for killing the tumor cell desired for the synthesis of a new kind of material suitable to be first used in BNCT and later on enable the conditions for Hyperthermia to destroy the tumor cell. The desire led to the synthesis of large band gap semiconductor nano-size Boron-10 enriched crystals of hexagonal boron nitride (10BNNCs). The contents of 10BNNCs are analyzed with the help of x-ray photoelectron spectroscopy (XPS) and counter checked with Raman and XRD. The 10B-contents in 10BNNCs produce 7Li and 4He nuclei. A Part of the 7Li and 4He particles released in the cell is allowed to kill the tumor (via BNCT) whereas the rest produce electron-hole pairs in the semiconductor layer of 10BNNCs suggested to work in Hyperthermia with an externally applied field.