Synthesis and characterization of some abundant nanoparticles, their antimicrobial and enzyme inhibition activity

Although the antimicrobial activity of the engineered nanoparticles (NPs) is well known, the biochemical mechanisms underlying this activity are not clearly understood. Therefore, four NPs with the highest global production, namely SiO2, TiO2, ZnO, and Ag, were synthesized and characterized. The synthesized SiO2, TiO2, ZnO, and Ag NPs exhibit an average size of 11.12, 13.4, 35, and 50 nm, respectively. The antimicrobial activity of the synthesized NPs against bacteria and fungi were also determined. NPs-mediated inhibition of two very important enzymes, namely urease and DNA polymerase, is also reported. The synthesized NPs especially Ag and ZnO show significant antimicrobial activity against bacteria and fungi including methicillin-resistant Staphylococcus aureus even at low concentration. The DNA polymerase activity was inhibited at a very low concentration range of 2–4 µg/ml, whereas the urease activity was inhibited at a high concentration range of 50–100 µg/ml. Based on their ability to inhibit the urease and DNA polymerase, NPs can be arranged in the following order: Ag > ZnO > SiO2 > TiO2 and Ag > SiO2 > ZnO > TiO2, respectively. As the synthesized NPs inhibit bacterial growth and suppress the activity of urease and DNA polymerase, the use of these NPs to control pathogens is proposed

Synthesis and Characterization of Hybrid Materials Consisting of n-octadecyltriethoxysilane by Using n-Hexadecylamine as Surfactant and Q0 and T0 Cross-Linkers

Novel hybrid xerogel materials were synthesized by a sol-gel procedure. n-octadecyltriethoxysilane was co-condensed with and without different cross-linkers using Q0 and T0 mono-functionalized organosilanes in the presence of n-hexadecylamine with different hydroxyl silica functional groups at the surface. These polymer networks have shown new properties, for example, a high degree of cross-linking and hydrolysis. Two different synthesis steps were carried out: simple self-assembly followed by sol-gel transition and precipitation of homogenous sols. Due to the lack of solubility of these materials, the compositions of the new materials were determined by infrared spectroscopy, 13C and 29Si CP/MAS NMR spectroscopy and scanning electron microscopy

Insights into the Electronic, Optical, and Anti-Corrosion Properties of Two-Dimensional ZnO: First-Principles Study

The electronic, optical, and anticorrosion properties of planer ZnO crystal and quantum dots are explored using density functional theory calculations. The calculations for the finite ZnO quantum dots were performed in Gaussian 16 using the B3LYP/6-31g level of theory. The periodic calculations were carried out using VASP with the plane wave basis set and the PBE functional. The subsequent band structure calculations were performed using the hybrid B3LYP functional that shows accurate results and is also consistent with the finite calculations. The considered ZnO nanodots have planer hexagonal shapes with zigzag and armchair terminations. The binding energy calculations show that both structures are stable with negligible deformation at the edges. The ZnO nanodots are semiconductors with a moderate energy gap that decreases when increasing the size, making them potential materials for anticorrosion applications. The values of the electronic energy gaps of ZnO nanodots are confirmed by their UV-Vis spectra, with a wide optical energy gap for the small structures. Additionally, the calculated positive fraction of transferred electrons implies that electron transfer occurs from the inhibitor (ZnO) to the metal surface to passivate their vacant d-orbitals, and eventually prevent corrosion. The best anti-corrosion performance was observed in the periodic ZnO crystal with a suitable energy gap, electronegativity, and fraction of electron transfer. The effects of size and periodicity on the electronic and anticorrosion properties are also here investigated. The findings show that the anticorrosion properties were significantly enhanced by increasing the size of the quantum dot. Periodic ZnO crystals with an appropriate energy gap, electronegativity, and fraction of electron transfer exhibited the optimum anticorrosion performance. Thus, the preferable energy gap in addition to the most promising anticorrosion parameters imply that the monolayer ZnO is a potential candidate for coating and corrosion inhibitors

Magnetic and Characterization Studies of CoO/Co3O4 Nanocomposite

CoO/Co3O4 nanoparticles (NPs) were synthesized by using a fresh egg white-assisted combustion method which acts as a new approach for green synthesis of this composite. This method was carried out by the direct heat of cobalt precursor with egg white at low temperature for very short period. In fact, this route is a novel, cheap and appropriate technique yielding nanoparticle-based materials. CoO/Co3O4 nanoparticles were characterized by examining the structure and identifying the elements and determining the morphology via XRD, FTIR, SEM, EDS and TEM techniques. The sample magnetic observations were measured through the use of a vibrating sample magnetometer (VSM). The results of XRD, EDS, SEM and TEM confirmed the positive synthesis of the cubic CoO/Co3O4 NPs with sponge crystals which proceed. For the as synthesized composite, 57.75 m2/g, 0.0148 cc/g and 10.31 nm were identified to be the SBET, Vp and ȓ, respectively. The cobalt oxide particles in their nature were polycrystalline, and the crystallite sizes varied from 10 to 20 nm. The magnetic measurement showed that the prepared nanocomposite displays room temperature ferromagnetism with an optimum value, 3.45 emu/g, of saturation magnetization

Magnetic and Electronic Properties of Edge-Modified Triangular WS₂ and MoS₂ Quantum Dots

The magnetic and electronic properties of zigzag-triangular WS2 and MoS2 quantum dots are investigated using density functional theory calculations. The pristine WS2 and MoS2 nanodots hold permanent spin on their edges which originates from the unpaired electrons of the transition metals at the edges. The ferromagnetic spin ordering in zigzag-triangular WS2 and MoS2 can be transformed to antiferromagnetic ordering with S = 0 and to nonmagnetic, respectively, by edge passivation with 2H. The calculations of the Curie Temperature indicate that these magnetic states are stable and withstand room temperature. The paramagnetic susceptibility of these structures significantly decreases by edge sulfuration. Moreover, it can be converted to diamagnetic susceptibility by edge passivation with 2H as found in WS2 nanodots. These structures are semiconductors with energy gaps of ~3.3 eV that decrease unexpectedly by edge passivation due to the existence of lone pairs from S atoms that give a high contribution to the low-energy molecular orbitals. With these preferable magnetic properties and controlled electronic ones, WS2 and MoS2 quantum dots are potential candidates for spintronic applications

Exploring the structural, electronic, and hydrogen storage properties of hexagonal boron nitride and carbon nanotubes: insights from single-walled to doped double-walled configurations

Abstract This study investigates the structural intricacies and properties of single-walled nanotubes (SWNT) and double-walled nanotubes (DWNT) composed of hexagonal boron nitride (BN) and carbon (C). Doping with various atoms including light elements (B, N, O) and heavy metals (Fe, Co, Cu) is taken into account. The optimized configurations of SWNT and DWNT, along with dopant positions, are explored, with a focus on DWNT-BN-C. The stability analysis, employing binding energies, affirms the favorable formation of nanotube structures, with DWNT-C emerging as the most stable compound. Quantum stability assessments reveal significant intramolecular charge transfer in specific configurations. Electronic properties, including charge distribution, electronegativity, and electrical conductivity, are examined, showcasing the impact of doping. Energy gap values highlight the diverse electronic characteristics of the nanotubes. PDOS analysis provides insights into the contribution of atoms to molecular orbitals. UV–Vis absorption spectra unravel the optical transitions, showcasing the influence of nanotube size, dopant type, and location. Hydrogen storage capabilities are explored, with suitable adsorption energies indicating favorable hydrogen adsorption. The desorption temperatures for hydrogen release vary across configurations, with notable enhancements in specific doped DWNT-C variants, suggesting potential applications in high-temperature hydrogen release. Overall, this comprehensive investigation provides valuable insights into the structural, electronic, optical, and hydrogen storage properties of BN and C nanotubes, laying the foundation for tailored applications in electronics and energy storage

Electronic and Optical Properties of Finite Gallium Sulfide Nano Ribbons: A First-Principles Study

The electronic and optical properties of finite GaS nanoribbons are investigated using density functional theory calculations. The effect of size, edge termination, and chemical modification by doping and edge passivation are taken into account. The dynamical stability is confirmed by the positive vibration frequency from infrared spectra; further, the positive binding energies ensure the stable formation of the considered nanoribbons. Accurate control of the energy gap has been achieved. For instance, in armchair nanoribbons, energy gaps ranging from ~ 1 to 4 eV were obtained in varying sizes. Moreover, the energy gap can be increased by up to 5.98 eV through edge passivation with F-atoms or decreased to 0.98 eV through doping with Si-atoms. The density of states shows that the occupied molecular orbitals are dominated by S-atoms orbitals, while unoccupied ones are mostly contributed to by Ga orbitals. Thus, S-atoms will be the electron donor sites, and Ga-atoms will be the electron acceptors in the interactions that the nanoribbons might undergo. The nature of electron–hole interactions in the excited states was investigated using various indices, such as electron–hole overlapping, charge–transfer length, and hole–electron Coulomb attraction energy. The UV-Vis absorption spectra reveal a redshift by increasing the size in the armchair or the zigzag directions. Chemical functionalization shows a significant influence on the absorption spectra, where a redshift or blueshift can be achieved depending on the dopant or the attached element

Electronic and gas sensing properties of ultrathin TiO2 quantum dots: A first-principles study

Clean air is essential for a sustainable and healthy human settlement. Hazardous gases produced by industry ruin the air quality, thus it is crucial to find efficient treatment methods. The capability of ultrathin TiO2 quantum dots to adsorb different gases, namely CO, CO2, SO2, H2S, NO2, NH3, and O3, are investigated using DFT calculations. Based on electronic properties and molecular electrostatic potential, edge Ti-atoms are highly interactive and are suitable active sites for gas adsorption. Adsorption energy, charge transfer, and atom in molecule analysis confirm that all the considered gases are successfully absorbed. The UV–Vis spectrum experience redshift /blueshift after adsorption of (CO, CO2, H2S, NH3)/(H2S, O3) and thus can be used to test the adsorption process. These favorable adsorption properties and the calculated quick recovery time make the two-dimensional TiO2 quantum dots potential candidates for efficient and reusable gas sensors

Role of N-Acetylcysteine and Coenzyme Q10 in the Amelioration of Myocardial Energy Expenditure and Oxidative Stress, Induced by Carbon Tetrachloride Intoxication in Rats

This study is designed to evaluate the potential impact of N-acetyl cysteine (NAC) and coenzyme Q10 (CoQ10) each alone or in combination against carbon tetrachloride (CCl 4 )-induced cardiac damage in rats. Animals were treated with CCl 4 in single intraperitoneal dose of 1 mL/Kg body weight; CCl 4 -intoxicated animals were pretreated with 20 mg/kg/d NAC or pretreated with 200 mg/kg/d CoQ10 or NAC and CoQ10 with the same previously mentioned doses. Carbon tetrachloride–intoxicated rats showed a significant elevation in nitric oxide and lipid peroxides and downregulation in reduced glutathione level and calcium adenosine triphosphatase. Cardiac glycolytic enzymes levels such as lactate dehydrogenase, phosphofructokinase, and hexokinase were declined coupled with a reduction in glucose content after CCl 4 treatment. Moreover, myocardial hydroxyproline level was significantly increased after CCl 4 -treatment indicating accumulation of interstitial collagen. N-acetyl cysteine and/or CoQ10 effectively alleviated the disturbances in myocardial oxidative stress and antioxidant markers. These antioxidants effectively upregulated the reduction in cardiac energetic biomarkers due to CCl 4 treatment. N-acetyl cysteine and/or CoQ10 significantly decreased hydroxyproline level compared to that of CCl 4 -treated rats. The current data showed that the aforementioned antioxidants have a remarkable cardioprotective effect, suggesting that they may be useful as prophylactic agents against the detrimental effects of cardiotoxins

Synthesis of biodiesel from castor oil catalyzed by sodium hydroxide dispersed on bentonite

The present study describes the production of biodiesel from castor plant (Riccinus communis) using heterogeneous base catalyst of NaOH dispersed on bentonite. The catalysts were prepared via wet impregnation by loading a known amount of NaOH on natural bentonite in various NaOH-to-bentonite ratios of 5 %, 10 %, 20 %, and 25 % (w/w). The prepared catalysts were characterized by AAS, FTIR, XRD, GSA, and SEM; and further used in a transesterification reaction at 60 ◦C for 4 h. The liquid yields were analyzed by FTIR and GC–MS, 1 H NMR, and ASTM. The modification of a larger concentration of NaOH led to decreasing the mineral structure of natural bentonite. The homogeneous distribution of NaOH on bentonite influenced the increasing pore size of catalyst compared to natural bentonite. The enhanced physicochemical properties significantly increased the catalytic activity. The transesterification reaction of castor oil into biodiesel over 25 % NaOH/bentonite catalyst showed the highest conversion of 76.94 % biodiesel yield. The obtained biodiesel properties was agreed with the ASTM standard specifications