Applied Nanoscience

The synthesis of water dispersible phosphor materials is important due to the possibility of their applications in sensors, bioimaging, magnetic resonance imaging (MRI), etc. Surfactants are in use for the controlled size synthesis of nanomaterials as well as for tuning the dispersibility of colloidal particles in different solvents. In this study, we exploited cetrimonium bromide (CTAB) with pre-added lanthanide ions or with “so called modified counterions” for the synthesis of water dispersible phosphor materials. Colloidal GdF3:Ce3+(5%), Eu3+(x%) (where x is 1, 3, 5 and 7% Eu+3) and GdF3:Ce3+(5%), Eu3+(5%)/SiO2 phosphor nanocomposites were synthesized. Initially, cationic CTAB system was altered by pre-adding selected lanthanides required for synthesizing phosphors as well as silica–phosphor nanocomposite. Later, the same modified CTABs were used for single step synthesis of nanoparticles as well as nanocomposites. The elemental and structural characterizations were performed using x-ray photoelectron spectroscopy (XPS), and powder x-ray diffraction (XRD) techniques. The size and morphology of the samples were checked using a transmission electron microscope (TEM). The photoluminescence (PL) properties were explored using a spectrofluorometer, and the results established the formation of phosphor nanocomposite. The method expanded the possibilities of size and shape control in for phosphor materials. Furthermore, the study offered a way to decrease the use of lanthanide while keeping the phosphor’s overall properties intact. The results shown that this study can pave an alternate way for the synthesis of nano-sized structures of GdF3: Ce3+(5%) Eu3+(x%) and also for size and shape control in GdF3: Ce3+(5%) Eu3+(x%)/SiO2 type nanocomposites.

Molecular simulations were performed to investigate the structural and electronic properties of graphene (G) nanosheet interacting with the monomer of chitosan (MCh) (C6H13O5N). The G nanosheet with the C54H18 chemical composition is modeled according to the armchair edge and is functionalized with boron atoms. The interaction between the nanosheet and the MCh is investigated to search for better bio-sensing characteristics. Simulations are done within the density functional theory, the generalized gradient approximation is applied to deal with the exchange–correlation energies, and the all-electron basis set with double polarization is used. To determine the structure stability, the minimum energy criterion is applied for the G + MCh system in seven different geometries; in addition, it is checked with the non-complex vibration frequency. Results show chemical interactions between the G nanosheets and the MCh in the ground-state geometry. In this geometry, the monomer is oriented perpendicular to the G nanosheet at a distance of 3.9 Å with the nanosheet remaining unchanged. The nanosheet functionalization with boron (to form an epoxy group) and interaction with the monomer yield improved adsorption conditions with a bond length of Cmesh–B–NAmine = 3.19 Å and the formation of B–N (boron attached to graphene–amine of the monomer) bond of length 1.57 Å. The polarity of the G + B and G + B + MCh systems displays ionic characteristics contrary to G behavior. The (HOMO–LUMO) energy difference is 1.30 eV for the G + B system and 0.75 eV for the G + B + MCh. Finally, the G + B + MCh system is investigated when D-(+)-glucose and cholesterol are adsorbed. Results show chemisorptions, which suggest the system to be used in biosensor devices.

In this investigation, pot culture experiment was carried out to estimate the ameliorating effect of triazole compounds, namely Triadimefon (TDM), Tebuconazole (TBZ), and Propiconazole (PCZ) on drought stress, photosynthetic pigments, and biochemical constituents of Zea mays L. (Maize). From 30 days after sowing (DAS), the plants were subjected to 4 days interval drought (DID) stress and drought with TDM at 15 mg l−1, TBZ at 10 mg l−1, and PCZ at 15 mg l−1. Irrigation at 1-day interval was kept as control. Irrigation performed on alternative day. The plant samples were collected on 40, 50, and 60 DAS and separated into root, stem, and leaf for estimating the photosynthetic pigments and biochemical constituents. Drought and drought with triazole compounds treatment increased the biochemical glycine betaine content, whereas the protein and the pigments contents chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid, and anthocyanin decreased when compared to control. The triazole treatment mitigated the adverse effects of drought stress by increasing the biochemical potentials and paved the way to overcome drought stress in corn plant.

In this study, a kind of ZnO/NiO/CeO2 nanocomposite constructed by solution method was adopted to remove malachite green (MG) dye from water. The nanocomposite was characterized by Zeta potential, SEM, TEM, FTIR, XRD, XPS and BET analysis. The results indicate that ZnO/NiO/CeO2 has hierarchical porous structure containing micropores, mesopores and macropores. Through the study of the adsorption process, the adsorption performance of ZnO/NiO/CeO2 was evaluated systematically. The adsorption conditions such as initial concentration of dye, pH value and adsorption time were considered, and the equilibrium adsorption and kinetic were described by different isotherm and kinetics models. We demonstrate that ZnO/NiO/CeO2 composite displays preferential adsorption performance to cationic dye MG with great adsorption capacity of 7600 mg g−1. The ZnO/NiO/CeO2 nanocomposite displays highest removal rate when pH is 7, with adsorption time of 60 min at room temperature. The pseudo-second-order kinetic and Langmuir isothermal models are well applied to the adsorption process of MG on ZnO/NiO/CeO2. The adsorbent can be recycled for four times and maintain good adsorption performance all the time.

Metal and metal oxide nanoparticles have gained huge interest due to their unique chemical and physical attributes that confer antimicrobial potential against a wide spectrum of pathogenic bacterial strains. Hence, the objective of the present study focused on synthesis of simple, cost-effective and environmentally friendly biofunctionalized cuprous oxide nanoparticles using root extract of Withania somnifera as antibacterial agents. The average size of the nanoparticles was found to be 410 nm with an energy band gap of 4.63 eV as confirmed by scanning electron microscopy and UV–visible spectroscopy, respectively. The chemical composition of the biofunctionalized Cu2O NPs was confirmed with the help of energy-dispersive X-ray analysis (EDAX). Vibrational studies of the cuprous oxide nanoparticles by Fourier transform infrared spectroscopy (FT-IR) gave a distinctive absorption band at 626 cm−1. The bactericidal effects of synthesized nanoparticles are attributed to different bioactive compounds, such as phthalic acid, purin-6-amine, hexadecanoic acid and benzene dicarboxylic acid, as analysed by gas chromatography–mass spectrometry (GC–MS). Finally, the antibacterial activities of cuprous oxide nanoparticles on Bacillus, Enterobacter, Escherichia and Mycobacterium were investigated by calculating the minimum bactericidal concentration (MBC) and colony forming unit (CFU) content by the broth dilution method. The biofunctionalized Cu2O NPs appeared to have strong antibacterial activity with 100% of inhibition against Escherichia coli, Enterobacter aerogenes and Mycobacterium smegmatis at MBC value 0.8 mg/ml whereas 100% inhibition against Bacillus subtilis at MBC value 1.0 mg/ml. The findings of our study suggest that the biofunctionalized Cu2O NPs coated with bioactive compounds from root extracts of Withania somnifera could be a promising antimicrobial agent for a wide range of pathogenic strains, especially Mycobacterium tuberculosis.

Hydroxyapatite (HA) nanoparticles have been synthesized using ortho-phosphoric acid as the source of PO43− ions, and calcium chloride, suitably complexed with triethanolamine, as the calcium source. The effect of temperature on the morphology of the product has been investigated. The chemical compositions of the samples have been established through Fourier transform infrared spectroscopy. This study reveals that A-type and B-type carbonate substitution are present in HA samples and the concentration of carbonate ions decrease with rise in temperature. Morphological analyses by TEM studies suggest that the average lengths and widths of the needle-shaped particles size increases with temperature up to 50 °C, while a morphological change of the particles from needle to spherical shape is observed on raising the temperature above 50 °C. This change in morphology has been assigned to the apparent solubility of HA at these temperatures, which has been studied by the determination of thermochemical properties of the reaction system by endpoint conductivity and electrophoretic mobility measurements.