Bio-fabrication of zinc oxide nanoparticles using leaf extract of curry leaf (Murraya koenigii) and its antimicrobial activities

The present study focused on the development of zinc oxide nanoparticles (ZnO NPs) from the leaf extract of Murraya koenigii where zinc nitrate acts as the precursor. The X-ray diffraction (XRD) analysis showed the crystalline structure, and atomic force microscopy (AFM) showed the morphology of the ZnO NPs to be spherical with an average size of 12 nm. Functional groups of the sample were identified by using Fourier transmission infrared (FT-IR) spectroscopy. Their shape, structure and composition were assessed by Field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The results depicted that synthesized ZnO NPs were moderately stable and hexagonal shape, spherical shape with maximum particle size less than 100 nm. The green-synthesized ZnO NPs had prominent activities against Staphylococcus aureus (14.0±0.50 mm) and followed by Bacillus subtilis (13.8±0.76 mm) at the concentration of 200 µg/mL.     

Enhanced photocatalytic degradation properties of zinc oxide nanoparticles synthesized by using plant extracts

ZnO nanoparticles were successfully prepared by biological synthesis using aqueous extracts of Allium sativum (garlic), Allium cepa (onion) and Petroselinum crispum (parsley). For all ZnO samples, the XRD studies reveal a hexagonal wurtzite structure, without supplementary diffraction lines. The particle size is influenced by the type of plant extract used and varies between 14 and 70 nm. The biomolecules involved in the biosynthetic procedure was evidenced by FTIR spectroscopy. The presence of Mn and Fe in ZnO powders synthesized by using plant extracts was highlighted by ICP-MS. The EPR spectroscopy confirms the presence of Fe³⁺ and Mn²⁺ ions in ZnO samples and its variation depending on the plant extract. Also, Zn vacancy complexes and oxygen vacancies are present in all analyzed samples. A narrowing of the band gap for the ZnO prepared with plant extracts was observed as compared to that of the ZnO, prepared using solely ultrapure water. The photodegradation studies conducted in the presence of UV light irradiation indicated that ZnO nanoparticles prepared using garlic extract exhibit the highest efficiency in the photodegradation of methylene blue dye.     

Green synthesis of multifunctional zinc oxide (ZnO) nanoparticles using Cassia fistula plant extract and their photodegradative,antioxidant and antibacterial activities

The present study involves green synthesis of ZnO nanoparticles (Nps) using aqueous Cassia fistula plant extract as fuel by solution combustion synthesis. The ZnO Nps were characterized by Powder X- ray diffraction (PXRD), UV–visible studies and Transmission electron microscopy (TEM). The Nps were evaluated for photodegradative, antimicrobial and antioxidant activities. The extract was found to contain reducing components such as polyphenols (11%) and flavonoids (12.5%). The Nps were found to have a hexagonal wurtzite structure. UV–visible absorption of ZnO Nps showed absorption band at 370 nm which can be assigned to the intrinsic band-gap absorption of ZnO due to the electron transitions from the valence band to the conduction band. TEM image confirms the formation of nanoparticles and the average crystallite sizes were found to be ~5–15 nm. Methylene blue (MB) dye was effectively degraded under UV and Sun light illumination in the presence of ZnO Nps. Significant antioxidant activity was exhibited by Nps through scavenging of 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals. Excellent bactericidal activity was shown by the Nps on Klebsiella aerogenes, Escherichia coli, Plasmodium desmolyticum and Staphylococcus aureus. Synthesis of multifunctional ZnO Nps using naturally occurring plant products has been advocated as a possible environment friendly alternative to chemical methods.     

Facile and rapid production of conductive flexible films by deposition of polythiophene nanoparticles on transparent poly(ethyleneterephthalate): Electrical and morphological properties

In this work, polythiophene (PTh) nanoparticles were successfully deposited on poly(ethyleneterephthalate) (PET) substrate as thin film by a facile and rapid chemical oxidative deposition method using a binary organic solvent system in the presence of N-cetyl-N,N,N-trimethylammonium bromide (CTAB) as cationic surfactant. The electrical conductivity of PTh nanoparticles deposited on PET was optimized by adjusting the surfactant/oxidant/monomer molar ratio, monomer concentration and time of polymerization. Resulted film was conductive, transparent and flexible which can be used in electronic devices such as OLEDs. Electrical conductivity for the un-doped deposited PTh nanoparticles at oxidant/monomer molar ratio of 5:1 at 0 °C polymerized for 12 min was measured to be 1.18×10⁻² S/cm. The effect of oxidant and monomer concentration on polymerization yield was also investigated. The structural confirmation and transparency of the PTh nanoparticle coated PET films were characterized by FTIR and UV–vis spectroscopy, respectively. Field emission scanning electron microscopy (FESEM), laser particle size analysis and transmission electron microscopy (TEM) were employed for surface morphology and size distribution measurements of PTh nanoparticles. The results showed that the PTh nanoparticles are deposited as globular aggregates with average size of about 50 nm on PET.     

Growth and visible photoluminescence of highly oriented (1 0 0) zinc oxide film synthesized on silicon by plasma immersion ion implantation

High-quality (1 0 0) ZnO films with smooth surface topography have been synthesized on Si substrate by plasma immersion ion implantation. The materials exhibit compressive stress because of room temperature growth. After annealing at different temperatures, various visible photoluminescence bands are observed. The optical phenomenon as well as the transition mechanism which may involve defects such as [Zn_I], [V_Zn], and [O_i⁻] induced by the high substrate bias are discussed in this paper.