These days, research in agriculture is focusing on the theme of sustainability along with protection of agriculture produce. Nanotechnology in the agriculture sector aims for the enhancement of ...agricultural produce and the reduction of pesticides through providing innovative agrochemical agents and their novel delivery mechanisms. The current investigation involved the green synthesis of silver nanoparticles (AgNPs) from the aqueous leaf extract of
by following a microwave-assisted method to control
, the causal agent of tomato wilt. Biosynthesized
leaf extract (MLE)-AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectrometry, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential analysis. The intensity of the peak at 434 nm in UV-vis spectra, attributed to the surface plasmon resonance of MLE-AgNPs, changes with reaction parameters. TEM exhibits spherical shaped nanoparticles with an average particle size range from 12 to 46 nm. Efficient inhibition of
, the causal agent of tomato wilt, was achieved after exposure to MLE-AgNPs both
and
.
studies exhibited repressed fungal mycelial growth with 79-98% inhibition as compared to the control. Significant increases in growth parameters of tomato seedlings were observed after treatment with biosynthesized nanoparticles as compared to
-infected plants grown without them under greenhouse conditions. Furthermore, SEM imaging was done to reveal the prominent damage on the cell wall of hyphae and spores after MLE-AgNP treatment. Propidium iodide (PI) staining of mycelium indicated the extent of cell death, causing irretrievable damage and disintegration of cellular membranes by altering the membrane permeability. Also, 2',7'-dichlorofluorescin diacetate (DCFH-DA) fluorescence specifies intracellular reactive oxygen species (ROS) production in
after treatment with MLE-AgNPs. The current investigation suggested that biosynthesized nanoparticles can revolutionize the field of plant pathology by introducing an environment-friendly approach for disease management and playing a potential part in agriculture industry. However, to date, little work has been done to integrate nanotechnology into phytopathology so, this area of research is in need of adoption and exploration for the management of plant diseases.
The properties of manganese-doped ZnO nano-particles fabricated by the sol-gel method were studied. The concentration of Mn in the ZnO was 1–4% w/w. The X-ray diffraction (XRD) confirmed wurtzite ...phase of ZnO. The results showed that Mn
2+
ions substituted Zn
2+
ions without altering the wurtzite structure of ZnO. Crystallite size was increased with increase in Mn doping percentage. Optical transmission recorded by UV–VIS–NIR spectrophotometer decreased with increase in Mn doping percentage. The optical band gap energy was quite low in the range 2.99–3.18 eV as compared to undoped ZnO and found to change with the increase in Mn percentage. Magnetic study displays that the Mn doped ZnO nanoparticles show ferro-magnetism at room temperature and the variation of the Mn percentage can tailor the ferromagnetic behavior of the nano-particles. Maximum coercivity of 228.07(Oe) is achieved for 2.5% Mn dopant and saturation magnetization is 0.03780 emu/g for 1.5% of Mn. Photo-catalytic activity was explored against methylene blue. 1% Mn contents have shown better photo-catalytic activity. It was discovered that ZnO nanoparticles with Mn doping displayed good antibacterial efficiency against
Escherichia coli
(
E. coli
) and
Pseudomonas aeruginosa
(
P. aeruginosa
) bacteria. The results displayed that the antibacterial activity of Mn doped ZnO nano-particles enhances with an increase in Mn percentage. Surface morphology is modified with an increase in Mn percentage. All thin films consist of nano-sized dispersed particles which are in agreement with the XRD results.
Silver nanoparticles (AgNPs) of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC) and sodium ...borohydride as reducing agents, while polyvinylpyrrolidone (PVP) was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM), UV-visible spectroscopy (UV-VIS), and X-ray diffraction (XRD) techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR) peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The
antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria,
and
were examined by Kirby-Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs.
Enteric bacterial human pathogens,
, Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Klebsiella pneumoniae, are the major cause of diarrheal infections in children and adults. Their ...structure badly affects the human immune system. It is important to explore new antibacterial agents instead of antibiotics for treatment. This project is an attempt to explain how gold nanoparticles affect these bacteria. We investigated the important role of the mean particle size, and the inhibition of a bacterium is dose-dependent. Ultra Violet (UV)-visible spectroscopy revealed the size of chemically synthesized gold nanoparticle as 6-40 nm. Atomic force microscopy (AFM) analysis confirmed the size and X-ray diffractometry (XRD) analysis determined the polycrystalline nature of gold nanoparticles. The present findings explained how gold nanoparticles lyse Gram-negative and Gram-positive bacteria.
The present research describes the optical, structural, dielectric, photocatalytic, and antibacterial characteristics of potassium‐doped ZnO thin films synthesized via sol–gel dip coating technique ...with a K doping concentration of (1, 2, 3, 4, 5) wt%. Thin films are annealed at optimized temperatures. K‐doped ZnO has a hexagonal wurtzite phase having a preferential orientation along the (101) plane. The size of the crystallite decreases as the potassium doping percentage rises. Optical analysis reveals that the bandgap decreases when the quantity of K doping in ZnO increases. Dielectric constant experiments show that when the K doping % is raised, AC conductivity of thin films rises as well. Thin film resistivity and Hall coefficient decrease with increasing K concentration, but conductivity, mobility, and carrier concentration rise. Gram‐positive and gram‐negative bacteria are both responsive to K‐doped ZnO. With such antibacterial properties, K‐doped ZnO can be used in biomedicine and to protect the environment. The methylene blue dye is effectively degraded by the photocatalyst K‐doped ZnO, making it useful for removing pollution from wastewater.
Sol–gel-based phenolphthalein immobilized AuNPs (phph-AuNPs) of different shapes such as spherical, dendrites, and flower are observed by varying pHs 1–12. pH 1 induced the Au cages, and pH 2–6 ...revealed the different shapes of dendrites. Moreover, pH 7–8 assisted phph-AuNPs exhibited the spherical shape which transformed into truncated dendrites such as flowers at pH 9–11, and again spheres at pH 12. FTIR spectra exhibited the bonding vibration of AuNPs and phenols. pH 12 assisted phph-AuNPs are observed highly porous (79%) compared to pH 1 assisted phph-AuNPs (60%) porosity and low (1.1) refractive index. Furthermore, pH 1 assisted phph-AuNPs are found to possess RMS 11 nm and thickness 56 nm which increased up to 23 and 88 nm, respectively, by increasing the pH up to 12. The pKa ~9.4 of the pH 1–12 assisted phph dye is observed at 559 nm which increased up to 9.9 at 556 nm for pH 1–12 assisted phph-AuNPs, suggesting a wide range of sensitivity. Fast response time ~0.6 s is measured at pH 12 assisted phph-AuNPs. At acidic pH, higher photoluminescence (PL) intensity indicates a high charge carrier’s recombination. Experimental findings confirmed that pH has a great influence on the morphology of phph-AuNPs.
Highlights
Sol–gel based phph-AuNPs of different shapes such as spherical, dendrites, and flower is observed by varying the pHs 1–12.
FTIR spectra exhibited the bonding vibration of AuNPs and phenols.
pH 12 assisted phph-AuNPs are observed to be highly porous 79%.
The pKa ~9.9 at 559 nm of the pH 1–12 assisted phph-AuNPs, suggested a wide range of sensitivity.
Response time ~0.6 s is measured at pH 12 assisted phph-AuNPs.
Materials in the form of thin films are getting worldwide attention because of their rapid development in the electronics industry. The demand is not only to prepare thin films using low-cost methods ...but also to induce tunable electronic properties (i.e., ferroelectricity, dielectric/impedance behavior, etc.) at room temperature. Keeping in view today’s demand for electronic materials, iron oxide thin films have been prepared using a low-cost sol–gel method with variation in the sol concentration in the range of 0.2–2.0 mM. Spin-coated films have been annealed at 300°C for 60 and 120 min in the presence of a magnetic field. The magnetite (Fe
3
O
4
) phase was observed at 1.4 mM, with preferred orientation along the (220) plane, under as-deposited and annealed conditions. The rest of the concentration range we studied results in the inclusion of small traces of maghemite (
γ
-Fe
2
O
3
) along with magnetite under all the preparation conditions. However, such inclusions result in the shift of preferred orientation from the (220) to the (400) plane of the magnetite (Fe
3
O
4
) phase. Formation of Fe
3
O
4
phase has been confirmed using the Verwey transition at ∼ 124.8 K along with the appearance of a Raman A
1g
band at 667 cm
−1
. A high dielectric constant (∼ 80.23) and low tangent loss (∼ 0.00239) at log
f
= 5.0 were obtained at room temperature for 1.4 mM-based thin films. Such behavior may have been observed because of the high grain boundary resistance (5.5 × 10
4
Ω) and high grain boundary density (0.9939) at a sol concentration of 1.4 mM. An increase in dielectric constant and tangent loss was observed with the increase in temperature from 30 to 210°C. An activation energy of 2.007 eV was observed for the 1.4 mM-based thin films. The conductivity obeys Jonscher’s power law and has been associated with the overlapping large polaron tunneling model. Room-temperature ferroelectricity was observed for iron oxide thin films with maximum polarization (
P
max
∼ 14.74 μC/cm
2
) at 1.4 mM sol concentration.
B-doped ZnO thin films have been synthesized by a sol–gel dip-coating deposition technique. Deposition conditions were optimized to achieve highly ordered thin films. XRD patterns confirm that B ions ...are inserted into the ZnO; lattice and the crystallite size decrease from 25.83 to 20.94 nm as the amount of B increases to optimal value (9 at.wt%). Synthesized B-doped ZnO thin films have ordered hexagonal wurtzite structures and granular morphology with high specific surface area. Optical transmittance spectra display transparency in the visible region. The band gap of the films decreases from 3.89 to 3.04 eV with the increase in B concentration. Band gap lowering is due to increase of defect level with the increase in B dopant percentage. The origin of the ferromagnetism is explained in terms of oxygen vacancies and Zn interstitials. Dielectric constant increases while DC conductivity and AC conductivity decrease with the increase in B doping. Antibacterial activity increases with the increase in B doping percentage but lower than undoped ZnO due to large crystallite size of B-doped ZnO nanostructures.
Cu-doped zinc oxide thin films are dip coated on glass substrates. Zinc acetate and copper acetate are used as metal precursors to synthesize sol. XRD scanning discloses that all films have the ...hexagonal wurtzite structure of ZnO. All films are
a
-axis oriented with preferred orientation along (101). Crystallite size of thin films increased with the increase in the Cu doping percentage from 2 to 10 wt%. TGA scrutiny predicted that weight loss takes place till 530 °C. Increase in Cu doping leads to insignificant decrease in the optical band gap of the thin films. All films show ferromagnetic properties which are due to hybridization of p–d orbitals.
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