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Light-Induced Assembly of Metal Nanoparticles on ZnO Enhances the Generation of Charge Carriers, Reactive Oxygen Species and Antibacterial Activity
摘要： Increasing the photocatalytic activity of semiconductors by forming heterojunctions with metal improves their energy transfer efficiency and environmental remediation capabilities. However, our knowledge regarding the structure-activity relationship of semiconductor/metal hybrid nanostructures is lacking due to poor control over their physicochemical properties. Here, we report a facile way to make ZnO/metal heteronanoparticles by mixing/irradiation process of ZnO and metal nanoparticles. The resultant products provide an expedient model to explore the effects of various metal NPs on light-induced electron/hole separation, reactive oxygen species (ROS) production and antibacterial activities of ZnO NPs. Electron spin resonance spectroscopy was used to compare the effect of mixing Pt, Au, or Ag NPs at different size and concentration with ZnO NPs on light-induced electron-hole separation and ROS production. The enhancing effect of metal NPs depends on particle size, composition, and mass ratio of the metal NPs to the ZnO NPs. Smaller-sized Pt NPs are more efficient in promoting charge carrier generation and ROS production. At 5 nm, Ag NPs promoted charge carrier generation more efficiently than Pt and Au NPs, but Pt NPs promoted ROS generation more efficiently than Au and Ag NPs. These results provide valuable strategy to design the synthesis of semiconductor/metal hybrid nanostructures and easy tailoring of ROS and charge carrier production.
关键词： reactive oxygen species,photocatalytic activity,metal nanoparticles,antibacterial activity,ZnO
更新于2025-09-04 15:30:14
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Antibacterial and photocatalytic activity of hydrothermally synthesized SnO2 doped GO and CNT under visible light irradiation
摘要： Bacterial and dye pollution are major problems with wastewater treatment. An increasing number of photocatalysts are being used in industry to kill bacterial and reduce pollution. In the present study, highly stable SnO2-doped nanocomposites have been prepared successively by a hydrothermal method. The synthesized nanocomposite was characterized using a range of techniques, such as X-ray diffraction, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy and electron probe micro analysis, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, and high resolution transmission electron microscopy (HR-TEM). The nanocomposites showed significant dose-dependent bactericidal activity in the disc diffusion assay and cell viability test. The S-GO-SnO2 200 μg/mL produced a cell viability of 184.3 ± 11.71 and 172.3 ± 3.05 × 106 CFU/mL for E. coli and P. graminis, respectively. The S-GO-SnO2 showed significant photocatalytic degradation against MB in 120 min. The photocatalyst S-GO-SnO2 showed 159 and 161 × 106 CFU/mL at 150 min in E. coli and P. graminis, respectively. The cells treated with photocatalytic SnO2-doped nanocomposites showed 50% cell death. HR-TEM revealed 50% cell growth inhibition by bacterial damage. This photocatalytic SnO2-doped nanocomposite is a good candidate for treating industrial wastewater treatment contaminated with dyes and bacteria.
关键词： Antibacterial activity,Photocatalytic activity,Hydrothermal syntheses,Visible light irradiation,SGO-SnO2,SCNT-SnO2
更新于2025-09-04 15:30:14
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Alternative Green Chemistry Methods of Silver Nanoparticles Synthesis: Review and Comparison
摘要： Green chemistry is a branch of chemistry that deals with natural materials such as plants, fungi, bacteria, algae, and rocks rather than chemical components. Advantages of green chemistry rather than chemical are that no toxic components are released, inexpensive, available anytime, easy to get, and eco-friendly. Metallic nanoparticles have received great attention from chemists, physicists, biologists and engineers who wish to use them for the development of a new generation of nanodevices. One of the important metal nanoparticles is the silver nanoparticles (AgNPs). Silver is a nontoxic agent having an antibacterial, antifungal, and antioxidant properties. AgNPs have been used in many applications such as catalysis, biotechnology, biomedical applications, electronics, and in the treatment of burns and wounds. The green synthesis of AgNPs involves three main steps: the selection of the solvent medium, the selection of environmentally reducing agents, and the selection of non-toxic substances for the stability of AgNPs. In this review, we will discuss some green chemistry methods to synthesize AgNPs via plant extracts and other natural agents, such as fungi, bacteria, and algae. In addition, we will compare between these methods, according to their applications and stabilities.
关键词： Green Chemistry,Antibacterial Activity,Extract,AgNPs,Synthesis
更新于2025-09-04 15:30:14
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Towards understanding the enhancement of antibacterial activity in manganese doped ZnO nanoparticles
摘要： In this work we focus on enhancing the antibacterial activity of ZnO nanoparticles by Mn doping, synthesized using a wet-chemical method. The as-obtained precursor powders were deeply investigated by thermal analyses correlated with the evolved gas analysis (TG-DTA-FT-IR) and by in situ high-temperature XRD to elucidate the thermally induced processes and to understand the manganese doped ZnO nanoparticles formation. The hexagonal wurtzite-type structure and the morphological characteristics of the thermally treated samples have been investigated by X-ray diffraction, and HRTEM. An average particle size ranging between 10 to 29 nm and a polyhedral and spherical morphology with a tendency to form aggregates were evidenced by TEM images. Optical absorption measurements reveal that the band gap of ZnO decreased from 3.19 to 2.99 eV, which confirmed the existence of Zn-O-Mn interaction. The incorporation of the Mn ions into the ZnO lattice has been studied by EPR spectroscopy and also, the generation of reactive oxygen species (ROS) has been evidenced by using the EPR coupled with the spin trapping probe technique. Here, we report that in addition to altering the crystallite size, morphology and optical absorption characteristics of ZnO, the introduction of Mn dopant also improves the antibacterial efficiency against pathogenic microorganisms, namely Escherichia coli and Bacillus cereus.
关键词： Mn doping,antibacterial activity,ZnO nanoparticles,reactive oxygen species,wet-chemical synthesis
更新于2025-09-04 15:30:14
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Studies on growth and characterization of (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate: a nonlinear optical material
摘要： Hydrazone compound (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate (DMABHBH) was synthesized and single crystals of DMABHBH were grown by solvent evaporation method at room temperature. Molecular structure of DMABHBH compound was confirmed by 1H and 13C nuclear magnetic resonance techniques. The presence of functional groups was confirmed by Fourier transform infrared and FT Raman spectral analyses. The X-ray crystal structure was elucidated at 173 K by single crystal X-ray diffraction and the results were compared with the corresponding values obtained at 298 K. The compound crystallizes in the chiral monoclinic space group P21. Mechanical stability of the grown crystals was estimated from the Vicker’s microhardness test. Powder second harmonic generation efficiency of DMABHBH is about 1.1 times that of potassium dihydrogen phosphate. DMABHBH is found to show optical limiting behavior at high input light intensities, the third order nonlinear optical absorption coefficient measured using open aperture Z-scan studies, is 0.95 × 10?11 m/W. Anti-bacterial activity was studied using the well and disc diffusion methods.
关键词： X-ray diffraction,Mechanical properties,Nonlinear optical material,Thermal analysis,Antibacterial activity,Hydrazone,Crystal growth
更新于2025-09-04 15:30:14
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Visible active reduced graphene oxide loaded Titania for photodecomposition of ciprofloxacin and its antibacterial activity
摘要： The reduced Graphene Oxide based titanium dioxide (rGO-TiO2) nanocomposite was synthesized by a simple hydrothermal preparation and characterized by X-ray Diffraction Analysis (XRD), UV–Vis absorption spectroscopy (UV), Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The XRD pattern of rGO-TiO2 indicates the presence of anatase TiO2 and average crystalline size of particles is 32 nm. The optical band gaps of TiO2, GO and rGO-TiO2 nanocomposite are 3.24 eV, 4.3 eV and 2.7 eV respectively. Comparison of efficiencies of three catalysts shows that ciprofloxacin degrades at a faster rate under visible light irradiation in the presence of rGO-TiO2 at 60 min than in presence of pure TiO2 commercial TiO2-P25. Higher photocatalytic decomposition efficiency of rGO-TiO2 is explained by its reduced electron-hole recombination and visible light activity. The kinetics of photodecomposition reaction was analyzed. Antibacterial activity analysis of rGO-TiO2 nanoparticles reveals that it is more active against S. aureus than E.coli.
关键词： Titania,Antibacterial activity,Photocatalytic decomposition,Ciprofloxacin,Reduced graphene oxide
更新于2025-09-04 15:30:14