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Metal oxide nanomaterials are one of the preferences as antibacterial active materials. Due to its distinctive electronic configuration and suitable properties, ZnO is one of the novel antibacterial active materials. Nowadays, researchers are making a serious effort to improve the antibacterial activities of ZnO by forming a composite with the same/different bandgap semiconductor materials and doping of ions. Applying capping agents such as polymers and plant extract that control the morphology and size of the nanomaterials and optimizing different conditions also enhance the antibacterial activity. Forming a nanocomposite and doping reduces the electron/hole recombination, increases the surface area to volume ratio, and also improves the stability towards dissolution and corrosion. The release of antimicrobial ions, electrostatic interaction, reactive oxygen species (ROS) generations are the crucial antibacterial activity mechanism. This review also presents a detailed discussion of the antibacterial activity improvement of ZnO by forming a composite, doping, and optimizing different conditions. The morphological analysis using scanning electron microscopy, field emission-scanning electron microscopy, field-emission transmission electron microscopy, fluorescence microscopy, and confocal microscopy can confirm the antibacterial activity and also supports for developing a satisfactory mechanism.Graphical abstract showing the metal oxides antibacterial mechanism and the fluorescence and scanning electron microscopic images.

We reported a facile, green and eco-friendly approach for the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous extract of Garcinia mangostana ( G. mangostana ) fruit pericarp as reducing agent as well as capping agent. Biosynthesized ZnO NPs were characterized by various analytical tools using X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and UV–Vis spectroscopy. The results showed that ZnO NPs synthesized by aqueous extract of G. mangostana fruit pericarp with high purity, mostly spherical in shape with an average size of 21 nm. The photocatalytic activity of biosynthesized ZnO NPs was evaluated by carrying out the degradation of malachite green dye under solar irradiation. The extent of MG dye degradation was monitored spectrophotometrically by measuring absorbance at its characteristics λ max value of 615 nm. Degradation products were detected using liquid chromatography–mass spectrophotometry technique. The biosynthesized ZnO NPs showed an excellent photocatalyst performance due to the small size and high purity.

Graphene oxide (GO) was obtained through modified hummers method, and reduced graphene oxide (rGO) was acquired by employing heat treatment. Various concentrations (2.5, 5, 7.5, and 10 wt. %) of silver (Ag) were incorporated in GO nanosheets by adopting hydrothermal approach. Synthesized Ag decorated rGO photocatalyst Ag/rGO was characterized using X-ray diffraction (XRD) to determine phase purity and crystal structure. XRD patterns showed the formation of GO to Ag/rGO. Molecular vibration and functional groups were determined through Fourier Transform Infrared spectroscopy (FTIR). Optical properties and a decrease in bandgap with insertion of Ag were confirmed with UV-Visible (Uv-Vis) spectrophotometer and photoluminescence (PL). Electronic properties and disorders in carbon structures were investigated through Raman spectroscopy that revealed the existence of characteristic bands (D and G). Surface morphology of prepared samples was examined with field emission scanning electron microscope (FESEM). Homogeneous distribution, size, and spherical shape of Ag NPs over rGO sheets were further confirmed with the help of high-resolution transmission electron microscope (HR-TEM). Dye degradation of doped and undoped samples was examined through Uv-Vis spectra. Experimental results indicated that photocatalytic activity of Ag@rGO enhanced with increased doping ratio owing to diminished electron-hole pair recombination. Therefore, it is suggested that Ag@rGO can be used as a beneficial and superior photocatalyst to clean environment and wastewater.

Bacteria have an ability to produce cellulose in pure form without any impurities such as hemicellulose and lignin, unlike plant cellulose. Bacterial cellulose as-produced with 3-D interwoven nanofibrous network is superior to plant cellulose in terms of mechanical properties, porosity, crystallinity, water holding capacity, and sustainability. In its natural form, bacterial cellulose is in the form of a hydrogel, which implies high porosity and holding capacity, however, to use it for different applications, water needs to be removed. The physical properties of bacterial cellulose such as morphology, porosity, and mechanical strength are vastly affected by the drying method employed. This paper presents a case study in which we produced bacterial cellulose using two different strains, followed by systematically studying the effect of drying (oven and freeze drying) on physiochemical, morphological, and structural properties of as-produced bacterial cellulose using Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, BET surface area, and tensile testing. Oven-dried bacterial cellulose showed higher crystallinity, reduced fiber diameter, and narrow size distribution and higher mechanical properties as compared to freeze-dried bacterial cellulose. Understanding so developed in this work may allow us to simply tune the bacterial cellulose properties for a given application.

Background Increasing antibiotic resistance continues to focus on research into the discovery of novel antimicrobial agents. Due to its antimicrobial and wound healing-promoting activity, metal nanoparticles have attracted attention for dermatological applications. This study is designed to investigate the scope and bactericidal potential of zinc ferrite nanoparticles (ZnFe 2 O 4 NPs), and the mechanism of anti-bacterial action along with cytocompatibility, hemocompatibility, and wound healing properties. Results ZnFe 2 O 4 NPs were synthesized via a modified co-precipitation method. Structure, size, morphology, and elemental compositions of ZnFe 2 O 4 NPs were analyzed using X-ray diffraction pattern, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. In PrestoBlue and live/dead assays, ZnFe 2 O 4 NPs exhibited dose-dependent cytotoxic effects on human dermal fibroblasts. In addition, the hemocompatibility assay revealed that the NPs do not significantly rupture red blood cells up to a dose of 1000 µg/mL. Bacterial live/dead imaging and zone of inhibition analysis demonstrated that ZnFe 2 O 4 NPs showed dose-dependent bactericidal activities in various strains of Gram-negative and Gram-positive bacteria. Interestingly, NPs showed antimicrobial activity through multiple mechanisms, such as cell membrane damage, protein leakage, and reactive oxygen species generation, and were more effective against gram-positive bacteria. Furthermore, in vitro scratch assay revealed that ZnFe 2 O 4 NPs improved cell migration and proliferation of cells, with noticeable shrinkage of the artificial wound model. Conclusions This study indicated that ZnFe 2 O 4 NPs have the potential to be used as a future antimicrobial and wound healing drug.

Titanium modified UiO-66(Zr)-type metal–organic framework (MOF) nanophotocatalysts have been prepared via a modified one-step solvothermal methodology and evaluated in photocatalytic oxidative desulfurization. Extensive characterization by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption–desorption, and thermogravimetric analysis (TGA), have revealed the role of Ti loading, on Ti speciation and the structure of the synthesized materials. The performance of nanophotocatalysts have been evaluated for photocatalytic oxidative desulfurization (PODS). PODS reaction parameters, including temperature, photocatalyst dosage, oxidant to sulfur ratio, and solvent to fuel ratio, were optimized, with dibenzothiophene (DBT) conversion reaching 100% under optimal conditions (T = 50 °C, photocatalyst dosage = 2 g/L, oxidant to sulfur molar ratio (O/S = 8), and solvent/fuel = 1). Recyclability studies performed for the optimal catalyst showed good stability over six recycles, with total conversion dropping by only 18%. Kinetic studies showed that DBT PODS follows pseudo-first-order kinetics, with an activation energy value of 55.1 kJ mol −1 . Graphical Abstract

In this paper, we report the biosynthesis and characterization of copper oxide nanoparticles from an aquatic noxious weed, Eichhornia crassipes by green chemistry approach. The aim of this work is to synthesize copper oxide nanoparticles by simple, cost-effective and ecofriendly method as an alternative to other available techniques. The synthesized copper oxide nanoparticles were characterized by UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDX) analyses. The synthesized particles were highly stable, spherical in shape with an average diameter of 28 ± 4 nm. The synthesized nanoparticles were then explored to antifungal activity against plant pathogens. Highest zone of inhibition were observed in 100 μ g ml − 1 of Eichhornia -mediated copper oxide nanoparticle against Fusarium culmorum and Aspergillus niger. This Eichhornia -mediated copper oxide nanoparticles were proved to be good antifungal agents against plant fungal pathogens.

A novel hybrid material with excellent microwave absorption property has been designed by decorating reduced graphene oxide with Ba Tb0.2Eu0.2Fe11.6O19/PANI composite, and the effect of graphene content on microwave absorption property has been investigated. The microstructure of the composite is characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope and Raman spectroscopy. The mechanism of microwave absorption is discussed minutely. The result shows that the ternary nanocomposites demonstrate unexceptionable microwave absorption property due to its special nanostructures and synergistic effect among BaTb0.2Eu0.2Fe11.6O19, PANI and RGO. The minimum reflection loss can reach − 60.9 dB at 16.4 GHz with a thickness of only 1.95 mm, and the corresponding effective absorption bandwidth (below − 10 dB) is 4.2 GHz. BaTb0.2Eu0.2Fe11.6O19/PANI/RGO composite can be one of the most promising microwave absorption materials.

This article reports on silver nanoparticles (AgNPs) that were green-synthesized by using Eriobotrya japonica (Thunb.) leaf extract and their use for the catalytic degradation of reactive dyes. The properties of biogenic AgNPs were characterized using UV-vis absorption spectroscopy, field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), Fourier transforming infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) analysis. The UV-vis spectroscopy and X-ray analyses confirmed the formation of AgNPs and showed the strong absorbance around 467 nm with surface plasmon resonance (SPR). The mean diameter of biogenic AgNPs at room (20 °C), moderate (50 °C), and high temperatures (80 °C) were 9.26 ± 2.72, 13.09 ± 3.66, and 17.28 ± 5.78 nm, respectively. The reaction temperature had significant impacts on the sizes of synthesized AgNPs. The higher the synthesis temperature, the larger size and the lower catalysis activity for reductive decomposition of reactive dyes via NaBH4. The results supported a bio-green approach for developing AgNPs with a small size and stable degradation activity of reactive dyes over 92% in 30 min by using Eriobotrya japonica (Thunb.) leaf extract at pH 7, 20 °C, and 1:10 ratio of silver nitrate added to the leaf extract.

Bio‐inspired techniques are used for synthesis in terms of application, green chemical research, facile, and eco‐friendly chemistry study of silver nanostructures utilizing plant extracts as natural reducing/stabilization and solid adjuvants without the use of toxic and damaging reagents. The present study investigates the biosynthesis of Ag nanoparticles via the mediation of the methanolic extract of Heracleum persicum seeds, without utilizing any stabilizer or surfactant. These nanostructures were identified utilizing ultraviolet–visible spectroscopy, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, high‐resolution transmission electron microscopy, Fourier‐transform infrared spectroscopy and dynamic light scattering. The attributes of AgNPs versus usual human breast adenocarcinoma cell lines that is, Hs 281.T, MDA‐MB‐468, AU565 [AU‐565], MCF7, CAMA‐1, SK‐BR‐3, NMU, and RBA were evaluated. The livability of breast adenocarcinoma cell line diminishes dose‐dependently in the existence of AgNPs. After clinical studies, AgNPs can be used as a green drug in the treatment of human breast adenocarcinoma. The biosynthesis of Ag nanoparticles via the mediation of the methanolic extract of Heracleum persicum seeds, without utilizing any stabilizer or surfactant, is described. The AgNPs was assessed in biological applications like cytotoxicity and anticancer activities against common human breast adenocarcinoma cell lines.