Silver-doped ZnO embedded reduced graphene oxide hybrid nanostructured composites for superior photocatalytic hydrogen generation, dye degradation, nitrite sensing and antioxidant activities

New synthetic silver-doped ZnO nanorods trigger cytotoxicity in MCF-7 through apoptosis and antimicrobial activity

The structural, composition, and molecular interaction of silver integrated zinc oxide (20 wt.% Ag/ZnO) were investigated by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), and Fourier transforms infrared (FTIR) spectrum. The XRD analysis showed the polycrystalline of small crystallite size, whereas the EDX spectrum confirmed the purity of the nanocomposite. The FTIR spectrum indicated the presence of Ag-Zn-O stretching vibration at 1034 cm-1. SEM and TEM images identified the surface morphology and particle size, indicating that Ag/ZnO of nanorods linked with spherical-like shapes. The nanorods of an average length of ∼ 110 nm and an average diameter of ∼ 10 nm. The optical characteristics showed a direct transition of electrons through an energy gap in the 3.30 eV-3.60 eV. The tested nanocomposite exhibited potent cytotoxicity against MCF-7 cells with an IC50 value of 0.26 µg/ml with cell growth inhibition by 97.3% at the highest concentration compared to Doxorubicin (IC50=6.72 µg/ml). It significantly stimulated total apoptotic breast cancer cell death by 51-fold (32.16% compared to 0.63 for the control), arresting the cell progression at the G1 phase. For further validation of apoptotic activity, the tested Ag/ZnO-NP upregulated the proapoptotic genes and down-regulated the anti-apoptotic gene. Moreover, a molecular docking study highlighted the binding disposition of the nanocomposite as Bcl-2 inhibitors. Additionally, Ag/ZnO-NP exhibited potent antimicrobial activity. Hence, the synthesized nanocomposite can serve as an antimicrobial and cytotoxic agent through apoptosis-induction and could be developed as a biologically active nanocomposite.Communicated by Ramaswamy H. Sarma.

Lepidium sativum Seed Extract-Mediated Synthesis of Zinc Oxide Nanoparticles: Structural, Morphological, Optical, Hemolysis, and Antibacterial Studies

Nanomaterials have unique physicochemical properties compared to their bulk counterparts. Besides, biologically synthesized nanoparticles (NPs) have proven superior to other methods. This work aimed to biosynthesize zinc oxide (ZnO) NPs using an aqueous extract of Lepidium sativum seed. The obtained ZnO NPs were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and ultraviolet-visible spectroscopy. The in vitro antibacterial activity of ZnO NPs against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria was assessed using the disk diffusion technique. The hemolytic impact was quantified spectrophotometrically. The results indicated a 24.2 nm crystallite size, a hexagonal structure phase, and a 3.48 eV optical bandgap. Antibacterial studies revealed a dose-dependent response with comparable activity to the standard drug (gentamicin) and higher activity against S. aureus than E. coli, e.g., the zone of inhibition at 120 mg/mL was 23 ± 1.25 and 16 ± 1.00 mm, respectively. The hemolysis assay showed no potential harm due to ZnO NPs toward red blood cells if utilized in low doses. As a result, it could be concluded that the reported biogenic method for synthesizing ZnO NPs is promising, resulting in hemocompatible NPs and comparable bactericidal agents.

Modulation of the Morphological Architecture of Mn2O3 Nanoparticles to MnCoO Nanoflakes by Loading Co3+ Via a Co-Precipitation Approach for Mosquitocidal Development

The spread of many infectious diseases by vectors is a globally severe issue. Climate change and the increase of vector resistance are the primary sources of rising mosquito populations. Therefore, advanced approaches are needed to prevent the dispersal of life-threatening diseases. Herein, Mn₂O₃ NPs and MnCoO nanocomposites were presented as mosquitocidal agents. The synthesized samples were prepared by a co-precipitation route and characterized using different techniques indicating the change of host Mn₂O₃ structure to 2D MnCoO nanoflakes with Co³⁺ integration. The thermal decomposition of the nanoparticles was examined by TGA analysis, showing high stability. The energy gap (Eg) of Mn₂O₃ was estimated within the visible spectrum of the value 2.95 eV, which reduced to 2.80 eV with doping support. The impact of Mn₂O₃ and MnCoO on immature stages was investigated by semithin photomicrographs exhibiting significant changes in the midgut, fat tissue and muscles of the third larval instar. Moreover, the external deformations in pupae were examined using scanning electron microscopy (SEM).

Enhanced Photocatalytic Degradation of Methylene Blue Using Ti-Doped ZnO Nanoparticles Synthesized by Rapid Combustion

ZnO and Ti-doped ZnO (Ti-ZnO) nanoparticles were synthesized using rapid combustion. The morphology of ZnO and Ti-ZnO featured nanoparticles within cluster-like structures. The ZnO and Ti-ZnO structures exhibited similar hexagonal wurtzite structures and crystal sizes. This behavior occurred because Zn²⁺ sites of the ZnO lattice were substituted by Ti⁴⁺ ions. The chemical structure characterization implied the major vibration of the ZnO structure. The physisorption analysis showed similar mesoporous and non-rigid aggregation structures for ZnO and Ti-ZnO using N₂ adsorption-desorption. However, Ti-ZnO demonstrated a specific surface area two times higher than that of ZnO. This was a major factor in improving the photocatalytic degradation of methylene blue (MB). The photocatalytic degradation analysis showed a kinetic degradation rate constant of 2.54 × 10^-3 min^-1 for Ti-ZnO, which was almost 80% higher than that of ZnO (1.40 × 10^-3 min^-1). The transformation mechanism of MB molecules into other products, including carbon dioxide, aldehyde, and sulfate ions, was also examined.

Photodegradation under UV Light Irradiation of Various Types and Systems of Organic Pollutants in the Presence of a Performant BiPO4 Photocatalyst

In this study, we prepared spheroid microstructures of monoclinic bismuth phosphate BiPO4 by a facile solid-state reaction at 500 °C. The crystal structure was refined using the Rietveld method, where the crystal cell was resolved using a monoclinic system (parameters a, b, c, β) with space group P21/n. SEM images showed that the solid catalyst presented homogeneous morphologies. These BiPO4 microparticles (BiP-500) have been used as photocatalysts to photodegrade, under UV light irradiation, three cationic dyes (Rhodamine B, RhB; Methylene Blue, MB; and Toluidine Blue, TB), three anionic dyes (Congo Red, CR; Orange G, OG; and Methyl Orange, MO) and mixtures of RhB-MB, RhB-OG and MO-OG organic dyes. The photodegradation efficiency of these BiP-500 microparticles is found to be optimal in the case of RhB solutions, RhB-MB and RhB-OG binary mixtures. The BiP-500 catalyst shows a high selectivity for the conversion of the mixture of dyes into CO2 and H2O. Total organic carbon analysis of an anionic dye and a cationic dye (RhB, OG and RhB-MB) confirms the mineralization of the pollutants in the presence of BiP-500 particles. The photocatalytic efficiency of our BiP-500 photocatalyst has been confirmed, with a view to facilitate applications in the field of the depollution of wastewater in the agricultural environment by the degradation of parathion-methyl (PM) as a pollutant.