Background: The biosynthesis of silver nanoparticles (AgNPs) is an area of interest for researchers due to its eco-friendly approach. The use of biological approaches provides a clean and promising alternative process for the synthesis of AgNPs. We used for the first time the supernatant of Leclercia adecarboxylata THHM under optimal conditions to produce AgNPs with an acceptable antimicrobial activity against important clinical pathogens. Results: In this study, soil bacteria from different locations were isolated and screened for their potential to form AgNPs. The selected isolate, which was found to have the ability to biosynthesize AgNPs, was identified by molecular methods as Leclercia adecarboxylata THHM and its 16S rRNA gene was deposited in GenBank under the accession number OK605882. Different conditions were screened for the maximum production of AgNPs by the selected bacteria. Five independent variables were investigated through optimizations using one variable at a time (OVAT) and the Plackett–Burman experimental design (PBD). The overall optimal parameters for enhancing the biosynthesis of AgNPs using the supernatant of Leclercia adecarboxylata THHM as a novel organism were at an incubation time of 72.0 h, a concentration of 1.5 mM silver nitrate, a temperature of 40.0 °C, a pH of 7.0, and a supernatant concentration of 30% (v/v) under illumination conditions. The biosynthesized AgNPs have been characterized by UV–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The biosynthesized AgNPs showed an absorption peak at 423 nm, spherical shape, and an average particle size of 17.43 nm. FTIR shows the bands at 3321.50, 2160.15, and 1636.33 cm⁻¹ corresponding to the binding vibrations of amine, alkyne nitrile, and primary amine bands, respectively. The biosynthesized AgNPs showed antimicrobial activity against a variety of microbial pathogens of medical importance. Using resazurin-based microtiter dilution, the minimum inhibitory concentration (MIC) values for AgNPs were 500 µg/mL for all microbial pathogens except for Klebsiella pneumoniae ATCC13883, which has a higher MIC value of 1000 µg/mL. Conclusions: The obtained data revealed the successful green production of AgNPs using the supernatant of Leclercia adecarboxylata THHM that can be effectively used as an antimicrobial agent against most human pathogenic microbes.

Nickel sulfide nanoparticles were successfully synthesized through a meticulous process involving a well-mixed powder of Ni(CH₃COO)₂∙2H₂O and Thiourea. The X-ray diffraction analysis provided insights into the structural nature of NiS, revealing its polycrystalline characteristics with a hexagonal system. This information is fundamental, as it forms the basis for understanding the material’s behavior and functionality in various applications. Determining the average values of mean crystallite size, microstrain, and dislocation Nickel sulfide nanoparticles were successfully synthesized through a careful process involving a well-mixed powder of Ni(II)₂∙2H₂O and Thiourea. The X-ray diffraction analysis provided insights into the structural nature of NiS, revealing its polycrystalline characteristics with a hexagonal system. This information is crucial as it forms the basis for understanding the material’s behavior and functionality in various applications. Determining the average values of mean crystallite size, microstrain, and dislocation density for the (100) plane (32.62 nm, 0.000296, and 0.000939 nm-2, respectively) contributes to a comprehensive understanding of the material’s structural features. The photoluminescence spectrum of NiS in the visible region revealed split peaks at 405.8 and 428.25 nm, shedding light on the radiative recombination process between electrons and holes. The confirmation of thermal stability through a thermogravimetry diagram is essential for applications in elevated temperature environments, ensuring the material’s reliability under varying conditions. Analyzing the stoichiometry of NiS using energy dispersive spectroscopy attached to transmission electron microscopy provides insights into the material’s composition. Cyclic voltammetry results indicating a diffusion coefficient greater than that of NiS added to carbon hold significance for electrochemical applications. The unique characteristic peaks observed in cyclic voltammetry for fuel cell applications suggest the potential use of NiS in energy conversion technologies, broadening its scope of application. The confirmation of NiS’s ability to elucidate the physical and electronic properties of electrochemical systems through electrochemical impedance spectroscopy underlines its importance as a versatile material in various research and practical domains.

Due to their high specific surface area and its characteristic’s functionalized nanomaterials have great potential in medical applications specialty, as an anticancer. Herein, functional nanoparticles (NPs) based on iron oxide Fe₂O₃, iron oxide modified with copper oxide Fe₂O₃@CuO, and tungsten oxide WO₃ were facile synthesized for biomedical applications. The obtained nanomaterials have nanocrystal sizes of 35.5 nm for Fe₂O₃, 7 nm for Fe₂O₃@CuO, and 25.5 nm for WO₃. In addition to octahedral and square nanoplates for Fe₂O₃, and WO_3; respectively. Results revealed that Fe₂O₃, Fe₂O₃@CuO, and WO₃ NPs showed remarked anticancer effects versus a safe effect on normal cells through cytotoxicity test using MTT-assay. Notably, synthesized NPs e.g. our result demonstrated that Fe₂O₃@CuO exhibited the lowest IC₅₀ value on the MCF-7 cancer cell line at about 8.876 µg/ml, compared to Fe₂O₃ was 12.87 µg/ml and WO₃ was 9.211 µg/ml which indicate that the modification NPs Fe₂O₃@CuO gave the highest antiproliferative effect against breast cancer. However, these NPs showed a safe mode toward the Vero normal cell line, where IC₅₀ were monitored as 40.24 µg/ml for Fe₂O₃, 21.13 µg/ml for Fe₂O₃@CuO, and 25.41 µg/ml for WO₃ NPs. For further evidence. The antiviral activity using virucidal and viral adsorption mechanisms gave practiced effect by viral adsorption mechanism and prevented the virus from replicating inside the cells. Fe₂O₃@CuO and WO₃ NPs showed a complete reduction in the viral load synergistic effect of combinations between the tested two materials copper oxide instead of iron oxide alone. Interestingly, the antimicrobial efficiency of Fe₂O₃@CuO NPs, Fe₂O₃NPs, and WO₃NPs was evaluated using E. coli, S. aureus, and C. albicans pathogens. The widest microbial inhibition zone (ca. 38.45 mm) was observed with 250 mg/ml of WO₃ NPs against E. coli, whereas using 40 mg/ml of Fe₂O₃@CuO NPS could form microbial inhibition zone ca. 32.86 mm against S. aureus. Nevertheless, C. albicans was relatively resistant to all examined NPs. The superior biomedical activities of these nanostructures might be due to their unique features and accepted evaluations.

The success of fuel cells depends on the proper design of the electrodes and membrane allowing easy access of oxygen and protons. Using non-precious catalyst electrodes based on recyclable carbon nanostructures is most important to produce clean energy and increase the ability to commercialize the fuel cells. Herein, reduced graphene oxide (rGO) and graphene/magnetic iron oxide nanocomposite (rGO/MIO) are successfully synthesized as anode and cathode, respectively, from polyethylene terephthalate (PET) waste bottles using easy steps in order to simplify the method and reducing the production cost. While, the membrane is prepared from low cost and eco-friendly ternary polymers blend which are polyvinyl alcohol (PVA), polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) then doped with sulfonated graphene oxide. The prepared electrodes have characteristic high porosity and their electrocatalytic performances are evaluated using three-electrode cell electrochemical studies as cyclic voltammetry and linear scan voltammetry combined with rotating disk electrode. A new assembly of the membrane between two non-precious catalyst electrodes as a single polymer electrolyte membrane fuel cell (PEMFC) was developed using a catalyst-coated membrane technique. The membrane electrode assembly (MEA) design parameters which affect its performance in hydrogen fuel cells as number of used catalyst layers (CL) or using gas diffusion layer (GDL) were evaluated in a single cell set-up with H₂/O₂ operation and the results revealed that the performance MEA was enhanced with using GDL more than that of MEA without GDL by 66% at a current density of 0.8 A cm⁻² while the performance with double CL was better than that of the conventional single CL by 30% at a current density of 0.98 mA cm⁻².