Recent advancements in nanotechnology have improved the application of copper oxide (CuO) nanostructures, known for their diverse antibacterial, electrical, catalytic, optical, and pharmacological properties, which depend on nanoparticle morphology. This study investigated two synthesis methods for structured CuO: microwave-assisted hydrolysis and ultrasound using copper acetate and KOH, and an eco-friendly method involving cholesterol-free egg white albumin and Solanum lycopersicum extract. Characterization techniques, including XRD, FTIR, and SEM-EDS, were utilized to analyze the produced CuO. XRD confirmed high-purity monoclinic CuO structures in the sample obtained via the chemical method, while characteristic peaks of tenorite and dolerophanite were observed in the albumin-synthesized sample. ATR-FTIR analysis revealed O-H stretching bands around 3400 cm⁻¹, indicating adsorbed H-OH or -OH and strong Cu-O bond peaks at 434 cm⁻¹. The CuO synthesized via microwave and ultrasound methods displayed superior crystallinity compared to commercial CuO. SEM illustrated various morphologies, such as flakes, microspheres, and irregular polyhedra, influenced by the presence of proteins and organic acids. Antibacterial tests demonstrated the effective inhibition of Escherichia coli and Enterococcus faecalis, confirming the potential of CuO as a promising antibacterial agent. Overall, the findings highlight the effectiveness of green chemistry in developing crystalline CuO for various applications.

Among the various available synthesis approaches, hydrolytic precipitation offers a simple, cost-effective, and scalable route for producing phase-pure NiO with a controlled morphology and crystallite size. However, the influence of calcination temperature on its crystalline phase, particle size, and antimicrobial activity remains an active field of research. This study aims to investigate the structural, morphological, and antibacterial properties of NiO nanoparticles synthesized via hydrolytic methods and thermally treated at different temperatures. XRD data indicate the presence of the hexagonal crystallographic phase of NiO (space group 166: R-3m), a structural variant less commonly reported in the literature, stabilized under mild hydrolytic synthesis conditions. The average crystallite size increases significantly from 4.97 nm at 300 °C to values of ~17.8 nm at 500–700 °C, confirming the development of the crystal lattice. The ATR-FTIR analysis confirms the presence of the characteristic Ni–O band for all samples, positioned between 367 and 383 cm⁻¹, with a reference value of 355 cm⁻¹ for commercial NiO. The displacements and variations in intensity reflect a thermal evolution of the crystalline structure, but also an important influence of the size of the crystallites and the agglomeration state. The results reveal a systematic evolution in particle morphology from porous, flake-like nanostructures at 300 °C to dense, well-faceted polyhedral crystals at 900 °C. With an increasing temperature, particle size increases. EDS spectra confirm the high purity of the NiO phase across all samples. Additionally, the NiO nanoparticles exhibit calcination-temperature-dependent antibacterial activity, with the complete inhibition of Escherichia coli and Enterococcus faecalis observed after 24 h for the sample calcined at 300 °C and over 90% CFU reduction within 4 h. A significant reduction in E. faecalis viability across all samples indicates time- and strain-specific bactericidal effects. Due to its remarkable multifunctionality, NiO has emerged as a strategic nanomaterial in fields ranging from energy storage and catalysis to antimicrobial technologies, where precise control over its structural phase and particle size is essential for optimizing performance.

Marine mollusk shells are a promising renewable source of calcium-based materials, offering a sustainable alternative for their synthesis. In this study, five types of marine shells—Chamelea gallina, Mya arenaria, Rapana venosa, Mytilus edulis, and Pecten maximus—were calcined at 900 °C for 2 h. The resulting powders were characterized by XRD, FTIR, SEM, PSD, and zeta potential analyses. XRD confirmed the dominant presence of CaO, with residual calcite and portlandite. FTIR spectra supported these findings, indicating the decomposition of carbonate phases and the formation of Ca–O bonds. SEM imaging revealed species-specific microstructures ranging from lamellar and wrinkled textures to compact aggregates, while particle size distributions varied from 15 to 37 μm. Thermogravimetric analysis revealed a two-step decomposition process for all samples, with significant species-dependent differences in mass loss and conversion efficiency, highlighting the influence of biogenic origin on the thermal stability and CaO yield of the resulting powders. Zeta potential measurements showed low colloidal stability, with the best performance found in Rapana venosa and Pecten maximus calcinated samples. Antibacterial activity was evaluated using a direct contact method against Escherichia coli and Enterococcus faecalis. All samples exhibited complete inactivation of E. coli, regardless of exposure time, while E. faecalis required prolonged contact (3.3 h) for full inhibition. The results highlight the potential of biogenic CaCO₃ and CaO powders as functional, antimicrobial materials suitable for environmental and biomedical applications. This study underscores the viability of marine shell waste valorization within a circular economy framework.

Nanomaterials are materials at the nanometric scale that have distinctive functionalities and properties. Due to their unique properties relative to traditional materials, nanomaterials attract great interest from researchers. ZnO-based nanomaterials especially demonstrate versatility, accessibility, biocompatibility and low toxicity. In recent years, there has been a growing interest in developing eco-friendly and sustainable approaches for synthesizing nanomaterials. In the development of ecological techniques for their synthesis, using natural resources is a popular choice. Employing egg white for ZnO nanoparticle synthesis represents an environmentally method that uses a natural resource. The great advantage of green synthesis using egg white is that it is a cost-effective, renewable, and bio-degradable resource that offers biocompatibility. Egg white is rich in proteins, amino acids, and other biomolecules that possess reducing properties. These biomolecules interact with metal ions, leading to the reduction and nucleation of nanoparticles. Additionally, the proteins in egg white act as capping agents, stabilizing the nanoparticles and preventing their aggregation. The proteins of white albumen have different functional groups and maintain product attributes, such as dispersion and stability. This paper focuses on the characterization of ZnO nanoparticles obtained by the assisted synthesis of egg white. This study explores the potential of ovalbumin, the major protein in egg white, as a template for the synthesis of nanostructured ZnO. The synthesis process utilized egg white from different sources (commercially raised hens, home-raised hens, and ducks) and varying zinc nitrate concentrations (1M and 2M) to evaluate their influence on nanoparticle morphology and size. Various complementary techniques are employed to analyze the resulting nanostructures: XRD, SEM, and ATR-FTIR. Also, antibacterial properties are investigated. This study underscores the viability of different egg whites as a green resources for synthesizing nanostructured ZnO and contributes to the development of sustainable nanotechnology approaches.

Sustainable and eco-friendly synthesis methods for nanoparticles are crucial for advancing green nanotechnology. This study presents the biogenic synthesis of zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles using ovalbumin, an abundant and non-toxic protein from egg white. The synthesis process was optimized by varying metal ion concentrations to control particle size and morphology. Characterization using ATR-FTIR, XRD, SEM, and UV-VIS confirmed the successful formation of uniform, well-crystallized nanoparticles with sizes ranging from 7.9 to 13.5 nm. ZnO nanoparticles exhibited superior antimicrobial efficacy against Escherichia coli and Enterococcus faecalis, while MgO nanoparticles showed enhanced potential environmental remediation. These findings highlight ovalbumin as a versatile agent for the green synthesis of ZnO and MgO nanomaterials, with promising applications in the medical, environmental, and optoelectronic fields. The results indicate that this biogenic method can serve as a sustainable proposal to produce nanostructured materials with diverse applications in the medical and environmental fields, such as eliminating pathogenic bacteria and purifying contaminated environments. Overall, this study significantly contributes to the development of sustainable nanomaterials and opens up new perspectives on the use of ovalbumin protein in the synthesis of multifunctional nanostructured materials.

This study investigates the elaboration, structural characteristics, and antibacterial performance of silver-based nanoparticles obtained via a hydrolytic chemical route, with and without assistance from ultrasound and microwave irradiation. Two silver nitrate precursor concentrations (1 M and 2 M) were employed to evaluate the influence of synthesis conditions on phase composition, morphology, and antimicrobial efficiency. The obtained powders were characterized by ATR-FTIR, X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD analysis revealed that drying at 120 °C led to oxide-rich systems dominated by Ag₂O, with minor contributions from metallic Ag and carbonate species, while calcination at 550 °C resulted in complete phase transformation into highly crystalline metallic silver. SEM observations demonstrated that precursor concentration and synthesis assistance strongly affect particle size, aggregation degree, and surface morphology. Ultrasound- and microwave-assisted synthesis promoted finer crystallite sizes and more homogeneous particle distributions compared to non-assisted routes. The antibacterial activity was evaluated against Escherichia coli (Gram-negative) and Clostridium perfringens (Gram-positive, anaerobic, spore-forming). Oxide-rich samples, particularly Ox.Ag/2 M, exhibited rapid and complete bacterial inactivation within 30 min, while metallic silver samples showed time-dependent antibacterial behavior, achieving full inhibition after 4 h. The results demonstrate that antibacterial efficiency is governed by a synergistic interplay between silver oxidation state, nanoscale morphology, and surface reactivity. These findings highlight the potential of tailored silver-based nanomaterials as effective antibacterial materials for biomedical, food safety, and environmental applications.