Reducing the size of macroscopic systems to nanometers can be achieved by top down synthesis by different chemical or physical methods. The bottom-up approach is a method in which the components of the atomic or molecular dimensions are assembled together to form nanoparticles. The bottom-up method is used for the elaboration of nanoparticles, because it allows the control of their size. This article presents a review of the advantages and disadvantages of chemical methods for the development of nanomaterials.

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.

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 review provides a comprehensive and critical analysis of geopolymers, focusing on structure–property relationships and functionalization strategies for sustainable applications. A structured narrative review methodology was adopted, following PRISMA principles, based on literature retrieved from Web of Science, Scopus, ScienceDirect, and MDPI databases, primarily covering the period 2015–2025. The influence of precursor type, alkaline activators, and Si–Al ratio on reaction kinetics, microstructure, porosity, and mechanical performance is systematically discussed. Functionalization approaches using additives are critically reviewed with respect to durability, fire resistance, photocatalytic activity, and antibacterial performance. The analysis highlights that the geopolymer matrix primarily acts as stable and versatile support, while functional performance is governed by the controlled integration of active particles. Key limitations related to the variability of raw materials, lack of standardization, and long-term durability are identified. Future research directions are outlined, emphasizing the need for standardized processing protocols and the application-oriented design of multifunctional geopolymer systems.