Journal of Nanomaterials

The preparation of metallic nanoparticles using green synthetic approaches and its application toward the efficient degradation of environmentally hazardous dyes constitutes an attractive alternative to currently employed methods. In the current report, the green synthesis of silver nanoparticles (AgNPs) was successfully achieved using Actinidia deliciosa (kiwifruit) peel aqueous extract as a bioreducing agent under optimized synthesis conditions. The experimental parameters were optimized in terms of reactant ratio, reaction temperature, and reaction time. The biogenic nanoparticles exhibited SPR absorption band at λ_max 480 nm. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images revealed quasispherical monodisperse nanoparticles which were 36 nm in diameter. The hydrodynamic diameter of the nanoparticles was 106 nm as determined by dynamic light scattering, and the highly negative ζ-potential (−34 mV) supported its superior colloidal stability. Energy dispersive X-ray confirmed that silver is a major constituent of the nanoparticles. X-ray diffraction (XRD) diffractograms confirmed the crystallinity of the nanoparticles and its face-centered cubic (fcc) lattice structure. The functional groups in the plant’s phytochemicals facilitating the reduction of Ag⁺ ions and stabilization of the formed AgNPs were identified by fourier transform infrared (FTIR) spectroscopy. In specific, the bands in the FTIR spectra at 3,412, 1,618, 1,419, and 1,237 cm⁻¹ suggested the presence of phenolic compounds. Phytochemical analysis by colorimetric assays revealed that the kiwifruit peel extract was rich in phenolic compounds. When evaluated in the catalytic degradation of organic dyes, the biosynthesized AgNPs induced instant and complete discoloration of the methylene blue dye when 1.6 mg of nanoparticles was used. At a lower dose of AgNPs (0.4 mg), 80% degradation of the dye occurred after 3 hr of treatment. The degradation reaction followed second-order kinetics with a rate constant of 0.01083 mM⁻¹s⁻¹. The current study highlights the immense potential of the prepared nanoparticles as efficient catalysts for the degradation of hazardous organic dyes such as methylene blue and presents an intriguing argument for investigating the catalytic efficiency of the biogenic AgNPs for the degradation of other structurally different dye pollutants.

This research aims to improve antimicrobial materials based on functional silica nanoparticles. Three different methods were used in the study to create silica nanoparticles with other properties. The nanoparticles’ morphological structures are porous, hollow, and filled with spherical forms. The surface of these nanoparticles was grafted with poly(1-vinyl-1,2,4-triazole) (PVTri). The morphological properties of nanocomposites were used for analysis. In contrast, thermal gravimetric analysis was used to characterize the thermal properties of nanocomposites (thermogravimetric analysis). The silica nanoparticles were evaluated for their in vitro antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae using minimum inhibitory concentration measurement. Silica nanoparticles have different antifungal and antibacterial properties related to their structure. The cytotoxic effects of the silica nanoparticles on HaCaT cells were performed with an MTS assay. In this study, we observed that high doses of HSS and e-SiO₂ decreased cell growth, while HSS and e-SiO₂ composite with PVTri increased cell proliferation.

The submerged arc discharge (SAD) allows the production of high-quality carbon nanostructures. The SAD method uses simple and inexpensive equipment. However, the carbon nanostructures obtained contain contaminants that are difficult to remove. The study of the published articles shows that reporting similar operating parameters informs quite different results. Reducing the generation of pollutants requires optimization of the design and the operation of installations. Nevertheless, the study of the state-of-the-art indicates that this aspect has been underestimated, which is manifested in the absence of publications on this subject. On the other hand, the increase in the production scale causes new problems that are not manifested in small-volume productions that are carried out in a research laboratory. The present work aims to analyze the SAD installation design and operation criteria to reduce the presence of contaminants. This study indicated that the key elements of the design and the operation are the electrodes alignment, feeding and attachment mechanisms, the electrode micropositioning system, the synthesis reactor design, the sensitive parameters control, the data acquisition system, and the selection of the liquid medium. Herein, these elements are analyzed and the best strategies for their design and operation are exposed. Those aspects relevant to scaling up of production are emphasized.

Apart from our imagination, the nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nanoelectronics, environmental remediation, and medical healthcare. In the medical field, magnetic materials play vital roles such as magnetic resonance imaging (MRI), hyperthermia, and magnetic drug delivery. Among them, manganese oxide garnered great interest in biomedical applications due to its different oxidation states (Mn²⁺, Mn³⁺, and Mn⁴⁺). Manganese oxide nanostructures are widely explored for medical applications due to their availability, diverse morphologies, and tunable magnetic properties. In this review, cogent contributions of manganese oxides in medical applications are summarized. The crystalline structure and oxidation states of Mn oxides are highlighted. The synthesis approaches of Mn-based nanoparticles are outlined. The important medical applications of manganese-based nanoparticles like magnetic hyperthermia, MRI, and drug delivery are summarized. This review is conducted to cover the future impact of MnO_x in diagnostic and therapeutic applications.

Synthetic organic dyes are coloring agents used in various industries. Despite the fact that they offer exciting colors and long-lasting effects, certain organic dyes can have harmful impacts on human health and aquatic ecosystems. This study investigates the photocatalytic degradation of malachite green dye using Ni–TiO₂ nanoparticles (NPs) and Ni–TiO₂/PANI nanocomposites (NCs) in various reaction conditions. The surface and compositional change of synthesized photocatalysts were characterized by XRD, FTIR, AAS, and UV–vis spectrophotometer. Accordingly, the XRD results signify the crystal structure of photocatalysts found to be tetragonal anatase phase while the FT-IR spectra indicate the titanium has predominantly form a coordination compound upon reaction with nitrogen atom through weakening the bond strength between C═N, C═C, and C─N in the PANI. The UV–vis measurement shows that the energy bandgaps were decreased from 3.20 to 2.77 eV and 2.59 eV for Ni–TiO₂ NPs and Ni–TiO₂/PANI NCs, respectively. From AAS data, the authors confirmed that Ni metal has significantly existed in the aforementioned photocatalysts after the calcination process. The photocatalytic degradation of Ni–TiO₂ NPs and Ni–TiO₂/PANI NCs on the model dye has studied and their efficiency was 94.22% and 99.09%, respectively. The photocatalytic degradation follows pseudo-first order with 2.23 × 10⁻² min⁻¹ reaction rate at optimum conditions of pH 8.5, initial dye concentration of 0.2 g/L, catalyst load of 0.2 g/L, and irradiation time of 90 min. With this, the outstanding result recorded using Ni–TiO₂/PANI NCs is ascribed to the smaller particle size as compared to Ni–TiO₂ NPs, and it is found to be the promising photocatalyst for the removal of wastewater containing organic dyes.

Dendrimers are highly defined hyperbranched artificial macromolecules, synthesised by convergent or divergent approach with specific applications in various fields. Dendrimers can be represented as graph models, from which a quantitative description can be drawn in relation with their structural properties. The distance-based and the degree-based descriptors have great importance and huge applications in structural chemistry. These indices together with entropy measures are found to be more effective and have found application in scientific fields. The idea of graph entropy is to characterise the complexity of graphs. The use of these graph invariants in quantitative structure property relationship and quantitative structure activity relationship studies has become of major interest in recent years. In this paper, the distance-based molecular descriptors of pyrene cored dendrimers are studied applying the technique of converting original graph into quotient graphs using -classes. It is to be noted that, since the pyrene cored dendrimer, is not a partial cube, usual cut method is not applicable. Further, various degree-based descriptors and their corresponding graph entropies of the pyrene cored dendrimers are also studied. Based on the obtained results, a comparative analysis as well as a regression analysis was carried out.