Synthesis and Characterization of Various Bimetallic Nanoparticles and Their Application

Bimetallic nanoparticles are a complex nanoscale combination of two metal constituents. The superior properties of bimetallic nanoparticles (BNPs) compared with monometallic nanoparticles have attracted much attention from both scientific and technological perspectives. In recent years, many fabrication techniques have been proposed, and the detailed characterization of bimetallic nanoparticles has been made possible by the rapid advancement of nanomaterial analysis techniques. Metallic nanoparticles can be classified according to their origin, size, and structure, and their synthesis process can be physical, chemical, or biological. Bimetallic nanoparticles are more attractive than metal nanoparticles due to their unique mixing patterns and synergistic effects of two metal nanoparticles forming the bimetal. In this review, the different bimetallic synthesis methods and various characterization techniques are discussed. The paper will also discuss various applications for bimetallic nanoparticles. Different characterization techniques for bimetallic nanoparticles include X-ray diffraction (XRD) to investigate crystallinity and phase composition; the morphology and composition analysis of nanoparticles are studied using a scanning electron microscope fitted with an energy-dispersive X-ray analyzer (EDX); transmission electron microscopy (TEM), UV–vis spectrum, FTIR, and TGA analysis are also among the characterization tools used. Finally, we report on the various applications of BNPs, which include antimicrobial activity, pollutant removal, and wastewater application.

Mycosynthesis of Metal-Containing Nanoparticles-Fungal Metal Resistance and Mechanisms of Synthesis

In the 21st century, nanomaterials play an increasingly important role in our lives with applications in many sectors, including agriculture, biomedicine, and biosensors. Over the last two decades, extensive research has been conducted to find ways to synthesise nanoparticles (NPs) via mediation with fungi or fungal extracts. Mycosynthesis can potentially be an energy-efficient, highly adjustable, environmentally benign alternative to conventional physico-chemical procedures. This review investigates the role of metal toxicity in fungi on cell growth and biochemical levels, and how their strategies of resistance, i.e., metal chelation, biomineral formation, biosorption, bioaccumulation, compartmentalisation, and efflux of metals from cells, contribute to the synthesis of metal-containing NPs used in different applications, e.g., biomedical, antimicrobial, catalytic, biosensing, and precision agriculture. The role of different synthesis conditions, including that of fungal biomolecules serving as nucleation centres or templates for NP synthesis, reducing agents, or capping agents in the synthesis process, is also discussed. The authors believe that future studies need to focus on the mechanism of NP synthesis, as well as on the influence of such conditions as pH, temperature, biomass, the concentration of the precursors, and volume of the fungal extracts on the efficiency of the mycosynthesis of NPs.

Photocatalytic Removal of Dyes from Aqueous Medium by Fe, Mn and Fe-Mn Nanoparticles Synthesized Using Cannabis sativa Leaf Extract

Current work describes green synthesis of Fe, Mn (monometallic) and Fe-Mn (bimetallic) nanoparticles using Cannabis sativa leaf extract as stabilizing and capping agent. In order to assess the formation of nanoparticles UV/Vis and FTIR analysis was carried out. In addition, Scanning electron microscopy and XRD studies confirmed synthesis as well as morphology of the nanoparticles. All the nanoparticles were found having particle size 20–80 nm and crystallite 3–20 nm. Photocatalytic activity of synthesized nanoparticles has been evaluated by carrying out degradation of two dyes methyl orange (MO) and Congo red (CR) in the presence of nanocatalysts. Degradation of both the dyes was carried out separately using Fe, Mn and Fe-Mn nanoparticles to compare the efficiency of monometallic with bimetallic nanoparticles. Iron and manganese monometallic particles have completely degraded MO in 18 min and 20 min and CR in 24 min and 18 min respectively. However, due to increased synergistic effect Fe-Mn BNPs completely degraded MO dye in just 12 min and CR in 14 min. In nutshell, this work is actually a step towards the synthesis of bimetallic nanoparticles using a plant extract with improved synergistic photocatalytic activities which impart various properties to the designed nanomaterial.

Synthesis, Characterization, and Antiproliferative Effect of CuO-TiO2-Chitosan-Amygdalin Nanocomposites in Human Leukemic MOLT4 Cells

The main aim of this study was to synthesize copper oxide- (CuO-) titanium oxide- (TiO2-) chitosan-amygdalin nanocomposites (CTCANc) and to characterize them physically and biologically (antimicrobial and anticancer activity using MOLT4 blood cancer cell line) to endorse their useful applications as potential drug candidates in anticancer avenues. CuO-TiO2-chitosan-amygdalin nanocomposites were synthesized according to standard, reported methods. Physical characterization of the nanocomposites was performed using methods like X-ray diffractometer (XRD), and morphological and ultrastructural analysis of nanocomposites were done using electron microscope scanning and transmission. FTIR was recorded using a Perkin-Elmer spectrometer, and photoluminescence (PL) spectra were done using the spectrometer. Further, antibacterial activities were assessed using standard bacterial cultures. To demonstrate the nanocomposite’s anticancer effects, MTT assay, morphological analysis, apoptosis studies using acridine orange/ethidium bromide (AO/EtBr) dual staining, reactive oxygen species (ROS) analysis, and levels of antioxidant enzymes were analyzed using the MOLT4 blood cancer cell line. Synthesized nanocomposites were characterized using XRD and showed various peaks, respectively, for CuO-TiO2, amygdalin, and chitosan. MTT assay indicated an IC50 value of 38.41 μg/ml concentration of CTCANc. Hence, 30 and 40 μg/ml were used for the subsequent experiments. Morphological analysis, staining for apoptosis using AO/EtBr, mitochondrial membrane potential (MMP or ΔΨm) analysis, ROS analysis, and determination of the SOD, CAT, MDA, and GSH levels were performed. Observations like a significant loss of morphology, induction of apoptosis, elevated ROS, and decreased MMP were significant in 30 and 40 μg/ml nanocomposite-treated cells when compared to control cells. The bimetallic nanocomposites exhibited typical nanocomposites characteristics and significant antibacterial and anticancer effects. The study results endorse the antibacterial, anticancer activity of CuO-TiO2-chitosan-amygdalin nanocomposites and strongly suggest that further in-depth research using CuO-TiO2-chitosan-amygdalin nanocomposites could reveal their efficacy in the clinical scenario.

Ecotoxicological assessment of magnetite and magnetite/Ag nanoparticles on terrestrial and aquatic biota from different trophic levels

The aim of the study is an ecotoxicological assessment of magnetite iron oxide-based nanoparticles (NPs), which have risen in popularity in the last decade, on selected terrestrial and aquatic organisms from various levels of the food chain. In the presented study various organisms, from both the terrestrial and aquatic environment, were used as targets for the assessment of NPs ecotoxicity. Plants (radish, oat), marine bacteria (A. fischeri) and crustacean (H. incongruens) were used to represent producers, decomposers, and consumers, respectively. It was found that examined NPs were harmful (to a different degree) to biota from three different trophic levels. Physicochemical characterization (size/morphology, crystallinity, composition, and magnetic properties) of the tested nanoparticles was performed by: transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and Mossbauer spectroscopy, respectively. Phytotoxicity was evaluated according to the OECD 208 Guideline, while acute and chronic toxicity of NPs was conducted using bioassays employing bacteria and crustacea, respectively. The phytotoxicity of all investigated iron oxide-based NPs was dependent on concentration and type of NPs formulation and was measured via biomass, seed germination, root length, shoot height, and content of plant pigments. Increasing the concentration of NPs increased phytotoxicity and mortality of aquatic organisms. Ecotoxicity of iron oxide/silver was dependent on the size and content of silver. Iron oxide NPs coated with nanosilver in a percentage ratio of 69/31 were found to be the most toxic on tested terrestrial and aquatic biota.

Bimetallic silver-platinum (AgPt) nanoparticles and chitosan fabricated cotton gauze for enhanced antimicrobial and wound healing applications

Wound healing is a significant clinical and socioeconomic problem that is often affected by microbial infection. Inappropriate monitoring leads to unfavorable concerns for surrounding tissues. Cotton gauzes have been used as low-cost wound dressing material but prolong healing owing to strong adherence and secondary microbial infections. Hence, we prepared the bimetallic (silver and platinum) nanoparticles (AgPt NPs) using citric acid (CA) as a reducing agent and then coated them on chitosan (CS) fabricated cotton gauze (CG) for enhanced antimicrobial and wound healing applications. The synthesis of AgPt NPs was evidenced UV-Visible spectroscopy, FE-TEM, and elemental mapping analysis. The average size of AgPt NPs was 21.48 ± 6.32 nm and spherical in structure. Besides, AgPt NPs showed a hydrodynamic size of 63.64 (d.nm) with a polydispersity index of 0.220 and a zeta potential of -28.1 mV. The FT-IR and XRD analysis demonstrated the functional changes and crystalline properties of AgPt NPs. The antimicrobial efficacy of AgPt NPs was significantly higher than standard antibiotic against bacteria, yeast, and filamentous fungi. Furthermore, the AgPt NPs-CS/CG exhibited a substantial hydrophobic nature with better antimicrobial and antioxidant activity. In addition, pH-dependent Ag and Pt release from the AgPt NPs-CS/CG was determined by ICP-MS analysis. The treatment of AgPt NPs-CS/CG augmented the in vitro wound healing in mouse embryonic fibroblast cells (NIH3T3). Hence, we concluded that AgPt NPs-CS/CG could be used to enhance antimicrobial and wound healing applications.