Synthesis of hollow trimetallic Ag/Au/Pd nanoparticles for reduction of 4-nitrophenol

Enhanced applications in dentistry through autoclave-assisted sonochemical synthesis of Pb/Ag/Cu trimetallic nanocomposites

In recent years, researchers have increasingly focused on the development of multiphase trimetallic nanocomposites (TMNC) incorporating ternary metals or metal oxides, which hold significant potential as alternatives for combatting biofilms and bacterial infections. Enhanced oral health is ensured by the innovative techniques used to effectively prevent bacterial adherence and formation of biofilm on dental sutures. In this investigation, TMNC, which consists of Pb, Ag, and Cu, was synthesized using an autoclave-assisted sonochemical technique. Following synthesis, TMNC were characterized using FTIR, XRD, BET, XPS, TGA, and Raman spectroscopy to analyze their shape and microstructure. Subsequent evaluations, including MTT assay, antibacterial activity testing, and biofilm formation analysis, were conducted to assess the efficiency of the synthesized TMNC. Cytotoxicity and anti-human oral squamous cell carcinoma activities of TMNC were evaluated using the Human Oral Cancer cell line (KB) cell line through MTT assay, demonstrating a dose-dependent increase in anti-human oral squamous cell carcinoma activity against the KB cell line compared to the normal cell line, resulting in notably high cell viability. Furthermore, an ultrasonic probe was employed to incorporate TMNC onto dental suturing threads, with different concentrations of TMNC, ultrasonic power levels, and durations considered to determine optimal embedding conditions that result in the highest antibacterial activity. The inhibitory effects of TMNC, both in well diffusion assays and when incorporated into dental suturing threads, against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria on Mueller-Hinton agar (MHA) were assessed using various concentrations of TMNC. The results of the study indicated that the efficacy of TMNC in inhibiting bacterial growth on dental suturing threads remained impressive, even at low concentrations. Moreover, an evaluation of their potential to destabilize biofilms formed by S. aureus and E. coli, the two pathogens in humans, indicated that TMNC would be a promising anti-biofilm agent.

Surface Deposition of Magnesium Ferrite-Based Supports with Bimetallic Gold/Silver Nanoparticles for the Catalytic Reduction of Nitroaromatics

Surface deposition of magnesium ferrite nanoparticles (MgFe2O4 NPs) with bimetallic gold/silver (Au/Ag) nanoparticles was conducted using the seed-mediated growth method to obtain magnetic-metallic composite catalysts for use in the catalytic reduction of nitroaromatics. Two types of amine-functionalized MgFe2O4 and MgFe2O4@SiO2 NPs were used as magnetic supports for the surface deposition process. The combination of several characterization analyses (i.e., XRD, XPS, TEM, SEM, EDS, and VSM) confirmed the successful syntheses of the MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag NPs. The catalytic reduction of 4-nitrophenol using sodium borohydride as a reducing agent revealed that the reaction was completed within 2 min by using MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag NPs as catalysts. The appearance rate constant of the MgFe2O4/Au/Ag NPs was slightly higher than that of the MgFe2O4@SiO2/Au/Ag NPs. In terms of reusability, high conversion (>80%) of the reduction of 4-nitrophenol was still obtained after 7 and 10 consecutive cycles for the MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag catalysts, respectively. Interestingly, these two catalysts exhibited the highly catalytic conversion of the chosen nitroaromatic derivatives (i.e., 4-nitrobenzaldehyde and 4-nitroaniline). On the whole, the MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag NPs could be utilized as suitable and sustainable catalysts for the catalytic reduction of nitroaromatics due to several desirable features (i.e., high activity, facile and rapid separation by a magnet, and good reusability).

A review of physical, chemical and biological synthesis methods of bimetallic nanoparticles and applications in sensing, water treatment, biomedicine, catalysis and hydrogen storage

This article provides an in-depth analysis of various fabrication methods of bimetallic nanoparticles (BNP), including chemical, biological, and physical techniques. The review explores BNP's diverse uses, from well-known applications such as sensing water treatment and biomedical uses to less-studied areas like breath sensing for diabetes monitoring and hydrogen storage. It cites results from over 1000 researchers worldwide and >300 peer-reviewed articles. Additionally, the article discusses current trends, actionable recommendations, and the importance of synthetic analysis for industry players looking to optimize manufacturing techniques for specific applications. The article also evaluates the pros and cons of various fabrication methods, highlighting the potential of plant extract synthesis for mass production of capped BNPs. However, it warns that this method may not be suitable for certain applications requiring ligand-free surfaces. In contrast, physical methods like laser ablation offer better control and reactivity, especially for applications where ligand-free surfaces are critical. The report underscores the environmental benefits of plant extract synthesis compared to chemical methods that use hazardous chemicals and pose risks to extraction, production, and disposal. The article emphasizes the need for life cycle assessment (LCA) articles in the literature, given the growing volume of research on nanotechnology materials. This article caters to researchers at all stages and applies to various fields applying nanomaterials.

Integration of Gold Nanoparticles into Crosslinker-Free Polymer Particles and Their Colloidal Catalytic Property

This work demonstrates the incorporation of gold nanoparticles (AuNPs) into crosslinker-free poly(N-isopropylacrylamide), PNIPAM, particles in situ and the examination of their structural and catalytic properties. The formation process of the AuNPs across the crosslinker-free PNIPAM particles are compared to that of crosslinked PNIPAM particles. Given the relatively larger free volume across the crosslinker-free polymer network, the AuNPs formed by the in situ reduction of gold ions are detectably larger and more polydisperse, but their overall integration efficiency is slightly inferior. The structural features and stability of these composite particles are also examined in basic and alcoholic solvent environments, where the crosslinker-free PNIPAM particles still offer comparable physicochemical properties to the crosslinked PNIPAM particles. Interestingly, the crosslinker-free composite particles as a colloidal catalyst display a higher reactivity toward the homocoupling of phenylboronic acid and reveal the importance of the polymer network density. As such, the capability to prepare composite particles in a controlled polymer network and reactive metal nanoparticles, as well as understanding the structure-dependent physicochemical properties, can allow for the development of highly practical catalytic systems.

Remediation of wastewater containing 4-nitrophenol using ionic liquid stabilized nanoparticles: Synthesis, characterizations and applications

In the present study, an ionic liquid (IL) based on 1-butyl-3- (trimethoxysilylpropyl) -imidazolium tetrafluoroborate (IL) was prepared using metathesis and anion exchange reactions and used to stabilize silver (AgNPs) nanoparticles. The IL-stabilized silver nanoparticles AgNPs@[BMSI]BF₄ were produced in an aqueous solution with NaBH₄ as a reducing agent. TGA, FTIR, XRD, BET, FSEM, TEM/HRTEM, XPS, and UV-Vis spectra were used to analyze AgNPs@[BMSI]BF₄ and were used for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH₄. AgNPs@[BMSI]BF₄ showed excellent catalytic properties for the reduction of 4-NP to 4-AP and showed 100% conversion of 4-NP to 4-AP within 6 min and the rate constant (k) was found to be 8.33 × 10^-3 s^-1. The reusability results indicated that 97.8% of 4-NP was converted to 4-AP with highly stable rate constants over six consecutive cycles. The activity factor (AF) and the turn-over frequency (TOF) at room temperature were 3.33 s^-1 gm^-1 and 0.166 s^-1, respectively. This study extends a new approach to the production of stable catalysts for the growing needs in wastewater treatment.

Green synthesis of P − ZrO2CeO2ZnO nanoparticles using leaf extracts of Flacourtia indica and their application for the photocatalytic degradation of a model toxic dye, Congo red

In the present work P−ZrO2CeO2ZnO nanoparticles were synthesised for the first time using phytochemical extracts from Flacourtia indica leaves and applied in the photocatalytic degradation of Congo Red in the presence of Light Emitting Diode warm white light. The photocatalytic degradation was optimized with respect to P−ZrO2CeO2ZnO nanoparticle dosage, initial Congo Red concentration, and degradation time. The optimum conditions for P−ZrO2CeO2ZnO nanoparticle synthesis was pH 9, leaves extracts of F. indica dosage 4 g 100 mL⁻¹, Zirconia, Cerium and Zinc metal ion concentration 0.05 mg/L and metal ion to plant volume ratio of 1:4. The leaves extract dosage, pH and metal concentration had the most significant effects on the synthesis of the nanoparticles. The nanoparticles followed type III physisorption adsorption isotherms with surface area of 0.4593 m³g⁻¹, pore size of 6.80 nm, pore volume 0.000734 cmg−13 and average nanoparticle size 0.255 nm. A degradation efficiency of 86% was achieved and the optimum degradation conditions were 0.05 g/L of P−ZrO2CeO2ZnO nanoparticle dosage, 10 mg/L initial Congo red concentration, and 250 minutes irradiation time. Data from kinetic studies showed that the degradation followed pseudo first order kinetics at low concentration, with a rate constant of 0.069 min⁻¹. The superoxide, h+ holes and light were the main determinants of the reaction mechanisms for the degradation of Congo Red. The investigation outcomes demonstrated that P−ZrO2CeO2ZnO nanoparticles offer a high potential for photocatalytic degradation of Congo Red.

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The most significant factors on P−ZrO2CeO2ZnO nanoparticles synthesis were plant leaves dosage, pH and initial metal concentration.

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The nanoparticles exhibited high catalytic activity towards photocatalytic degradation of Congo red.

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Superoxide, h+ holes and light were the main determinants of the photocatalytic degradation mechanisms.

One-pot synthesis of Au-M@SiO2 (M = Rh, Pd, Ir, Pt) core-shell nanoparticles as highly efficient catalysts for the reduction of 4-nitrophenol

The conversion of p-nitrophenol (4-NP) to p-aminophenol (4-AP) is of great significance for pharmaceutical and material manufacturing. In this work, Au-M@SiO₂ (M = Rh, Pd, Ir, Pt) nanoparticles (NPs) with core-shell structures, which are expected to be excellent catalysts for the transformation of 4-NP to 4-AP, were synthesized by a facile one-pot one-step method. The structure and composition of the NPs were characterized through transmission electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. Au-M@SiO₂ (M = Rh, Pd, Ir, Pt) core-shell NPs showed excellent catalytic activity in the reduction of 4-NP, which is superior to most catalysts reported in the previous literature. The enhanced catalytic activity of Au-M@SiO₂ core-shell NPs is presumably related to the bimetallic synergistic effect. This study provides a simple strategy to synthesize core-shell bimetallic NPs for catalytic applications.

Rational design of biogenic PdxAuy nanoparticles with enhanced catalytic performance for electrocatalysis and azo dyes degradation

The green biogenic PdAu nanoparticles (bio-PdAu NPs) exhibits remarkable catalytic performance in hydrogenation, which is highly desired. However, the catalytic principles and effectiveness of bio-Pd^xAu^y NPs in response to various catalytic systems (electrocatalysis and suspension-catalysis) are unclear. Herein, a facile synthetic strategy for bio-Pd^xAu^y NPs synthesis with controlled size and the catalytic principles for hydrogen evolution reaction (HER) and azo dye degradation is reported. In the biosynthetic process, the size and composition of the bio-Pd^xAu^y NPs could be precisely controlled by predesigning the precursor mass ratio of Pd/Au, and the Au proportion showed a linear relationship with the size of NPs (R² = 0.92). The obtained bio-Pd^xAu^y NPs exhibit variable activity in electrocatalysis (HER) and suspension-catalysis (azo dye degradation). For electrocatalysis, the formation of conductive networks that facilitates the extracellular electron transfer is crucial. It was revealed that the bio-Pd²Au⁸ exhibited superior electrocatalytic performance in HER/toward hydrogen evolution, with a maximum current density of 1.65 mA cm^-2, which was 1.54 times higher than that commercial Pd/C (1.07 mA cm^-2). The high electrocatalytic activity was attributed to its appropriate size (81.38 ± 6.14 nm) and uniform distribution on the cell surface, which promoted the extracellular electron transfer by constructing a conductive network between catalyst and electrode. However, for suspension-catalysis, the size effect and synergistic effect of bimetallic NPs have a more prominent effect on the degradation of azo dyes. As the increase of Au proportion the particle size decreases, and the catalytic activity of bio-Pd^xAu^y improved significantly. The response principles of bio-Pd^xAu^y proposed in this study provide a reliable reference for the rational design of bio-based bimetallic catalysts with enhanced catalytic performance.

Synthesis and potential applications of trimetallic nanostructures

The present review highlights the synthetic strategies and potential applications of TMNs for organic reactions, environmental remediation, and health-related activities.

Facile synthesis of Au/ZnO/Ag nanoparticles using Glechoma hederacea L. extract, and their activity against leukemia

Metal combinations have been attracting the attention of scientists for some time. They usually exhibit new characteristics that are different from the ones possessed by their components. In this work, Au/ZnO/Ag nanoparticles were synthesized biologically using Glechoma hederacea L. extract. The synthesized Au/ZnO/Ag nanoparticles were characterized by UV-Vis, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Atomic Force Microscopy (AFM). The microscopic methods confirmed the presence of spherical nanoparticles of 50–70 nm. The influence of biologically synthesized Au/ZnO/Ag nanoparticles on the vitality of human cells was evaluated in vitro with the use of established human Acute T Cell Leukemia cell line, Jurkat (ATCC® TIB-152™), as well as mononuclear cells isolated from peripheral blood (PBMC) of voluntary donors. Cell survival and the half-maximal inhibitory concentration index (IC50) were analyzed by the MTT test. The studies showed that the total loss of cell viability occurred at the Au/ZnO/Ag nanoparticle concentration range of 10 µmol–50 µmol. The use of Au/ZnO/Ag nanoparticles at the concentration of 100 µmol eliminated almost all living cells from the culture in 24h. The above observation confirms the result obtained during the MTT test.

Biochemical synthesis of palladium nanoparticles: The influence of chemical fixatives used in electron microscopy on nanoparticle formation and catalytic performance

Palladium nanoparticles (PdNPs) can catalyse a range of reductive chemical reactions transforming both organic and inorganic environmental pollutants. PdNPs that ranged from <2 to 2-40 nm were synthesized using chemical methods, and bacterial biomass with/without chemical fixatives. PdNP formation was enhanced by adsorption of Pd(II) to bacterial biomass, followed by fixation with formate or glutaraldehyde. TEM-SAED analyses confirmed that the cell associated PdNPs were polycrystalline with a face-centered cubic structure. Chemically formed PdNPs possessed a higher Pd(0):Pd(II) ratio and produced structurally similar nanoparticles as the biotic systems. These PdNPs were employed to catalyze two, reductive chemical reactions, transforming 4-nitrophenol (4-NP) and hexavalent chromium [Cr(VI)], into 4-aminophenol and Cr(IV), respectively. In the reduction of 4-NP, the catalytic performance was directly proportional to PdNP surface area, i.e., the smallest PdNPs in formate-PdCH34 cells had the fastest rate of reaction. The mass of Pd(0) as PdNPs was the main contributor to Cr(VI) reduction; the chemically synthesized PdNPs showed the highest removal efficiency with 96% at 20 min. The use of glutaraldehyde enhanced the reduction of Pd(II) and promoted PdNPs formation, i.e., creating an artefact of fixation; however, this treatment also enhanced the catalytic performance of these PdNPs.

Anti-Leukemia Activity of Au/CuO/ZnO Nanoparticles Synthesized used Verbena officinalis Extract

As biological synthesis has become an alternative to chemical and physical methods for synthesizing nanoparticles, this work describes the synthesis of Au/CuO/ZnO nanoparticles using Verbena officinalis extract. The synthesized Au/CuO/ZnO nanoparticles were characterized using Ultraviolet–Visible, Fourier Transform-Infrared, Transmission Electron Microscopy and Atomic Force Microscopy. The influence of Au/CuO/ZnO nanoparticles on cell viability was evaluated in vitro, using the established cell line – Jurkat (ATCC® TIB-152™). The Annexin V binding test confirmed the previous results of the MTT assay, which indicate that the studied complex of Au/CuO/ZnO nanoparticles has a strong cytotoxic effect on the Jurkat cell line. The type of death and the effectiveness of cell elimination depended both on the concentration of the complex and the duration of culture.

Optimization of sol-immobilized bimetallic Au-Pd/TiO2 catalysts: reduction of 4-nitrophenol to 4-aminophenol for wastewater remediation

A sol-immobilization method is used to synthesize a series of highly active and stable Au_xPd_1-x/TiO₂ catalysts (where x = 0, 0.13, 0.25, 0.5, 0.75, 0.87 and 1) for wastewater remediation. The catalytic performance of the materials was evaluated for the catalytic reduction of 4-nitrophenol, a model wastewater contaminant, using NaBH₄ as the reducing agent under mild reaction conditions. Reaction parameters such as substrate/metal and substrate/reducing agent molar ratios, reaction temperature and stirring rate were investigated. Structure-activity correlations were studied using a number of complementary techniques including X-ray powder diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. The sol-immobilization route provides very small Au-Pd alloyed nanoparticles, with the highest catalytic performance shown by the Au_0.5Pd_0.5/TiO₂ catalyst. This article is part of a discussion meeting issue 'Science to enable the circular economy'.

Au–Cu–M (M = Pt, Pd, Ag) nanorods with enhanced catalytic efficiency by galvanic replacement reaction

This work reports a general wet-chemistry method to produce Au–Cu–X (X = Pt, Pd, and Ag) trimetallic nanorods using galvanic replacement reaction with Au–Cu nanorods as the templates.