Noble metal-based bimetallic nanoparticles: the effect of the structure on the optical, catalytic and photocatalytic properties

Novel litchi-like Au-Ag nanospheres driven dual-readout lateral flow immunoassay for sensitive detection of pyrimethanil

Pyrimethanil (PYR) is a fungicide that is harmful to consumers when present in foods at concentrations greater than maximum permitted residue levels. High-performance immunoprobes and dual-readout strategy may be useful for constructing sensitive lateral flow immunoassay (LFIA). Herein, the prepared litchi-like Au-Ag bimetallic nanospheres (LBNPs) exhibited high mass extinction coefficients and fluorescence quenching constants. Benefiting from LBNPs and dual-readout mode, the limits of detection of LBNPs-CM-LFIA and LBNPs-FQ-LFIA for PYR were 0.957 and 0.713 ng mL-1, which were 2.54- and 3.41-fold lower than that of gold nanoparticles-based LFIA, respectively. The limits of quantitation of LBNPs-CM-LFIA and LBNPs-FQ-LFIA were 3.740 and 1.672 ng mL-1, respectively. LBNPs-LFIA was applied to detect PYR in cucumber and grape samples with satisfactory recovery (90%-111%). LBNPs-LFIA showed good agreement with LC-MS/MS for the detection of PYR in the samples. Accordingly, this sensitive and accurate dual-readout LFIA based on LBNPs can be effectively applied for food safety.

Surface Segregation Studies in Ternary Noble Metal Alloys: Comparing DFT and Machine Learning with Experimental Data

Surface segregation, whereby the surface composition of an alloy differs systematically from the bulk, has historically been hard to study, because it requires experimental and modeling methods that span alloy composition space. In this work, we study surface segregation in catalytically relevant noble and platinum-group metal alloys with a focus on three ternary systems: AgAuCu, AuCuPd, and CuPdPt. We develop a data set of 2478 fcc slabs with those compositions including all three low-index crystallographic orientations relaxed with Density Functional Theory using the PBEsol functional with D3 dispersion corrections. We fine-tune a machine learning model on this data and use the model in a series of 1800 Monte Carlo simulations spanning ternary composition space for each surface orientation and ternary chemical system. The results of these simulations are validated against prior experimental surface segregation data collected using composition spread alloy films for AgAuCu and AuCuPd. Our findings reveal that simulations conducted using the (110) orientation most closely match experimentally observed surface segregation trends, and while predicted trends qualitatively match observation, biases in the PBEsol functional limit numeric accuracy. This study advances understanding of surface segregation and the utility of computational studies and highlights the need for further improvements in simulation accuracy.

B and N Codoped Cellulose-Supported Ag-/Bi-Doped Mo(S,O)3 Trimetallic Sulfo-Oxide Catalyst for Photocatalytic H2 Evolution Reaction and 4-Nitrophenol Reduction

Cellulose plays a significant role in designing efficient and stable cellulose-based metallic catalysts, owing to its surface functionalities. Its hydroxyl groups are used as anchor sites for the nucleation and growth of metallic nanoparticles and, as a result, improve the stability and catalytic activity. Meanwhile, cellulose is also amenable to surface modifications to be more suitable for incorporating and stabilizing metallic nanoparticles. Herein, the Ag-/Bi-doped Mo(S,O)3 trimetallic sulfo-oxide anchored on B and N codoped cellulose (B-N-C) synthesized by a facile approach showed excellent stability and catalytic activity for PHER at 573.28 μmol/h H2 with 25 mg of catalyst under visible light, and 92.3% of the 4-nitrophenol (4-NP) reduction was achieved within 135 min by in situ-generated protons. In addition to B and N codoping, our use of the calcination method for B-N-C preparation further increases the structural disorders and defects, which act as anchoring sites for Ag-/Bi-doped Mo(S,O)3 nanoparticles. The Ag-/Bi-doped Mo(S,O)3@B-N-C surface active site also stimulates H2O molecule adsorption and activation kinetics and reduces the photogenerated charge carrier's recombination rate. The Mo4+ → Mo6+ electron hopping transport and the O 2p and Bi 6s orbital overlap facilitate the fast electron transfer by enhancing the electron's lifetime and photoinduced charge carrier mobility, respectively. In addition to acting as a support, B-N-C provides a highly conductive network that enhances charge transport, and the relocated electron in B-N-C activates the H2O molecule, which enables Ag-/Bi-doped Mo(S,O)3@B-N-C to have appreciable PHER performance.

A general strategy for the enhanced H2 production performance of CdS/noble metal sulfide nanorods photocatalysts by cation exchange

In this work, we report a series of noble metal (Ag, Au, Pt, etc.) sulfides that act as co-catalysts anchoring on CdS nanorods (NRs) obtained via a cation exchange strategy to promote photocatalytic hydrogen evolution. CdS NRs are first generated via a hydrothermal routine, noble metal sulfides are then in-situ grown on CdS NRs by a cation exchange method. CdS/Ag2S, CdS/Au2S and CdS/PtS NRs show improved hydrogen production rates (2506.88, 1513.17 and 1004.54 μmol g-1h-1, respectively), approximately 18, 11 and 7 times higher than CdS NRs (138.27 μmol g-1h-1). Among CdS/noble metal sulfide NRs, CdS/Ag2S NRs present the best H2 production performance. The apparent quantum efficiency (AQE) of CdS/Ag2S NRs achieves 3.11 % at λ = 370 nm. The improved photocatalytic performance of CdS/noble metal sulfide NRs dues to the following points: i) Noble metal sulfides on CdS NRs are beneficial for elevating light-absorbing and light-utilizing capacities, contributing to generating more photoexcited charges; ii) Noble metal sulfides are in-situ grown on CdS NRs as electron acceptors by a cation exchange method, thus the photoexcited electrons generated by CdS NRs rapidly migrate to the surface of noble metal sulfides, successfully accelerating the carriers separation efficiency. This series of noble metal sulfides acting as co-catalysts anchoring on CdS NRs offer new insights into the construction principles of high-performance photocatalytic hydrogen evolution catalysts.

Sustainable Nanoparticles from Stephania glabra and Analysis of Their Anticancer Potential on 2D and 3D Models of Prostate Cancer

In pursuit of a novel effective treatment for prostate cancer, methanolic extract of Stephania glabra tubers (Sg-ME) was utilized to fabricate silver (Sg-AgNP), copper oxide (Sg-CuONP), and silver-copper bimetallic nanoparticles (Sg-BNP). The characterization of the nanoparticles confirmed spherical shape with average diameters of 30.72, 32.19, and 25.59 nm of Sg-AgNP, Sg-CuONP, and Sg-BNP, respectively. Interestingly, these nanoparticles exhibited significant cytotoxicity toward the prostate cancer (PC3) cell line while being non-toxic toward normal cells. The nanoparticles were capable of inducing apoptosis in PC3 cells by enhancing reactive oxygen species (ROS) generation and mitochondrial depolarization. Furthermore, the shrinkage of 3D prostate tumor spheroids was observed after 4 days of treatment with these green nanoparticles. The 3D model system was less susceptible to nanoparticles as compared to the 2D model system. Sg-BNP showed the highest anticancer potential on 2D and 3D prostate cancer models.

The Molecular Footprint of Peptides on the Surface of Ultrasmall Gold Nanoparticles (2 nm) Is Governed by Steric Demand

Ultrasmall gold nanoparticles were functionalized with peptides of two to seven amino acids that contained one cysteine molecule as anchor via a thiol-gold bond and a number of alanine residues as nonbinding amino acid. The cysteine was located either in the center of the molecule or at the end (C-terminus). For comparison, gold nanoparticles were also functionalized with cysteine alone. The particles were characterized by UV spectroscopy, differential centrifugal sedimentation (DCS), high-resolution transmission electron microscopy (HRTEM), and small-angle X-ray scattering (SAXS). This confirmed the uniform metal core (2 nm diameter). The hydrodynamic diameter was probed by 1H-DOSY NMR spectroscopy and showed an increase in thickness of the hydrated peptide layer with increasing peptide size (up to 1.4 nm for heptapeptides; 0.20 nm per amino acid in the peptide). 1H NMR spectroscopy of water-dispersed nanoparticles showed the integrity of the peptides and the effect of the metal core on the peptide. Notably, the NMR signals were very broad near the metal surface and became increasingly narrow in a distance. In particular, the methyl groups of alanine can be used as probe for the resolution of the NMR spectra. The number of peptide ligands on each nanoparticle was determined using quantitative 1H NMR spectroscopy. It decreased with increasing peptide length from about 100 for a dipeptide to about 12 for a heptapeptide, resulting in an increase of the molecular footprint from about 0.1 to 1.1 nm2.

Element specific atom counting for heterogeneous nanostructures: Combining multiple ADF STEM images for simultaneous thickness and composition determination

In this paper, a methodology is presented to count the number of atoms in heterogeneous nanoparticles based on the combination of multiple annular dark field scanning transmission electron microscopy (ADF STEM) images. The different non-overlapping annular detector collection regions are selected based on the principles of optimal statistical experiment design for the atom-counting problem. To count the number of atoms, the total intensities of scattered electrons for each atomic column, the so-called scattering cross-sections, are simultaneously compared with simulated library values for the different detector regions by minimising the squared differences. The performance of the method is evaluated for simulated Ni@Pt and Au@Ag core-shell nanoparticles. Our approach turns out to be a dose efficient alternative for the investigation of beam-sensitive heterogeneous materials as compared to the combination of ADF STEM and energy dispersive X-ray spectroscopy.

NIR-Mediated Cu2O/Au Nanomotors for Synergistically Treating Hepatoma Carcinoma Cells

We presented a NIR-driven Janus Cu2O/Au nanomotor. The nanomotor has a truncated octahedral structure. By asymmetric Au evaporation, the light response range of Cu2O nanomotor is extended to near-infrared range, and the speed of Cu2O/Au nanomotors under NIR is significantly increased. In promoting apoptosis of hepatocellular carcinoma, except the nanotoxicity of Cu2O itself, the Au layer enhances the photothermal properties, allowing Cu2O/Au nanomotors to induce apoptosis in hepatocellular carcinoma cells by heating them. On the other hand, a Schottky barrier formed at the interface of Cu2O and Au, preventing the recombination of electrons, which makes more electrons react with biomolecules to produce toxic ROS to kill hepatocellular cells. The killing rate of hepatocellular carcinoma cells reached 87 % by the combined effect of nanotoxicity inhibition of proliferation and photothermal & photodynamic therapy (PTT & PDT). Nanomotors in combination with multiple approaches are explored as a new treatment to tumor in this article.

Fungus-mediated synthesis of Se-BiO-CuO multimetallic nanoparticles as a potential alternative antimicrobial against ESBL-producing Escherichia coli of veterinary origin

Bacterial infections emerge as a significant contributor to mortality and morbidity worldwide. Emerging extended-spectrum β-lactamase (ESBL) Escherichia coli strains provide a greater risk of bacteremia and mortality, are increasingly resistant to antibiotics, and are a major producer of ESBLs. E. coli bacteremia-linked mastitis is one of the most common bacterial diseases in animals, which can affect the quality of the milk and damage organ functions. There is an elevated menace of treatment failure and recurrence of E. coli bacteremia necessitating the adoption of rigorous alternative treatment approaches. In this study, Se-Boil-CuO multimetallic nanoparticles (MMNPs) were synthesized as an alternate treatment from Talaromyces haitouensis extract, and their efficiency in treating ESBL E. coli was confirmed using standard antimicrobial assays. Scanning electron microscopy, UV-visible spectroscopy, and dynamic light scattering were used to validate and characterize the mycosynthesized Se-BiO-CuO MMNPs. UV-visible spectra of Se-BiO-CuO MMNPs showed absorption peak bands at 570, 376, and 290 nm, respectively. The average diameters of the amorphous-shaped Se-BiO-CuO MMNPs synthesized by T. haitouensis extract were approximately 66-80 nm, respectively. Se-BiO-CuO MMNPs (100 μg/mL) showed a maximal inhibition zone of 18.33 ± 0.57 mm against E. coli. Se-BiO-CuO MMNPs also exhibited a deleterious impact on E. coli killing kinetics, biofilm formation, swimming motility, efflux of cellular components, and membrane integrity. The hemolysis assay also confirms the biocompatibility of Se-BiO-CuO MMNPs at the minimum inhibitory concentration (MIC) range. Our findings suggest that Se-BiO-CuO MMNPs may serve as a potential substitute for ESBL E. coli bacteremia.

Targeted color design of silver-gold alloy nanoparticles

This research article focuses on the targeted color design of silver-gold alloy nanoparticles (NPs), employing a multivariate optimization approach. NP synthesis involves interconnected process parameters, making independent variation challenging. Data-based property-process relationships are established to optimize optical properties effectively. We define a color target, employ a green chemical co-reduction method at room temperature and optimize process parameters accordingly. The CIEL*a*b* color space (Commission Internationale de l'Éclairage - International Commission on Illumination) and Euclidean distances facilitate accurate color matching to establish the property-process relationship. Concurrently, theoretical Mie calculations explore the structure-property relationship across particle sizes, concentrations, and molar gold contents. The theoretically optimal structure agrees very well with experimental particle structures at the property-process relationship's optimum. The data-driven property-process relationship provides valuable insights into the formation mechanism of a complex particle system, sheds light on the role of relevant process parameters and allows to evaluate the practically available property space. Model validation beyond the original grid demonstrates its robustness, yielding colors close to the target. Additionally, Design of Experiments (DoE) methods reduce experimental work by threefold with slight accuracy trade-offs. Our novel methodology for targeted color design demonstrates how data-based methods can be utilized alongside structure-property relationships to unravel property-process relationships in the design of complex nanoparticle systems and paves the way for future developments in targeted property design.

Green waste immobilized Ag/Cu feather like Bi-matrix on garment dye decomposes and their bio-efficacy

This paper describes a simple phyto-remediation of feather-like silver/copper bi-matrix (BMs) was constructed by employing pommagrant waste peel (PWP) extract as crucial role of reducing agent and chelating agents. Numerous strategies, including UV-Visible, XRD, SEM-EDX, and TEM and BET isotherm were used to analysis the optical, structural, surface area and functional properties. Ag/Cu BPNMs of TEM characterization shows feather-like architectural features with constrained size and shape. The Ag/Cu co-catalytic nanoparticles have a particle size of 34-64 nm. The photocatalytic efficiency of Ag/Cu BMs was investigated using a garment dye, Congo red (CR), at successive time intervals under halogen lamp exposure. For Ag/Cu bimetallic nanoparticles, the photocatalytic degradation rate was recorded to be 100% after 40 min which is caused by adsorption of Congo red dye molecules on Ag/Cu and their degradation by reactive oxygen species (ROS). ROS are free hydroxyl radicals such as •OH and O2• ions that have high oxidizing capacity. The developed Ag/Cu BMs shown effective bacteriostatic action against many infections.

Catalytic and anti-cancer properties of platinum, gold, silver, and bimetallic Au-Ag nanoparticles synthesized by Bacillus sp. bacteria

Metallic nanoparticles play a significant role in the catalysis of chemical processes, besides, bimetallic nanoparticles with abundant active sites can reduce metallic nanoparticles toxicity in addition to increasing their catalytic performances. In this work, the platinum, gold, and silver nanoparticles are bio-synthesized using a native bacterium (GFCr-4). Also, the Au-Ag and Au@Ag bimetallic nanoparticles with alloy and core-shell structures, respectively, are biologically synthesized. To improve the synthesis, the effects of various factors like pH, temperature, electron donor, and ionic liquids were investigated. The as-synthesized nanoparticles were characterized with different techniques. The microscope images and dynamic light scattering (DLS) analysis confirm the uniform distribution of as-synthesized nanoparticles with average sizes of 25, 30, 47, 77, and 86 nm obtained for Ag, Au, Pt, Au-Ag alloy, and Au@Ag core-shell, respectively. The catalytic performances of as-synthesized nanoparticles were investigated. The Au-Ag alloy nanoparticles exhibit better catalytic performance than the as-synthesized metallic Au nanoparticles, according to the Gewald reaction. According to the photocatalytic study, the yield can be increased by up to 92% by using PtNPs in the presence of a green LED. Additionally, for the first time, PtNPs were utilized as an effective catalyst in a peroxyoxalate chemiluminescence (POCL) system in the presence of nuclear fast red (NFR) as a novel fluorophore. In addition, the results of the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay revealed that the synthesized eco-friendly nanoparticles have a low effect on the lethality of 3T3 normal cells whereas MCF-7 cancer cells were inhibited up to 77.3% after treatment by PtNPs nanoparticles.

Bimetallic Nanozyme: A Credible Tag for In Situ-Catalyzed Reporter Deposition in the Lateral Flow Immunoassay for Ultrasensitive Cancer Diagnosis

The lateral flow immunoassay (LFIA) is a sought-after point-of-care testing platform, yet the insufficient sensitivity of the LFIA limits its application in the detection of tumor biomarkers. Here, a colorimetric signal amplification method, bimetallic nanozyme-mediated in situ-catalyzed reporter deposition (BN-ISCRD), was designed for ultrasensitive cancer diagnosis. The bimetallic nanozyme used, palladium@iridium core-shell nanoparticles (Pd@Ir NPs), had ultrahigh enzyme-like activity, which was further explained by the electron transfer of Pd@Ir NPs and the change in the Gibbs free energy during catalysis through density functional theory calculations. With gastric cancer biomarkers pepsinogen I and pepsinogen II as model targets, this assay could achieve a cutoff value of 10 pg/mL, which was 200-fold lower than that without signal enhancement. The assay was applied to correctly identify 8 positive and 28 negative clinical samples. Overall, this BN-ISCRD-based LFIA showed great merits and potential in the application of ultrasensitive disease diagnosis.

Synergistic antibacterial mechanism of silver-copper bimetallic nanoparticles

The excessive use of antibiotics in clinical settings has resulted in the rapid expansion, evolution, and development of bacterial and microorganism resistance. It causes a significant challenge to the medical community. Therefore, it is important to develop new antibacterial materials that could replace traditional antibiotics. With the advancements in nanotechnology, it has become evident that metallic and metal oxide nanoparticles (MeO NPs) exhibit stronger antibacterial properties than their bulk and micron-sized counterparts. The antibacterial properties of silver nanoparticles (Ag NPs) and copper nanoparticles (Cu NPs) have been extensively studied, including the release of metal ions, oxidative stress responses, damages to cell integrity, and immunostimulatory effects. However, it is crucial to consider the potential cytotoxicity and genotoxicity of Ag NPs and Cu NPs. Numerous experimental studies have demonstrated that bimetallic nanoparticles (BNPs) composed of Ag NPs and Cu NPs exhibit strong antibacterial effects while maintaining low cytotoxicity. Bimetallic nanoparticles offer an effective means to mitigate the genotoxicity associated with individual nanoparticles while considerably enhancing their antibacterial efficacy. In this paper, we presented on various synthesis methods for Ag-Cu NPs, emphasizing their synergistic effects, processes of reactive oxygen species (ROS) generation, photocatalytic properties, antibacterial mechanisms, and the factors influencing their performance. These materials have the potential to enhance efficacy, reduce toxicity, and find broader applications in combating antibiotic resistance while promoting public health.

Thermally Induced Surface Structure and Morphology Evolution in Bimetallic Pt-Au/HOPG Nanoparticles as Probed Using XPS and STM

Bimetallic nanoparticles expand the possibilities of catalyst design, providing an extra degree of freedom for tailoring the catalyst structure in comparison to purely monometallic systems. The distribution mode of two metal species defines the structure of surface catalytic sites, and current research efforts are focused on the development of methods for their controlled tuning. In light of this, a comprehensive investigation of the factors which influence the changes in the morphology of bimetallic nanoparticles, including the elemental redistribution, are mandatory for each particular bimetallic system. Here we present the combined XPS/STM study of the surface structure and morphology of bimetallic Pt-Au/HOPG nanoparticles prepared by thermal vacuum deposition and show that thermal annealing up to 350 °C induces the alloying process between the two bulk-immiscible metal components. Increasing the treatment temperature enhances the extent of Pt-Au alloying. However, the sintering of nanoparticles starts to occur above 500 °C. The approach implemented in this work includes the theoretical simulation of XPS signal intensities for a more meticulous analysis of the compositional distribution and can be helpful from a methodological perspective for other XPS/STM studies of bimetallic nanoparticles on planar supports.

Facile Synthesis of Ru Nanoboxes with a Hexagonal Close-Packed Structure by Templating with Ag Nanocubes and Their Catalytic Properties

Noble-metal nanoboxes offer an attractive form of nanomaterials for catalytic applications owing to their open structure and highly efficient use of atoms. Herein, we report the facile synthesis of Ag-Ru core-shell nanocubes and then Ru nanoboxes with a hexagonal close-packed (hcp) structure, as well as evaluation of their catalytic activity toward a model hydrogenation reaction. By adding a solution of Ru(acac)3 in ethylene glycol (EG) dropwise to a suspension of silver nanocubes in EG at 170 °C, Ru atoms are generated and deposited onto the entire surface of a nanocube. As the volume of the RuIII precursor is increased, Ru atoms are also produced through a galvanic replacement reaction, generating Ag-Ru nanocubes with a hollow interior. The released Ag+ ions are then reduced by EG and deposited back onto the nanocubes. By selectively etching away the remaining Ag with aqueous HNO3 , the as-obtained Ag-Ru nanocubes are transformed into Ru nanoboxes, whose walls are characterized by an hcp structure and an ultrathin thickness of a few nanometers. Finally, we evaluated the catalytic properties of the Ru nanoboxes with two different wall thicknesses by using a model hydrogenation reaction; both samples showed excellent performance.

Tuning atomic-scale mixing of nanoparticles produced by atmospheric-pressure spark ablation

Nanoparticles (NPs) mixed at the atomic scale have been synthesized by atmospheric-pressure spark ablation using pairs of Pd and Hf electrodes. Gravimetric analysis of the electrodes showed that the fraction of each material in the resulting mixed NPs can be varied from ca. 15-85 at% to 85-15 at% by employing different combinations of electrode polarities and thicknesses. These results were also qualitatively corroborated by microscopy and elemental analysis of the produced NPs. When using pairs of electrodes having the same diameter, the material from the one at negative polarity was represented at a substantially higher fraction in the mixed NPs regardless of whether a pair of thin or thick electrodes were employed. This can be attributed to the higher ablation rate of the electrodes at the negative polarity, as already known from earlier experiments. When using electrodes of different diameters, the fraction of the element from the thinner electrode was always higher. This is because thinner electrodes are ablated more effectively due to, at least in part, the increased importance of the associated heat losses compared to its thicker counterpart. In those cases, the polarity of the electrodes had a significantly smaller effect. Overall, our results demonstrate, for the first time, that spark ablation can be used to control atomic scale mixing and thus produce alloyed NPs with compositions that can be tuned to a good extent by simply using different combinations of electrode diameters and polarities. This expands the capabilities of the technique for producing mixed nanoparticle building blocks of well-defined composition that are highly desired for a wide range of applications.

Degradation of Pesticides Using Semiconducting and Tetrapyrrolic Macrocyclic Photocatalysts-A Concise Review

Exposure to pesticides is inevitable in modern times, and their environmental presence is strongly associated to the development of various malignancies. This challenge has prompted an increased interest in finding more sustainable ways of degrading pesticides. Advanced oxidation processes in particular appear as highly advantageous, due to their ability of selectively removing chemical entities form wastewaters. This review provides a concise introduction to the mechanisms of photochemical advanced oxidation processes with an objective perspective, followed by a succinct literature review on the photodegradation of pesticides utilizing metal oxide-based semiconductors as photosensitizing catalysts. The selection of reports discussed here is based on relevance and impact, which are recognized globally, ensuring rigorous scrutiny. Finally, this literature review explores the use of tetrapyrrolic macrocyclic photosensitizers in pesticide photodegradation, analyzing their benefits and limitations and providing insights into future directions.

A MXene@AgAu@PDA nanoplatform loaded with AgAu nanocages for enhancing catalytic activity and antibacterial performance

With the rapid development of social industrialization, environmental problems seriously threaten people's health, especially water pollution. Therefore, there is an urgent need to construct a multifunctional nanoplatform for different scenarios. Two-dimensional MXene@AgAu@PDA nanosheets loaded with AgAu bimetallic nanocages have been prepared by a one-step method. First, the in situ generated MXene@Ag is used as an auxiliary template, and then HAuCl4 and dopamine are added for in situ redox-oxidizing polymerization reactions to obtain AgAu catalytic nanocages and the protective polydopamine (PDA) layer which can improve the stability and biocompatibility. MXene and PDA have excellent photothermal conversion ability while hollow AgAu nanocages have strong absorption in the near-infrared region and a local surface plasmonic resonance effect. In comparison to the catalytic reaction rates under dark and room temperature conditions, the catalytic kinetic rate of MXene@AgAu@PDA nanosheets under near-infrared irradiation increases from 0.13 to 0.69 min-1 mg-1. Density functional theory (DFT) is used to study the electron transfer behavior between AgAu nanocages and MXene nanosheets, and the mechanism of the enhanced catalytic reaction rate is analyzed. Besides, due to its Ag ions and photothermal coupling antibacterial properties, 40 μg mL-1 MXene@AgAu@PDA nanosheets inactivates nearly all E. coli and S. aureus after irradiation with near-infrared light for 6 min.

New insights into the influence of plasmonic and non-plasmonic nanostructures on the photocatalytic activity of titanium dioxide

The results of this work cover the influence of plasmonic (gold) and non-plasmonic (palladium) nanostructures on the photocatalytic activity and redox properties of titanium dioxide. Materials decorated with gold, palladium and both materials were examined using photoelectrochemical and spectroelectrochemical methods to establish the changes introduced by the modifications and the possibility of the influence of the plasmonic effect from gold on their activity. Additionally, the photocatalytic tests of hydroxyl radical generation and hydrogen evolution were performed to confirm the activity of modified materials in oxidation and reduction reactions. It turned out that in the observed system the catalytic properties of palladium determine mostly the activity of modified materials, and the surface plasmon resonance of gold does not affect the activity. Moreover, the influence of the nanostructures on the activity, besides the catalytic performance, is the same for plasmonic and non-plasmonic ones and results in a change in the redox properties of the semiconductor.

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.

Ultrastructure and Surface Composition of Glutathione-Terminated Ultrasmall Silver, Gold, Platinum, and Alloyed Silver-Platinum Nanoparticles (2 nm)

Alloyed ultrasmall silver-platinum nanoparticles (molar ratio Ag:Pt = 50:50) were prepared and compared to pure silver, platinum, and gold nanoparticles, all with a metallic core diameter of 2 nm. They were surface-stabilized by a layer of glutathione (GSH). A comprehensive characterization by high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), differential centrifugal sedimentation (DCS), and UV spectroscopy showed their size both in the dry and in the water-dispersed state (hydrodynamic diameter). Solution NMR spectroscopy (1H, 13C, COSY, HSQC, HMBC, and DOSY) showed the nature of the glutathione shell including the number of GSH ligands on each nanoparticle (about 200 with a molecular footprint of 0.063 nm2 each). It furthermore showed that there are at least two different positions for the GSH ligand on the gold nanoparticle surface. Platinum strongly reduced the resolution of the NMR spectra compared to silver and gold, also in the alloyed nanoparticles. X-ray photoelectron spectroscopy (XPS) showed that silver, platinum, and silver-platinum particles were at least partially oxidized to Ag(+I) and Pt(+II), whereas the gold nanoparticles showed no sign of oxidation. Platinum and gold nanoparticles were well crystalline but twinned (fcc lattice) despite the small particle size. Silver was crystalline in electron diffraction but not in X-ray diffraction. Alloyed silver-platinum nanoparticles were almost fully amorphous by both methods, indicating a considerable internal disorder.

Production of Metallic Alloy Nanowires and Particles Templated Using Tomato Mosaic Virus (ToMV)

We demonstrate a simple, low-energy method whereby tomato mosaic virus (ToMV) particles can be used to template the production of nanowires and particles consisting of alloys of gold (Au), platinum (Pt) and palladium (Pd) in various combinations. Selective nanowire growth within the inner channel of the particles was achieved using the polymeric capping agent polyvinylpyrrolidone (PVPK30) and the reducing agent ascorbic acid. The reaction conditions also resulted in the deposition of alloy nanoparticles on the external surface of the rods in addition to the nanowire structures within the internal cavity. The resulting materials were characterized using a variety of electron microscopic and spectroscopic techniques, which revealed both the structural and chemical composition of the alloys within the nanomaterials.

Recent advances in synthesis and characterization of iron-nickel bimetallic nanoparticles and their applications as photo-catalyst and fuel additive

Iron-nickel bimetallic nanoparticles (Fe-Ni BMNPs) are prepared by combining two different metals by using the bottom-up approach. The resulting material has entirely different properties as compared to both the metals. The product is examined by using different analytical instruments such as.; scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), MDIJADE, ORIGIN pro to characterize their morphology, crystallinity and elemental composition and the final data has been statistically analyzed. SEM findings show that most nanoparticles are irregular in form and range in size from 10 nm to 100 nm. The findings of the TEM verified that the particles between 10 nm and 50 nm are irregular in size shape. The products acquired utilized as a fuel additive to monitor oil effectiveness by studying various parameters. The degradation of methylene blue dye depends directly on the concentration of the nanocatalyst. Different parameters also use the freshly prepared bimetallic nanocatalyst to investigate the efficacy of the kerosene fuel. By adding a tiny quantity of the nanocatalyst, the value of the flash point and fire point is significantly reduced. The nanocatalyst does not affect the cloud point and pour point to a large extent. The bimetallic nanocatalyst therefore has very excellent catalytic characteristics.

Green Synthesized Iron-Coated Silver Nanoparticles: Economic Bimetallic Nanoparticles Potential Against Methicillin-Resistance Staphylococcus aureus

Iron coating was introduced as one of the novel techniques to improve physicochemical and biological properties of silver nanoparticles (AgNPs). In the current experiment, impact of iron coating on the antimicrobial potency of AgNPs was investigated against methicillin-resistance Staphylococcus aureus (MRSA). To obtain more accurate data about the antimicrobial potency of examined nanostructures, the experiment was done on the 10 isolates of MRSA which were isolated from skin lesions. AgNPs and iron-coated AgNPs (Fe@AgNPs) were fabricated based on a green one-pot reaction procedure. Minimal inhibitory concentration (MIC) of Fe@AgNPs was not significantly different with MIC of AgNPs against eight out of 10 examined MRSA isolates. Also, by iron coating a reduction in the minimal inhibitory concentration (MIC) of AgNPs was observed against two MRSA isolates. The average MIC of AgNPs against 10 MRSA isolates was calculated to be 2.16 ± 0.382 mg/mL and this value was reduced to 1.70 ± 0.638 mg/mL for Fe@AgNPs. However, this difference was not considered significant statistically (P-value > 0.05). From productivity point of view, it was found that iron coating would improve the productivity of the synthesis reaction more than fivefold. Productivity of AgNPs was calculated to be 1.02 ± 0.07 g/L, meanwhile this value was 5.25 ± 0.05 g/L for Fe@AgNPs. Iron coating may provide another economic benefit to reduce final price of AgNPs. It is obvious that the price of a particular nanostructure made of silver and iron is significantly lower than that of pure silver. These findings can be considered for the fabrication of economic and potent antimicrobial nanoparticles.

Recent Advances in Bimetallic Nanoporous Gold Electrodes for Electrochemical Sensing

Bimetallic nanocomposites and nanoparticles have received tremendous interest recently because they often exhibit better properties than single-component materials. Improved electron transfer rates and the synergistic interactions between individual metals are two of the most beneficial attributes of these materials. In this review, we focus on bimetallic nanoporous gold (NPG) because of its importance in the field of electrochemical sensing coupled with the ease with which it can be made. NPG is a particularly important scaffold because of its unique properties, including biofouling resistance and ease of modification. In this review, several different methods to synthesize NPG, along with varying modification approaches are described. These include the use of ternary alloys, immersion-reduction (chemical, electrochemical, hybrid), co-electrodeposition-annealing, and under-potential deposition coupled with surface-limited redox replacement of NPG with different metal nanoparticles (e.g., Pt, Cu, Pd, Ni, Co, Fe, etc.). The review also describes the importance of fully characterizing these bimetallic nanocomposites and critically analyzing their structure, surface morphology, surface composition, and application in electrochemical sensing of chemical and biochemical species. The authors attempt to highlight the most recent and advanced techniques for designing non-enzymatic bimetallic electrochemical nanosensors. The review opens up a window for readers to obtain detailed knowledge about the formation and structure of bimetallic electrodes and their applications in electrochemical sensing.

A Meta-Analysis of Influencing Factors on the Activity of BiVO4-Based Photocatalysts

With the continuous advancement of global industrialization, a large amount of organic and inorganic pollutants have been discharged into the environment, which is essential for human survival. Consequently, the issue of water environment pollution has become increasingly severe. Photocatalytic technology is widely used to degrade water pollutants due to its strong oxidizing performance and non-polluting characteristics, and BiVO4-based photocatalysts are one of the ideal raw materials for photocatalytic reactions. However, a comprehensive global analysis of the factors influencing the photocatalytic performance of BiVO4-based photocatalysts is currently lacking. Here, we performed a meta-analysis to investigate the differences in specific surface area, kinetic constants, and the pollutant degradation performance of BiVO4-based photocatalysts under different preparation and degradation conditions. It was found that under the loading condition, all the performances of the photocatalysts can be attributed to the single BiVO4 photocatalyst. Moreover, loading could lead to an increase in the specific surface area of the material, thereby providing more adsorption sites for photocatalysis and ultimately enhancing the photocatalytic performance. Overall, the construct heterojunction and loaded nanomaterials exhibit a superior performance for BiVO4-based photocatalysts with 136.4% and 90.1% improvement, respectively. Additionally, within a certain range, the photocatalytic performance increases with the reaction time and temperature.

Light-Driven Catalytic Activity of Green-Synthesized SnO2/WO3-x Hetero-nanostructures

This work reports an environmentally friendly and economically feasible green synthesis of monometallic oxides (SnO₂ and WO₃) and their corresponding mixed metal oxide (SnO₂/WO_3-x) nanostructures from the aqueous Psidium guajava leaf extract for light-driven catalytic degradation of a major industrial contaminant, methylene blue (MB). P. guajava is a rich source of polyphenols that acts as a bio-reductant as well as a capping agent in the synthesis of nanostructures. The chemical composition and redox behavior of the green extract were investigated by liquid chromatography-mass spectrometry and cyclic voltammetry, respectively. Results acquired by X-ray diffraction and Fourier transform infrared spectroscopy confirm the successful formation of crystalline monometallic oxides (SnO₂ and WO₃) and bimetallic SnO₂/WO_3-x hetero-nanostructures capped with polyphenols. The structural and morphological aspects of the synthesized nanostructures were analyzed by transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. Photocatalytic activity of the synthesized monometallic and hetero-nanostructures was investigated for the degradation of MB dye under UV light irradiation. Results indicate a higher photocatalytic degradation efficiency for mixed metal oxide nanostructures (93.5%) as compared to pristine monometallic oxides SnO₂ (35.7%) and WO₃ (74.5%). The hetero-metal oxide nanostructures prove to be better photocatalysts with reusability up to 3 cycles without any loss in degradation efficiency or stability. The enhanced photocatalytic efficiency is attributed to a synergistic effect in the hetero-nanostructures, efficient charge transportation, extended light absorption, and increased adsorption of dye due to the enlarged specific surface area.

Sequential-Dependent Synthesis of Bimetallic Silver-Chromium Nanoparticles for Multichannel Sensing, Logic Computing, and 3 in 1 Information Protection

Bimetallic nanomaterials (BNMs) have been used in sensing, biomedicine, and environmental remediation, but their multipurpose and comprehensive applications in molecular logic computing and information security protection have received little attention. Herein, This synthesis method is achieved by sequentially adding reactants under ice bath conditions. Interestingly, Ag-Cr NPs can dynamically selectively sense anions and reductants in multiple channels. Especially, ClO^- can be quantitatively detected by oxidizing Ag-Cr NPs with detection limits of 98.37 nM (at 270 nm) and 31.83 nM (at 394 nm). Based on sequential-dependent synthesis process of Ag-Cr NPs, Boolean logic gates and customizable molecular keypad locks are constructed by setting the reactants as the inputs, the states of the resulting solutions as the outputs. Furthermore, dynamically selective response patterns of the Ag-Cr NPs can be converted into binary strings to exploit molecular crypto-steganography to encode, store, and hide information. By integrating the three dimensions of authorization, encryption, and steganography, 3 in 1 advanced information protection based on Ag-Cr nanosensing system can be achieved, which can enhance the anti-cracking ability of information. This research will promote the development and application of nanocomposites in the field of information security and deepen the connection between molecular sensing and the information world.

Green room temperature synthesis of silver-gold alloy nanoparticles

Metallic alloy nanoparticles (NPs) exhibit interesting optical, electrical and catalytic properties, dependent on their size, shape and composition. In particular, silver-gold alloy NPs are widely applied as model systems to better understand the syntheses and formation (kinetics) of alloy NPs, as the two elements are fully miscible. Our study targets product design via environmentally friendly synthesis conditions. We use dextran as the reducing and stabilizing agent for the synthesis of homogeneous silver-gold alloy NPs at room temperature. Our approach is a one-pot, low temperature, reaction-controlled, green and scalable synthesis route of well-controlled composition and narrow particle size distribution. The composition over a broad range of molar gold contents is confirmed by scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy (STEM-EDX) measurements and auxiliary inductively coupled plasma-optical emission spectroscopy measurements (ICP-OES). The distributions of the resulting particles in size and composition are obtained from multi-wavelength analytical ultracentrifugation using the optical back coupling method and further confirmed by high-pressure liquid chromatography. Finally, we provide insight into the reaction kinetics during the synthesis, discuss the reaction mechanism and demonstrate possibilities for scale-up by a factor of more than 250 by increasing the reactor volume and NP concentration.

Recyclable Cu-Ag bimetallic nanocatalyst for radical scavenging, dyes removal and antimicrobial applications

An ecofriendly and cost effective green method has been used for the synthesis of recyclable, high functional nanoparticles. Bimetallic nanoparticles (BmNPs), Cu-Ag, have been synthesized using beetroot extract as reducing and capping agent. Formation of BmNPs was initially confirmed by UV-visible analysis, having distinct peaks of Ag at 429 nm and Cu at 628 nm. FTIR analysis also confirmed the association of bioactive phytochemicals with Cu-Ag nanoparticles. Crystallinity and morphology of BmNPs was determined through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS) and energy dispersion X-ray spectroscopy (EDAX). The size of spherical shape Cu-Ag BmNPs was found to be 75.58 nm and EDAX studies confirmed the percent elemental composition of Cu and Ag in synthesized nanocatalyst. Results of different analysis provided supported evidences regarding the formation of BmNPs. Catalytic potential of BmNPs was tested for the degradation of rhodamine B (Rh-B), methylene blue (MB) and methyl orange (MO) dyes. Cu-Ag BmNPs exhibited outstanding catalytic activity for the degradation of selected organic dyes and percent degradation was recorded more than 90% for each dye. In addition, antiradical property of BmNPs was tested employing DPPH^● and ABTS^●+ assays and it was found to be promising. Synthesized BmNPs also exhibited strong antimicrobial activity against Salmonella typhimurium and Bacillus subtilis. Recyclability of nanoparticles was also evaluated and recovery from dye degradation reaction mixture was successfully achieved. The recovered nanoparticles exhibited same catalytic potential for the degradation of Rh-B. The objective of the current study was to synthesize BmNPs Cu-Ag employing a cost effective green method having promising catalytic, antiradical and antimicrobial potential. Further, BmNPs were reused after recovery from catalytic reactions, proving that BmNPs can be recycled having the same efficiency as that of a freshly prepared Cu-Ag BmNPs.

Innovations in the synthesis of graphene nanostructures for bio and gas sensors

Sensors play a significant role in modern technologies and devices used in industries, hospitals, healthcare, nanotechnology, astronomy, and meteorology. Sensors based upon nanostructured materials have gained special attention due to their high sensitivity, precision accuracy, and feasibility. This review discusses the fabrication of graphene-based biosensors and gas sensors, which have highly efficient performance. Significant developments in the synthesis routes to fabricate graphene-based materials with improved structural and surface properties have boosted their utilization in sensing applications. The higher surface area, better conductivity, tunable structure, and atom-thick morphology of these hybrid materials have made them highly desirable for the fabrication of flexible and stable sensors. Many publications have reported various modification approaches to improve the selectivity of these materials. In the current work, a compact and informative review focusing on the most recent developments in graphene-based biosensors and gas sensors has been designed and delivered. The research community has provided a complete critical analysis of the most robust case studies from the latest fabrication routes to the most complex challenges. Some significant ideas and solutions have been proposed to overcome the limitations regarding the field of biosensors and hazardous gas sensors.

Optimistic and possible contribution of nanomaterial on biomedical applications: A review

Nanomaterials have many advantages over bulk materials, including enhanced surface-to-volume proportion as well as magnetic traits. It has been a steady rise in research with using nanomaterials in various biomedical fields in the past few decades. Constructing nanomaterials has emerged as a leading research primary concern in order to discover specialized biomedical applications. Since, their advantageous properties including chemical stability, non-toxicity, bio - compatibility, relatively high magnetization, and strong magnetic vulnerability, nanoparticles of iron oxide had already influenced implementations in different biomedical fields. Nanomaterials can be divided up into four nanomaterials such as metallic nanomaterials, bimetallic or alloy nanomaterials, metal oxide nanomaterials, as well as magnetic nanomaterials. Hence, the purpose of this review is to conduct such in discussion on emerging advancements in nanomaterials for biomedical, with such a special emphasis upon those options of nanomaterials including metallic nanomaterials: Au and Ag, bimetallic nanomaterials: Fe-Co and Fe-Pt, and metal oxides: TiO₂ and CeO₂. Securing this information gap will result in a better comprehension of the contribution of nanomaterial type and subsequent huge-scale applications in aspects of both their potential and challenges.

The role of the gold-platinum interface in AuPt/TiO2-catalyzed plasmon-induced reduction of CO2 with water

Bimetallic gold-platinum nanoparticles have been widely studied in the fields of nanoalloys, catalysis and plasmonics. Many preparation methods can lead to the formation of these bimetallic nanoparticles (NPs), and the structure and related properties of the nanoalloy often depend on the preparation method used. Here we investigate the ability of thermal dimethylformamide (DMF) reduction to prepare bimetallic gold-platinum sub-nm clusters supported on titania. We find that deposition of Pt preferentially occurs on gold. Formation of sub-nm clusters (vs. NPs) appears to be dependent on the metal concentration used: clusters can be obtained for metal loadings up to 4 wt% but 7-8 nm NPs are formed for metal loadings above 8 wt%, as shown using high resolution transmission electron microscopy (HRTEM). X-ray photoelectron spectroscopy (XPS) shows electron-rich Au and Pt components in a pure metallic form and significant platinum enrichment of the surface, which increases with increasing Pt/Au ratio and suggests the presence of Au@Pt core-shell type structures. By contrast, titania-supported bimetallic particles (typically >7 nm) obtained by sodium borohydride (NaBH₄) reduction in DMF, contain Au/Pt Janus-type objects in addition to oxidized forms of Pt as evidenced by HRTEM, which is in agreement with the lower Pt surface enrichment found by XPS. Both types of supported nanostructures contain a gold-platinum interface, as shown by the chemical interface damping, i.e. gold plasmon damping by Pt, found using UV-visible spectroscopy. Evaluation of the materials for plasmon-induced continuous flow CO₂ reduction with water, shows that: (1) subnanometer metallic clusters are not suitable for CO₂ reduction with water, producing hydrogen from the competing water reduction instead, thereby highlighting the plasmonic nature of the reaction; (2) the highest methane production rates are obtained for the highest Pt enrichments of the surface, i.e. the core-shell-like structures achieved by the thermal DMF reduction method; (3) selectivity towards CO₂ reduction vs. the competing water reduction is enhanced by loading of the plasmonic NPs, i.e. coverage of the titania semi-conductor by plasmonic NPs. Full selectivity is achieved for loadings above 6 wt%, regardless of the NPs composition and alloy structure.

Soluble porous organic cages as homogenizers and electron-acceptors for homogenization of heterogeneous alloy nanoparticle catalysts with enhanced catalytic activity

The creation of ultrafine alloy nanoparticles (<5 nm) that can maintain surface activity and avoid aggregation for heterogeneous catalysis has received much attention and is extremely challenging. Here, ultrafine PtRh alloy nanoparticles imprisoned by the cavities of reduced chiral covalent imine cage (PtRh@RCC3) are prepared successfully by an organic molecular cage (OMC) confinement strategy, while the soluble RCC3 can act as a homogenizer to homogenize the heterogeneous PtRh alloy in solution. Moreover, the X-ray absorption near-edge structure (XANES) results show that the RCC3 can act as an electron-acceptor to withdraw electrons from Pt, leading to the formation of higher valence Pt atoms, which is beneficial to improving the catalytic activity for the reduction of 4-nitrophenol. Attributed to the synergistic effect of Pt/Rh atoms and the unique function of the RCC3, the reaction rate constants of Pt₁Rh₁₆@RCC3 are 49.6, 8.2, and 5.5 times than those of the Pt₁Rh₁₆ bulk, Pt@RCC3 and Rh@RCC3, respectively. This work provides a feasible strategy to homogenize heterogeneous alloy nanoparticle catalysts in solution, showing huge potential for advanced catalytic application.

Phytochemical-Stabilized Platinum-Decorated Silver Nanocubes INHIBIT Adenocarcinoma Cells and Enhance Antioxidant Effects by Promoting Apoptosis via Cell Cycle Arrest

(1) Background: The increasing use of silver and platinum bimetallic nanoparticles in the diagnosis and treatment of cancer presents significant advances in biomedical applications due to their extraordinary physicochemical properties. This study investigated the role of aqueous phytochemical extract in stabilizing platinum nanodots-decorated silver nanocubes (w-Pt@AgNPs) for enhancing antioxidant activities and their mechanism. (2) Methods: UV-Vis, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM) were used to characterize the formed w-Pt@AgNPs. LC-QToF-MS/MS was used to analyze the bioactive compounds, while DPPH, ABTS, and FRAP were used to detect the scavenging potential. Flow cytometric assays were performed to investigate the cytotoxicity and the mechanism of cell death. (3) Results: Morphological studies indicated that w-Pt@AgNPs were cube in shape, decorated by platinum nanodots on the surfaces. Compared to ethanolic extract-synthesized e-Pt@AgNPs, w-Pt@AgNPs exhibited the strongest antioxidant and cytotoxic activity, as data from Annexin V and Dead cell labeling indicated higher induction of apoptosis. Despite the high proportion of early apoptotic cells, the w-Pt@AgNPs triggered a decrease in G1/G0 cell cycle phase distribution, thereby initiating a G2/M arrest. (4) Conclusions: By enhancing the antioxidant properties and promoting apoptosis, w-Pt@AgNPs exhibited remarkable potential for improved cancer therapy outcomes.

Element Specific Atom Counting at the Atomic Scale by Combining High Angle Annular Dark Field Scanning Transmission Electron Microscopy and Energy Dispersive X-ray Spectroscopy

A new methodology is presented to count the number of atoms in multimetallic nanocrystals by combining energy dispersive X-ray spectroscopy (EDX) and high angle annular dark field scanning transmission electron microscopy (HAADF STEM). For this purpose, the existence of a linear relationship between the incoherent HAADF STEM and EDX images is exploited. Next to the number of atoms for each element in the atomic columns, the method also allows quantification of the error in the obtained number of atoms, which is of importance given the noisy nature of the acquired EDX signals. Using experimental images of an Au@Ag core-shell nanorod, it is demonstrated that 3D structural information can be extracted at the atomic scale. Furthermore, simulated data of an Au@Pt core-shell nanorod show the prospect to characterize heterogeneous nanostructures with adjacent atomic numbers.

Cefotaxime incorporated bimetallic silver-selenium nanoparticles: promising antimicrobial synergism, antibiofilm activity, and bacterial membrane leakage reaction mechanism

In this research, we reported for the first time the simple incorporation of antibiotic cefotaxime (CFM) with the synthesized Ag NPs, Se NPs, and bimetallic Ag-Se NPs by gamma rays, as a promising cost-effective, and eco-friendly method. The synthesized nanocomposites were characterized by UV-Vis. spectroscopy, XRD, EDX, HR-TEM, SEM/mapping, and EDX studies. The antimicrobial synergistic potential was investigated after CFM drug incorporation. Antibiofilm activity, growth curve assay, and effect of UV illumination were examined against some pathogenic microbes. The antibacterial reaction mechanism was evaluated by protein leakage assay and SEM imaging. HRTEM imaging confirmed the spherical shape and an average diameter of 10.95, 20.54, and 12.69 nm for Ag NPs, Se NPs, and Ag-Se NPs, respectively. Ag NPs-CFM, Se NPs-CFM, and Ag-Se NPs-CFM possessed antimicrobial activity against Staphylococcus aureus (40, 42, and 43 mm ZOI, respectively), Escherichia coli (33, 35, and 34 mm ZOI, respectively) and Candida albicans (25, 22, and 23 mm ZOI, respectively). CFM-incorporated Ag-Se NPs were able to inhibit biofilm formation of S. aureus (96.09%), E. coli (98.32%), and C. albicans (95.93%). Based on the promising results, the synthesized nanocomposites showed superior antimicrobial potential at low concentrations and continued-phase durability; they may find use in pharmaceutical, and biomedical applications.

Gold Nanomaterials and their Composites as Electrochemical Sensing Platforms for Nitrite Detection

Nitrite is one of the abundant toxic components existing in the environment and is likely to have a great potential to affect human health badly. For that reason, it has become crucial to build a reliable nitrite detection method. In recent years, several nitrite monitoring systems have been proposed. Compared with traditional analytical strategies, the electrochemical approach has a bunch of advantages, including low cost, rapid response, easy operation, simplicity, etc. In this case, noble metal nanomaterials, especially Au-based nanomaterials, have attracted attention in electrode modification because of higher catalytic activity, facile mass transfer, and broad active area for determining nitrite. This review is based on the state-of-the-art, which includes a variety of nanomaterials that have been coupled with AuNPs for the creation of nanocomposites, and the construction as well as development of electrochemical sensors for nitrite detection over the last few years (2016-2022). A background study on synthesizing different morphological AuNPs and nanocomposites has also been introduced. The fabrication methods and sensing capabilities of modified electrodes are given special consideration.