Au Ru Research Articles

A universal ratiometric method for Micro-RNA detection based on the ratio of electrochemical/electrochemiluminescence signal, and toehold-mediated strand displacement amplification

An ultra-selective and reproductive ratiometric platform was introduced based on the ratio of Ru(phen)32+ electrochemiluminescence (ECL) signal and methylene blue (MB) electrochemistry (EC) signal, which was amplified using a specific and efficient toehold-mediated strand displacement (TMSD). The stable DNA nanoclews (NCs) were efficiently loaded with MB (MB-NCs) as EC signal tags after being synthesized utilizing a simple rolling circle amplification reaction. Besides, Ti3C2-based nanocomposite could apply as a superb carrier for both Ru(phen)32+ and gold nanoparticles (Ti3C2–Au–Ru), resulting in a nearly constant ECL internal reference to eliminate the possible interferences. The Ti3C2–Au–Ru was attached to the surface of the electrode using Nafion, which exhibited excellent conductivity, and hairpin DNAs (hDNAs) were fixed on AuNPs via an Au–S bond. The designed biosensor was finally applied for miRNA-18a detection as a target model.The TMSD method made it possible to concurrently convert and amplify a single miRNA-18ainput into a large amount of output DNAs with high selectivity. These output DNAs were designed to unfold the stem-locked area of hDNAs. The opened hDNAs then hybridized with the MB-NCs to produce an EC signal. In the proposed biosensing system, by raising the target concentration of miRNA, the EC signal gradually rose, the ECL signal remained nearly constant, and the ratiometric detection method markedly promoted biosensor accuracy. Linear correlations of the ratio value of the EC/ECL with miRNA-18a concentrations between 20 aM and 50 pMwere observed, with the limit of detection of 9 aM. The biosensor was applied to detect miRNA-18a in real serum samples with satisfactory results.

Au–Ru Composite for Enzyme-Free Epinephrine Sensing

We report the synthesis and investigation of Au–Ru composite with highly developed specific surface area exhibiting excellent electrocatalytic performance suitable for detection of such hydrophobic metabolites as epinephrine in the physiological environment. This electrode material was fabricated using two-stage laser-assisted metal deposition technique. The morphological and structural studies of Au–Ru were performed using methods of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The voltammetric methods, including cyclic voltammetry (CV), differential pulse voltammetry (DPV) and direct amperometry, were used to analyze the composite’s electrochemical properties. The Au–Ru sensor exhibited two linear ranges of the non-enzymatic epinephrine detection: 0.01–10 μM and 10–1000 μM. The calculated sensitivities within these two ranges were 32.8 and 3.3 μA μM−1 cm−2, whereas the corresponding limits of detection were 9 and 20 nM, respectively. The Au–Ru sensor also revealed good stability and reproducibility, as well as high selectivity towards epinephrine detection in the presence of a number of the interfering species.

An Effect of Co–W Barrier Sublayer on the Functional Characteristics of Au–Ru Contact Coatings

The performance characteristics (microhardness, porosity, roughness, and transient resistance) of Au–Ru coatings with and without the Co–W alloy barrier sublayer electrodeposited on the surface of contact blades of commercially produced reed switches were investigated. It was found that the barrier sublayer reduces the average roughness of the coatings without significant change in their porosity. The Au–Ru coatings without sublayer exhibited a greater variation in the transient resistance during an increase in the pressing force. The service time of reed switches with the barrier sublayer increased in both testing modes: in low-power (50 mV, 5 μA, 50 Hz) by more than 4 × 106 switching cycles, and in mean-power (12 V, 0.25 A, 50 Hz) by more than 1.8 × 106 switching cycles.

The occupancy preferences of transition metal elements and its effects on ductility and brittleness of γ/β phases in TiAl alloys: a first-principles investigation

ABSTRACT The occupancy tendency of M elements in γ/β-TiAl and the bonding strength, electronic structure, and tough-brittle transition of γ/β-TiAl-M were systematically investigated by first-principles calculations. According to the point defect anti-site-formation energy, charge density difference and electron localization function simulations, in the fourth and sixth cycles, M = Fe, Co, Os, Ir, Pt and Au (Ru in β-TiAl) elements preferentially occupy Al sites and lead to the formation of strong covalent-like directional bonds between themselves and surrounding Ti or Al elements. The electronic structure and chemical bonding features are analyzed. γ/β-TiAl-M compounds consist of covalent and metallic bonds, and M elements in the intermediate region give rise to strong covalent bonding features. In addition, transition metal elements that form metallic bonds with Ti or Al will contribute to the ductility of TiAl-based alloys. The diagram of B/G reflects this very well.

First exfoliated Ru-Ru-Au organometallic polymer with layered structure.

A new water soluble heterometallic polymeric complex [{(PTA)2CpRu-μ-CN-1κC:2κ2N-RuCp(PTA)2}-μ-{Au(CN)4}4]n·2H2O (1) is synthesized and characterized by single crystal X-ray diffraction. This complex self-assembles forming 3D polymeric structures with large scale hexagonal conformation. They also organize as 3D stacks of polymer sandwiches that can be exfoliated providing mono heterometallic-3D layers, as shown by electron microscopy. Regarding the polymer dynamics, quasi-elastic neutron scattering shows a transition from vibrational Debye-Waller behaviour to a more dynamically active state as a result of the loss of structural water molecules.

A heterometallic ruthenium-gold complex displays antiproliferative, antimigratory, and antiangiogenic properties and inhibits metastasis and angiogenesis-associated proteases in renal cancer.

Heterobimetallic compounds are designed to harness chemotherapeutic traits of distinct metal species into a single molecule. The ruthenium-gold (Ru-Au) family of compounds based on Au-N-heterocyclic carbene (NHC) fragments [Cl2(p-cymene)Ru(μ-dppm)Au(NHC)]ClO4 was conceived to combine the known antiproliferative and cytotoxic properties of Au-NHC-based compounds and the antimigratory, antimetastatic, and antiangiogenic characteristic of specific Ru-based compounds. Following recent studies of the anticancer efficacies of these Ru-Au-NHC complexes with promising potential as chemotherapeutics against colorectal, and renal cancers in vitro, we report here on the mechanism of a selected compound, [Cl2(p-cymene)Ru(μ-dppm)Au(IMes)]ClO4 (RANCE-1, 1). The studies were carried out in vitro using a human clear cell renal carcinoma cell line (Caki-1). These studies indicate that bimetallic compound RANCE-1 (1) is significantly more cytotoxic than the Ru (2) or Au (3) monometallic derivatives. RANCE-1 significantly inhibits migration, invasion, and angiogenesis, which are essential for metastasis. RANCE-1 was found to disturb pericellular proteolysis by inhibiting cathepsins, and the metalloproteases MMP and ADAM which play key roles in the etiopathogenesis of cancer. RANCE-1 also inhibits the mitochondrial protein TrxR that is often overexpressed in cancer cells and facilitates apoptosis evasion. We found that while auranofin perturbed migration and invasion to similar degrees as RANCE-1 (1) in Caki-1 renal cancer cells, RANCE-1 (1) inhibited antiangiogenic formation and VEGF expression. We found that auranofin and RANCE-1 (1) have distinct proteolytic profiles. In summary, RANCE-1 constitutes a very promising candidate for further preclinical evaluations in renal cancer.

Preparation of gold-containing binary metal clusters by co-deposition-precipitation method and for hydrogenation of chloronitrobenzene

Nano-gold catalyst has been reported to have high activity and selectivity for liquid phase hydrogenation reaction. In this study, gold-containing bimetals were loaded on TiO2. For bimetallic catalysts, gold and different metals were prepared by the deposition-precipitation method, and then used NaBH4 to reduce metal cations. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic properties of these catalysts were tested by hydrogenation of p-chloronitrobenzene (p-CNB) in a batch reactor at 1.1 MPa H2 pressure, 373 K and 500 rpm. Cu, Ag, Ru, and Pd formed nano-alloy with Au. In addition, Cu–Au, Ag–Au, and Ru–Au alloy had Cu-, Ag-, and Ru-enriched surface, respectively. Instead, Pd–Au alloy had Pd-enriched surface. There are two kinds of alloy effects: (1) geometric effects, i.e., the surface-enriched metal would change the distance of Au–Au atoms that is required for facilitating the hydrogenation of chloronitrobenzene; and (2) electronic effects, which involve charge transfer between the metals. The activity decreased in the following order: PdAu/TiO2 > Au/TiO2 > NiAu/TiO2 > AgAu/TiO2 > RuAu/TiO2 > CuAu/TiO2. Comparing with other metals, adding Pd in Au showed a higher activity. Adding palladium could reduce gold-valence state, and increased active sites for reaction.

Catalytically driven assembly of trisegmented metallic nanorods and polystyrene tracer particles.

Trisegmented Au-Ru-Au and Ru-Au-Ru nanorods catalyze the decomposition of hydrogen peroxide, pumping fluid along their axis as "pullers" and "pushers" respectively. Numerical simulations and experiments with passive tracer particles show that catalytically generated hydrodynamic and electrostatic forces both contribute to pairwise and collective particle assembly.

Catalytic oxidation of cellobiose over TiO2 supported gold-based bimetallic nanoparticles

A series of TiO2 supported Au–M (M = Cu, Co, Ru and Pd) bimetallic catalysts were tested for cellobiose oxidation. Cu–Au and Ru–Au provided excellent gluconic acid selectivity’s, although via contrasting mechanism.

Cellular transport mechanisms of cytotoxic metallodrugs: an overview beyond cisplatin.

The field of medicinal inorganic chemistry has grown consistently during the past 50 years; however, metal-containing coordination compounds represent only a minor proportion of drugs currently on the market, indicating that research in this area has not yet been thoroughly realized. Although platinum-based drugs as cancer chemotherapeutic agents have been widely studied, exact knowledge of the mechanisms governing their accumulation in cells is still lacking. However, evidence suggests active uptake and efflux mechanisms are involved; this may be involved also in other experimental metal coordination and organometallic compounds with promising antitumor activities in vitro and in vivo, such as ruthenium and gold compounds. Such knowledge would be necessary to elucidate the balance between activity and toxicity profiles of metal compounds. In this review, we present an overview of the information available on the cellular accumulation of Pt compounds from in vitro, in vivo and clinical studies, as well as a summary of reports on the possible accumulation mechanisms for different families of experimental anticancer metal complexes (e.g., Ru Au and Ir). Finally, we discuss the need for rationalization of the investigational approaches available to study metallodrug cellular transport.

Fabrication and thermal stability characterisation of Ru electrode used for high power contact radio frequency microelectromechanical system switch

Reported are the fabrication and thermal stability of an Ru electrode, which is used for a high power Ru–Au contact radio frequency microelectromechanical system switch with a microspring contact design. In this reported work, a new process with bilayer lift-off and a strain release layer is developed, thereby acquiring the 3000 A Ti/Au/Ru electrode with excellent smooth edges for high-power handling capacity and low loss. Furthermore, thermal tests under 400, 500 and 600°C for over 1 h have been performed. Investigation of the surface with scanning electron microscopy and energy dispersive X-ray spectroscopy shows that the electrode has a good thermal stability at 400°C, which is proper for high-power handling. The cold switch DC current handling capacity is advanced from <90 mA per point (failed) to 100 mA per point (still working).

Direct Synthesis of Hydrogen Peroxide Using Ruthenium Catalysts

The direct synthesis of hydrogen peroxide is investigated using ruthenium containing catalysts. Ruthenium is not soluble in Au but forms alloys with palladium. We have therefore investigated Ru–Au, Ru–Pd as well as trimetallic formulations supported on titania. The addition of ruthenium enhances the direct synthesis activity for all the catalysts studied and the effect is dependent on the amount of ruthenium added. The calcination conditions are shown to affect both activity and reusability.

Bifunctional N–P ligands as building blocks for construction of multilayered metallodendrimers

The synthesis of 4-amino(N-methylendiphenylphosphino)pyridine (1a) and its reaction with [PdCl2(cod)], [PtCl2(cod)], [AuCl(tht)], [RuCl2(p-cymene)]2, [RhCl(cod)]2 and [Pd(η3-2-MeC3H4)Cl]2 to give [PdCl2(1a)2] (2), [PtCl2(1a)2] (3), [AuCl(1a)] (4), [RuCl2(p-cymene)(1a)] (5), [RhCl(cod)(1a)] (6) and [Pd(η3-2-MeC3H4)Cl(1a)] (7) respectively are described. The new chelate complex [Pd(η3-2-MeC3H4)(py–N(CH2–PPh2)2)](OTf) (8) is also reported. Compounds 5 and 8 were characterized by single crystal X-ray diffraction. In all complexes prepared the metal atoms appear to be bonded through the P atom of 1a. The metalloligands 4, 5 and 8 have been reacted with the ruthenocarbosilanedendrimer 10 to afford new Ru–Au and Ru–Pd concentric metal layered dendrimers 11, 12 and 13.

An improved SPM-based contact tester for the study of microcontacts

An improved scanning probe microscope based contact tester has been designed, constructed and used for cyclic testing of various metal contacts. The tester is designed for contact material evaluation, especially for metal-contact MEMS switch applications, and is capable of simultaneous measurements of contact force and resistance. The tester uses a specially designed silicon force sensor with an integrated contact bump and a mating silicon pillar in order to simulate switch operation. The sensor and the pillar are coated with contact materials, allowing a wide range of contact metals and metal pairs to be evaluated. The testing takes place within a custom-built test chamber in which both plasma and UV-ozone treatments are available for contact cleaning and surface modification. It was found that a dissimilar contact pair of Au–Ru with O2 plasma cleaning can provide low contact adhesion and low resistance as compared with Au, Ru and Ir contact pairs. Layered structures with a thin layer of Ru on top of Au were also modeled and tested. Ru layers between 50 and 100 nm were effective in reducing adhesion and contact resistance provided the contact force is greater than 300 µN.

Iridium–Ruthenium–gold cluster complexes: Structures, and skeletal Rearrangements

Three new IrRuAu trimetallic cluster complexes: IrRu3(CO)13AuPPh3, 1, HIrRu3(CO)12(AuPPh3)2, 2 and IrRu3(CO)12(AuPPh3)3, 3 were obtained in low yields from the reaction of HIrRu3(CO)13 with [(AuPPh3)3O][BF4]. Compounds 1 and 3 were subsequently obtained in much better yields (82%) and (84%) from the reactions of [AuPPh3][NO3] and [(AuPPh3)3O][BF4] with [PPN][IrRu3(CO)13], respectively. The molecular structures of all three compounds were established by single crystal x-ray diffraction methods. Compounds 1 and 2 contain an Au(PPh3) group that bridges one triangular face of a tetrahedral IrRu3 cluster. Compound 2 contains a second Au(PPh3) capping group that bridges an Ir–Ru–Au triangle. Compound 3 consists of a pentagonal bipyramidal Au3IrRu3 cluster that has three gold atoms and two of the ruthenium atoms in the equatorial plane. There is a bond between the apical Ir and Ru atoms. Compounds 2 and 3 exhibit dynamical activity in the metal skeleton that leads to a rapid averaging of the inequivalent Au(PPh3) groups on the NMR timescale at room temperature.

Anchoring of Ru–Pt and Ru–Au Clusters onto a Phosphane‐Functionalized Carbon Support

AbstractTwo mixed‐metal clusters, [Ru5PtC(CO)14(COD)] (1) and [Ru6Au2C(CO)16(PPh3)2] (2), were anchored onto a prefunctionalized active carbon support (C) with chelating phosphane groups on its surface. These clusters were also deposited onto the unmodified support (CSX+) for comparison. The incorporation of 1 and 2 on both supports was studied by a combination of SIMS and XPS. When the clusters were anchored onto the functionalized carbon support, SIMS spectra displayed characteristic patterns that were different from those obtained in the case of their deposition on the unmodified support. In the latter case, spectra corresponded to the results obtained with pure unsupported clusters. XPS analyses of the supported species seemed to indicate that the stoichiometry of the clusters was retained after anchoring and that their dispersion was better on C than on CSX+. This indicates that the phosphanes act as anchors for noble metal compounds through a ligand exchange mechanism. The supported samples were then thermally activated and characterized by SIMS, XPS, TEM/EDXS and XRD. Analyses by SIMS showed that the cluster ligand shell was removed during thermal treatment. XPS measurements indicated that the composition of the supported particles corresponded to that of the starting clusters and that the dispersion remained higher in the case of C. Well‐dispersed bimetallic‐supported nanoparticles (1–2 nm) were obtained when cluster 1 was used as the precursor, whereas anchoring of cluster 2 resulted in its fragmentation leading to supported nanoparticles of variable stoichiometries. Reactions with soluble model molecules were carried out to prove the chemical bonding of 1. Crystallization of the new cluster [Ru5PtC(CO)14{(PPh2CH2)2NC3H7}] confirmed the chemical bonding of cluster 1 onto the C support through a ligand exchange mechanism involving COD.

Oxidation of Oxygenated Volatile Organic Compound Over Monometallic and Bimetallic Ru–Au Catalysts

Temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) of methanol and oxygen were used to probe the surface properties, relating to the oxidation reaction of methanol (a representative of oxygenated volatile organic compounds) over a series of monometallic and bimetallic Ru–Au catalysts. The relative amounts of ruthenium and gold in these bimetallic catalysts were found to strongly affect their surface characteristics (TPR and TPD profiles, BET surface areas, surface morphologies observed in SEM micrographs, and XRD patterns) and methanol oxidation activity. Although ruthenium and gold were immiscible in their bulk state, the TPR profiles, SEM micrographs, and XRD patterns provided evidence for the interactions between ruthenium and gold in the bimetallic catalysts, especially the 3.32 wt% Ru–0.61 wt% Au/SiO2 exhibiting the highest methanol oxidation activity. After the oxidation reaction, even though Ru was oxidized to RuO2, the interaction between ruthenium and gold on silica still remained the same. The support material was also found to affect both the catalyst characteristics and the methanol oxidation activity. No bimetallic clusters were observed on the Ru–Au catalysts supported on alumina. Various products, including CO2, were found when using the catalysts supported on alumina, causing a higher methanol conversion than the catalysts supported on silica. The objective of the present work was to develop comprehensive information for the interactions of the oxygenated VOC with mono- and bimetallic Ru–Au catalyst surfaces as a function of temperature and gold content. The outcomes of this work directly provide a better understanding of the catalytic oxidation of oxygenated VOCs on the bimetallic Ru–Au catalysts.

Structural, electronic, bonding, magnetic, and optical properties of bimetallic [RunAum]0/+ (n + m ≤ 3) clusters

The structural, electronic, bonding, magnetic, and optical properties of bimetallic [Ru(n)Au(m)](0/+) (n + m ≤ 3; n, m = 0-3) clusters were computed in the framework of the density functional theory (DFT) and time-dependent DFT (TD-DFT) using the full-range PBE0 non local hybrid GGA functional combined with the Def2-QZVPP basis sets. Several low-lying states have been investigated and the stability of the ground state spinomers was estimated with respect to all possible fragmentation schemes. Molecular orbital and population analysis schemes along with computed electronic parameters illustrated the details of the bonding mechanisms in the [Ru(n)Au(m)](0/+) clusters. The TD-DFT computed UV-visible absorption spectra of the bimetallic clusters have been fully analyzed and compared to those of pure gold and ruthenium clusters. Assignments of all principal electronic transitions are given and interpreted in terms of contribution from specific molecular orbital excitations.

Novel Nanoporous Binary AuRu Electrocatalysts for Glucose Oxidation

AbstractIn this work, we study the fabrication, structural characterization, and electrochemical activity of titanium‐supported binary AuRu catalysts for glucose oxidation. The catalysts including Au99Ru1, Au95Ru5, Au93Ru7 and Au88Ru12 were prepared by a hydrothermal method using formaldehyde as a reduction agent. The morphologies of the prepared AuRu catalyst structures are characterized by porous dendritic particles with roughened surfaces with nano‐sized flakes. Electrochemical catalytic activity of the binary AuRu catalysts towards glucose oxidation in alkaline solutions was investigated using cyclic voltammetry and chronoamperometry. All binary AuRu catalysts facilitate glucose oxidation at the lower potentials and deliver higher anodic oxidation currents compared to pure Au catalyst. Among them, the binary Au95Ru5 catalyst presents the most negative onset potential of −0.872 V (vs. Ag/AgCl, 3 M KCl) for glucose oxidation in 0.1 M NaOH solution. For the Au95Ru5 catalyst, chronoamperometric data at the potential step of −0.65 V (vs. Ag/AgCl,3 M KCl) exhibit a well linear dependence of the anodic oxidation current density on glucose concentration in the range of 0 to 15 mM glucose.

Sonochemical synthesis and characterization of gold–ruthenium bimetallic nanoparticles

Gold–ruthenium (Au–Ru) bimetallic nanoparticles were synthesized by the sonochemical co-reduction of Au(III) and Ru(III) ions in aqueous solutions containing varying mole fractions (1:1, 1:3 and 1:5) of the metal ions using PEG as a stabilizer. The results observed in the current study suggest that the presence of Au nanoparticles significantly reduced the time required from 7 h to 4 h for Ru 3+ reduction due to the Au nanoparticles acting as electron sink mediating the Ru 3+ reduction process. Transmission electron microscopic images revealed that the bimetallic nanoparticles were formed with higher ruthenium content in the shell and higher gold content in the core. The mean diameter of Au–Ru bimetallic nanoparticles increased with an increase in the molar ratio of Ru. A decrease in the double layer current was observed when a Au–Ru bimetallic nanoparticles modified electrode was used in electrochemical experiments compared to a Ru-modified electrode, indicating the potential use of these bimetallic nanoparticles in methanol oxidation fuel cells.