Gold Platinum Alloy Nanoparticles Research Articles

Development of electrode by using gold-platinum alloy nanopar¬ticles for electrochemical detection of serum amyloid A protein

Gold-platinum alloy nanoparticles (AuPtNP) were electrochemically deposited on the surface of indium-tin-oxide (ITO) modified with (3-aminopropyl)triethoxysilane (APTES), after optimizing deposition conditions for the electroplating solution and number of deposition cycles. Different part ratios of Au/Pt used were 4/0, 3/1, 2/2, 1/3 and 0/4 (AuNP, Au3Pt1, Au2Pt2, Au1Pt3 and PtNP, respectively) in preparation of 1 mM solutions. FE-SEM, EDAX and XRD surface characterization techniques were used to confirm the presence of deposited AuPt alloy nanoparticles on the modified ITO surface. Electrochemical methods (CV, DPV and EIS) were used to investigate the electrochemical properties of prepared electrodes in the presence of ferri/ferrocyanide redox couple, which indicated the following increasing order of electrocatalytic peak current: Au < Au2Pt2 < Pt < Au1Pt3 < Au3Pt1. The most active electrode, Au3Pt1NP/APTES/ITO (with Au/Pt part ratio 3:1), was further used to fabricate the immunoelectrode SAA-Ab/Au3Pt1NP/APTES/ITO. The prepared immunoelec­trode was tested for detection of serum amyloid A protein biomarker (APO-SAA) by immobilising SAA-specific antibodies (SAA ½ Ab) on its surface. Sensing studies on this immunoelectrode, performed by DPV technique, revealed the SAA biomarker detection in the linear range of 10 to 106 fg ml-1. The limit of detection was calculated as 7.0 fg ml-1.

Development of a Copper-Based Metal Organic Electrode for Nitrite Sensing.

Nitrite is naturally present in vegetables and added to processed meats to enhance their color and prolong their shelf life. It is of concern because it reacts to form nitrosamines, which have been linked to cancer. To develop a quick, reliable, and inexpensive method for quantifying nitrite in foods. A copper-based metal organic framework (Cu-MOF)/gold-platinum alloy nanoparticle(Au@Pt)-modified glassy carbon electrode (GCE) was developed via a simple wet chemical synthesis followed by electrochemical deposition of gold-platinum alloy nanoparticles onto the surface of a GCE. Morphological characterization and component analysis of the prepared nanomaterials were carried out by Fourier transform infrared spectroscopy and scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy were used to study the electrochemical behavior of the fabricated electrodes. The quantitative and specific detection of nitrite was obtained by the amperometric i-t method. At a pH of 7, temperature of 25°C, and ionic strength of 0.4 M, the electrode exhibited a linear range of 0.001-12.2 mM nitrite with a low detection limit of 72 nM (S/N = 3). The Cu-MOF/Au@Pt/GCE exhibited good repeatability, reproducibility, stability, and selectivity to provide a capable analysis method for food samples. A Cu-MOF with a large surface area and high porosity was developed to provide an electrode with many active sites. The Au@Pt alloy nanoparticle improved the electrocatalytic activity toward nitrite. The synergistic action between the Cu-MOF and Au@Pt alloy nanoparticle enhanced the electrochemical performance of the sensor.

A Sensitive Electrochemical MUC1 Sensing Platform Based on Electroactive Cu-MOFs Decorated by AuPt Nanoparticles

Mucin 1 protein (MUC1) is a well-known tumor marker overexpressed in a variety of human malignancies, and thus its highly selective and sensitive detection is significantly desired for clinical diagnostics. Herein, a sensitive electrochemical MUC1 sensing platform has been fabricated based on copper-based metal-organic frameworks (Cu-MOFs) decorated with gold-platinum alloy nanoparticles (AuPt NPs). Besides serving as a redox probe to avoid introducing extra redox media, the electroactive Cu-MOFs function as catalysts in the hydrogen peroxide reduction, resulting in electrochemical signal amplification. Meanwhile, AuPt NPs loaded on the Cu-MOFs mimic horseradish peroxidase to promote the reduction of hydrogen peroxide, giving rise to the secondary-amplified electrochemical signal. Moreover, the target MUC1 triggered catalytic hairpin assembly (CHA) further improves the sensitivity of the developed biosensor via the target recycling amplification. The constructed sensing platform displayed a desirable dynamic range between 10 fM and 10 nM in the MUC1 detection, with a sufficiently low limit-of-detection (3.33 fM). The current strategy of utilizing hybrid nanocomposite consisting of MOFs and alloy NPs and enzyme-free CHA provides a promising platform for the detection of biomarkers in the clinical diagnosis with high selectivity and sensitivity.

Catalytic gold–platinum alloy nanoparticles and a novel glucose oxidase mimic with enhanced activity and selectivity constructed by molecular imprinting

Based on the research of the oxidase-like activity of various Au-based nanostructures, a novel AuPtNPs based GOD mimic with substrate-selectivity and an enhanced catalytic activity was constructed by molecular imprinting technology.

Ag@Fe2O3-graphene oxide nanocomposite as a novel redox probe for electrochemical immunosensor for alpha-fetoprotein detection

In this paper, a high sensitivity label-free electrochemical immunosensor for alpha-fetoprotein (AFP) detection using Ag@Fe2O3-graphene oxide (GO) nanocomposite (Ag@Fe2O3-GO) as a new type of redox nano-probe is reported. The Ag@Fe2O3-GO nanocomposite with tunable loading density up to full monolayer coverage is synthesized by adopting a simple phase transfer method and applied as a redox probe to fabricate an immunosensor for AFP. The obtained Ag@Fe2O3-GO nanocomposite has favorable electrical conductivity with the advantage of biocompatibility and chemical stability, which improves both the sensitivity and stability of the immunosensor. Furthermore, due to their excellent conductivity and large surface area, gold–platinum alloy nanoparticles (Au–Pt NPs) are served to immobilize an antibody (anti-AFP) and the electrochemical signal is further amplified accompanied by the enhanced sensitivity and the stability of the immunosensor. The novel Ag@Fe2O3-GO nanocomposite probe for AFP detection developed in this work exhibits excellent sensitivity with a linear response in the concentration range from 0.005 to 100 ng mL−1 and a detection limit of 0.2 pg mL−1 (S/N = 3).

Ultrasensitive electrochemical biosensor based on reduced graphene oxide-tetraethylene pentamine-BMIMPF6 hybrids for the detection of α2,6-sialylated glycans in human serum.

In this paper, a simple, ultrasensitive and label-free electrochemical α2,6-sialylated glycans biosensor based on reduced graphene oxide-tetraethylene pentamine-1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) hybrids was developed. Due to the abundance of amino groups from reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) and the electrostatic interaction of BMIMPF6, bimetallic gold platinum alloy nanoparticles (AuPtNPs) were densely adsorbed onto the surface of the nanocomposite, providing a large surface area available for the immobilization of Sambucus nigra agglutinin (SNA). AuPtNPs have excellent conductivity and catalytic activity, which can promote electron transfer between the electrolyte solution and the surface of electrode and can enhance the sensitivity of biosensor. SNA, which specifically binds α2,6-sialylated glycans, was covalently immobilized on AuPtNPs for specific detection of α2,6-sialylated glycans in human serum. Under optimal experimental conditions, amperometric response changes were used to detect α2,6-sialylated glycans with a broad linear range of 10 fg mL(-1) -1 μg mL(-1) and a low detection limit of 3 fg mL(-1) (S/N=3). When applied to spiked serum samples, the recovery of the developed biosensor ranged from 100.8% to 101.4%, suggesting that the electrochemical biosensor would be suitable for the practical detection of α2,6-sialylated glycans.

A facile and efficient synthesis of polystyrene/gold-platinum composite particles and their application for aerobic oxidation of alcohols in water.

Herein we develop a facile and effective method for the synthesis of composite particles composed of polystyrene microspheres decorated with gold-platinum alloy nanoparticles, which exhibited excellent catalytic activity and recyclability for 1-phenylethanol oxidation under mild conditions (without a base, air as an oxidant, in water, at 40 °C).

Gold–platinum alloy nanoparticles through water-in-oil microemulsion

Au–Pt alloy nanoparticles have been synthesized by the reduction of tetrachloroauric acid (HAuCl4) and chloroplatinic acid (H2PtCl6) using sodium borohydride in water-in-oil (w/o) microemulsion of water/Triton X-100/cyclohexene/1-hexanol at 25 ± 2 °C. The observed nanoparticles looked like a chain with diameter of 2.5 nm. The particles formation was characterized by UV–visible spectrometry and transmission electron microscopy images. The particles are crystalline confirmed by high-resolution transmission electron microscopy and diffraction pattern. A bright-field and dark-field images were compared to find out the nature of the nanochains.

Fabrication and Optical Absorption Properties of Gold - Silver and Gold-Platinum Alloy Nanoparticles Formed by Laser Ablation

Gold, silver and platinum nanoparticles were fabricated by a laser-induced breakdown technique of Au, Ag and Pt metal plates. On the other hand, bimetallic nanoalloys consisting of Au–Ag and Au–Pt have been synthesized by irradiation of the prepared nanoparticles under UV light, which leads to an alloy type of structure. The optical characterization and particle sizes were determined by using absorption spectroscopy and transmission electron microscopy.

Determination of ascorbic acid using an electrode modified with cysteine self-assembled gold-platinum nanoparticles

We report on a new type of indium tin oxide (ITO) electrode for sensing ascorbic acid (AA). The ITO film was modified with gold-platinum alloy nanoparticles (Au-Pt NPs) functionalized with a self-assembled film of L-cysteine. The Au-Pt NPs were electrodeposited on the ITO film and characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. A cyclic voltammetric study revealed that the electrode exhibits excellent electrocatalytic activity towards the oxidation of AA. The calibration plot for AA is linear over the concentration range from 2 to 400 μM with a correlation coefficient of 0.9991. The detection limit of AA is 1 μM.

Size‐Controllable Gold–Platinum Alloy Nanoparticles on Nine Functionalized Ionic‐Liquid Surfaces and Their Application as Electrocatalysts for Hydrogen Peroxide Reduction

A series of room-temperature ionic liquids (RTILs) containing different functional groups such as hydroxyl, nitrile, carboxyl, and thiol attached to imidazolium cations, combined with various anions such as chloride [Cl], tetrafluoroborate [BF(4)], hexafluorophosphate [PF(6)], and bis[(trifluoromethyl)sulfonyl]imide [Tf(2)N], have been successfully synthesized. Dissolved in chitosan (Chi), the Chi/RTIL composites can be employed as flexible templates for the preparation of Au/Pt nanostructures. These Au/Pt nanostructures can be facilely deposited in situ on the surface of Chi/RTILs through electrodeposition. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results demonstrate that the alloy size is significantly dependent on the structure of the Chi/RTILs, with sizes ranging from 2.8 to 84.7 nm. Based upon the functionalized RTILs, nine Chi/RTIL-Au/Pt biosensors have been fabricated. First, the size-dependent electrochemistry of Chi/RTIL-Au/Pt was investigated using potassium ferricyanide as the probe. The reversible electron transfer of the Fe(CN)(6)(3-/4-) redox couple was realized for the nine biosensors, and the peak currents, as well as the peak-to-peak separations (ΔE(p)) and electron-transfer rates, differ greatly from each other because of the diversity of the RTILs. Further electrochemical research reveals that the functional groups of these RTILs exert an evident influence on the reduction behavior of H(2)O(2), which in turn illustrates that the electrocatalytic activity of Chi/RTIL-Au/Pt nanocomposites can be tuned by means of employing RTILs with different functional groups, and an appropriate combination of cations and anions may produce a higher activity. The facilitated electron transfer and the intrinsic catalytic activity of Au/Pt NPs provide a facile way to construct a third-generation H(2)O(2) biosensor with a high sensitivity, low detection limit, quick response time, and excellent selectivity.

Electrodeposition of gold–platinum alloy nanoparticles on carbon nanotubes as electrochemical sensing interface for sensitive detection of tumor marker

A novel electrochemical sensing interface, electrodeposition of gold–platinum alloy nanoparticles (Au–PtNPs) on carbon nanotubes, was proposed and used to fabricate a label-free amperometric immunosensor. On the one hand, the multiwalled carbon nanotubes (MWCNTs) could increase active area of the electrode and enhance the electron transfer ability between the electrode and redox probe; on the other hand, the Au–PtNPs not only could be used to assemble biomolecules with bioactivity kept well, but also could further facilitate the shuttle of electrons. In the meanwhile, horseradish peroxidase (HRP) instead of bovine serum albumin (BSA) was employed to block the possible remaining active sites and avoid the nonspecific adsorption. With the synergetic catalysis effect of Au–PtNPs and HRP towards the reduction of hydrogen peroxide (H 2O 2), the signal could be amplified and the sensitivity could be enhanced. Using alpha-fetoprotein (AFP) as model analyte, the fabricated immunosensor exhibited two wide linear ranges in the concentration ranges of 0.5–20 ng mL −1 and 20–200 ng mL −1 with a detection limit of 0.17 ng mL −1 at a signal-to-noise of 3. Moreover, the immunosensor exhibited good selectivity, stability and reproducibility. The developed protocol could be easily extended to other protein detection and provided a promising potential in clinical diagnosis application.

Electrodeposition of gold–platinum alloy nanoparticles on ionic liquid–chitosan composite film and its application in fabricating an amperometric cholesterol biosensor

An electrodeposition method was applied to form gold–platinum (AuPt) alloy nanoparticles on the glassy carbon electrode (GCE) modified with a mixture of an ionic liquid (IL) and chitosan (Ch) (AuPt–Ch–IL/GCE). AuPt nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. AuPt–Ch–IL/GCE electrocatalyzed the reduction of H 2O 2 and thus was suitable for the preparation of biosensors. Cholesterol oxidase (ChOx) was then, immobilized on the surface of the electrode by cross-linking ChOx and chitosan through addition of glutaraldehyde (ChOx/AuPt–Ch–IL/GCE). The fabricated biosensor exhibited two wide linear ranges of responses to cholesterol in the concentration ranges of 0.05–6.2 mM and 6.2–11.2 mM. The sensitivity of the biosensor was 90.7 μA mM −1 cm −2 and the limit of detection was 10 μM of cholesterol. The response time was less than 7 s. The Michaelis–Menten constant ( K m) was found as 0.24 mM. The effect of the addition of 1 mM ascorbic acid and glucose was tested on the amperometric response of 0.5 mM cholesterol and no change in response current of cholesterol was observed.

A signal-on electrochemical probe-label-free aptasensor using gold–platinum alloy and stearic acid as enhancers

In the present study, a new electrochemical probe-label-free aptasensor for thrombin (TB) based on the amplification of gold–platinum alloy nanoparticles (Au–PtNPs) and stearic acid was reported. Nafion@multiwalled carbon nanotubes (MWCNTs) coated electrode was firstly modified with electrochemical probe of methylene blue (MB). Then, Au–PtNPs were electrodeposited onto the electrode surface for the immobilization of aptamer and further hybridization of stearic acid labeled thrombin aptamer (TBA). In the presence of TB, the TBA bound with TB and released from the self-assembled duplex on the electrode into solution, decreasing the steric hindrance of the aptasensor and facilitating catalytic efficiency of Au–PtNPs in the presence of MB toward H 2O 2 with an enhanced electrochemical signal. With the enhanced effect of Au–PtNPs/MB modified electrode and stearic acid, a detection limit as low as 3 pM for TB was achieved. The aptasensor also exhibited good selectivity and reproducibility.

Electrochemical deposition of gold–platinum alloy nanoparticles on an indium tin oxide electrode and their electrocatalytic applications

Gold–platinum (Au–Pt) hybrid nanoparticles (Au–PtNPs) were successfully deposited on an indium tin oxide (ITO) surface using a direct electrochemical method. The resulting nanoparticles were characterized by scanning electron microscopy (SEM), UV–vis spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and electrochemical methods. It was found that the size of the Au–PtNPs depends on the number of electrodeposition cycles. Au–PtNPs obtained by 20 electrodeposition cycles had a cauliflower-shaped structure with an average diameter of about 60 nm. These Au–PtNPs exhibited alloy properties. Electrochemical measurements showed that the charge transfer resistivity was significantly decreased for the Au–PtNPs/ITO electrode. Additionally, the Au–PtNPs displayed an electrocatalytic activity for nitrite oxidation and oxygen reduction. The Au–PtNPs/ITO electrodes reported herein could possibly be used as electrocatalysts and sensors.

Ultrasonic-electrodeposition of gold–platinum alloy nanoparticles on multi-walled carbon nanotubes – ionic liquid composite film and their electrocatalysis towards the oxidation of nitrite

We report here for the first time on the electrochemical co-deposition of gold–platinum (AuPt) nanoparticles on multi-walled carbon nanotubes (MWNT) – ionic liquid (i.e. trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, [P 6,6,6,14][NTf 2]) composite surface in ultrasonic field. The obtained AuPt nanoparticles were characterized by scanning electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy. It was found that they were well-dispersed on the composite surface, with particle size about 10 nm. Furthermore, they exhibited alloy features. Electrochemical impedance spectroscopy and voltammetric experiments showed that the resulted AuPt-MWNT-[P 6,6,6,14][NTf 2] modified electrode possessed rather small electron transfer resistance and good catalytic activity towards nitrite oxidation. Under the optimized conditions, the oxidation current of nitrite was linear to its concentration in the range of 5–200 nM and the detection limit was down to 1.0 nM (S/N = 3).

A novel glucose biosensor based on immobilization of glucose oxidase in chitosan on a glassy carbon electrode modified with gold–platinum alloy nanoparticles/multiwall carbon nanotubes

A novel glucose biosensor was constructed, based on the immobilization of glucose oxidase (GOx) with cross-linking in the matrix of biopolymer chitosan (CS) on a glassy carbon electrode (GCE), which was modified with gold–platinum alloy nanoparticles (Au–PtNPs) by electrodeposition on multiwall carbon nanotubes (CNTs) in CS film (CNTs/CS). The properties of Au–PtNPs/CNTs/CS were characterized by scan electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), and electrochemical impedance spectra (EIS). Primary study indicated that Au–PtNPs/CNTs had a better synergistic electrocatalytic effect on the reduction of hydrogen peroxide than did AuNPs/CNTs or PtNPs/CNTs at a low applied potential window. With GOx as a model enzyme, a new glucose biosensor was fabricated. The biosensor exhibited excellent performances for glucose at a low applied potential (0.1 V) with a high sensitivity (8.53 μA mM −1), a low detection limit (0.2 μM), a wide linear range (0.001–7.0 mM), a fast response time (<5 s), and good reproducibility, stability, and selectivity. In addition, the biosensor was applied in the determination of glucose in human blood and urine samples, and satisfied results were obtained.

Electrocatalytic Oxidation of Glucose at Carbon Electrodes Modified with Gold and Gold–Platinum Alloy Nanoparticles in an Alkaline Solution

Abstract The electrocatalytic oxidation of glucose in an alkaline solution was examined using gold and gold–platinum alloy nanoparticles as catalysts. In electrolysis, the catalytic activity for oxidation of glucose could be kept much longer time at gold nanoparticle-modified electrode than at a gold plate electrode. Preliminary electrolysis results at 0.3 V indicated that current efficiency for oxalate as 18-electron oxidation product at gold nanoparticle-modified electrode was approximately twice higher than that at gold–platinum alloy nanoparticle-modified electrode.