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Background: As nanotechnology advances rapidly, the nanozymes which could replace protein enzymes in bioanalytical assays bring a new opportunity to the development of simple and sensitive diagnostic tools., Purpose: Antibody-conjugated Au-Pt core/shell nanorods (Au@Pt NRs) have been used for nanozyme probes for diagnosis of rubella virus. Au@Pt NRs, prepared by Au nanorod-mediated growth, exhibit peroxidase-like activities and could serve as an inexpensive replacement for horseradish peroxidase (HRP) in conjugation of antigen., Method: Using a capture enzyme-linked immunosorbant assay for the determination of rubella virus., Results: Compared with antibody-conjugated HRP, the antigen-conjugated Au@Pt NRs are more stable and more robust, but less expensive. Based on the enhanced catalytic properties of this nanozyme probe, it was found that the antigen-conjugated Au@Pt NRs-based enzyme-linked immunosorbant assay exhibited good sensitivity., Conclusion: Our results indicate that these antigen-conjugated Au@Pt NRs represent a suitable nanozyme probe for future clinical applications under various conditions., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Nanostructured materials are a new class of enzyme mimics, the inhibitors of which have not been studied. Herein, we demonstrate the screening of inhibitors for Au@Pt nanorod (NR) oxidase mimics. In addition, based on the enzyme inhibition reaction, determination of "poisoning" inhibitors is demonstrated.

In this paper, we demonstrated that Au nanorods coated with a shell composed of Pt nanodots (Au@Pt nanostructures) exhibited intrinsic oxidase-like, peroxidase-like and catalase-like activity, catalyzing oxygen and hydrogen peroxide reduction and the dismutation decomposition of hydrogen peroxide to produce oxygen. Based on these findings, we established an Au@Pt nanostructures based enzyme linked immunosorbent assay (ELISA) for the detection of mouse interleukin 2 (IL-2). In comparison with natural enzymes, Au@Pt nanostructures have advantages of low cost, easy preparation, better stability, and tunable catalytic activity (compared with HRP), which make them a promising enzyme mimetic candidate and may find potential applications in biocatalysis, bioassays, and nano-biomedicine such as reactive oxygen species (ROS)-related fields (anti-aging and therapeutics for neurodegenerative diseases and cancers)., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

An effective way is developed to fabricate AgPt alloy nanoislands on gold nanorods based on the galvanic replacement between Ag and PtCl(4)(2-) in the presence of cetyltrimethylammonium bromide (CTAB). The optical and catalytic properties benefit from the porous structure composed of AgPt nanoislands. A large red shift (265 nm) after etching is observed for longitudinal surface plasmon resonance (SPR) in comparison with Au@Pt0.1@Ag. Alloy compositions in bulk miscibility gap can be obtained and finely tuned from Ag(0.56)Pt(0.44) to Ag(0.38)Pt(0.62). A unique composition dependence is found for both electrocatalytic oxidation of methanol and catalytic oxidation of o-phenylenediamine (OPD) by hydrogen peroxide. In both systems, the highest catalytic activity is achieved at the alloy composition of Pt(0.62)Ag(0.38). Proper alloying with Ag not only improves the CO poisoning of Pt catalyst but also enhances the catalytic activity greatly.

A facile and general strategy has been employed to fabricate a "nanoreactor" consisting of a hollow Pt nanocage-encapsulated mesoporous SiO2 shell. The hollow composite, which contained highly dispersed catalytic Pt nanoparticles inside the cavity enclosed by the mesoporous SiO2 shell, was considered an ideal framework structure for a nanoreactor that efficiently catalyzes substrate molecules with enhanced activity. The designed SiO2 shell can not only maintain active Pt nanoparticle resistance to harsh environments but also isolate the molecular recognition sites from the surface of Pt nanoparticles, thus retaining their catalytic activity. In addition, the certain space confinement effect aroused by the hollow structure led to a higher catalytic activity. Based on their catalytic activity, these nanoreactors have been demonstrated to function as biosensors for highly sensitive detection of measles-specific IgM antibodies in capture enzyme-linked immunosorbent assays. The detection limit of the prepared biosensor was as low as 1 ng/mL, 3 orders of magnitude lower than that of the conventional immunoassay. The specific catalytic properties of this nanoreactor could have great potential applications that include catalysis, biological labeling, and bioassays. [ABSTRACT FROM AUTHOR]

Coordination-driven suprastructures have attracted much interest due to their unique properties. Among these structures, platinum-based architectures have been broadly studied due to their facile preparation. The resultant two- or three-dimensional (2D or 3D) systems have many advantages over their precursors, such as improved emission tuning, sensitivity as sensors, and capture and release of guests, and they have been applied in biomedical diagnosis as well as in catalysis. Herein, we review the recent results related to platinum-based coordination-driven self-assembly (CDSA), and the text is organized to emphasizes both the synthesis of new metallacycles and metallacages and their various applications. [ABSTRACT FROM AUTHOR]

Abstract: Au nanorods @ Pt nanodots core/shell nanostructures, prepared by the Au nanorods (NRs)-mediated growth, exhibit dual functional enzyme-like (peroxidase and oxidase-like) activities. From the viewpoint of enzyme mimics, the relationship between apparent enzyme kinetic parameters and nanomaterials structure is investigated in order to rationally design the catalytic activity. Using peroxidase-like properties of the Au@Pt NRs, the determination of hydrogen peroxide (H2O2) was demonstrated with a limit of detection (LOD) of 4.5×10−5 M and a linear range of 4.5×10−5–1×10−3 M using o-phenylenediamine (OPD) as chromogenic substrate. Furthermore, in combination with highly specific reactions provided by natural enzymes, selective detections of glucose and lipophilic cholesterol were demonstrated with similar LODs and linear ranges. Additionally, owing to the specific oxidase-like activity of the Au@Pt NRs (ascorbate oxidase), interference of ascorbic acid in the detection of glucose could be eliminated. In conclusion, considering the flexibility in the design of nanomatererials, there is a lot of space to improve their activity and explore their potential applications, especially in relatively harsh conditions. [Copyright &y& Elsevier]

A method for the quantitative analysis of lead ores by wavelength-dispersive x-ray fluorescence spectrometry (WD-XRF) using sepharose was proposed. The sample was decomposed with aqua regia and then the solution was mixed with sepharose. The mixture was heated to boiling and became a quasi-solid gel at ambient temperature. The quasi-solid gel was detected by WD-XRF. This method was adapted in detecting high content ores, because it avoided the risk of using platinum crucible. In addition, cobalt was used as an internal standard to reduce the matrix effects caused by the loss of water in dissolving samples. Analytical characteristics of the methods used were compared, and their reliability tested against several certified geological reference materials. The results showed high precision and accuracy. This method has been applied to the determination of lead in lead concentrates successfully. [ABSTRACT FROM AUTHOR]