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Abstract: Platinum nanoparticles (Pt-NPs) were deposited onto N-(trimethoxy-silylpropyl) ethylenediamine triacetic acid (EDTA-silane) modified reduced graphene oxide (EDTA-RGO). The EDTA-RGO/Pt-NPs were coated onto a glass carbon electrode and characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectra, and electrochemical tests. The chelating groups create a micro-environment that is suitable for the catalytic behavior of Pt-NPs. Compared with traditional carbon-based Pt catalysts, EDTA-RGO/Pt-NPs exhibit great tolerance towards poisoning by CO. Graphene-supported Pt nanoparticles can be used for the fabrication of fuel cell electrodes and other catalytic devices. [Copyright &y& Elsevier]

In this study, we proposed 'switching ultrasonic amplitude' as a new strategy of applying ultrasonic energy to prepare a hybrid of buckminsterfullerene (C 60) and gallium oxide (Ga 2 O 3), C 60 /Ga 2 O 3. In the proposed method, we switched the ultrasonic amplitude from 25% to 50% (by 5% amplitude per 10 min, within 1 h of ultrasonic irradiation) for the sonochemical treatment of a heterogeneous aqueous mixture of C 60 and Ga 2 O 3 by a probe-type ultrasonic horn operating at 20 kHz. We found that compared to the conventional techniques associated with high amplitude oriented ultrasonic preparation of functional materials, switching ultrasonic amplitude can better perform in preparing C 60 /Ga 2 O 3 with respect to avoiding titanium (Ti) as an impurity generating from the tip erosion of a probe-type ultrasonic horn during high amplitude ultrasonic irradiation in an aqueous medium. Based on SEM/EDX analysis, the quantity of Ti (wt.%) in C 60 /Ga 2 O 3 prepared by the proposed technique of switching ultrasonic amplitude was found to be 1.7% less than that prepared at 50% amplitude of ultrasonic irradiation. The particles of C 60 /Ga 2 O 3 prepared by different modes of amplitude formed large (2–12 μm) aggregates in their solid phase.Whereas, in the aqueous medium, they were found to disperse in their nano sizes. The minimum particle size of the as-synthesized C 60 /Ga 2 O 3 in an aqueous medium prepared by the proposed method of switching ultrasonic amplitude reached to approximately 467 nm. Comparatively, the minimum particle sizes were approximately 658 nm and 144 nm, using 25% and 50% amplitude, respectively. Additionally, Ga 2 O 3 went under hydration during ultrasonic irradiation. Moreover, due to the electron cloud interference from C 60 in the hybrid structure of C 60 /Ga 2 O 3 , the vibrational modes of Ga 2 O 3 were Raman inactive in C 60 /Ga 2 O 3. [ABSTRACT FROM AUTHOR]

• This study explores the free vibration and bending of FG-GPLRC spherical shells based on the three-dimensional elasticity theory. • The analytical solutions are obtained. • Further illustrative parametric investigations are performed with respect to the distribution pattern, the weight fraction, and the geometric parameters of GPLs. • For free vibration, the FG-A, FG-O and FG-X increase the natural frequencies of breathing, torsional and fundamental modes more effectively, respectively; While for bending, FG-X possesses the smallest displacement, and FG-V holds the lowest stress. This paper presents analytical investigations on the free vibration and static bending of functionally graded graphene-reinforced nanocomposite (FG-GPLRC) spherical shells. The GPL nanofillers are dispersed into polymer matrix uniformly and un-uniformly in the thickness direction with a piece-wise type, and UD, FG-O, FG-X, FG-V and FG-A types of GPL distribution patterns are taken into account. The effective material properties of graphene-reinforced nanocomposites are estimated by using the modified Halpin-Tsai multi-scaled model and the rule of mixtures. Governing differential equations for free vibration and bending of the FG-GPLRC spherical shells are derived based on the three-dimensional elasticity theory with the aid of the state space method, and the layer-wise model is employed to obtain the analytical solutions. The validity of the present method is first examined, followed by the illustrative parametric studies to further scrutinize the free vibration and static bending behaviors of the FG-GPLRC spherical shells with the various reinforcement schemes, including the distribution pattern, the weight fraction, and geometric parameter of GPLs in details. [ABSTRACT FROM AUTHOR]

The accurate therapeutic evaluation for chronic myeloid leukemia (CML) drug is of great importance to minimize side effects and enhance efficacy. Herein, a facile and precise surface-enhanced scattering (SERS) approach based on coupled plasmonic field has been introduced to evaluate the therapeutic outcomes of antileukemia drug through ultrasensitive assay of caspase-3 activity in apoptotic cells. Caspase-3 as an apoptosis indicator could specifically cleave the N-terminus of biotinylated DEVD-peptide (biotin-Gly-Asp-Gly-Asp-Glu-Val-Asp-Gly-Cys) immobilized on the Au nanoparticle-decorated TiO 2 nanotube arrays (TiO 2 /Au NTAs) substrate. After the enzyme cleavage with caspase-3, Raman-labelled Au nanostar (AuNS) probes captured the residual DEVD-peptides via the recognition between streptavidin and biotin, thus resulting in an enhanced Raman response on the SERS platform. The variation of Raman intensity revealed caspase-3 activity that reflected the chemotherapeutic effect. On this platform, AuNS nanoprobes offered a large number of binding sites and intrinsic “hot spots” for Raman reporters, while TiO 2 /Au NTAs rendered a homogenously coupled electromagnetic field between the adjacent repeated units over the large area. In particular, a spatially expanding plasmonic field formed by coupling AuNSs with TiO 2 /Au NTAs would further heighten Raman enhancement. Taking these advantages, the strong and uniform Raman signals were achieved. Furthermore, the practicability investigation witnessed that the proposed SERS strategy was available to evaluate the therapeutic effect of dasatinib on CML K562 cells. The developed method possesses fascinating advantages of cost-effectiveness, excellent reproducibility and high sensitivity, which endows it with promising potential in apoptosis monitoring and anticancer drug development. [ABSTRACT FROM AUTHOR]

CO oxidation has been performed on Co 3 O 4 nanocubes and Co(OH) 2 nanosheets as model catalysts. The reaction rate of CO on Co 3 O 4 /Co(OH) 2 nanocomposites obtained by one-pot synthesis is about ~ two orders of magnitude higher than that on Co 3 O 4 nanomaterials. The catalytic behaviors of different nanomaterials revealed that the assembly with nano building blocks cause the catalytic sites much more active for CO oxidation. The kinetic data showed that the activation energy for CO oxidation over Co 3 O 4 /Co(OH) 2 nanocomposites was lower than that of other nanomaterials. Since Co(OH) 2 nanosheets can prevent Co 3 O 4 nanocubes aggregating, nanocomposites kept good catalytic stability. [ABSTRACT FROM AUTHOR]

Abstract: A sensitive colorimetric detection for biomolecules based on aptamer was described. Poly(dimethylsiloxane) (PDMS)–gold nanoparticles (AuNPs) composite film was used as a platform for immobilizing anti-target aptamer. PDMS–AuNPs composite film only covered with aptamer showed high inhibiting ability towards silver reduction, after target molecules were conjugated on the modified surface, the catalytic efficiency of AuNPs for silver reduction was increased. In this system, the darkness density of silver enhancement was applied for target quantitative measurement. Lysozyme and adenosine 5′-triphosphate (ATP) were tested as the models, quantitative measurements with imaging software or semiquantitative measurements with naked eyes were carried out in the range of 1×10−2–1μg/mL and 1×10−4–1×103 μg/mL, the volume of reagent using in each assay is 15μL or less. We speculated that aptamer-target conjugates’ inhibition ability for AuNPs’ catalytic efficiency toward silver reduction might come from charge and spatial effects. This study can offer a completely novel and relatively general approach for colorimetrical aptamer sensors with good analytical properties and potential applications. The sensor could be coupled with digital transmission of images for remote monitoring system in diagnosis, food control, and environmental analysis. [Copyright &y& Elsevier]

Abstract: The nanocomposite composed of carboxymethyl chitosan (CMCS) and gold nanoparticles was successfully prepared by a novel and in situ process. It was characterized by transmission electron microscopy (TEM) and Fourier transform infrared spectrophotometer (FTIR). The nanocomposite was hydrophilic even in neutral solutions, stable and inherited the properties of the AuNPs and CMCS, which make it biocompatible for enzymes immobilization. HRP, as a model enzyme, was immobilized on the silica sol–gel matrix containing the nanocomposite to construct a novel H2O2 biosensor. The direct electron transfer of HRP was achieved and investigated. The biosensor exhibited a fast amperometric response (5s), a good linear response over a wide range of concentrations from 5.0×10−6 to 1.4×10−3 M, and a low detection limit of 4.01×10−7 M. The apparent Michaelis–Menten constant () for the biosensor was 5.7×10−4 M. Good stability and sensitivity were assessed for the biosensor. [Copyright &y& Elsevier]