Highly-dispersed Ta-oxide catalysts prepared by electrodeposition in a non-aqueous plating bath for polymer electrolyte fuel cell cathodes

The Ta-oxide cathode catalysts were prepared by electrodeposition in a non-aqueous solution. These catalysts showed excellent catalytic activity and have an onset potential of 0.92 V(RHE) for the oxygen reduction reaction (ORR). The highly-dispersed Ta species at the nanometer scale on the carbon black was an important contributor to the high activity.     

A rapid and facile signal enhancement method for microcantilever-based immunoassays using the agglomeration of ferromagnetic nanoparticles

A rapid and facile signal enhancement method for detecting alpha-fetoprotein (AFP) was developed using the magnetic agglomeration of ferromagnetic nanoparticles and microcantilever sensors. The resonance frequency and deflection of the cantilevers were found to be more than 10-fold greater than that before physical agglomeration of the free nanoparticles around the magnetized nanoparticles.     

Some properties and an application of multivariate exponential polynomials

In the paper, the authors introduce a notion “multivariate exponential polynomials” which generalize exponential numbers and polynomials, establish explicit formulas, inversion formulas, and recurrence relations for multivariate exponential polynomials in terms of the Stirling numbers of the first and second kinds with the help of the Faà di Bruno formula, two identities for the Bell polynomials of the second kind, and the inversion theorem for the Stirling numbers of the first and second kinds, construct some determinantal inequalities and product inequalities for multivariate exponential polynomials with the aid of some properties of completely monotonic functions and other known results, derive the logarithmic convexity and logarithmic concavity for multivariate exponential polynomials, and finally find an application of multivariate exponential polynomials to white noise distribution theory by confirming that multivariate exponential polynomials satisfy conditions for sequences required in white noise distribution theory.     

Antibiofouling polymer-coated gold nanoparticles as a contrast agent for in vivo X-ray computed tomography imaging

Current computed tomography (CT) contrast agents such as iodine-based compounds have several limitations, including short imaging times due to rapid renal clearance, renal toxicity, and vascular permeation. Here, we describe a new CT contrast agent based on gold nanoparticles (GNPs) that overcomes these limitations. Because gold has a higher atomic number and X-ray absorption coefficient than iodine, we expected that GNPs can be used as CT contrast agents. We prepared uniform GNPs ( approximately 30 nm in diameter) by general reduction of HAuCl4 by boiling with sodium citrate. The resulting GNPs were coated with polyethylene glycol (PEG) to impart antibiofouling properties, which extends their lifetime in the bloodstream. Measurement of the X-ray absorption coefficient in vitro revealed that the attenuation of PEG-coated GNPs is 5.7 times higher than that of the current iodine-based CT contrast agent, Ultravist. Furthermore, when injected intravenously into rats, the PEG-coated GNPs had a much longer blood circulation time (>4 h) than Ultravist (<10 min). Consequently, CT images of rats using PEG-coated GNPs showed a clear delineation of cardiac ventricles and great vessels. On the other hand, relatively high levels of GNPs accumulated in the spleen and liver, which contain phagocytic cells. Intravenous injection of PEG-coated GNPs into hepatoma-bearing rats resulted in a high contrast ( approximately 2-fold) between hepatoma and normal liver tissue on CT images. These results suggest that PEG-coated GNPs can be useful as a CT contrast agent for a blood pool and hepatoma imaging.     

Bioinspired Colorimetric Detection of Calcium(II) Ions in Serum Using Calsequestrin‐Functionalized Gold Nanoparticles

Seeing is sensing : Calsequestrin (CSQ) functionalized gold nanoparticles undergo calcium‐dependent CSQ polymerization, which results in a clear color change (see picture) together with precipitation. The sensing system is specific for Ca²⁺ ions and the differences between normal and disease‐associated abnormal (hypercalcemia) Ca²⁺ ion levels in serum can be distinguished with the naked eye.

     

In Situ Synthesis of Self‐Assembled Gold Nanoparticles on Glass or Silicon Substrates through Reactive Inkjet Printing

A facile and low cost method for the synthesis of self‐assembled nanoparticles (NPs) with minimal size variation and chemical waste by using reactive inkjet printing was developed. Gold NPs with diameters as small as (8±2) nm can be made at low temperature (120 °C). The size of the resulting NPs can be readily controlled through the concentration of the gold precursor and oleylamine ink. The pure gold composition of the synthesized NPs was confirmed by energy‐dispersive X‐ray spectroscopy (EDXS) analysis. High‐resolution SEM (HRSEM) and TEM (HRTEM), and X‐ray diffraction revealed their size and face‐centered cubic (fcc) crystal structure, respectively. Owing to the high density of the NP film, UV/Vis spectroscopy showed a red shift in the intrinsic plasmonic resonance peak. We envision the extension of this approach to the synthesis of other nanomaterials and the production of tailored functional nanomaterials and devices.