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We report reproducible and sensitive surface-enhanced Raman spectroscopy (SERS) detection achieved with a developed nanoparticle platform, Ag&MH. Ag&MH is comprised of silver nanoparticles (AgNPs), as a sensing substrate that is efficiently and uniformly magnetically concentrated with the assistance of maghemite, γ-Fe2O3, nanoparticles (MHNPs). MNHPs were optimized synthetically for minimal charge interactions with AgNPs and low optical absorbance. At sufficiently high concentrations, magnetic maghemite NPs hydrodynamically trap AgNPs and concentrate them on the inner surface of a quartz optical cell to form an Ag&MH SERS substrate for highly reproducible SERS detection. The reproducibility is a combination of several factors contributing to uniform “hot spots”: homogeneous magnetic concentration by gentle hydrodynamic trapping and weak electrostatic interactions of the same-charge nanoparticles and non-close packing of AgNPs, in particular decahedra. Size-uniform silver decahedra nanoparticles (AgJ13NPs) featuring sharp localized surface plasmon resonance (LSPR) peaks, coupled with minimized optical interference from MHNPs, enable sensitive and reproducible SERS detection, where 5,5′-dithiobis-(2-nitrobenzoic acid), DTNB, was used as a probe molecule. Reproducibility of independent measurements at nanomolar level was ca. 10% – consistently overcoming the “hot spot” problem through uniform distribution of AgJ13NPs in the Ag&MH SERS substrate. Picomolar concentrations were detected using a simple fiber-optic Raman spectrometer. The developed AgJ13&MH sensing platform is promising for convenient and reproducible SERS detection of analytes in common laboratory settings.

A robust and reasonably simple experiment is described that introduces students to the visualization of nanoscale properties and is intended for a first-year laboratory. Silver nanoprisms (NPs) that display different colors due to variation of their plasmonic absorption with respect to size are prepared. Control over the size of the silver nanoprisms is achieved using a novel approach, where bromide is added to the reaction as a size-determining agent, and silver ions are reduced by borohydride in the presence of citrate and peroxide as stabilizing and shape-directing agents, respectively. In a typical experiment, four dispersions of silver nanoprisms with different sizes are produced that are colored from blue (largest) to yellow (smallest). The colors attainable in between are violet, purple, red, and orange. The synthesis of these colored silver NPs is described for the first time as an undergraduate experiment. Once synthesized, the nanoprisms are characterized using UV−vis spectroscopy, and a Beer’s ...

This article examines the process of identity development in gifted adolescents and provides a theoretical and research-based explanation of its importance for influencing achievement and quality of life in adulthood. Teachers, counselors, and parents can use Harry Potter and the Sorcerer's Stone (Rowling, 1997) as a springboard into discussion of identity issues with adolescents, helping them to understand and successfully negotiate the challenges of this phase of life. The article describes the theoretical rationale for such an approach, outlines some practical issues involved, and closes with a sample lesson plan of a session suitable for gifted middle school students.

We investigated the possibility that the Ca2+ channel agonist FPL-64176 (FPL) might also activate the cardiac sarcoplasmic reticulum (SR) Ca2+ release channel ryanodine receptor (RyR). The effects of FPL were tested on single channel activity of purified and crude vesicular RyR (RyR2) isolated from human and dog hearts using the planar lipid bilayer technique. FPL (100–200 μM) increased single channel open probability ( P o) when added to the cytoplasmic side of the channel ( P o = 0.070 ± 0.021 in control RyR2; 0.378 ± 0.086 in 150 μM FPL, n = 9, P < 0.01) by prolonging open times and decreasing closed times without changing current magnitude. FPL had no effect on P o when added to the trans (luminal) side of the bilayer ( P o = 0.079 ± 0.036 in control and 0.103 ± 0.066 in FPL, n = 4, no significant difference). The bell-shaped [Ca2+] dependence of [3H]ryanodine binding and of P o was altered by FPL, suggesting that the mechanism by which FPL increases channel activity is by an increase in Ca2+-induced activation at low [Ca2+] (without a change in threshold) and suppression of Ca2+-induced inactivation at high [Ca2+]. However, the fact that inactivation was restored at elevated [Ca2+] suggests a competitive interaction between Ca2+ and FPL on inactivation. FPL had no effect on RyR skeletal channels (RyR1), where P o was 0.039 ± 0.005 in control versus 0.030 ± 0.006 in 150 μM FPL (no significant difference). These results suggest that, in addition to its ability to activate the L-type Ca2+channels, FPL activates cardiac RyR2 primarily by reducing the Ca2+ sensitivity of inactivation.

The use of nanoparticles (NPs) for efficient, environmentally benign catalysis is receiving increasing attention, with gold and palladium NPs being an important area of research. Herein we present a simple, reliable and cost-effective preparation of a catalytically active gold-palladium NP system that is stabilized by an aqueous titania dispersion (AuPd/TiO2) in the absence of organic ligands. The major advantages of this system are that it is catalytically active in the as-prepared colloidal state, eliminating the need for drying and sintering before use and is colloidally stable in oxidative conditions. The AuPd/TiO2 system exhibits efficient oxidative catalysis in both the presence of hydrogen peroxide and atmospheric oxygen, even at ambient temperatures for our model aqueous phase reaction of 1-phenylethanol oxidation. The preparation and characterization of the AuPd/TiO2 system is described with respect to the effects of colloidal stability, particle size and morphology on aqueous oxidative catalysis. The major finding is that NPs with a gold core and thin palladium shell (70 mol% gold, 30 mol% palladium, Au70Pd30/TiO2) provides the most catalytically active system. The ability of the catalyst to use atmospheric oxygen at ambient temperatures in aqueous media highlights the strong potential of the developed catalytic system for green oxidative processes. The presented approach provides a new platform of all-inorganic colloidal nanoparticle systems for future development of industrially viable, environmentally friendly catalysts.

We studied effects of halides on morphology of planar twinned silver nanoparticles and demonstrated application of these effects to precisely tune silver surface plasmon resonance maxima in a broad vis-NIR range using a reliable two-stage modification protocol.