Nanoparticle-Supported, Rapid, and Electronic Detection of SARS-CoV-2 Antibodies and Antigens at Attomolar Level.

A gold nanoparticle (AuNP)-supported rapid, electronic detection (NasRED) platform is demonstrated with high specificity to differentiate SARS-CoV-2 from human coronaviruses while achieving high sensitivity. Uniquely, active fluidic force is exerted on AuNPs in a microcentrifuge tube, through engineered centrifugation and vortex agitation, to accelerate signal transduction from biochemical protein binding to physical AuNP aggregation and precipitation and finally to electronic signals in a customized, stabilized circuitry. The limits of detection are found <80 aM (12 fg/mL) and ∼700 aM (105 fg/mL) to detect antibodies in human pooled serum and 20% diluted whole blood, and <900 aM (45 fg/mL) and 4.

Simultaneous Determination of Total Vitamins B1, B2, B3, and B6 in Infant Formula and Related Nutritionals by Enzymatic Digestion and LC-MS/MS-A Multi-Laboratory Testing Study Final Action: AOAC Method 2015.14.

Background/objective: A multi-laboratory study was completed for AOAC First Action Method 2015.14. Ten laboratories from eight countries participated.

High Throughput Differential Scanning Fluorimetry (DSF) Formulation Screening with Complementary Dyes to Assess Protein Unfolding and Aggregation in Presence of Surfactants.

Purpose: The purpose was to evaluate DSF for high throughput screening of protein thermal stability (unfolding/ aggregation) across a wide range of formulations. Particular focus was exploring PROTEOSTAT® - a commercially available fluorescent rotor dye - for detection of aggregation in surfactant containing formulations. Commonly used hydrophobic dyes (e.

A new sample preparation and separation combination for precise, accurate, rapid, and simultaneous determination of vitamins B1, B2, B3, B5, B6, B7, and B9 in infant formula and related nutritionals by LC-MS/MS.

An improved method was developed for simultaneous determination of the fortified forms of thiamine (B1), riboflavin (B2), nicotinamide and nicotinic acid (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), and folic acid (B9) in infant formulas and related nutritionals. The method employed a simple, effective, and rapid sample preparation followed by liquid chromatography tandem mass spectrometry (LC-MS/MS). It improved upon previous methodologies by offering facile and rugged sample preparation with improved chromatographic conditions, which culminated in a highly accurate and precise method for water-soluble vitamin determination in a wide range of formulas.

Simultaneous Determination of Total Vitamins B1, B2, B3, and B6 in Infant Formula and Related Nutritionals by Enzymatic Digestion and LC-MS/MS: Single-Laboratory Validation, First Action 2015.14.

This method provides simultaneous determination of total vitamins B1, B2, B3, and B6 in infant formula and related nutritionals (adult and infant). The method was given First Action for vitamins B1, B2, and B6, but not B3, during the AOAC Annual Meeting in September 2015. The method uses acid phosphatase to dephosphorylate the phosphorylated vitamin forms.

Planar oxide supported rhodium nanoparticles as model catalysts.

C(2)H(4)/CO/H(2) reaction is investigated on Rh/SiO(2) model catalyst surfaces. Kinetic reactivity and infrared spectroscopic measurements are investigated as a function of Rh particle size under near atmospheric reaction conditions. Results show that propionaldehyde turnover frequency (TOF) (CO insertion pathway) exhibits a maximum activity near = 2.

Electrostatic layer-by-layer assembly of CdSe nanorod/polymer nanocomposite thin films.

Electrostatic layer-by-layer assembly was the basis for the synthesis of multilayer nanorod/polymer composite films. Cationic and water-soluble CdSe nanorods (NRs) were synthesized and partnered with anionic polymers including poly(sodium 4-styrenesulfonate) (PSS) and two polythiophene-based photoactive polymers, sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate (PTEBS) and poly[3-(potassium-6-hexanoate)thiophene-2,5-diyl] (P3KHT). Controlled multilayer growth is shown through UV-vis spectroscopy, cross-sectional SEM and surface analytical techniques including atomic force microscopy.

Characterization of active sites on Rh/SiO(2) model catalysts.

Rh/SiO(2) model catalyst surfaces are prepared under ultra-high vacuum conditions and examined in situ using scanning tunneling microscope and CO infrared reflection absorption techniques, to quantify the number and kinds of active Rh surface sites available for kinetic reaction (CO oxidation) as a function of Rh particle size. The results are compared against CO desorption measurements and elevated pressure CO oxidation reaction kinetics, to evaluate the extent of the correlation between the low and elevated pressure site characterization techniques. Data demonstrate that estimates of Rh active sites exhibit good agreement between the characterization methods and illustrate the utility of low pressure surface science characterization techniques in understanding elevated pressure reaction kinetics on model catalyst surfaces.

Binding in thiophene and benzothiophene dimers investigated by density functional theory with dispersion-correcting potentials.

We report the use of a newly developed dispersion-corrected density functional approach to study noncovalent binding in a series of thiophene and benzothiophene dimers. These are of interest in both petrochemistry and molecular electronics. We find increasing influence of dispersion forces over dipole interactions as the number of benzene moieties increases from 0 (thiophene) to 3 (tribenzothiophene).

Reactivity of molecularly chemisorbed oxygen on a Au/TiO2 model catalyst.

We present results of an investigation into the reactivity of molecularly chemisorbed oxygen with CO on a Au/TiO2 model catalyst at 77 K. We previously discovered that exposing the model catalyst sample to a radio-frequency-generated plasma jet of oxygen results in co-population of both atomically and molecularly chemisorbed oxygen species on the sample. We tested the reactivity of the molecularly chemisorbed oxygen by comparing the CO2 produced from a sample populated with both species to the CO2 produced from a sample that has been cleared of molecularly chemisorbed oxygen employing collision-induced desorption.

Transport in amorphous solid water films: implications for self-diffusivity.

Thermal desorption spectroscopy is employed to examine transport mechanisms in structured, nanoscale films consisting of labeled amorphous solid water (ASW, H(2)(18)O, H(2)(16)O) and organic spacer layers (CCl(4), CHCl(3)) prior to ASW crystallization (T approximately 150-160 K). Self-transport is studied as a function of both the ASW layer and the organic spacer layer film thickness, and the effectiveness of these spacer layers as a bulk diffusion "barrier" is also investigated. Isothermal desorption measurements of structured films are combined with gas uptake measurements (CClF(2)H) to investigate water self-transport and changes in ASW film morphology during crystallization and annealing.

Formation of molecularly chemisorbed oxygen on TiO2-supported gold nanoclusters and Au(111) from exposure to an oxygen plasma jet.

We present results of an investigation into the low-temperature formation of molecularly chemisorbed oxygen on a Au/TiO(2) model catalyst and on a Au(111) single crystal during exposure to a plasma jet of oxygen. Through the use of collision-induced desorption measurements and isotopic mixing experiments we show evidence suggesting that at least some of the molecular oxygen is formed as a result of recombination of oxygen atoms on the samples during the plasma exposure. Of course, adsorption of excited molecular oxygen directly from the gas phase may also take place.

Evidence that amorphous water below 160 K is not a fragile liquid.

We have examined transport mechanisms in amorphous solid water (ASW) by studying thermal desorption of layered nanoscale films of CCl4 and labeled ASW. The interlayer mixing observed near T approximately 150-160 K is inconsistent with a mechanism involving diffusion through a dense phase. Instead, intermixing occurs via vapor-phase transport through an interconnected porous network created within the film during crystallization.

Reaction of CO with molecularly chemisorbed oxygen on TiO2-supported gold nanoclusters.

In this study we present results of an investigation into the reactivity of molecularly chemisorbed oxygen species on a Au/TiO2 model catalyst. We have previously shown that a Au/TiO2 model catalyst sample can be populated with both atomically and molecularly chemisorbed oxygen species following exposure to a radio frequency-generated oxygen plasma-jet. To test the reactivity of the molecularly chemisorbed oxygen species, we compare the CO2 produced from a sample that is populated with both oxygen species to the CO2 produced from a sample that has been given an identical exposure but has been cleared of molecularly chemisorbed oxygen employing collision-induced desorption.

Evidence for molecularly chemisorbed oxygen on TiO2 supported gold nanoclusters and Au(111).

In this study, we present evidence for the existence of a molecularly chemisorbed oxygen species on a Au/TiO2 model catalyst and a Au(111) single crystal following exposure of these samples to an oxygen plasma-jet molecular beam. We present evidence for the molecularly chemisorbed oxygen species from thermal desorption, collision-induced desorption, and heat of adsorption/reaction-induced desorption measurements. Thermal desorption measurements reveal a peak desorption temperature at approximately 145 K which corresponds to an activation energy for desorption of approximately 0.