Antioxidation Properties and Surface Interactions of Polyvinylpyrrolidone-Capped Zerovalent Copper Nanoparticles Synthesized in Supercritical Water

Zerovalent copper nanoparticles (CuNPs) (diameter, 26.5 ± 9 nm) capped with polyvinylpyrrolidone (PVP) were synthesized in supercritical water at 400 °C and 30 MPa with a continuous flow reactor. The PVP-capped CuNPs were dispersed in distilled water, methanol, ethanol, 1-propanol, 2-propanol, butanol, and their mixed solvents to study their long-term stability. Temporal variation of UV–vis spectra and surface plasmon resonance were measured and showed that ethanol, the propanols, and butanol solvents provided varying degrees of oxidative protection for Cu⁰. Fourier transform infrared spectroscopy showed that PVP adsorbed onto the surface of the CuNPs with a pyrrolidone ring of PVP even if the CuNPs were oxidized. Intrinsic viscosities of PVP were higher for solvents that provided antioxidation protection than those that give oxidized CuNPs. In solvents that provided Cu⁰ with good oxidative protection (ethanol, the propanols, and butanol), PVP polymer chains formed large radii of gyration and coil-like conformations in the solvents so that they were arranged uniformly and orderly on the surface of the CuNPs and could provide protection of the Cu⁰ surface against dissolved oxygen. In solvents that provided poor oxidative protection for Cu⁰ (water, alcohol–water mixed solvents with 30% water), PVP polymer chains had globular-like conformations due to their relatively high hydrogen-bonding interactions and sparse adsorption onto the CuNP surface. Antioxidative properties of PVP-capped CuNPs in a solvent can be ascribed to the conformation of PVP polymer chains on the Cu⁰ particle surface that originates from the interaction between polymer chains and its interaction with the solvent

Measurement of High-Pressure Densities and Atmospheric Viscosities of Ionic Liquids: 1‑Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide and 1‑Hexyl-3-methylimidazolium Chloride

Atmospheric densities and viscosities of ionic liquids, 1-hexyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([C₆C₁Im]­[Tf₂N]) and 1-hexyl-3-methylimidazolium chloride ([C₆C₁Im]­[Cl]), were measured with a Stabinger viscometer at temperatures from (293 to 373) K. High-pressure densities (<i>p</i> ≤ 200 MPa) for [C₆C₁Im]­[Tf₂N] and [C₆C₁Im]­[Cl] were measured with a bellows type apparatus at temperatures from (312 to 452) K. Samples were analyzed for the water and 1-methylimidazole content before and after the measurements. For [C₆C₁Im]­[Tf₂N], combined expanded uncertainties were estimated to be (1.0 and 1.8) kg·m^–3 for atmospheric and high-pressure density, respectively, and 0.85 % for viscosity. For [C₆C₁Im]­[Cl], combined expanded uncertainties were estimated to be (1.1 and 2.5) kg·m^–3 for atmospheric and high-pressure density, respectively, and 1.59 % for viscosity. The measured densities and viscosities of [C₆C₁Im]­[Tf₂N] in this work agreed with some of the available literature values within their experimental uncertainties. The effect of colored impurities and the source of sample on densities and viscosities of [C₆C₁Im]­[Cl] were determined to be less than the experimental uncertainties. The [C₆C₁Im]­[Tf₂N] did not decompose over the full temperature range during the measurements, while [C₆C₁Im]­[Cl] decomposed at temperatures greater than 392 K

Winterization of Vegetable Oil Blends for Biodiesel Fuels and Correlation Based on Initial Saturated Fatty Acid Constituents

Winterization is a simple method to remove saturated fatty acid contents in biodiesel fuels for improving their cold flow properties. In this work, biodiesel fuels with different initial long-chain (C16 and above) saturated fatty acid constituents (<i>S</i>_i) were prepared from blends of palm, canola, and corn oils. The prepared biodiesels were treated at various winterization temperatures (<i>T</i>_w) to investigate the effect of <i>T</i>_w and <i>S</i>_i on the final saturated fatty acid constituents (<i>S</i>_w) of the winterized biodiesel fuel. Optical microscopy showed that ball-like crystals formed with fluid regions at moderate cooling rates (−6 °C/h) could allow solid–liquid separation by filtration. A saturated fatty acid reduction ratio, <i>R</i>_s, defined as (<i>S</i>_i – <i>S</i>_w)/<i>S</i>_i × 100, was used with the experimental results on large samples (ca. 600 mL) to develop a correlation for winterization temperature as <i>T</i>_w (°C) = 0.659 <i>S</i>_i (wt%) – 0.104 <i>R</i>_s (wt%) – 10.197. The correlation can provide estimation of the required winterization temperature for reducing a specified ratio of fatty acids in a biodiesel fuel that mainly contains long-chain fatty acids from the initial saturated fatty acid constituents. When used with literature relationships for cold filter plugging point (CFPP) and <i>S</i>_w, estimation of the CFPP of winterized biodiesel fuels is possible without requiring actual winterization treatment

Hydrothermal Extraction of Antioxidant Compounds from Green Coffee Beans and Decomposition Kinetics of 3‑<i>o</i>‑Caffeoylquinic Acid

Separation of antioxidant compounds (caffeoylquinic acids (CQAs), phenolics, melanoidin, and caffeine) from green coffee beans with hydrothermal extraction and decomposition kinetics of 3-<i>o</i>-caffeoylquinic acid (3-CQA) are reported. Antioxidant capacity (AOC) of the extracts increased as extraction temperature was increased up to 410 K and then it decreased up to extraction temperatures of 500 K. As extraction temperature was further increased above 500 K, AOC remarkably increased. The decomposition rate of 3-CQA in water was determined from 433 to 513 K. The increase and decrease in AOC with extraction temperature can be attributed to the hydrolysis of oligomeric structures (glycosides) in the coffee beans that yield CQAs, the decomposition of the CQAs, and to the formation of melanoidins that had a characteristic brown color. Hydrothermal extraction provides an effective method for the separation of antioxidant compounds from green coffee beans, and the effluent extracts may be suitable for food products

High-Density Dielectrophoretic Microwell Array for Detection, Capture, and Single-Cell Analysis of Rare Tumor Cells in Peripheral Blood

<div><p>Development of a reliable platform and workflow to detect and capture a small number of mutation-bearing circulating tumor cells (CTCs) from a blood sample is necessary for the development of noninvasive cancer diagnosis. In this preclinical study, we aimed to develop a capture system for molecular characterization of single CTCs based on high-density dielectrophoretic microwell array technology. Spike-in experiments using lung cancer cell lines were conducted. The microwell array was used to capture spiked cancer cells, and captured single cells were subjected to whole genome amplification followed by sequencing. A high detection rate (70.2%–90.0%) and excellent linear performance (R² = 0.8189–0.9999) were noted between the observed and expected numbers of tumor cells. The detection rate was markedly higher than that obtained using the CellSearch system in a blinded manner, suggesting the superior sensitivity of our system in detecting EpCAM− tumor cells. Isolation of single captured tumor cells, followed by detection of <i>EGFR</i> mutations, was achieved using Sanger sequencing. Using a microwell array, we established an efficient and convenient platform for the capture and characterization of single CTCs. The results of a proof-of-principle preclinical study indicated that this platform has potential for the molecular characterization of captured CTCs from patients.</p></div

Plots of the Number of Detected Cells against the Number of Spiked Cells in the Spike-in Experiments.

<p>Cultured tumor cells (SK-BR-3 (breast), PC-9 (non-small cell lung), PC-14 (non-small cell lung), H69 (small cell lung), and SBC-3 (small cell lung)) were separately spiked, in numbers of 10, 100, and 1000, into 3 mL of blood obtained from healthy donors. After enrichment of mononucleated cells from the blood, the cells were entrapped in microwells, followed by immunofluorescent staining with DAPI, chromophore conjugated anti-CK mAb, and anti-CD45 mAb. Then, fluorescent images of the entire area of the microwell array were captured, and the numbers of tumor cells were measured (solid circles). For PC-14, H69, and SBC-3, a further staining protocol, using Alexa Fluor 488 conjugated secondary antibody, was applied for amplification of the weak CK signal (diamonds). The circles and diamonds represent individual data points. The straight lines are the linear fittings, with their slopes and correlation coefficients (R²) given on the plots. Dotted lines represent the function y = x. The plots of spiked tumor cell numbers from 0 to 100 are magnified for easier viewing (logarithmic axes).</p

Typical Examples of Captured Images of Tumor Cells and White Blood Cells in the Spike-in Experiments.

<p>Pictured are tumor cell-enriched mononucleated cells after immunofluorescent staining with DAPI, CK-FITC, or CD45-PE. Fluorescent images of the respective wavelengths (for DAPI, FITC, and PE) over the entire area of the microwell array were captured. Tumor cells were defined according to the criteria DAPI+ and CK+ and CD45–, while the white blood cells were defined as DAPI+ and CK–and CD45+. (a) An example of captured images of a tumor cell and white blood cells in the spike-in experiments. The SK-BR-3 cell line was spiked into blood, followed by serial procedures. The cell indicated by the solid arrow was defined as a tumor cell, while those indicated by dotted arrows were defined as white blood cells. The images were captured with a 10× objective lens. (b) An example of captured images of debris and white blood cells in the spike-in experiments. Bright-field image cells with black filling (solid arrow) were defined as debris, while the dotted-arrowed cells were defined as white blood cells. The images were captured with a 4× objective lens.</p

Features of the Cell Entrapment Chamber Utilizing Dielectrophoresis (DEP).

<p>(a) The suspension containing target cells is introduced into the space between the upper and lower electrode substrates. The electric field generated between the upper electrode and the lower electrode exposed on the bottom surface of each microwell shows non-uniformity in this configuration, with the result that a DEP force is exerted on the cells. The DEP force exerted on a cell is proportional to the volume of the cell, as noted in the Material and Methods section; thus, relatively larger CTCs (radius = R) are preferentially entrapped into the microwells, compared with smaller white blood cells (radius = r). (b) The microwell array fabricated on the plane ITO electrode. The center-to-center distance between microwells is 50 μm. The Cr light-shielding film is sheeted beneath the entire area of the photoresist, with the exception of the microwell regions. (c) The cell entrapment chamber, consisting of the microwell array substrate and another glass substrate coated with ITO thin film, with an open space between them which includes a silicon rubber sheet spacer of thickness 1 mm (thus the distance between the pair of electrodes is 1 mm), and with roughly 300,000 microwells opening onto the space, enables the accommodation of roughly 800 μL of cell-containing suspension in the open space.</p

Comparative Detection Data from the Spike-in Experiments using Tumor Cell Lines (our System vs. the CellSearch System).

<p>Footnote: CV: coefficient of variation.</p><p>Comparative Detection Data from the Spike-in Experiments using Tumor Cell Lines (our System vs. the CellSearch System).</p