Polymer Composites with Plasmonic Metal Nanoparticles

Summary: A two-phase method has been adapted for the preparation of polymer composites consisting of regioregular poly(3-octylthiophene-2,5-diyl) and Au or Ag nanoparticles. This work compares optical and morphological properties of nanocomposites formed by mixing metal organosols and polymer solution (type I composites) with nanocomposites formed by in-situ reduction in polymer solutions (type II composites). Both types contained very small metal nanoparticles (1–10 nm). Interestingly, more than ten-fold enhancement of Raman scattering of the polymer by the electromagnetic (EM) mechanism of SERS (surface-enhanced Raman scattering) resulted from the coupling of the polymer with plasmonic Au nanoparticles into a nanocomposite system.     

Metabolomics Based on MS in Mice with Diet-Induced Obesity and Type 2 Diabetes Mellitus: the Effect of Vildagliptin,Metformin, and Their Combination

Applied Biochemistry and Biotechnology - Type 2 diabetes mellitus (T2DM) is a major epidemiological problem. Metformin and vildagliptin are well-established antidiabetic drugs. The aim of the study...     

Adsorbate-induced silver nanoparticle aggregation kinetics

Metal sols are often stabilized in solution by the presence of a charged double layer surrounding each colloidal nanoparticle that produces a coulomb barrier to aggregation. The nanoparticles can be induced to aggregate by replacing the charged surface species by uncharged adsorbate. We present a simple analysis that produces an expression for the initial rate constant describing the aggregation process, which is shown to depend nontrivially on the adsorbate concentration. The expression is tested experimentally by following and analyzing the time rate of decrease of the surface plasmon resonance absorption of isolated Ag nanoparticles in aqueous solution. The experimental result accords well with theory, producing a rough estimate of the (adsorbate-concentration dependent) barrier to aggregation that in the absence of added adsorbate is approximately equal to 0.08 eV.     

Synthesis and Cytotoxic and Antiviral Activity Profiling of All-Four Isomeric Series of Pyrido-Fused 7-Deazapurine Ribonucleosides

All four isomeric series of novel 4-substituted pyrido-fused 7-deazapurine ribonucleosides possessing the pyridine nitrogen atom at different positions were designed and synthesized. The total synthesis of each isomeric fused heterocycle through multistep heterocyclization was followed by glycosylation and derivatization at position 4 by cross-coupling reactions or nucleophilic substitutions. All compounds were tested for cytostatic and antiviral activity. The most active were pyrido[4′,3′:4,5]pyrimidine nucleosides bearing MeO, NH₂, MeS, or CH₃ groups at position 4, which showed submicromolar cytotoxic effects and good selectivity for cancer cells. The mechanism involved activation by phosphorylation and incorporation to DNA where the presence of the modified ribonucleosides causes double-strand breaks and apoptosis.     

Oscillation theorems for second-order superlinear neutral differential equations

The purpose of this paper is to investigate the oscillation of the second-order neutral differential equations of the form (E) $$ (r(t)|z'(t)|^{\alpha - 1} z'(t))' + q(t)|x(\sigma (t))|^{\alpha - 1} x(\sigma (t)) = 0, $$ where z(t) = x(t) + p(t)x(τ(t)). The obtained comparison principles essentially simplify the examination of the studied equations. Further, our results extend and improve the results in the literature.     

Rapid determinations of saccharides in high-energy drinks by short-capillary electrophoresis with contactless conductivity detection

The methodology for separations of saccharides in standard electrophoretic systems has been transferred to the short-capillary electrophoresis format. The laboratory-designed apparatus used employs a quartz capillary with an internal diameter of 10 μm, a total length of 10 cm, and an effective length of 4 cm, in combination with contactless conductivity detection. It has been applied to separations of neutral mono- and disaccharides. The saccharides are separated in the anionic form, in solutions of alkali hydroxides, namely, KOH, NaOH, and LiOH. The separation of a model mixture of five saccharides (sucrose, lactose, glucose, fructose, and ribose) takes less than 1 min, the LOD equaling 15, 35, 19, 17, and 24 mg L(-1) and the LOQ equaling 52, 117, 63, 53, and 79 mg L(-1) for sucrose, lactose, glucose, fructose, and ribose, respectively. The technique developed has been used to determine sucrose, glucose and fructose in high-energy drinks. The separation is finished within less than 50 s; the saccharide contents determined are identical with the declared values within the reliability interval in most cases, the RSD value being mostly less than 2%. In general, the separation system developed is very convenient for rapid analyses of large sets of similar samples, e.g., in product quality control or environmental monitoring.