[Determination of Trace Boron Based on Gold Nanorod Plasmonic Resonance Rayleigh Scattering Energy Transfer to the Coordinate].

B is a necessary trace element for human and animals, but the excess intake of B caused poison. Thus, it is very important to determination of B in foods and water. The target of this study is development of a new, sensitive and selective resonance Rayleigh scattering energy transfer (RRS-ET) for the determination of B. The combination of energy transfer with resonance Rayleigh scattering (RRS) has developed a new technology called RRS-ET, which can realize selective and sensitive detection of boric acid. The gold nanorods in diameter of 12 nm and length of 37 nm were prepared by the seed growth procedure. In pH 5. 6 NH4 Ac-HAc buffer solution and in the presence of azomethine-H (AMH), the gold nanorod particles exhibited a strong resonance Rayleigh scattering (RRS) peak at 404 nm. In the presence of boric acid, it reacts with AMH to form AMH-boric acid (AMH-B) complexes. When the complexe as a receptor close to the gold nanorod as a donor, the resonance Rayleigh scattering energy transfer (RRS-ET) take placed that resulted in the Rayleigh scattering signal quenching. With the increase of the concentration of boric acid, the formed complexes increased, the scattering light energy of gold nanorod transfer to the complexes increased, resulting in the Rayleigh scattering intensity linearly reduced at 404 nrn. The decreased RRS intensity responds linearly to the concentration of boron over 10~750 ng . mL-1 B, with a regress equation of ΔI404 nm =3. 53c+24 and a detection of 5 ng mL-1 B. The influence of coexistence substances on the RRS-ET determination of 2. 3 X 10(-7) mol . L-1 B was considered in details. Results showed that this new RRS-ET method is of high selectivity, that is, 4 X 10(-4) mol . L-1 Mn2+, Cd2+, Zn2+, Bi+, Na+, Al3+, glucose, Hg2+, IO3-, F-, SO(2-)3, SiO3-, NO3-, CIO4-, H2O2, mannitol, glycerol, and ethylene glycol, 4X 10(-5) mol . L-1 L-tyrosine, and 2 X 10(-4) mol . L-1 L-glutamic acid do not interfere with the determination. Based on this, a new sensitive, selective, simple and rapid RRS-ET method has been developed for the determination of trace boron in six mineral water samples that contain 24. 9, 29. 3, 57. 9, 59. 0, 84. 9, and 105. 1 ng . mL-1 B, with relative standard deviation of 1. 6%~ 4. 1% and recovery of 95. 61~9. 6%.

Highly sensitive fluorescence and SERS detection of azide through a simple click reaction of 8-chloroquinoline and phenylacetylene.

In 0.19 mol/L acetic acid (HAc), a click reaction of 8-chloroquinoline/azide/phenylacetylene take places in aqueous solution without Cu(I) as a catalyst. 8-Chloroquinoline (CQN) exhibited a strong fluorescence peak at 430 nm that was quenched linearly as the concentration of azide increased from 20 to 1000 ng/mL. This quenching was due to consumption of CQN in the click reaction and a decrease in the number of efficiently excited photons due to the presence of triazole-quinoline ramification molecules with strong hydrophobicity. Using blue nanosilver sol as the substrate, CQN absorbed onto the surface of nanosilver particles, showing a strong surface-enhanced Raman scattering (SERS) peak at 1585 cm(-1) that decreased linearly as the azide concentration increased from 8 to 500 ng/mL; the detection limit was 4 ng/mL. Thus, two new, simple and sensitive fluorescence and SERS methods have been developed for the determination of azide via the click reaction.

First and second generation γ-secretase modulators (GSMs) modulate amyloid-ß (Aß) peptide production through different mechanisms.

γ-Secretase-mediated cleavage of amyloid precursor protein (APP) results in the production of Alzheimer disease-related amyloid-ß (Aß) peptides. The Aß42 peptide in particular plays a pivotal role in Alzheimer disease pathogenesis and represents a major drug target. Several γ-secretase modulators (GSMs), such as the nonsteroidal anti-inflammatory drugs (R)-flurbiprofen and sulindac sulfide, have been suggested to modulate the Alzheimer-related Aß production by targeting the APP. Here, we describe novel GSMs that are selective for Aß modulation and do not impair processing of Notch, EphB2, or EphA4. The GSMs modulate Aß both in cell and cell-free systems as well as lower amyloidogenic Aß42 levels in the mouse brain. Both radioligand binding and cellular cross-competition experiments reveal a competitive relationship between the AstraZeneca (AZ) GSMs and the established second generation GSM, E2012, but a noncompetitive interaction between AZ GSMs and the first generation GSMs (R)-flurbiprofen and sulindac sulfide. The binding of a (3)H-labeled AZ GSM analog does not co-localize with APP but overlaps anatomically with a γ-secretase targeting inhibitor in rodent brains. Combined, these data provide compelling evidence of a growing class of in vivo active GSMs, which are selective for Aß modulation and have a different mechanism of action compared with the original class of GSMs described.

A highly sensitive resonance scattering spectral assay for carcinoembryonic antigen using immunonanogold as probe and nanocatalyst of NH2(OH-Cu(II) particle reaction.

Nanogold of 10 nm was used to label carcinoembryonic antigen antibody (CEAAb) to prepare a probe (Au-CEAAb) for carcinoembryonic antigen (CEA). In a Na2HPO4-NaH2PO4 buffer solution of pH 6.8, CEA reacted with Au-CEAAb to form a big Au-CEAAb-CEA immunocomplex that can be removed by centrifugation. The unreacted Au-CEAAb in the centrifugal supernatant exhibited catalytic effect on the Cu2O particle reaction, and the Cu2O particles displayed a resonance scattering (RS) peak at 602 nm. When CEA increased, the RS intensity at 602 nm decreased, and the decreased RS intensity (ΔI (602 nm)) was linear to CEA concentration (C (CEA)) in the range of 0.02-12 ng mL(-1), with the regression equation of ΔI (602 nm) = 27.1 C (CEA) + 3.3, correlation coefficient of 0.9978 and detection limit of 3 pg mL(-1) CEA. The proposed method was applied to detect CEA in real samples, with satisfactory results.

[Resonance scattering spectral detection of trace K+ by aptamer-modified nanogold probe].

In pH 7.0 Na2HPO4-NaH2PO4 buffer solution, nanogold particles interacted with the aptamer to form a stable aptamer-nanogold complex that was not aggregation by NaCl. At 80 degrees C, K+ and aptamer folded to form a stable G-quadruplex that released nanogold particles, the uncombined nanogold particles aggregated to large nanogold clusters that caused the increase in resonance scattering (RS) intensity at 563 nm in high concentration of NaCl, and the laser scattering showed that the average diameter was 120 nm. In the present paper, the resonance scattering spectral characteristics of K+ -ssDNA1-Au, K+ -ssDNA2-Au and K+ -aptamer-Au systems were investigated, and the structural changes of aptamer were studied by circular dichroism spectral technology. Effects of pH value, NaCl concentration, nanogold concentration, aptamer concentration, and the reactation temperature and time on the resonance scattering intensity were considered in detail. The influence of coexistent substances on the determination of K+ was investigated, result showed that the common heavy metal ions such as Cu2+, Mg2+, Pb2+, Ca2+, Al3+, Zn2+ and Fe3+ do not interfere with the determination, and the method has good selectivity. Under the conditions selected, a 0. 67-3 350 micromol x L(-1) K+ can be detected by the aptamer-nanogold RS assay, with a detection limit of 0.3 micromol x L(-1) K+, regression equation deltaI = 0.167c-0.7, and a coefficient of 0.9932. The method was used for analysis of K+ in serum sample with the results consistent with the ion-selective electrode method.

Synthesis and antibacterial activity of the C-7 side chain of 3-aminoquinazolinediones.

A novel series of bacterial topoisomerase (3-aminoquinazolinediones) inhibitors are described. The side-chain SAR against Gram-positive and Gram-negative organisms as well as DNA gyrase activity is reported.

Discovery of 6-ethyl-2,4-diaminopyrimidine-based small molecule renin inhibitors.

Novel 2,4-diaminopyrimidine-based small molecule renin inhibitors are disclosed. Through high throughput screening, parallel synthesis, X-ray crystallography, and structure based drug design, we have developed the first non-chiral, non-peptidic, small molecular template to possess moderate potency against renin. The designed compounds consist of a novel 6-ethyl-5-(1,2,3,4-tetrahydroquinolin-7-yl)pyrimidine-2,4-diamine ring system that exhibit moderate potency (IC(50): 91-650 nM) against renin while remaining 'Rule-of-five' compliant.

Ketopiperazine-based renin inhibitors: optimization of the "C" ring.

A systematic investigation of the S3 sub-pocket activity requirements was conducted. It was observed that linear and sterically small side chain substituents are preferred in the S3 sub-pocket for optimal renin inhibition. Polar groups in the S3-sub-pocket were not well tolerated and caused a reduction in renin inhibitory activity. Further, compounds with clog P's < or = 3 demonstrated a dramatic reduction in CYP3A4 inhibitory activity.

Spectral properties of the association nanoparticle system of ciprofloxacin-phloxine and its application to fluorescence analysis.

There is a fluorescence peak at 570 nm, and a maximum absorption peak at 560 nm for phloxine (PHLO) in a pH 7 water solution. Under these conditions, the ciprofloxacin cation (CPFX+) and PHLO- combine into hydrophobic CPFX-PHLO association molecule by means of static gravitation. There are stronger van der Waals forces and hydrophobic forces among the CPFX-PHLO molecules. Thus, they aggregate automatically to the (CPFX-PHLO)n association nanoparticle in red-violet color. That was characterized by scan electron microscopy (SEM), hyperfiltration and dialysis tests. In 0.04 M HCl, the red-violet nanoparticles exhibited a Rayleigh scattering peak at 470 nm, a resonance scattering peak at 580 nm, a maximum absorption wavelength at 565 nm, and a fluorescence peak at 450 nm. The fluorescence analytical conditions of CPFX have been considered. The CPFX concentration in the range of 1.0 x 10(-6)-4.0 x 10(-5) M is linear to the fluorescence intensity, F450nm. The detection limit was achieved at 4.0 x 10(-7) M CPFX. The CPFX in real samples was determined with satisfactory results.