Light‐Harvesting Nanoparticle Probes for FRET‐Based Detection of Oligonucleotides with Single‐Molecule Sensitivity

Controlling the emission of bright luminescent nanoparticles by a single molecular recognition event remains a challenge in the design of ultrasensitive probes for biomolecules. Herein, we developed 20‐nm light‐harvesting nanoantenna particles, built of a tailor‐made hydrophobic charged polymer poly(ethyl methacrylate‐co‐methacrylic acid), encapsulating circa 1000 strongly coupled and highly emissive rhodamine dyes with their bulky counterion. Being 87‐fold brighter than quantum dots QDots 605 in single‐particle microscopy (with 550‐nm excitation), these DNA‐functionalized nanoparticles exhibit over 50 % total FRET efficiency to a single hybridized FRET acceptor, a highly photostable dye (ATTO665), leading to circa 250‐fold signal amplification. The obtained FRET nanoprobes enable single‐molecule detection of short DNA and RNA sequences, encoding a cancer marker (survivin), and imaging single hybridization events by an epi‐fluorescence microscope with ultralow excitation irradiance close to that of ambient sunlight.     

Analysis of hemoglobin adducts of acrylamide and glycidamide by liquid chromatography-electrospray ionization tandem mass spectrometry, as exposure biomarkers in French population

The determination of biomarkers of acrylamide exposure in humans from general French population by measurement of hemoglobin adduct levels of acrylamide (AA) and glycidamide (GA) is presented. The analytical procedure included modified Edman degradation and LC-ESI-MS/MS analysis of the final derivatives using deuterated internal standards. Method performances were evaluated in terms of linearity, precision, accuracy, and sensitivity. The method was firstly assessed on rat blood samples and then applied to the study of background adducts levels of AA and GA in 68 human hemoglobin samples, showing mean levels of 33 and 23 pmol/g globin for AA and GA adducts, respectively.     

Total synthesis of two natural phenanthrenes: confusarin and a regioisomer

The title compounds were synthesized by radical cyclization of the corresponding stilbenes intermediates. The latter ones arose from a Wittig reaction in a stereoselective manner (Z isomer is either the only one or the major one). Confusarin (1) was prepared in 13 steps from gallic acid. Its regioisomer (2) was obtained in five steps from syringaldehyde.     

Plane overpartitions and cylindric partitions

Generating functions for plane overpartitions are obtained using various methods such as nonintersecting paths, RSK type algorithms and symmetric functions. We extend some of the generating functions to cylindric partitions. Also, we show that plane overpartitions correspond to certain domino tilings and we give some basic properties of this correspondence.     

Quasi-stationary distributions for structured birth and death processes with mutations

We study the probabilistic evolution of a birth and death continuous time measure-valued process with mutations and ecological interactions. The individuals are characterized by (phenotypic) traits that take values in a compact metric space. Each individual can die or generate a new individual. The birth and death rates may depend on the environment through the action of the whole population. The offspring can have the same trait or can mutate to a randomly distributed trait. We assume that the population will be extinct almost surely. Our goal is the study, in this infinite dimensional framework, of the quasi-stationary distributions of the process conditioned on non-extinction. We first show the existence of quasi-stationary distributions. This result is based on an abstract theorem proving the existence of finite eigenmeasures for some positive operators. We then consider a population with constant birth and death rates per individual and prove that there exists a unique quasi-stationary distribution with maximal exponential decay rate. The proof of uniqueness is based on an absolute continuity property with respect to a reference measure.     

A one-pot synthesis of 7-phenylindolo[3,2-a]carbazoles from indoles and β-nitrostyrenes, via an unprecedented reaction sequence

A six-step one-pot reaction was designed for synthesizing homodimeric 7-phenylindolo[3,2-a]carbazoles from 1H-indoles and β-nitrostyrenes, in the presence of SnCl(2)·2H(2)O. The reactions proceeded under very mild conditions and the desired heterocycles were obtained in moderate to good yields. An unprecedented mechanism involving sequential indole dimerization, regioselective nucleophilic conjugate addition of the resulting 2,3'-biindole to β-nitrostyrene and formal intramolecular [4 + 2]-cycloaddition is proposed.     

From tectons to luminescent supramolecular ionic liquid crystals

New phosphorescent and room-temperature liquid-crystalline materials were obtained by combining dicyanometallate anions with dicationic bisamidinium based tectons bearing four peripheral lipophilic pyrogallate moieties.     

Capillary zone electrophoresis and capillary electrophoresis-mass spectrometry for analyzing qualitative and quantitative variations in therapeutic albumin

The present study describes a reproducible and quantitative capillary zone electrophoresis (CZE) method, which leads to the separation of nine forms (native, oxidized and glycated) of human serum albumin (HSA). In an attempt to identify the different species separated by this CZE method, the capillary electrophoresis was coupled to mass spectrometry using a sheath liquid interface, an optimized capillary coating and a suitable CE running buffer. CE-MS analyses confirmed the heterogeneity of albumin preparation and revealed new truncated and modified forms such as Advanced Glycation End products (AGEs). Assignment of the CZE peaks was carried out using specific antibodies, carboxypeptidase A or sample reduction before or during the CE separation. Thus, five HSA forms were unambiguously identified. Using this CZE method several albumin batches produced by slightly different fractionation ways could be discriminated. Furthermore, analyses of HSA preparations marketed by five pharmaceutical industries revealed that two therapeutic albumins, including that marketed by LFB, contained the highest proportion of native form and lower levels of oxidized forms.     

Separation of Lactoferrin from Human Saliva Using Monolithic Disc

In this study, we optimized method for the isolation and detection of lactoferrin from human saliva using 3 mm short monolithic disc. We optimized the conditions for separation as flow rate 4 mL min^?1 and ionic strength of effluent as 2 M·NaCl. We estimated limit of detection of whole method, which was hyphenated to the Bradford’s assay, down to 100 ng mL^?1. The purity of the isolated fractions was verified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and recovery of isolation was found to be 51 % using minimally processed sample of saliva. Further, we tested the optimized method on group of healthy volunteers (n = 7). We were able to distinguish between the healthy subjects and subject suffering from celiac disease, which reported at least 2.5× higher level of lactoferrin in comparison to healthy ones. The results were correlated with standard enzyme-linked immunosorbent assay (ELISA) kit with obtained correlation coefficient R ² = 0.8446. Analysis of lactoferrin in saliva by monolithic disc and subsequent offline photometric detection is faster and cheaper method compared to ELISA commercial kit. The total analysis of one sample takes <20 min.     

Facile Oxime Ether Synthesis: Free Carbonyl Compound Derivatization by a Brominated O-Benzylhydroxylamine

The lipid peroxidation of fatty acids leads to secondary products, among which several carbonyl compounds are of concern in food toxicology. The detection of these reactive aldehydes for identification and evaluation is required. Derivatization is necessary to improve their stability and detection in liquid chromatography/high-resolution mass spectrometry (LC/HRMS) trace analyses. Therefore, a brominated O-benzylhydroxylamine, namely 1-((ammoniooxy)methyl)-2-bromobenzene chloride, was selected as a new probe for the mild and selective derivatization of carbonyl compounds. New oxime ethers were thus synthesized under mild reaction and workup conditions, with full analytical characterization. The relevance of the chemical reaction was assessed with nine aldehydes, especially conjugated and deuterium-labeled aldehydes, and two ketones. Virtually, the reaction should be applicable to a large set of carbonyl compounds for derivatization in complex biological samples and selective detection of the in situ–synthesized brominated oxime ethers by LC/HRMS methodology.