Headspace-programmed temperature vaporization-mass spectrometry for the rapid determination of possible volatile biomarkers of lung cancer in urine

Abstract

We propose a new method for the rapid determination of five volatile compounds described in the literature as possible biomarkers of lung cancer in urine samples. The method is based on the coupling of a headspace sampler, a programmed temperature vaporizer in solvent-vent injection mode, and a mass spectrometer (HS-PTV-MS). This configuration is known as an electronic nose based on mass spectrometry. Once the method was developed, it was used for the analysis of urine samples from lung cancer patients and healthy individuals. Multivariate calibration models were employed to quantify the biomarker concentrations in the samples. The detection limits ranged between 0.16 and 21 μg/L. For the assignment of the samples to the patient group or the healthy individuals, the Wilcoxon signed-rank test was used, comparing the concentrations obtained with the median of a reference set of healthy individuals. To date, this is the first time that multivariate calibration and non-parametric methods have been combined to classify biological samples from profile signals obtained with an electronic nose. When significant differences in the concentration of one or more biomarkers were found with respect to the reference set, the sample is considered as a positive one and a new analysis was performed using a chromatographic method (HS-PTV-GC/MS) to confirm the result. The main advantage of the proposed HS-PTV-MS methodology is that no prior chromatographic separation and no sample manipulation are required, which allows an increase of the number of samples analyzed per hour and restricts the use of time-consuming techniques to only when necessary.

Graphical abstract

Schematic diagram of the developed methodology

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Ángela Molina and Joaquín GonzáIez: Pulse voltammetry in physical electrochemistry and electroanalysis: theory and applications

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Improved electrochemiluminescence labels for heterogeneous microbead immunoassay

Abstract

Ruthenium(II) complexes with carboxylic acid as a bioconjugatable group, i.e., [Ru(bathophenanthroline disulfonate)(2,2′-bipyridine)(4-methyl-4′-(3-carboxypropyl)-2,2′-bipyridine)]⁰, (C₄₉H₃₈N₆O₈S₂Ru), and [Ru(bathophenanthroline disulfonate)₂(4-methyl-4′-(3-carboxypropyl)-2,2′-bipyridine)]²⁻ · 2Na⁺, (C₆₃H₄₄N₆O₁₄S₄RuNa₂) were characterized spectroscopically and electrochemically. As potential labels for electrochemiluminescence (ECL) immunoassays, the ECL intensities of the free labels in homogenous aqueous buffer solutions were compared under a condition that is similar to the one employed by a commercial clinical immunoassay system. The two labels were found to be more emissive and, thus, can be detected at 10^{- 12} pM compared with 5× 10⁻¹² pM of the label currently used in the commercial ECL system. Furthermore, the improved ECL emission of the free labels in homogenous solutions was proven to be translated into more intense ECL signal in heterogeneous sandwich immunoassay and, thus, leading to a lower limit of detection in immunoassay. The data obtained from these ECL labels shed light on the further development of ECL-based clinical immunoassay technology.

Graphical abstract

Electrochemiluminescence immunoassays were carried out with three different ruthenium(II) complex labels. It was proved that the higher signal intensities found with the novel labels in homogeneous solutions were maintained in heterogeneous sandwich format.

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Determination of phthalate esters at trace level from environmental water samples by magnetic solid-phase extraction with Fe@SiO 2 @polyethyleneimine magnetic nanoparticles as adsorbent prior to high-performance liquid chromatography

Abstract

In this work, polyethyleneimine grafted silica-coated nanoscale zero valent iron (Fe@SiO₂@PEI) has been successfully synthesized and was investigated to be an effective adsorbent for efficient enrichment of five phthalate esters such as diphenyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, diphenyl isophthalate, and dicyclohexyl phthalate (DPP, DBP, BBP, DPIP, and DCHP) from environmental water samples. The structure and morphology of the materials were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction(XRD). The parameters that influenced the enrichment performance such as amount of sorbent, sample pH, type of eluent, volume of eluent, salting-out effect, adsorption time, and desorption time were investigated. Under optimal conditions, excellent linear relationships were found in the concentration range from 0.5 to 100 μg L⁻¹, the limits of detection (S/N = 3) were in the range of 0.26–0.45 μg L⁻¹, and the intra-day and inter-day precisions (n = 6) were in the range of 3.7–4.8 and 3.2–4.3 %, respectively. The developed method was evaluated with real water samples, and satisfied spiked recoveries in the range of 99–104 % were achieved. The experimental results proved that Fe@SiO₂@PEI had good adsorption for phthalate esters, and would be a good adsorbent for the magnetic solid-phase extraction of important pollutants from environmental water samples.

ᅟ Graphical abstract

A flowchart of the synthesis of polyethyleneimine grafted silica coated nanoscale zero valent iron (Fe@SiO₂@PEI) and the process of the developed magnetic solid phase extraction of phthalate esters before the analysis by high performance liquid chromatography

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Structural analysis of the activation-induced deoxycytidine deaminase required in immunoglobulin diversification

Publication date: Available online 13 May 2016
Source:DNA Repair
Author(s): Phuong Pham, Samir A. Afif, Mayuko Shimoda, Kazuhiko Maeda, Nobuo Sakaguchi, Lars C. Pedersen, Myron F. Goodman
Activation-induced deoxycytidine deaminase (AID) initiates somatic hypermutation (SHM) and class-switch recombination (CSR) by deaminating C→U during transcription of Ig-variable (V) and Ig-switch (S) region DNA, which is essential to produce high-affinity antibodies. Here we report the crystal structure of a soluble human AID variant at 2.8Å resolution that favors targeting WRC motifs (W=A/T, R=A/G) in vitro, and executes Ig V SHM in Ramos B-cells. A specificity loop extending away from the active site to accommodate two purine bases next to C, differs significantly in sequence, length, and conformation from APOBEC proteins Apo3A and Apo3G, which strongly favor pyrimidines at −1 and −2 positions. Individual amino acid contributions to specificity and processivity were measured in relation to a proposed ssDNA binding cleft. This study provides a structural basis for residue contributions to DNA scanning properties unique to AID, and for disease mutations in human HIGM-2 syndrome.



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Sensors, Vol. 16, Pages 700: Extracting Objects for Aerial Manipulation on UAVs Using Low Cost Stereo Sensors

Giving unmanned aerial vehicles (UAVs) the possibility to manipulate objects vastly extends the range of possible applications. This applies to rotary wing UAVs in particular, where their capability of hovering enables a suitable position for in-flight manipulation. Their manipulation skills must be suitable for primarily natural, partially known environments, where UAVs mostly operate. We have developed an on-board object extraction method that calculates information necessary for autonomous grasping of objects, without the need to provide the model of the object's shape. A local map of the work-zone is generated using depth information, where object candidates are extracted by detecting areas different to our floor model. Their image projections are then evaluated using support vector machine (SVM) classification to recognize specific objects or reject bad candidates. Our method builds a sparse cloud representation of each object and calculates the object's centroid and the dominant axis. This information is then passed to a grasping module. Our method works under the assumption that objects are static and not clustered, have visual features and the floor shape of the work-zone area is known. We used low cost cameras for creating depth information that cause noisy point clouds, but our method has proved robust enough to process this data and return accurate results.

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Molecules, Vol. 21, Pages 647: Broadband Two-Photon Absorption Characteristics of Highly Photostable Fluorenyl-Dicyanoethylenylated [60]Fullerene Dyads

We synthesized four C60-(light-harvesting antenna) dyads C60 (>CPAF-Cn) (n = 4, 9, 12, or 18) 1-Cn for the investigation of their broadband nonlinear absorption effect. Since we have previously demonstrated their high function as two-photon absorption (2PA) materials at 1000 nm, a different 2PA wavelength of 780 nm was applied in the study. The combined data taken at two different wavelength ranges substantiated the broadband characteristics of 1-Cn. We proposed that the observed broadband absorptions may be attributed by a partial π-conjugation between the C60 > cage and CPAF-Cn moieties, via endinitrile tautomeric resonance, giving a resonance state with enhanced molecular conjugation. This transient state could increase its 2PA and excited-state absorption at 800 nm. In addition, a trend of concentration-dependent 2PA cross-section (σ2 ) and excited-state absorption magnitude was detected showing a higher σ value at a lower concentration that was correlated to increasing molecular separation with less aggregation for dyads C60(>CPAF-C18) and C60(>CPAF-C9), as better 2PA and excited-state absorbers.

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