Evaluation of peroxidative stress of cancer cells in vitro by real-time quantification of volatile aldehydes in culture headspace

Exhaled Aldehydes as Biomarkers for Lung Diseases: A Narrative Review

Breath analysis provides great potential as a fast and non-invasive diagnostic tool for several diseases. Straight-chain aliphatic aldehydes were repeatedly detected in the breath of patients suffering from lung diseases using a variety of methods, such as mass spectrometry, ion mobility spectrometry, or electro-chemical sensors. Several studies found increased concentrations of exhaled aldehydes in patients suffering from lung cancer, inflammatory and infectious lung diseases, and mechanical lung injury. This article reviews the origin of exhaled straight-chain aliphatic aldehydes, available detection methods, and studies that found increased aldehyde exhalation in lung diseases.

Headspace analysis of mesothelioma cell lines differentiates biphasic and epithelioid sub-types

Malignant mesothelioma (MM) is an incurable cancer. MM is often misdiagnosed, with a poor 5-year survival and limited treatment options. The discovery of endogenous volatile organic compounds (VOCs) is required in order to accelerate the development of a breath test as an alternative to conventional MM diagnosis. For the first time, this study used solid-phase microextraction and gas chromatography-mass spectrometry to identify VOCs released directly from the biphasic MM cell line MSTO-211H and the epithelioid MM cell line NCI-H28 as well as the non-malignant mesothelial cell line MET-5A. Multivariate statistical analysis showed separation between MSTO-211H, NCI-H28 and MET-5A results. 2-ethyl-1-hexanol was significantly increased in both MSTO-211H and NCI-H28 cells compared to MET-5A controls. In addition, ethyl propionate and cyclohexanol were significantly increased in MSTO-211H cells and dodecane was significantly increased in NCI-H28 cells. This is the first study reporting headspace analysis of these MM cell lines and the first to consider the effects of mesothelioma sub-type on VOC profile. Current results further highlight the potential for a diagnostic mesothelioma breath test as well as providing proof of concept for the differentiation between biphasic and epithelioid mesothelioma based on VOC profiles.

Dynamic headspace analysis using online measurements: Modeling of average and initial concentration

Dynamic headspace sampling is an important technique for the analysis of consumer products, the study of biological samples and environmental water analyses. This paper shows the influence of experimental conditions, such as the sampling time, sampling flow rate, headspace volume, liquid volume and Henry coefficient on the measured average concentration values. A corresponding closed expression as function of these variables is introduced in order to quantify the deviation of the initial headspace concentration. The proposed bi-exponential function embeds different current existing models for recovery calculation in dynamic sampling analyses in one single expression. A fully automated and user-friendly Excel^® file to investigate or to model the dynamic headspace sampling results is added to everyone's easy use.

Volatile aldehydes sensing in headspace using a room temperature ionic liquid-modified electrochemical microprobe

The cyclic voltammetric behaviour of propionaldehyde (PA) and hexanaldehyde (HA), in 1-butyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl) imide ([BMIM][NTF₂]), 1-butyl-3-methylimidazolium hydrogen sulphate ([BMIM][HSO₄]) and 1-butyl-3-methylimidazolium hydroxide ([BMIM][OH]) was investigated at a platinum microelectrode. A clear oxidation process for both aldehydes was recorded only in [BMIM][OH]. On the basis of these evidences, an electrochemical microprobe (EMP), incorporating [BMIM][OH] as electrolyte, was assembled for sensing these aldehydes in gaseous phases. The EMP exposed in the headspace of the liquid aldehydes displayed voltammetric and amperometric responses, which depended on the aldehyde vapour pressures and, consequently, on the temperature employed. The usefulness of the [BMIM][OH] coated EMP for practical applications was assessed in the detection of HA vapour released from squalene (i.e., a lipid simulant matrix) samples spiked with known amounts of the aldehyde. Calibration plots were constructed at 40 °C, 50 °C and 60 °C, using both voltammetry and chronoamperometry. In both cases, good linearity between current and HA concentration in squalene was obtained over the range 3-300 ppm, with correlation coefficients higher than 0.991. Reproducibility, evaluated from at least three replicates, was within 5%. Detection limits, evaluated for a signal-to-noise ratio of 3, were in any case lower than 1.7 ppm. These analytical performances are suitable for monitoring VAs coming from lipid oxidation processes in food. An application concerning the determination of VAs in headspace of sunflower oil during an induced oxidative test to establish its thermal stability was also performed.

Volatile metabonomic profiling in urine to detect novel biomarkers for B-cell non-Hodgkin's lymphoma

To date, there have been a limited number of useful biomarkers for the screening and monitoring of B-cell non-Hodgkin's lymphoma (B-NHL), which leads to the impetus to discover novel biomarkers for the disease. In the present study, gas chromatography-mass spectrometry (GC-MS) combined with head-space solid-phase micro-extraction (HS-SPME) was employed to analyze the volatile metabolites in the urine samples of 131 subjects. The subjects were divided into 4 main groups: Aggressive B-NHL, indolent B-NHL, benign lymphatic diseases patients and healthy volunteers. The differences of the concentrations of the potential biomarkers among the groups were assessed by non-parametric Wilcoxon's test. The ability of the potential biomarkers to discriminate between the four aforementioned groups was evaluated by receiver operating characteristic curves (ROC). The present study indicated that 4-heptanone, 2-methylpyrazine, 2-methylbutanal, 2,6-dimethyl-7-octen-2-ol and decanoic acid may serve as potential biomarkers for B-NHL. The area under the curve (AUC) values of single potential biomarker ranged from 0.634 to 0.901. The diagnostic models established with combined biomarkers exhibited higher diagnostic values (AUC, 0.824–0.968) compared with the models established with single biomarkers. The present study indicated that urinary volatile metabolites might be potential biomarkers for screening and monitoring of B-NHL.