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Exploring Triple-isotopic Signatures of Water in Human Exhaled Breath, Gastric Fluid and Drinking Water Using Integrated Cavity Output Spectroscopy
摘要： Water, the major body fluid in humans, has four main naturally occurring isotopologues, H2 16O, H2 17O, H2 18O and H2H16O (i.e. HD16O) with different masses. The underlying mechanisms of the isotope-specific water-metabolism in human gastrointestinal (GI) tract and respiratory system are largely unknown and remained illusive for several decades. Here, a new strategy has been demonstrated that provides the direct quantitative experimental evidences of triple-isotopic signatures of water-metabolism in human body in response to the individual’s water intake habit. The distribution of water isotopes have been monitored in drinking water (DW) (δD =-36.59±10.64‰ (SD), δ18O= -5.41±1.47‰ (SD) and δ17O= -2.92±0.79‰ (SD)), GI fluid (GF) (δD =-35.91±7.30‰ (SD), δ18O= -3.98±1.29‰ (SD) and δ17O= -2.37±0.57‰ (SD)) and human exhaled breath (EB) (δD =-119.63±7.27‰ (SD), δ18O= -13.69±1.23‰ (SD) and δ17O= -8.77±0.98‰ (SD)) using the laser-based off-axis integrated cavity output spectroscopy (OA-ICOS) technique. This study explored a new analytical method to disentangle the competing effects of isotopic fractionations of water during respiration in humans. In addition, our findings revealed that deuterium-enriched exhaled semi-heavy water, i.e. HD16O is a new marker of the non-invasive assessment of the ulcer-causing H. pylori gastric pathogen. We also clearly showed that the water-metabolism-derived triple-isotopic compositions due to impaired water absorption in GI tract can be used as unique tracers to track the onset of various GI dysfunctions. These findings are thus bringing a new analytical methodology for better understanding the isotope-selective water-metabolism that will have enormous applications in clinical testing purpose.
关键词： triple-isotopic signatures,human exhaled breath,integrated cavity output spectroscopy,drinking water,water-metabolism,gastric fluid
更新于2025-09-23 15:21:01
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Advances in Mid-Infrared Spectroscopy-Based Sensing Techniques for Exhaled Breath Diagnostics
摘要： Human exhaled breath consists of more than 3000 volatile organic compounds, many of which are relevant biomarkers for various diseases. Although gas chromatography has been the gold standard for volatile organic compound (VOC) detection in exhaled breath, recent developments in mid-infrared (MIR) laser spectroscopy have led to the promise of compact point-of-care (POC) optical instruments enabling even single breath diagnostics. In this review, we discuss the evolution of MIR sensing technologies with a special focus on photoacoustic spectroscopy, and its application in exhaled breath biomarker detection. While mid-infrared point-of-care instrumentation promises high sensitivity and inherent molecular selectivity, the lack of standardization of the various techniques has to be overcome for translating these techniques into more widespread real-time clinical use.
关键词： point-of-care (POC),infrared lasers,MIR,photoacoustic spectroscopy,biomarkers,exhaled breath analysis,non-invasive diagnostics,QCL,quantum cascade lasers,mid-infrared
更新于2025-09-23 15:21:01
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Nitric oxide sensors using nanospiral ZnO thin film deposited by GLAD for application to exhaled human breath
摘要： ZnO is a promising gas sensing material for its excellent gas sensing response characteristics and long-term stability. Moreover, the improvement in the sensitivity and response speed of ZnO gas sensors can be achieved by the nanostructure fabrication. This paper proposes a facile method to deposit ZnO nanospirals using glancing angle deposition (GLAD) for application in nitric oxide (NO) sensors. ZnO nanospirals with porous characteristics have larger relative surface area and more active surfaces, compared with dense ZnO thin film. A sensor using nanospiral ZnO film shows a response factor of 16.9 to 100 ppb NO at 150 °C in 40% RH, which is 3 times larger than that of the sensor using dense ZnO film. Such a ZnO nanospiral sensor system can detect NO as low as 10 ppb which is below the NO concentration (>30 ppb) in exhaled breath of patients with asthma. The effects of working temperature and humidity on the sensor performance were investigated systematically in this work. Moreover, the sensor response showed a good selectivity to NO and high stability as the time increased up to 24 days. NO gas sensing mechanism was discussed in detail and nanospiral ZnO film sensors are promisingly applicable for exhaled human breath application compared with some other NO sensors.
关键词： exhaled breath,nitric oxide,GLAD,nanospiral,gas sensor,ZnO
更新于2025-09-23 15:19:57
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Sensitive, selective and rapid ammonia-sensing by gold nanoparticle-sensitized V2O5/CuWO4 heterojunctions for exhaled breath analysis
摘要： Marigold flower-like V2O5/CuWO4 heterojunctions were synthesized and its volatile organic compound (VOC)-sensing properties were tested and significantly enhanced after sensitizing by Au nanoparticles. Detailed characterizations were carried out by SEM, XRD and XPS to determine the morphology, crystal structure, elemental and chemical composition of the sensing materials, respectively. The fabricated gold-sensitized sensor was found to be rapidly responsive (a few seconds), highly sensitive to ammonia with good selectivity as compared to various types of VOCs. The limit of detection and linear range of sensor at 150°C were 212 ppb and 5-158 ppm, respectively, which is suitable for detection of exhaled breath ammonia of patients at their last stage of chronic kidney disease. Furthermore, it was found to be of high intra-day repeatability, which is properly explained by discussing the mechanism of NH3 sensing. Very long-term stability of the sensor was investigated over 56 days, once a week.
关键词： Ammonia-sensing,chronic kidney disease,exhaled breath analysis,Au-sensitized V2O5/CuWO4 heterojunctions
更新于2025-09-19 17:13:59
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Near-infrared tunable diode laser absorption spectroscopy-based determination of carbon dioxide in human exhaled breath
摘要： A spectroscopic detection system for the accurate monitoring of carbon dioxide (CO2) in exhaled breath was realized by tunable diode laser absorption spectroscopy (TDLAS) in conjunction with a vertical-cavity surface-emitting laser (VCSEL) and a multipass cell with an effective optical path-length of 20 m. The VCSEL diode emitting light with an output power of 0.8 mW, covered the strong absorption line of CO2 at 6330.82 cm?1 by drive-current tuning. The minimum detectable concentration of 0.769% for CO2 detection was obtained, and a measurement precision of approximately 100 ppm was achieved with an integration time of 168 s. Real-time online measurements were carried out for the detection of CO2 expirograms from healthy subjects, different concentrations were obtained in dead space and alveolar gas. The exhaled CO2 increased significantly with the increasing physical activity, reaches its maximal value at the beginning of respiratory compensation and then decreased slightly until maximal exercise. The developed measurement system has a great potential to be applied in practice for the detection of pulmonary diseases associated with CO2 retention.
关键词： CO2,human health monitoring,Tunable diode laser absorption spectroscopy,carbon dioxide,VCSEL,exhaled breath,TDLAS,vertical-cavity surface-emitting laser
更新于2025-09-16 10:30:52
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Indium Nitrite (InN)-Based Ultrasensitive and Selective Ammonia Sensor Using an External Silicone Oil Filter for Medical Application
摘要： Ammonia is an essential biomarker for noninvasive diagnosis of liver malfunction. Therefore, selective detection of ammonia is essential for medical application. Here, we demonstrate a portable device to selectively detect sub-ppm ammonia gas. The presented gas sensor is composed of a Pt coating on top of an ultrathin Indium nitrite (InN) epilayer with a lower detection limit of 0.2 ppm, at operating temperature of 200 ?C, and detection time of 1 min. The sensor connected with the external ?lter of nonpolar 500 CS silicone oil to diagnose liver malfunction. The absorption of 0.7 ppm acetone and 0.4 ppm ammonia gas in 10 cc silicone oil is 80% (0.56 ppm) and 21.11% (0.084 ppm), respectively, with a ?ow rate of 10 cc/min at 25?C. The absorption of acetone gas is 6.66-fold higher as compared to ammonia gas. The percentage variation in response for 0.7 ppm ammonia and 0.7 ppm acetone with and without silicone oil on InN sensor is 17.5% and 4%, and 22.5%, and 14% respectively. Furthermore, the percentage variation in response for 0.7 ppm ammonia gas with silicone oil on InN sensor is 4.3-fold higher than that of 0.7 ppm acetone. The results show that the InN sensor is suitable for diagnosis of liver malfunction.
关键词： silicone oil,InN,liver malfunction,exhaled-breath volatile organic compound (VOCs),selectivity,external ?lter
更新于2025-09-10 09:29:36