Breath Acetone Research Articles

Enhanced Photo-Assisted Acetone Gas Sensor and Efficient Photocatalytic Degradation Using Fe-Doped Hexagonal and Monoclinic WO3 Phase-Junction.

The development of WO3-based gas sensors for analysis of acetone in exhaled breath is significant for noninvasive diagnosis of diabetes. A series of Fe-doped hexagonal and monoclinic WO3 phase−junction (Fe−h/m−WO3) sensors were synthesized by the hydrothermal calcination method, and the influences of operating temperature and light irradiation on the response were studied. Under light emitting diode (LED) illumination, Fe−h/m−WO3 exhibited higher responses to acetone than those of the undoped WO3-based sensors at an operating temperature of 260 °C with 90% relative humidity, and good linearity between response and acetone concentration (0.5 to 2.5 ppm) was achieved under the 90% relative humidity condition. Meanwhile, the optimal Fe−h/m−WO3 sensor exhibited high selectivity and stability for a duration of three months. The excellent sensing performance of Fe−h/m−WO3 was attributed to the formation of phase−junction and Fe doping, and these were beneficial for the separation of photon−generated carriers and oxygen adsorption on the WO3 surface, promoting the generation of superoxide radicals, which was demonstrated by electron paramagnetic resonance and photocurrent tests. Additionally, the Fe−doped WO3 phase−junction sample also showed good photocatalytic performance for rhodamine B degradation. This study may provide some insights into rational design of new types of gas sensors and offer an alternative for noninvasive diagnosis of diabetes.

Ацетон выдыхаемого воздуха как маркер метаболической гибкости

A brief analysis of the metabolic flexibility and its role in human body was made. Metabolic flexibility is the ability to respond or adapt to conditional changes in metabolic demand. This broad concept has been propagated to explain insulin resistance and mechanisms governing fuel selection between glucose and fatty acids, highlighting the metabolic inflexibility of obesity and diabetes. Monitoring is relevant because disrupted metabolic flexibility, or metabolic inflexibility, however, is associated with many pathological conditions and may underlie the epidemic changes in metabolic disease. The number of the blood ketones increases when the human body tries to adapt metabolism and aptly utilize moderate amounts fatty acids in case the glucose is shortage. Acetone is formed by the non-enzymatic decarboxylation of acetoacetic acid. Acetone cannot be used by the tissues. It appears in urine, sweat and exhaled air. The correlation between breath acetone and lipid oxidation was studied to ensure that the level buildup is associated with increased lipid oxidation. Breath acetone concentration is well understood to be a non-invasive measure of ketosis and more accurately reflects the rate of lipid oxidation than urine or sweat acetone concentrations. Due to the thin capillary wall, ventilation and gaseous metabolism contributes rapid transmission of short-term and minimum acetone concentration changes in tissues or blood-stream, that up regulates correlation of metabolic disorders and acetone concentration in exhaled air. Metabolic flexibility control method using the breath acetone is relevant and the future potential is attributed for personalized diagnostics, pre-diagnosis and therapeutic modalities correction is huge.

Inhalation of molecular hydrogen increases breath acetone excretion during submaximal exercise: a randomized, single-blinded, placebo-controlled study.

Aerobic exercise is widely accepted as a beneficial option for reducing fat in humans. Recently, it has been suggested that molecular hydrogen (H2) augments mitochondrial oxidative phosphorylation. Therefore, the hypothesis that inhaling H2 could facilitate lipid metabolism during aerobic exercise was investigated in the current study by measuring the breath acetone levels, which could be used as non-invasive indicators of lipid metabolism. This study aimed to investigate the effect of inhaling H2 on breath acetone output during submaximal exercise using a randomized, single-blinded, placebo-controlled, and cross-over experimental design. After taking a 20-minute baseline measurement, breath acetone levels were measured in ten male subjects who performed a 60% peak oxygen uptake-intensity cycling exercise for 20 minutes while inhaling either 1% H2 or a control gas. In another experiment, six male subjects remained in a sitting position for 45 minutes while inhaling either 1% H2 or a control gas. H2 significantly augmented breath acetone and enhanced oxygen uptake during exercise (P < 0.01). However, it did not significantly change oxidative stress or antioxidant activity responses to exercise, nor did it significantly alter the breath acetone or oxygen uptake during prolonged resting states. These results suggest that inhaling H2 gas promotes an exercise-induced increase in hepatic lipid metabolism. The study was approved by the Ethical Committee of Chubu University, Japan (approved No. 260086-2) on March 29, 2018.

A059 Metabolomics and a Breath Sensor Identify Acetone as a Biomarker for Heart Failure

Metabolomics delivers more biological and clinical insight than targeted investigations. We applied metabolomics to patients with heart failure (HF) with reduced ejection fraction (HFrEF). 46 patients with HFrEF and 20 controls underwent metabolomic profiling, including liquid/gas chromatography mass spectrometry (LC-MS/GC-MS), nuclear magnetic resonance (NMR) metabolomics and solid-phase microextraction (SPME) volatilomics in plasma and urine. HFrEF was defined using left ventricular global longitudal strain (GLS) < 18%, ejection fraction < 50% and NTproBNP ≥ 35 pmol/L. A low cost consumer breath acetone (BrACE) sensor validated SPME results in 69 patients. 34 metabolites were identified by GCMS, 33 by LCMS and 2 volatiles by SPME (acetone, 2-pentanone in plasma and urine). Alanine, aspartate and glutamate, citric acid cycle, arginine biosynthesis, glyoxylate and dicarboxylate metabolism were altered in HFrEF. Plasma acetone correlated with NT-proBNP (r = 0.59, 95% CI 0.4 to 0.7), triacylglycerol (55:9), 2-oxovaleric and cis-aconitic acid, involved with ketone metabolism and mitochondrial energetics. BrACE > 1.5 ppm discriminated HF from other cardiac pathology (AUC 0.88, 95% CI 0.77 to 0.99, P < 0.0001). Breath acetone was detectable in HFrEF patients using a consumer sensor ($1/test) and although not cardiac specific, discriminated HF from other cardiac pathology.

Breath Acetone Sensors as Non-Invasive Health Monitoring Systems: A Review

Finding a non-invasive, painless and simple method for monitoring of health parameters and early detection of physiological disorders is of utmost importance in today’s world. Breath analysis has been attracted tremendous attention as a potentially powerful tool for studying the medical diagnosis diseases because of its noninvasive nature and capability of real-time monitoring. For metabolic monitoring, several candidates are attractive. As an example, acetone has been considered as a main breath biomarker for diabetes. In addition to diabetes, fat burn monitoring is another application for breath acetone. This article provides a comprehensive study on the state of the art research activities in gas sensor field. It mainly focuses on the metal oxide semiconductor based acetone sensors such as WO3, ZnO, SnO2, Fe2O3, In2O3, TiO2, Co2O3, NiO and etc. Several different type of acetone sensor technologies such as polymer based chemiresistors, mixed potential, optical and mass sensitive devices are presented as well. The effect of nano structures and morphology on response of sensors are discussed. The advantages and disadvantages of different techniques used for metal oxide semiconductor synthesis are also discussed. Finally, sensor arrays with different receptor materials and transducers for breath analyzing are discussed.

Construction of 1D/2D α-Fe2O3/SnO2 Hybrid Nanoarrays for Sub-ppm Acetone Detection.

Exhaled acetone is one of the representative biomarkers for the noninvasive diagnosis of type-1 diabetes. In this work, we have applied a facile two-step chemical bath deposition method for acetone sensors based on α-Fe2O3/SnO2 hybrid nanoarrays (HNAs), where one-dimensional (1D) FeOOH nanorods are in situ grown on the prefabricated 2D SnO2 nanosheets for on-chip construction of 1D/2D HNAs. After annealing in air, ultrafine α-Fe2O3 nanorods are homogenously distributed on the surface of SnO2 nanosheet arrays (NSAs). Gas sensing results show that the α-Fe2O3/SnO2 HNAs exhibit a greatly enhanced response to acetone (3.25 at 0.4 ppm) at a sub-ppm level compared with those based on pure SnO2 NSAs (1.16 at 0.4 ppm) and pure α-Fe2O3 nanorods (1.03 at 0.4 ppm), at an operating temperature of 340°C. The enhanced acetone sensing performance may be attributed to the formation of α-Fe2O3–SnO2 n-n heterostructure with 1D/2D hybrid architectures. Moreover, the α-Fe2O3/SnO2 HNAs also possess good reproducibility and selectivity toward acetone vapor, suggesting its potential application in breath acetone analysis.

Trace gas sensing using diode-pumped collinearly detected spontaneous Raman scattering enhanced by a multipass cell

A simple but highly effective method for enhancement of spontaneous Raman scattering from gases is described. It employs a multimode blue laser diode that receives feedback from a near-concentric bidirectional multipass cavity in such a way as to generate a circulating power on the order of 100 W for a sample volume of 10 m m 3 . The feedback, provided via a volume Bragg grating, reduces the laser bandwidth to 4 c m − 1 . Spectra of spontaneous Raman scattering from ambient atmospheric air, detected collinearly with the pump, were recorded with a limit of detection below 1 ppm. The performance of the setup is further illustrated through detection of acetone, methane, and isotopic carbon dioxide in breath.

Blood Ketone Bodies and Breath Acetone Analysis and Their Correlations in Type 2 Diabetes Mellitus.

Analysis of volatile organic compounds in the breath for disease detection and monitoring has gained momentum and clinical significance due to its rapid test results and non-invasiveness, especially for diabetes mellitus (DM). Studies have suggested that breath gases, including acetone, may be related to simultaneous blood glucose (BG) and blood ketone levels in adults with types 2 and 1 diabetes. Detecting altered concentrations of ketones in the breath, blood and urine may be crucial for the diagnosis and monitoring of diabetes mellitus. This study assesses the efficacy of a simple breath test as a non-invasive means of diabetes monitoring in adults with type 2 diabetes mellitus. Human breath samples were collected in Tedlar™ bags and analyzed by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS). The measurements were compared with capillary BG and blood ketone levels (β-hydroxybutyrate and acetoacetate) taken at the same time on a single visit to a routine hospital clinic in 30 subjects with type 2 diabetes and 28 control volunteers. Ketone bodies of diabetic subjects showed a significant increase when compared to the control subjects; however, the ketone levels were was controlled in both diabetic and non-diabetic volunteers. Worthy of note, a statistically significant relationship was found between breath acetone and blood acetoacetate (R = 0.89) and between breath acetone and β-hydroxybutyrate (R = 0.82).

Calibration-free breath acetone sensor with interference correction based on wavelength modulation spectroscopy near 8.2 $$\upmu$$m

Development of a robust breath acetone sensor based on laser absorption of multiple species near 8.2 $$\upmu$$m is presented. A scanned-wavelength modulation spectroscopy technique, involving intensity-normalized second harmonic detection, was paired with a multi-pass optical gas cell to attain signals related to differential absorbance of acetone, water vapor, and methane. A spectral fitting routine of the harmonic signals was used to infer the respective abundances of each species, correcting the acetone signal for interfering absorption. A detection limit ($$2\sigma$$) of approximately 0.11 ppm acetone was determined based on controlled measurements using reference test gases. The sensor was further tested in exhaled breath samples with varying amounts of interfering species, exhibiting capability for sensitive acetone detection with very high levels of exhaled methane (up to 40 ppm). The sensor is also shown to be insensitive to locally broadband interfering absorbers, namely methanol and ethanol in normal human breath. To highlight utility, the breath acetone sensor was used to track ketosis during a regimented ketogenic diet of several subjects, demonstrating regular non-intrusive monitoring of breath acetone over a clinically-relevant range (0.4–74 ppm) and sensitivity to dietary changes.

An overview on the exponential growth of non-invasive diagnosis of diabetes mellitus from exhaled breath by nanostructured metal oxide Chemi-resistive gas sensors and μ-preconcentrator.

The characterization of acetone in exhaled breath reflects the internal metabolism of glucose in bloodstream and airways. This phenomenon provides a great potential for non-invasive diagnosis of diabetes mellitus and has inspired medical sodalities as an alternative diagnostic tool. This review discusses about the origination of acetone in breath, its correlation with blood glucose level along with the ways to collect breath sample. Furthermore, we also discuss the detection of acetone by chemical sensors with emphasis on the use of pre-concentrators on a single lab-on-chip for the diagnosis of diabetes mellitus. Finally, this review outlines the future directions for the detection of acetone from exhaled breath. The first part of the review introduces the biochemistry and prevalence of diabetes in India along with the existing techniques to estimate the concentration of acetone. The second part focuses on the semiconducting metal oxide and polymer gas sensors which discusses about tailoring the dynamic sensitivity range and selectivity towards acetone in breath. The third part elaborates on the ways to pre-concentrate the target biomarkers along with future perspectives for non-invasive diabetes diagnosis. Finally we also provide the perspectives on future challenges to make it to clinical practice. Graphical abstract .

IoT Based Ketoacidosis Detection

Ketoacidosis also known as DKA (diabetic ketoacidosis) is a serious condition which occurs in patients who suffers from diabetes. It affects people above 25 years of age. It occurs due to insufficiency of insulin. Detection of ketone is done by the nitroprusside-based urinary dipstick ketone test and plasmlserum ketone analyses. Non-invasive detection of ketoacidosis is done by breath analyzer. In this paper we are using breath acetone as a biomarker for ketoacidosis. The resultant ketoacidosis values are transmitted through ESP8266. The ESP8266 sends the sensorvalues to think speak (private cloud). The new channel is created in Think Speak private clouding and Channel API keys are generated to read and write the sensor data from ESP8266. Through this simple IoT device the physician is always connected to the patient and can be able to monitor thet ketoacidosis condition of the subject

UV-activated ZnO/CdO n-n isotype heterostructure as breath sensor

The demand for developing a non-invasive sensor towards disease diagnosis such as diabetes, renal dysfunction, and cancer has been increasing tremendously. The presence of biomarkers such as ammonia, acetone, and ethanol in human exhaled breath indicates the onset of various diseases. In this context, the present investigation is focused on developing a cost-effective acetone sensor using isotype ZnO/CdO heterostructure thin film by spray pyrolysis technique. The sensing signatures of the heterostructure was examined in the presence of light activation using UV LED light. Structural analysis of the heterostructure divulged the growth of cubic phased CdO and hexagonal phased ZnO crystallites towards (1 1 1) and (1 0 1) planes respectively. Spin-orbit splitting of Cd 3d subshells was confirmed through the surface analysis. The heterostructure showed selective photo-response of 540 towards acetone at room temperature. Response and recovery times were observed as 61 and 47 s respectively towards 1 ppm of acetone vapor. The linear detection range of the sensor was observed to be 1–100 ppm with long-term stability. Since the sensor showed the lowest detection limit of 1 ppm, the sensor can be used for the identification of acetone from exhaled breath for disease diagnosis.

MgNi2O3 nanoparticles as novel and versatile sensing material for non-enzymatic electrochemical sensing of glucose and conductometric determination of acetone

In the present work, we report the synthesis of pure MgNi2O3 and MgNi2-xAxO3 (A = Co or Zn; x = 2.5, 10, 25 wt%) nanoparticles by chemical precipitation method and its novel applications in the field of chemical sensors. Powder XRD, SEM, HRTEM and XPS characterization of the synthesized samples indicate formation of nearly phase pure undoped MgNi2O3 nanoparticles. At lower concentration (2.5 and 5 wt%), both Co and Zn loading yielded nearly phase pure Mg-123 samples. On the other hand, increase in dopant concentration, led to the segregation of small quantity of impurity phases Co3O4 and ZnO with the major phase being Mg-123. Results of electrical and electrochemical characterization studies indicated the influence of the dopants on the physical and chemical properties of MgNi2O3. Both the pure and doped MgNi2O3 nanoparticles have been applied for the fabrication of electrochemical and conductometric sensors for monitoring blood glucose and breath acetone respectively. Electrochemical tests indicated that the Co–MgNi2O3 is highly effective for the electrochemical detection of glucose. Under optimal conditions, glucose was monitored at concentration from 0.05 mM to 5 mM with sensitivity of 528.6 μA mM−1cm−2. With regard to breath acetone detection, the Zn–MgNi2O3 conductometric sensor showed the best performances with high response and low detection limit (0.5 ppm at SN = 3), fast response/recovery times of about 25 s and 250 s, respectively, at the operating temperature of 200 °C. The good electrochemical and gas sensing performances suggest that MgNi2O3 based nanomaterials can be considered as versatile and promising candidates for developing chemical sensors helpful in the management of acute complications of insulin dependent diabetes, such as hypoglycemia and ketoacidosis.

The Effectiveness of Acetone Breath Content Using Chitosan Based Sensor in Patients Diabetes Mellitus.

BACKGROUND:The high incidence of diabetes mellitus in Indonesia to encourage researchers to continue to develop detection techniques are easy, inexpensive and minimally invasive. This study is expected to answer the challenge. Detection tool used in this research is the detection devices use traditional breath acetone levels of chitosan-based sensors. Acetone breath sensor works based on the chemical interaction between the breath of patients with diabetes and acetone sensor surface, which causes a change in the electrical response.AIM:This study was cross-sectional using diabetes mellitus patients as research subjects by measuring breath acetone levels and HbA1c and KGD as a comparison.METHODS:Research conducted at the primary health care facilities network services the University Hospital of North Sumatra. A total of 58 diabetic patients who meet the inclusion and exclusion criteria were included in this study. The relationship between the measurements analysed using Pearson correlation test.RESULTS:Measurements showed that statistically there is a great relationship between breath acetone levels with or KGD HbA1c levels in the diabetic patient with each R = 0.05 and p = 0.708 for the relationship acetone breath and HbA1c and R = 0.1 and p = 0.445 for the relationship acetone breath and KGD. However, clinically there is a linear relationship between increased levels consistent acetone in the breath with increased HbA1c levels as well as levels of KGD.CONCLUSION:Examination of breath acetone levels can be considered as an indicator of diabetes detection.

Metal-organic frameworks for the sorption of acetone and isopropanol in exhaled breath of diabetics prior to quantitation by gas chromatography.

A method is described for non-invasive glucose monitoring of diabetics by means of breath analysis. The metal-organic frameworks (MOFs) ZIF-7, UiO-66 and MOF-5 were chosen as sorbents in packed tubes for sampling and preconcentration of acetone and isopropanol which are established diabetes biomarkers. The MOF UiO-66 was found to be the most appropriate sorbent. Following thermal desorption, acetone and isopropanol where quantified by GC. The method has low limits of detection (0.79-0.84μg·L-1) and wide linear ranges (5-2000μg·L-1). It is assumed that the good performance of UiO-66 as a sorbent results from its large surface area and unique porous structure, and from van der Waals interactions. The relative standard deviation for six replicate cycles of sampling and preconcentration using one 50mg UiO-66 packed tube ranged between 2.3 and 6.7% for intra-day assays, and from 2.7 to 4.3% for inter-day assays. A tube packed with 50mg of UiO-66 packed tube can be used in over 120cycles of adsorption/desorption without significant loss of collection efficiency. The GC method has been applied for the analysis of diabetic breath samples, and the recoveries from spiked samples ranged from 89.1 to 107.6%. Graphical abstract Schematic presentation of metal-organic frameworks as sorbents combined with thermal desorption-gas chromatography for the determination of acetone and isopropanol in exhaled breath of diabetics.

A sampler prototype for the simultaneous collection of exhaled air and breath condensate.

Exhaled air and breath condensate contain a large number of health biomarkers, such as volatile and semi-volatile organic compounds, proteins and lipids. Nowadays, the collection of breath samples is carried out by commercial or lab-made sampling systems that collect only one type of sample (e.g. gaseous or condensate phase), thus limiting the diagnostic capability of breath tests. This work presents a portable prototype optimized for the simultaneous collection of gaseous exhaled breath and exhaled breath condensate within five minutes. The system is fully portable and has a total weight of about 1 Kg. An illustrative determination of ethanol, isoprene, acetone, isopropyl alcohol, 1-propanol, 2-butanone, 2-pentanone, toluene and xylenes in breath, and cortisol and 8-iso-prostaglandin F2α in breath condensate is discussed.

Impact of Reduced Carbohydrate Intake after Exercise on Breath Acetone Levels

PURPOSE: The purpose of the present study was to deter determine the impact of reduced carbohydrate (CHO) intake after sprint exercise on breath acetone levels during post-exercise. METHODS: Nine subjects (20.8 ± 0.2 yrs, 170.1 ± 1.6 cm, 65.1 ± 1.8 kg) conducted two trials, consisting lower CHO trial (LOW) or normal CHO trial (NOR). In each trial, the subjects came to the laboratory at 7:30 to evaluate breath acetone level, blood variables and resting metabolic rate. From 17:00, they started repeated sprint exercise (4 × 30 s maximal cycle sprint exercise). After exercise, isoenergetic meals (during 2-3 h after exercise) were provided with containing normal CHO (60% for CHO, 20% for protein, 20% for fat) for NOR or reduced CHO (20% for CHO, 20% for protein, 60% for fat) for LOW. Time course changes in breath acetone levels were monitored immediately before exercise, immediately after exercise, 1 h, 3h, 4h and on the following morning. RESULTS: In the LOW, exercise markedly increased breath acetone levels during post-exercise (trial × time interaction: p<0.05). At 4 h after exercise, breath acetone level was significantly higher in LOW (0.9 ± 0.02 ppm) than in NOR (0.66 ± 0.07 ppm, p < 0.05). However, a significant difference between the trials was not observed on the following morning. Respiratory exchange ratio (RER) on the following morning was significantly lower in the LOW (0.81 ± 0.02) than in the NOR (0.87 ± 0.02, p < 0.05). Moreover, LOW showed significantly lower contribution of CHO oxidation (34 ± 4.8 %) than that in NOR (50 ± 6.2 %, p < 0.05), whereas fat oxidation was significantly higher in LOW (66 ± 4.8 %) than in NOR (50 ± 6.2 %, p < 0.05). CONCLUSIONS: Reduced CHO intake after exercise increased breath acetone level during early phase of post-exercise (4 h after exercise), suggesting augmented fat metabolism in the liver under impaired CHO availability. However, the increased breath acetone level by reduced CHO intake was not evident on the following morning. The results may suggest that breath acetone levels can be available to evaluate CHO availability following intensive exercise.

A comparison of online and offline measurement of exhaled breath for diabetes pre-screening by graphene-based sensor; from powder processing to clinical monitoring prototype

Several breath analysis studies have suggested a correlation between blood glucose (BG) levels and breath acetone, indicating acetone as a primary biomarker in exhaled breath for diabetes diagnosis. Herein, we have (i) fabricated and validated graphene-based chemi-resistive sensors for selective and sensitive detection of acetone, (ii) performed offline breath analysis by a static gas sensing set-up to acquire olfactory signals, and (iii) developed an LED-based portable on/off binary e-nose system for pre-screening diabetes through online analysis. The fabricated sensors showed selective detection for acetone with high sensitivity (5.66 for 1 ppm acetone vapor) and fast response and recovery times (10 s and 12 s) at low concentrations. The sensor responses of end tidal fractional breath (collected in Tedlar bags) in the fasting and postprandial conditions were compared with BG levels and glycated hemoglobin (HbA1c) levels taken at the same time in 30 volunteers (13 healthy and 17 diabetic subjects). The mean sensor responses of the diabetic subjects as obtained by offline analysis were 1.1 times higher than those of the healthy subjects. The optimal regression equation framed with the significant correlating variables for HbA1c estimation achieved an accuracy of 66.67%. The online breath analysis by on/off binary prototype exhibited an accuracy of 60.51%. Though there exists a minimal uncertainty in classification, the on/off type portable prototype is easy to operate, gives a quicker response with a refresh/recovery rate of 19 s and can be used for preliminary diagnosis, and can be used for preliminary diagnosis. This inexpensive sensor technology may revolutionize personalized medicine in the near future and greatly benefit the underprivileged.

Synthesis of three-dimensionally ordered macro/mesoporous C-doped WO3 materials: Effect of template sizes on gas sensing properties

WO3-based materials have received substantial attention for their great potentials in workplace acetone detection and in breath acetone analysis. However, several key challenges, including acetone response, selectivity and material stability, should be further addressed before their practical applications. In this work, three-dimensionally ordered macroporous/mesoporous (3DOM) C-doped WO3 materials are synthesized and characterized extensively. The gas sensing properties of 3DOM C-doped WO3 materials are investigated and the calcination and operating temperature are optimized. Emphasis is placed on identifying how the pore sizes of 3DOM materials affecting gas sensing properties. The results show that the optimal material with 410 nm pore size exhibits the highest responses to acetone. Upon exposure to NH3, CO, methanol, ethanol, and formaldehyde, only slight responses are observed, implying an excellent selectivity. In addition, the sensor exhibits good repeatability and long-term stability. More attractively, it is found that the responses to acetone are related to the pore sizes of 3DOM C-doped WO3 materials. We suggest that the size of the basic building units in 3DOM structure plays a key role in acetone responses. The results gained herein may be useful for rational design of sensing materials with tunable gas sensing properties.

Exhaled acetone and isoprene in perioperative lung cancer patients under intensive oral care: possible indicators of inflammatory responses and metabolic changes.

One of the most severe complications of lung resection is postoperative pneumonia, and its prevention and prediction are critical. Exhaled acetone and isoprene are thought to be related to metabolism; however, little is known on their relationship with bacteria living in the oral cavity or their meaning in the acute phase in perioperative lung cancer patients. We measured acetone and isoprene in exhaled breath of 13 Japanese patients with lung cancer (3 women and 10 men, age range 62-82 years, mean 72.4 years) before breakfast during hospitalization, and compared with two acute-phase proteins, C-reactive protein (CRP) and albumin in blood serum, as well as the total number of bacteria in saliva and their activity to produce acetone and isoprene. Before operation, intensive oral care was carried out for each patient to prevent postoperative pneumonia, and swallowing and cough reflexes were measured for 12 of 13 patients to assess risk of postoperative pneumonia. Breath and saliva were sampled before intensive oral care (T1), after oral care but before operation (T2), and after operation (T3) during hospitalization. The total number of oral bacteria in saliva decreased significantly from T1 to T2 among 13 patients. No acetone or isoprene was detected from saliva after in vitro incubation under anaerobic or aerobic conditions, but both acetone and isoprene were detected in breath. After operation, breath acetone correlated significantly with CRP (Spearman's ρ = 0.559, P = 0.03), but not with albumin. Breath isoprene correlated significantly with albumin (Spearman's ρ = 0.659, P = 0.008), but not with CRP after operation. Although the number of subjects was small, our results support the hypothesis that breath acetone and isoprene may be related with these acute-phase proteins, which reflect inflammatory reactions and subsequent changes in metabolism in the early postoperative phase of lung resection.