Noninvasive Strategy Based on Real-Time in Vivo Cataluminescence Monitoring for Clinical Breath Analysis

Determination of acetic acid in enzymes based on the cataluminescence activity of graphene oxide-supported carbon nanotubes coated with NiMn layered double hydroxides

A cataluminescence (CTL) method has been developed for the rapid determination of acetic acid in enzyme products. The NiMn LDH/CNT/GO was synthesized based on the nanohybridization of NiMn layered double hydroxide (NiMn LDH), carbon nanotubes (CNTs), and graphene oxide (GO). The composite has excellent CTL activity against acetic acid. It could be ascribed to the larger specific surface area and more exposure to active sites. NiMn LDH/CNT/GO is used as a catalyst in the CTL method based on its special structure and advantages. There is a linear relationship between CTL response and the acetic acid concentration in the range 0.31-12.00 mg·L^-1 with the detection limit of 0.10 mg·L^-1. The developed method is rapid and takes only about 13 s. The method is applied to the determination of acetic acid in enzyme samples with little sample preparation. The result of the CTL method shows good agreement with that of the gas chromatography method. The proposed CTL method possesses promising potential in the quality monitoring of enzymes.

Design of an Artificial Opal/Photonic Crystal Interface for Alcohol Intoxication Assessment: Capillary Condensation in Pores and Photonic Materials Work Together

Alcohol intoxication has a dangerous effect on human health and is often associated with a risk of catastrophic injuries and alcohol-related crimes. A demand to address this problem adheres to the design of new sensor systems for the real-time monitoring of exhaled breath. We introduce a new sensor system based on a porous hydrophilic layer of submicron silica particles (SiO₂ SMPs) placed on a one-dimensional photonic crystal made of Ta₂O₅/SiO₂ dielectric layers whose operation relies on detecting changes in the position of surface wave resonance during capillary condensation in pores. To make the active layer of SiO₂ SMPs, we examine the influence of electrostatic interactions of media, particles, and the surface of the crystal influenced by buoyancy, gravity force, and Stokes drag force in the frame of the dip-coating preparation method. We evaluate the sensing performance toward biomarkers such as acetone, ammonia, ethanol, and isopropanol and test sensor system capabilities for alcohol intoxication assessment. We have found this sensor to respond to all tested analytes in a broad range of concentrations. By processing the sensor signals by principal component analysis, we selectively determined the analytes. We demonstrated the excellent performance of our device for alcohol intoxication assessment in real-time.

Online evaluation of the catalytic performance of MnO2 and its application in H2S cataluminescence sensing

As a catalyst widely used in industry, manganese dioxide (MnO₂) has different crystalline forms and shows excellent performance in catalytic reactions. Therefore, it is of significance to rapidly evaluate the catalytic performance of MnO₂ online. In this paper, a highly efficient evaluation method based on H₂S cataluminescence (CTL) sensing was proposed for MnO₂ with different crystalline forms. Firstly, α-, β- and δ-MnO₂ were synthesized successfully and performed diacritical CTL behaviours in the catalytic oxidation of H₂S. Based on these interesting phenomena, the catalytic performance of α-, β- and δ-MnO₂ was efficiently evaluated online through CTL method for the first time. Results showed that β-MnO₂ had the best catalytic oxidation performance, followed by α- and δ-MnO₂, and the reactive oxygen species of MnO₂ was the most significant influencing factor. Subsequently, β-MnO₂ was selected to design a CTL sensor for H₂S detection with a wide linear range (2.43-29.1 μg/mL) and a low limit of detection (LOD, S/N = 3, 0.280 μg/mL). This work not only provided a new and feasible method for online evaluation of the catalytic performance of materials, but also designed a CTL sensor for H₂S determination with high selectivity and sensitivity.

Real-time pharmacokinetics via online analysis of exhaled breath

The advantages that on-line breath analysis has shown in different fields have already made it stand as an interesting tool for pharmacokinetic studies. This review summarizes recent progress in the field, diving into the different analytical methods and the different advantages and hurdles encountered. We conclude that there is a wealth of limitations in the application of this technique, and key aspects like standardization are still outstanding. Nevertheless, this is an experimental field that has not yet been fully explored; and the advantages it offers for animal welfare, decrease in the amount of drug needed in experimental studies, and complementary insights to current pharmacological studies, warrant further exploration. Further studies are needed to overcome current limitations and incorporate this technique into the toolbox of pharmacological studies, both at an industrial and academic level.

Novel Strategy for Engineering the Metal-Oxide@MOF Core@Shell Architecture and Its Applications in Cataluminescence Sensing

Cataluminescence is an attractive oxydic luminescence on the gas-solid interface, and metal-oxide@MOF core@shell architectures show great potential for cataluminescence sensing due to their integrated synergistic effect from core and shell components. However, restricting the direct nucleation and growth of metal-organic frameworks (MOFs) on the topologically distinct surface of metal oxides is a great challenge, owing to the high interface energy from the topology mismatch. Herein, for the first time, a novel liquid-phase concentration-controlled nucleation strategy is exploited to induce the direct assembly of a ZIF-8 layer on the surface of CeO₂ nanospheres without any sacrificial templates or further surface modifications. The results show that the construction of the CeO₂@ZIF-8 core@shell architecture can be accomplished within 1 min under the mediation of boosted nucleation kinetics. Furthermore, the universality of this developed strategy is demonstrated by the encapsulation of other metal-oxide cores such as magnetic Fe₃O₄ and ZnCo₂O₄ core particles with a ZIF-8 shell. Notably, compared to the pure CeO₂ and ZIF-8, the obtained CeO₂@ZIF-8 nanocomposite exhibits enhanced analytical performance for the cataluminescence sensing of propanal, in which the shell acts as the major catalytic reaction center, while the core contributes to further improving the catalytic efficiency. The proposed facile synthesis strategy with excellent simplicity, rapidity, and universality brings new insights into the engineering of core@shell advanced functional materials with mismatched topologies for catering to the diverse application demands.

Human Breathomics Database

Breathomics is a special branch of metabolomics that quantifies volatile organic compounds (VOCs) from collected exhaled breath samples. Understanding how breath molecules are related to diseases, mechanisms and pathways identified from experimental analytical measurements is challenging due to the lack of an organized resource describing breath molecules, related references and biomedical information embedded in the literature. To provide breath VOCs, related references and biomedical information, we aim to organize a database composed of manually curated information and automatically extracted biomedical information. First, VOCs-related disease information was manually organized from 207 literature linked to 99 VOCs and known Medical Subject Headings (MeSH) terms. Then an automated text mining algorithm was used to extract biomedical information from this literature. In the end, the manually curated information and auto-extracted biomedical information was combined to form a breath molecule database—the Human Breathomics Database (HBDB). We first manually curated and organized disease information including MeSH term from 207 literatures associated with 99 VOCs. Then, an automatic pipeline of text mining approach was used to collect 2766 literatures and extract biomedical information from breath researches. We combined curated information with automatically extracted biomedical information to assemble a breath molecule database, the HBDB. The HBDB is a database that includes references, VOCs and diseases associated with human breathomics. Most of these VOCs were detected in human breath samples or exhaled breath condensate samples. So far, the database contains a total of 913 VOCs in relation to human exhaled breath researches reported in 2766 publications. The HBDB is the most comprehensive HBDB of VOCs in human exhaled breath to date. It is a useful and organized resource for researchers and clinicians to identify and further investigate potential biomarkers from the breath of patients.

Database URL: https://hbdb.cmdm.tw

Skin ethanol gas measurement system with a biochemical gas sensor and gas concentrator toward monitoring of blood volatile compounds

We developed a biochemical gas sensor (bio-sniffer) using the enzymatic reaction of alcohol dehydrogenase (ADH) to target ethanol in skin gas. By introducing a gas concentrator using liquid nitrogen, we constructed a highly sensitive system for skin gas measurements. The ethanol bio-sniffer was built from an optical-fiber probe employing an ADH enzyme membrane, an UV-LED light source for excitation, and a photomultiplier tube. Ethanol was measured by detecting the autofluorescence of the coenzyme NADH due to the enzymatic reaction of ADH. We established a system for measuring concentrated gases by connecting the sensor with a gas concentrator and introducing concentrated skin gas to the sensing surface. This suppressed diffusion of the concentrated gases to achieve maximum fluorescence intensity by optimizing the measurement system. The calibration curve from obtained peak values showed ethanol gas can be measured over 1-3100 ppb, which included skin gas concentrations during alcohol consumption. Finally, when applied to measurements of ethanol in skin gas following alcohol consumption, the output was found to be dependent on concentration, similarly to using standard gases. Consecutive measurements were possible using periodic sampling with 6-min intervals for 180 min of monitoring. Skin ethanol concentrations rose from 20 min after consuming the alcohol, exhibited a peak value of 25 ppb skin gas ethanol at around 60 min, and gradually declined. Thus, the system can be used for non-invasive percutaneous evaluation of human volatile organic chemicals in blood.

Digging deeper into volatile organic compounds associated with cancer

Volatile organic compounds (VOCs), produced and emitted through the metabolism of cancer cells or the body's immune system, are considered novel cancer biomarkers for diagnostic purposes. Of late, a large number of work has been done to find a relationship between VOCs' signature of body and cancer. Cancer-related VOCs can be used to detect several types of cancers at the earlier stages which in turn provide a significantly higher chance of survival. Here we aim to provide an updated picture of cancer-related VOCs based on recent findings in this field focusing on cancer odor database.

Synthesis of Nano-Praseodymium Oxide for Cataluminescence Sensing of Acetophenone in Exhaled Breath

In this work, we successfully developed a novel and sensitive gas sensor for the determination of trace acetophenone based on its cataluminescence (CTL) emission on the surface of nano-praseodymium oxide (nano-Pr₆O₁₁). The effects of working conditions such as temperature, flow rate, and detecting wavelength on the CTL sensing were investigated in detail. Under the optimized conditions, the sensor exhibited linear response to the acetophenone in the range of 15-280 mg/m³ (2.8-52 ppm), with a correlation coefficient (R²) of 0.9968 and a limit of detection (S/N = 3) of 4 mg/m³ (0.7 ppm). The selectivity of the sensor was also investigated, no or weak response to other compounds, such as alcohols (methanol, ethanol, n-propanol, iso-propanol, n-butanol), aldehyde (formaldehyde and acetaldehyde), benzenes (toluene, o-xylene, m-xylene, p-xylene), n-pentane, ethyl acetate, ammonia, carbon monoxide, carbon dioxide. Finally, the present sensor was applied to the determination of acetophenone in human exhaled breath samples. The results showed that the sensor has promising application in clinical breath analysis.

Cataluminescence Coupled with Photoassisted Technology: A Highly Efficient Metal-Free Gas Sensor for Carbon Monoxide

With the development of green chemistry, metal-free nanocatalysts have gradually substituted metal-based materials, causing widespread concern among researchers in many fields, especially in cataluminescence sensing, because of their long-term stability and environmental friendliness as well as low costs. Besides the catalysts, innovations of assistant technologies for cataluminescence are needed to enhance the oxidation reactivity of the gas molecules or catalytic efficiency of sensing materials. Although, there are some groups enhancing the cataluminescence reaction via various assistant technologies, the development of assistant technologies in cataluminescence sensors is still in its infancy; the design, effect mechanism, and application are still stimulating challenges. Herein, with photodynamic assistant, fluorinated nanoscale hexagonal boron nitride is first employed as a metal-free catalyst to establish a novel cataluminescence method for detecting CO gases, and the cataluminescence reaction mechanism of CO is also investigated in detail. Under the best conditions, the detection limit (3σ) of the CO concentration is 0.005 μg mL^-1, which has been largely improved in cataluminescence methods. The realization of detection of CO from theory to practice through the method of cataluminescence is beneficial for the practical application of metal-free catalysts to detect CO rather than staying at the possibility to detect CO by means of theoretical calculation only.

Cataluminescence sensor for highly sensitive and selective detection of iso-butanol

In this paper, a gaseous sensor was described for detection of iso-butanol on the basis of its strong cataluminescence (CTL) emission on nano-MgO surface. The sensor showed high sensitivity and specificity to iso-butanol with response time less than 1 s and recovery time less than 18 s. A good linearly relationship between CTL intensity and the concentration of iso-butanol was observed in the range of 7.6-3350 mg/m³ (r = 0.9992), the limit of detection was 2.5 mg/m³. The proposed CTL sensor exhibits good specificity to iso-butanol against other compounds including common alcohols. The possible reaction paths of iso-butanol on the MgO surface were investigated in detail. Results shows that the hydrogen atom abstraction of iso-butanol to form β-R_iso following consumption via Waddington mechanism possible is a major reaction channel for CTL emission. The sensor was applied to analyze iso-butanol in spiked samples, satisfactory recoveries were obtained in the range of 96.6-112.8% and the RSDs were 5.0-10.1%, indicating that the proposed sensor is a promising candidate for rapid analysis of iso-butanol.

UV-Assisted Cataluminescent Sensor for Carbon Monoxide Based on Oxygen-Functionalized g-C3N4 Nanomaterials

Cataluminescence (CTL) is one of the most important sensing-transduction principles for the real-time monitoring of atmospheric pollutants. Highly sensitive CTL-based CO detection still remains a challenge because of the relatively poor reactivity of CO and the low catalytic efficiency of the catalysts. Herein, combining ultraviolet (UV)-light activation and chemical modification of the sensing element, we have successfully established a UV-assisted CTL sensor for gaseous CO based on g-C₃N₄ with high sensitivity, selectivity, and stability. UV irradiation can efficiently activate CO molecules and induce the generation of reactive oxygen species (ROS) for CO oxidation. Furthermore, carboxyl groups greatly facilitate the chemisorption of CO on functionalized g-C₃N₄ nanomaterials, thus enhancing the CTL sensitivity. The influences of experimental conditions and the possible catalytic mechanism of CO on functionalized g-C₃N₄ have been investigated in detail. Under the optimal experimental conditions, the proposed CTL sensor presents a detection limit (3σ) toward CO of 0.008 μg mL^-1, which is much lower than the maximum allowable emission concentration of CO in atmospheric conditions (0.030 μg mL^-1). The UV-CTL system is green, sensitive, stable, and low cost, and thus it possesses great potential application in gas sensing.

Cataluminescence sensing of carbon disulfide based on CeO2 hierarchical hollow microspheres

Material morphology-dependent cataluminescence (CTL) sensing characteristic and application are presented in this work. Hierarchical hollow microspheres CeO₂ were synthesized via the hydrothermal reaction of glucose and N, N-dimethyl-formamide (Glu-DMF). SEM, XRD, TEM, HRTEM and BET were used to characterize the prepared CeO₂ materials. Compared with CeO₂ cubics (CeO₂ Cubs), CeO₂ hierarchical hollow microspheres (CeO₂ HMs) show an enhanced CTL response to carbon disulfide. The response and recovery times of CeO₂ HMs-based CTL sensor towards carbon disulfide are about 8 s and 20 s, respectively. CeO₂ HMs exhibits a linear CTL response to carbon disulfide in the concentration range of 0.50~10 μg•mL^-1 with an excellent sensitivity and selectivity. These results suggest that CeO₂ HMs will be a highly promising CTL sensing material for the detection and monitoring carbon disulfide. Graphical abstract CeO₂ hierarchical hollow microspheres (CeO₂ HMs) were synthesized via the hydrothermal reaction of glucose and N, N-dimethyl-formamide (Glu-DMF). Meanwhile, the prepared CeO₂ HMs shows commendable CTL response towards carbon disulfide. Due to the excellent analytical performance of designed CeO₂ HMs-based sensor for carbon disulfide, it has potential application value in various locations.