Ines Weber

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Weber

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Ines

ORCID

0000-0002-2251-4753

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Publications 1 - 8 of 8

The Influence of ZnO-ZrO2 Interface in Hydrogenation of CO2 to CH3OH
Šot, Petr; Noh, Gina; Weber, Ines; et al. (2022)
Helvetica Chimica Acta
The influence of the interface in ZnO-ZrO2 catalysts for the selective hydrogenation of CO2 to CH3OH is investigated. Specifically, we perturbed its structure using two different synthetic methods: surface organometallic chemistry (SOMC) and flame-spray pyrolysis (FSP) and investigated the speciation of the resulting materials by spectroscopic techniques, such as XAS, NMR, IR, UV-Vis, and EPR. The results indicate that oxidic Zn particles that co-exist with ZrO2, as synthesized by FSP, show a superior selectivity in contrast to Zn(0) nanoparticles or Zn(II) single sites on ZrO2, formed using SOMC. Further experiments underlined the importance of the ZnO-ZrO2 interface in the process: only materials with such an interface exhibit highly selective production of CH3OH, proceeding likely via the formation of the surface CH3O intermediates.
Handheld device quantifies breath acetone for real-life metabolic health monitoring
Bastide, Grégoire M.G.B.H.; Remund, Anna L.; Oosthuizen, Dina Naude; et al. (2023)
Sensors & Diagnostics
Non-invasive breath analysis with mobile health devices bears tremendous potential to guide therapeutic treatment and personalize lifestyle changes. Of particular interest is the breath volatile acetone, a biomarker for fat burning, that could help in understanding and treating metabolic diseases. Here, we report a hand-held (6 × 10 × 19.5 cm3), light-weight (490 g), and simple device for rapid acetone detection in breath. It comprises a tailor-made end-tidal breath sampling unit, connected to a sensor and a pump for on-demand breath sampling, all operated using a Raspberry Pi microcontroller connected with a HDMI touchscreen. Accurate acetone detection is enabled by introducing a catalytic filter and a separation column, which remove and separate undesired interferents from acetone upstream of the sensor. This way, acetone is detected selectively even in complex gas mixtures containing highly concentrated interferents. This device accurately tracks breath acetone concentrations in the exhaled breath of five volunteers during a ketogenic diet, being as high as 26.3 ppm. Most importantly, it can differentiate small acetone changes during a baseline visit as well as before and after an exercise stimulus, being as low as 0.5 ppm. It is stable for at least four months (122 days), and features excellent bias and precision of 0.03 and 0.6 ppm at concentrations below 5 ppm, as validated by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS). Hence, this detector is highly promising for simple-in-use, non-invasive, and routine monitoring of acetone to guide therapeutic treatment and track lifestyle changes.
Highly selective gas sensing enabled by filters
van den Broek, Jan; Weber, Ines; Güntner, Andreas; et al. (2021)
Materials Horizons
Portable and inexpensive gas sensors are essential for the next generation of non-invasive medical diagnostics, smart air quality monitoring & control, human search & rescue and food quality assessment to name a few of their immediate applications. Therein, analyte selectivity in complex gas mixtures like breath or indoor air remains the major challenge. Filters are an effective and versatile, though often unrecognized, route to overcome selectivity issues by exploiting additional properties of target analytes (e.g., molecular size and surface affinity) besides reactivity with the sensing material. This review provides a tutorial for the material engineering of sorption, size-selective and catalytic filters. Of specific interest are high surface area sorbents (e.g., activated carbon, silica gels and porous polymers) with tunable properties, microporous materials (e.g., zeolites and metal-organic frameworks) and heterogeneous catalysts, respectively. Emphasis is placed on material design for targeted gas separation, portable device integration and performance. Finally, research frontiers and opportunities for low-cost gas sensing systems in emerging applications are highlighted.
Superior Acetone Selectivity in Gas Mixtures by Catalyst‐Filtered Chemoresistive Sensors
Weber, Ines; Braun, Hugo P.; Krumeich, Frank; et al. (2020)
Advanced Science
Acetone is a toxic air pollutant and a key breath marker for non‐invasively monitoring fat metabolism. Its routine detection in realistic gas mixtures (i.e., human breath and indoor air), however, is challenging, as low‐cost acetone sensors suffer from insufficient selectivity. Here, a compact detector for acetone sensing is introduced, having unprecedented selectivity (>250) over the most challenging interferants (e.g., alcohols, aldehydes, aromatics, isoprene, ammonia, H2, and CO). That way, acetone is quantified with fast response (<1 min) down to, at least, 50 parts per billion (ppb) in gas mixtures with such interferants having up to two orders of magnitude higher concentration than acetone at realistic relative humidities (RH = 30–90%). The detector consists of a catalytic packed bed (30 mg) of flame‐made Al2O3 nanoparticles (120 m2 g−1) decorated with Pt nanoclusters (average size 9 nm) and a highly sensitive chemo‐resistive sensor made by flame aerosol deposition and in situ annealing of nanostructured Si‐doped ε‐WO3 (Si/WO3). Most importantly, the catalytic packed bed converts interferants continuously enabling highly selective acetone sensing even in the exhaled breath of a volunteer. The detector exhibits stable performance over, at least, 145 days at 90% RH, as validated by mass spectrometry.
Dynamic Breath Limonene Sensing at High Selectivity
Weber, Ines; Oosthuizen, Dina Naude; Mohammad, Rawan W.; et al. (2023)
ACS Sensors
Liver diseases (e.g., cirrhosis, cancer) cause more thantwo milliondeaths per year worldwide. This is partly attributed to late diagnosisand insufficient screening techniques. A promising biomarker for noninvasiveand inexpensive liver disease screening is breath limonene that canindicate a deficiency of the cytochrome P450 liver enzymes. Here,we introduce a compact and low-cost detector for dynamic and selectivebreath limonene sensing. It comprises a chemoresistive sensor basedon Si/WO3 nanoparticles pre-screened by a packed bed Tenaxseparation column at room temperature. We demonstrate selective limonenedetection down to 20 parts per billion over up to three orders ofmagnitude higher concentrated acetone, ethanol, hydrogen, methanol,and 2-propanol in gas mixtures, as well as robustness to 10-90%relative humidity. Most importantly, this detector recognizes theindividual breath limonene dynamics of four healthy volunteers followingthe ingestion (swallowing or chewing) of a limonene capsule. Limonenerelease and subsequent metabolization are monitored from breath measurementsin real time and in excellent agreement (R (2) = 0.98) with high-resolution proton transfer reaction mass spectrometry.This study demonstrates the potential of the detector as a simple-to-useand noninvasive device for the routine monitoring of limonene levelsin exhaled breath to facilitate early diagnosis of liver dysfunction.
Room-Temperature Catalyst Enables Selective Acetone Sensing
Weber, Ines; Wang, Chang-ting; Güntner, Andreas (2021)
Materials
Catalytic packed bed filters ahead of gas sensors can drastically improve their selectivity, a key challenge in medical, food and environmental applications. Yet, such filters require high operation temperatures (usually some hundreds °C) impeding their integration into low-power (e.g., battery-driven) devices. Here, we reveal room-temperature catalytic filters that facilitate highly selective acetone sensing, a breath marker for body fat burn monitoring. Varying the Pt content between 0–10 mol% during flame spray pyrolysis resulted in Al2O3 nanoparticles decorated with Pt/PtOx clusters with predominantly 5–6 nm size, as revealed by X-ray diffraction and electron microscopy. Most importantly, Pt contents above 3 mol% removed up to 100 ppm methanol, isoprene and ethanol completely already at 40 °C and high relative humidity, while acetone was mostly preserved, as confirmed by mass spectrometry. When combined with an inexpensive, chemo-resistive sensor of flame-made Si/WO3, acetone was detected with high selectivity (≥225) over these interferants next to H2, CO, form-/acetaldehyde and 2-propanol. Such catalytic filters do not require additional heating anymore, and thus are attractive for integration into mobile health care devices to monitor, for instance, lifestyle changes in gyms, hospitals or at home.
Monitoring Lipolysis by Sensing Breath Acetone down to ppb
Weber, Ines; Derron, Nina; Königstein, Karsten; et al. (2021)
Small Science
Mobile health technologies can provide routinely and on‐demand information to manage metabolic diseases (e.g., diabetes, obesity) and optimize their treatment (e.g., exercise or dieting). Most promising is breath acetone monitoring to track lipolysis and complement standard glucose monitoring. Yet, accurate quantification of acetone down to parts‐per‐billion (ppb) is difficult with compact and mobile devices in the presence of interferants at comparable or higher concentrations. Here, a low‐cost detector that quantifies end‐tidal acetone during exercise and rest (challenging since fine alterations need to be resolved) is presented with excellent bias (25 ppb) and unprecedented precision (169 ppb) in 146 breath samples. It combines a flame‐made Pt/Al2O3 catalyst with a chemoresistive Si/WO3 sensor. The detector is robust against order of magnitude higher ethanol concentrations from disinfection and exercise‐driven endogenous breath isoprene ones, as validated by mass spectrometry. This detector accurately tracked the individual lipolysis dynamics in all volunteers, as confirmed by blood ketone measurements. It can be integrated readily into handheld devices for personalized metabolic assessment at home, in gyms and clinics.
Alternate-day fasting elicits larger changes in fat mass than time-restricted eating in adults without obesity – A randomized clinical trial
Derron, Nina; Güntner, Andreas; Weber, Ines; et al. (2025)
Clinical Nutrition
Background & aims Intermittent fasting (IF) is a popular nutritional strategy for weight control and improved metabolic health, however it is unclear which type of intermittent fasting is most effective. This randomized trial directly compared short-term alternate-day fasting (ADF) and time-restricted eating (TRE) with controls in adults with overweight or a high normal weight. The aim was to compare the effects of ADF and TRE versus controls regarding whole-body fat mass loss, weight control and cardiometabolic health. Methods In this 4-week, parallel-arm, randomized clinical trial (February 2021–May 2022), participants aged 18–40 years with a body mass index between 23 and 30 kg/m2 were assigned to ADF (alternating fasting and ad libitum eating days), to TRE (eating only between 12:00–20:00), or control (no change in eating times). The primary outcome was change in total fat volume (assessed by whole-body magnetic resonance imaging). Secondary outcomes were subcutaneous and visceral fat mass, body weight, resting metabolic rate, biochemical markers, energy intake, activity energy expenditure and health-related quality of life. Results Seventy-six participants (mean [standard deviation (SD)] age, 29.6 [5.6] years; body mass index, 25.8 [2.2] kg/m2; 34 [44 %] female) were randomized to ADF (n = 26), TRE (n = 26), or control (n = 24). Seventy-five participants completed the trial (25 in ADF, 26 in TRE, 24 in control). ADF led to a greater reduction in total fat volume than control (mean difference −1059.8 cm3, 95 % CI: −1380.0 cm3 to −739.6 cm3, p < 0.001) and TRE (−695.7 cm3, 95 % CI: −1013.9 to −377.6 cm3, p < 0.001). TRE also reduced total fat volume compared to control (−364.0 cm3, 95 % CI: −621.3 cm3 to −106.7 cm3, p = 0.007). Energy intake was reduced by 34 % [18 %] in ADF, 15 % [21 %] in TRE and 3 % [22 %] in control. ADF, but not TRE, reduced visceral fat mass, resting metabolic rate, triiodothyronine and non-HDL cholesterol compared to controls. Only ADF increased activity energy expenditure and health-related quality of life. No serious adverse events occurred. Conclusions In this randomized clinical trial, ADF was more effective in reducing energy intake than TRE which has subsequent effects on fat mass and body weight. Only ADF improved several cardiometabolic risk factors.

Publications 1 - 8 of 8

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