Monitoring Lipolysis by Sensing Breath Acetone down to Parts‐per‐Billion

Abstract

Mobile health technologies can provide information routinely and on demand to manage metabolic diseases (e.g., diabetes and 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. Herein, a low‐cost detector that quantifies end‐tidal acetone during exercise and rest 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 orders of magnitude higher ethanol concentrations from disinfection and exercise‐driven endogenous breath isoprene ones, as validated by mass spectrometry. This detector accurately tracks 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.

Acetone Sensing and Catalytic Conversion by Pd-Loaded SnO2

“…Depending on the application, the requirements on the response time can be quite different. For example, in breath sensing, response times below 30 s are desired to reach a steady-state response within the duration of one buffered breath pulse [37]. This restricts already the use of operating temperatures below 212.5 • C.…”

Room-Temperature Catalyst Enables Selective Acetone Sensing

“…The resulting selectivity at the same analyte concentrations range from 0.4-600 and are in fair agreement with earlier reports for ethanol (6.7 but at 400 °C [63]) and isoprene (0.5 [19]). However, these are insufficient and can lead to significant measurement errors, for instance, when monitoring breath acetone in situ during cardio-respiratory fitness-adapted [64] cycling [26]. Response of a Si/WO3 sensor to 1 ppm acetone, acetaldehyde, H2, isoprene, CO, methanol, ethanol, formaldehyde and 2-propanol (a) with 30 mg pure Al2O3 (i.e., inactive, Figure 3a) and (b) 3 mol% Pt/Al2O3 (i.e., active, Figure 3c) at 40 °C and 90% RH.…”

“…While Co 3 O 4 and PdO nanocatalysts on In 2 O 3 hollow spheres removed toluene, CO, H 2 and NH 3 quite effectively over acetone, their performance on ethanol has not been evaluated yet to assess possible interference [25]. This was addressed with a 0.2 mol% Pt/Al 2 O 3 catalyst at 135 • C that featured unprecedented acetone selectivity (>250) over ethanol, H 2 , CO, isoprene, NH 3 , methanol, formaldehyde, acetaldehyde, toluene and m-xylene at 90% relative humidity (RH) [19], as proven also for human breath with mass spectrometry [26]. The high acetone selectivity was associated [19] with interferant oxidation (e.g., ethanol/methanol [27]) by hydroxyl-related species on Al 2 O 3 surfaces.…”

Two-photon fluorescence imaging of mitochondrial viscosity with water-soluble pyridinium inner salts

“…However, inorganic probes have limited further biomedical applications due to their inherent cytotoxicity, low solubility and medium photostability. 10 In comparison, organic fluorogenic probes have attracted much attention due to their high spatiotemporal imaging and noninvasive manner in living systems. 11,12 The traditional viscosity fluorogenic probes are not sensitive enough, which are only used at the level of living cells, and could not be used to monitor mitochondrial viscosity in tissues or/even in vivo.…”