Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

Abstract

Endogenous volatile organic compounds (VOCs) such as acetone in exhaled human breath are associated with metabolic conditions in the bloodstream. Development of compact, rapid detectors of exhaled breath chemical composition in clinical settings is challenging due to the small sample size that can be collected during a single exhalation as well as spectroscopic interference by the abundance of water. In this paper, we show that the activity of a catalytic polymer membrane (Nafion 117) toward the heterogeneous condensation reaction of immobilized resorcinol reagent with gas-phase acetone can be preserved even at 100% ambient relative humidity through the incorporation of organic acids such as vanillic or tiglic. The reaction produces a colored flavan product that permits highly selective and sensitive correlation to acetone concentration in exhaled breath. Such behavior suggests solvent displacement, analogous to homogeneous liquid-phase systems. However, unlike classic acid-base equilibria, the extent of optode water resistance is shown to increase with the pK of the imbibed organic acid while peak signal intensity of the imbibed acid undergoes a bathochromic shift to longer wavelengths. These observations are consistent with competition between organic acid deprotonation by water in a mixed solvent system on the one hand and immobilization on the other. Finally, we demonstrate how when applied to the direct chemical analysis of acetone in exhaled human breath, the approach yields excellent correlation to blood glucose in diabetics.

Mitigation of Humidity Interference in Colorimetric Sensing of Gases

“…Similar to the biosystems, there are two kinds of colorimetric sensing platforms: (1) the lock-and-key sensing platform, where the sensing probe is highly selective to a specific analyte, e.g., the antibody–antigen interaction; (2) the colorimetric sensor array, where the sensing probes in the array cross-react with a large set of analytes, such as the mammalian olfactory system. As for the lock-and-key sensing platform, the concentration of the analyte can be quantified by the optical signal, ,, while in the colorimetric sensor array, a large set of analytes can be classified through pattern recognition based on the high dimensional data. ,, …”

“…(C) Membrane response with acetone exposure at 100% RH. Reproduced with permission from ref . Copyright 2018 American Chemical Society.…”

“…Nafion membrane 35,101 The incorporated organic acids played an important role in mitigating the humidity interference to the Nafion membrane catalysts in humid breath environment. 35 Nitric oxide (NO) NO level is elevated in asthma with inflammatory.…”

“…Worrall et al reported an approach of using organic acid incorporated Nafion membranes to maintain the catalytic capability in colorimetric detection of exhaled acetone in the humid breath environment for diabetes diagnosis. 35 The colorimetric detection was based on the chemical reaction between breath acetone and membrane-immobilized resorcinol, producing colored flavan, as shown in Figure 26A. 35 In order to preserve the catalytic activity of Nafion membrane, organic acids such as vanillic or tiglic were immobilized in the membrane.…”

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

“…There are abundant volatile organic compounds (VOCs) in human exhaled breath, some of them have been identified as biomarkers of diseases [25,26]. Analysis of concerned VOCs in exhaled breath has been recognized as a useful method for diagnosis of disease such as diabetes [27,28,29], asthma [30,31], lung cancer [32,33,34] and breast cancer [35,36]. The most outstanding advantage of breath analysis is that the pain-free and noninvasive collection of sample represents minimal risk to the human subjects [13,37].…”