Nanomaterial-Based Sensors for Exhaled Breath Analysis: A Review

Abstract

The quantification of gases in breath has gained significant attention as a modern diagnosis method due to its non-invasive nature, and as a painless and straightforward method for the early detection of physiological disorders. Several notable clinical applications have been established for disease diagnosis by correlating exhaled breath samples and specific diseases. In addition, diverse breath molecules represent a biomarker of specific illnesses and are precisely identified by the standard analytical method. However, because of the bulky equipment size, expensive cost, and complexity in measurement when using analytical methods, many researchers are focusing on developing highly selective, sensitive, stable, robust, and economical sensors for breath analysis. It is essential to optimize approaches such as breath sampling, biomarker sensing, data analysis, etc. However, the detection of ppb-level biomarkers in exhaled breath is too challenging to solve due to the abundance of interfering gases. We present a brief and comprehensive review of a recent diagnostic technique that employs nanomaterial (NM)-based sensors to identify the volatile organic compounds (VOCs) associated to diseases. Because they are easily fabricated, chemically versatile, and can be integrated with existing sensing platforms, NMs are ideal for such sensors. Initially, this review provides crucial details about certain representative biomarkers found in diseased patients’ exhaled breath and the demand for breath sensors. Subsequently, the review highlights diverse sensor technologies such as electrical, optical, and mass-sensitive gas sensors and describes their sensing capability for detecting the biomarkers’ concentrations and their primary endeavor of diagnosing disease. Finally, the pitfalls and challenges of sensor characteristics are discussed. This article lays the basis for developing high-performance gas sensors based on novel NMs.

Diabetes noninvasive diagnostics and monitoring through volatile biomarkers analysis in the exhaled breath using optical absorption spectroscopy

“…The main issues to chemical sensors are cross-sensitivity to the other volatile molecules and short operation lifetime. Also, influence of humidity and temperature on sensors measurement results should be reduced [106].…”

“…Some other DM-associated VMBs are also presented in the literature: octane; pentane; decane; 2-methylpentane; heptane; 2,3,5-trimethylhexane; 2,4-dimethyl-1-heptane [82,106].…”

“…The oxygen-containing compounds Acetone (C 3 H 6 O) Ketone bodies' overproduction [78,83,84] BG level Toxic effect associated with diabetic ketoacidosis [89] Fasting, lung cancer [106] The nitrogencontaining compounds Nitric oxide (NO), methyl nitrate (CH 3 NO…”

“…Isopropanol is metabolized from propanoates, enzyme isopropanol dehydrogenase catalysis [116]. Also, in the liver, alcohol dehydrogenase can convert acetone to isopropanol [117] The metabolism of the microbiome influences on the BG level [97,98] Breast cancer, lung cancer [106] The sulfur-containing compounds Hydrogen sulfide (H₂S), Ethyl mercaptan (C₂H₆S), dimethyl sulfide (C 2 H 6 S) Originating from the incomplete metabolism of methionine via the transamination pathway [76,79,80], they are considered as liver failure markers [76] Liver failure markers, such as serum alpha-fetoprotein, apoptosis-associated proteins, serum actin-free Gc-globulin, and serum glycodeoxycholic acid [118] H 2 S is a mediator of oxidative stress, apoptosis, or inflammation [119] Liver failure [118] breath acetone and plasma beta-hydroxybutyrate was 0.821 (Figure 6). For healthy subjects, physiological hyperglycemia causes insulin increase, suppresses lipolysis, and transiently reducing circulating free fatty acids, and also ketone bodies.…”

Influence of ventilatory parameters on the concentration of exhaled volatile organic compounds in mechanically ventilated patients

“…12 A wide variety of analytical techniques have been employed for disease detection in breath, including mass spectrometry either after chromatographic separation or as direct injection technique, 13 ion mobility spectrometry (IMS), 14 optical and laser-based spectroscopy, [15][16][17] electronic noses 18 and nanomaterial-based gas sensors. 19 The analytical technique used and the fraction of breath being sampled will influence the choice of breath sampling method. Breath can be sampled using bags, 20 canisters 21 or by taking advantage of bespoke solutions either developed in-house or commercial ones.…”