Dual-target gas-phase biosensor (bio-sniffer) for assessment of lipid metabolism from breath acetone and isopropanol

Volatile organic compounds (VOCs) in breath and skin gas are promising samples for non-invasive and simple disease screening and metabolism assessment. In addition, simultaneous measurement of multiple VOCs helps to improve the examination quality and allows for more reliable disease screening and investigation of detailed metabolic pathways. In this study, we have developed a dual-target gas-phase biosensor (bio-sniffer) that allows for measurement of isopmpanol (IPA) and acetone vapours, relevant VOCs for lipid metabolisms, by simply exchanging coenzyme solutions. The measurement exploited a reversible redox reaction that was catalysed by secondary alcohol dehydmgenase (S-ADH). IPA/acetone was oxidised/reduced together with reduction/oxidation of a coenzyme, oxidised (NAD(+))/reduced (NADH) form of beta-nicotinamide adenine dinucleotide, depending on surrounding pH (8.5/7.5). This reaction resulted in producing/consuming NADH which exhibited autofluorescence (lambda(ex) = 340 nm, lambda(fl) = 490 nm), by which IPA/acetone was measured. The characterization of the dual-target bio-sniffer showed the dynamic ranges for IPA and acetone vapour were 3.3-1000 ppb and 13.0-3000 ppb, respectively, which encompasses those in the breath of healthy people (IPA, 10-30 ppb; acetone, 200-900 ppb). Finally, the dual-target bio-sniffer was applied for measurement of IPA and acetone in the breath of healthy people. As with the standard IPA and acetone vapour, intermittent and repeated measurement of both VOCs in the breath was demonstrated. These results indicated that the dual-target bio-sniffer would be a useful tool to assess the lipid metabolism in detail by measuring temporal changes of IPA and acetone concentrations in the breath.

Automated summary

VOCs in breath and skin gas are promising samples for disease screening and metabolism assessment, with simultaneous measurement of multiple VOCs improving examination quality. A dual-target gas-phase biosensor was developed to measure IPA and acetone vapours, relevant to lipid metabolisms, showing dynamic ranges that encompass those in the breath of healthy people. The biosensor was applied for measurement of IPA and acetone in the breath of healthy people, demonstrating intermittent and repeated measurement of both VOCs.