Screening diabetes mellitus through monitoring lipid metabolism by measuring and imaging breath acetone using bio-fluorometric gas sensors
K. Iitani 1, Z . Geng 1, N. Mizukoshi 2, M. Ye 2, P-J. Chien and K. Mitsubayashi,1,2
1. Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Japan
2. Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
Abstract:
| The human body produces energy by metabolizing fatty acids when blood glucose and glycogen are not available. Ketone bodies are produced in this process and exist in the blood. Acetone, one of the ketone bodies has high volatility and is exchanged from blood to the exhaled breath in the lung at a ratio of 330:1. Particularly, patients with diabetes mellitus who cannot utilize glucose as an energy source emit higher concentrations of acetone (> 1 ppm) than healthy people at rest. Here we report nicotinamide adenine dinucleotide (NAD) dependent secondary alcohol dehydrogenase (S-ADH) based gas-phase biosensor “bio-sniffer” and gas-imaging system “sniff-cam”. S-ADH catalyzes an enzymatic reaction that produces isopropanol and oxidized NAD (NAD+) from gaseous acetone and reduced NAD (NADH) in a slightly acidic environment. NADH that is consumed in the reaction shows fluorescence (ex:340 nm, em:490 nm). Therefore, the concentration of acetone can be quantified by decreasing fluorescence. The bio-sniffer was constructed by a fiber optic system. The acetone bio-sniffer showed a wide dynamic range (20–5300 ppb) that encompassed breath acetone concentration of healthy and patients with diabetes (200–900 ppb and >900 ppb, respectively) with enough selectivity against typical chemicals contained in exhaled breath. The acetone bio-sniffer enabled evaluate fasting state, exercise effect, and classification of diabetes mellitus by measuring breath acetone. Note that human subject experiments were conducted with the approval of an IRB of TMDU (#2014-01 and #2015-06). Based on the bio-sniffer technology, a sniff-cam was developed for imaging acetone gas distribution. The dynamic range of the sniff-cam was 50–2000 ppb. When exhaled breath was applied to the S-ADH immobilized membrane, a decrease in fluorescence intensity was observed at around the breath application point. The sniff-cam was also allowed to evaluate the fasting state by imaging breath acetone. |
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