A handheld biofluorometric system for acetone detection in exhaled breath condensates

As a marker of human metabolism, acetone is important for lipid metabolism monitoring and early detection of diabetes. In this study, we developed a handheld biosensor for acetone based on fluorescence detection by utilizing the enzymatic reaction of secondary alcohol dehydrogenase (S-ADH) with β-nicotinamide adenine dinucleotide (NADH, λ_ex = 340 nm, λ_em = 490 nm). In the reaction, NADH is oxidized when acetone is reduced to 2-propanol by S-ADH, and the acetone concentration can be measured by detecting the amount of NADH consumed in this reaction. First, we constructed a compact and light-weight fluorometric NADH detection system (209 g for the sensing system and 342 g for the PC), which worked using battery power. Then, sensor characteristics were evaluated after optimization of the working conditions. The developed system was able to quantify acetone in a range of 510 nM-1 mM within 1 minute. The developed battery-operated acetone biosensor demonstrated its ability to measure the acetone concentration in the exhaled breath condensate of 10 healthy subjects at rest (23.4 ± 15.1 μM) and after 16 h of fasting (37.7 ± 14.7 μM) and it distinguished the results with significant differences (p = 0.011). With the advantages of handheld portability, and high levels of sensitivity and selectivity, this sensor is expected to be widely used in clinical diagnosis and wearable biochemical sensors in the future.