Image-based parallel measurement of alcohol metabolism-related ethanol and acetaldehyde in exhaled air

Abstract

Measurement of volatile organic compounds (VOCs) contained in exhaled air and skin gas would be effective for the noninvasive assessment of metabolism and disease screening. Furthermore, simultaneous measurement of multiple VOCs that were generated at the same metabolic pathway is important for understanding metabolic functions, e.g., evaluation of alcohol metabolism possible by measuring ethanol (EtOH) and acetaldehyde (AcH). Here we report a parallel gas-imaging system of breath EtOH and AcH using the oxidation and reduction reactions of nicotinamide adenine dinucleotide (NADH)-dependent alcohol dehydrogenase (ADH). This system allowed gas-imaging of two VOCs by using a high-sensitivity camera to capture a fluorescence of NADH (excitation:340 nm, fluorescence: 490 nm), which increased by the oxidation of EtOH and decreased by the reduction of AcH catalyzed by the ADH in the enzyme immobilized meshes placed parallel in front of the camera. In addition, the system was possible to quantify the EtOH and AcH in exhaled air after alcohol consumption based on the image analysis technique.