Highly sensitive and selective imaging of human-borne volatile organic compounds (VOCs) enables an intuitive understanding of their concentrations and release sites. While multi-VOC imaging methods have the potential to facilitate step-by-step metabolic tracking and improve disease screening accuracy, no such system currently exists. In this study, we achieved simultaneous imaging of ethanol (EtOH) and acetaldehyde (AcH), the starting molecule and an intermediate metabolite of alcohol metabolism, using a multiwavelength VOC imaging system. The system employed alcohol dehydrogenase-catalyzed substrate oxidation (ADH_OX) and reduction (ADH_RD) reactions. The oxidation of EtOH by ADH_OX in the presence of NAD⁺ produced NADH, which was subsequently oxidized by diaphorase (DP) with resazurin, leading to the resorufin formation, characterized by red fluorescence (excitation at 560 nm and fluorescence at 590 nm). Reduction of AcH by ADH_RD consumed NADH, leading to a decrease in blue fluorescence (ex. 340 nm, fl. 490 nm). Meshes incorporating ADH_OX-DP or ADH_RD were arranged in tandem in front of a camera. Fluorescence images were captured, while a mixture of gaseous EtOH and AcH was applied by switching between two bandpass filters at 1 Hz. Each mesh exhibited selective responses to the target VOCs, with no significant impact on the dynamic range observed in either the single or tandem configurations (EtOH 1–300 ppm, AcH 0.2–5 ppm). The 90% response time was close after time–domain image differential analysis (EtOH = 26 s and AcH = 15 s). Furthermore, the system enabled simultaneous and quantitative imaging of EtOH and AcH concentrations in the breath after alcohol consumption. It also distinguished differences in alcohol metabolism based on the alcohol dehydrogenase 2 (ALDH2) activity, as indicated by the EtOH/AcH ratio (ALDH2 active vs nonactive: 120.9/0.71 ppm vs 129.2/1.99 ppm).

中文翻译：

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基于多波长酶法生物荧光法的呼吸乙醇和乙醛串联成像


对人源性挥发性有机化合物 （VOC） 进行高灵敏度和选择性成像，可以直观地了解其浓度和释放位点。虽然多 VOC 成像方法有可能促进逐步代谢跟踪并提高疾病筛查的准确性，但目前尚不存在这样的系统。在这项研究中，我们使用多波长 VOC 成像系统实现了乙醇 （EtOH） 和乙醛 （AcH） 的同步成像，乙醇 （EtOH） 和乙醛 （AcH） 是酒精代谢的起始分子和中间代谢物。该系统采用醇脱氢酶催化的底物氧化 （ADH_OX） 和还原 （ADH_RD） 反应。在 NAD⁺ 存在下，ADH_OX 氧化 EtOH 产生 NADH，随后被刃天青的心肌黄酶 （DP） 氧化，导致试卤灵形成，其特征是红色荧光（560 nm 激发和 590 nm 荧光）。ADH_RD 消耗 NADH 减少 AcH，导致蓝色荧光减少（例如 340 nm，fl. 490 nm）。结合 ADH_OX-DP 或 ADH_RD 的网格在相机前串联排列。捕获荧光图像，同时通过在两个 1 Hz 的带通滤光片之间切换来施加气态 EtOH 和 AcH 的混合物。每个网格都对目标 VOC 表现出选择性响应，对在单一或串联配置（EtOH 1–300 ppm，AcH 0.2–5 ppm）中观察到的动态范围没有显著影响。时域图像差异分析后，90% 的响应时间接近 （EtOH = 26 s 和 AcH = 15 s）。此外，该系统能够对饮酒后呼吸中的 EtOH 和 AcH 浓度进行同步定量成像。 它还根据乙醇脱氢酶 2 （ALDH2） 活性区分酒精代谢的差异，如 EtOH/AcH 比率所示（ALDH2 活性与非活性：120.9/0.71 ppm vs 129.2/1.99 ppm）。