A novel electronic nose for sensing (E)-2-hexenal based on Mn-MOF nanonets with NADPH-like activity

Bioreceptors are increasingly popular for selective aroma sensing but face challenges with receptor separation and cell culture. Here, we developed a bioreceptor-free electronic nose employing Mn-metal organic framework (Mn-MOF) nanonets as sensing materials for rapid electrochemical quantification of (E)-2-hexenal, a characteristic aroma commonly found in various foods. A simple solvent-mediated morphology engineering technology was proposed to create Mn-MOF structures, including nanoparticles, nanowires, and nanonets. Among them, Mn-MOF nanonets with unique cross-linked structures demonstrated high Eh adsorption capacity, mimicked bioreceptors' trapping effect, and exhibited NADPH-like activity to selectively recognize Eh through the hydrogenation reduction of aldehyde groups. This resulting Mn-MOF-based (E)-2-hexenal sensor offers excellent performance, with a wide dynamic range of 0.2-322 μM and a low detection limit of 177 nM. This study presents a novel method for rapid aroma quantification.