Xiaoxiao Cheng, Tatsuya Nishimura, Ritsuko Yamase, Hiromi Nishikawa, Sumana Mandal, Sandip Das, Masaya Ueno, Hiroshi Arakawa, Shafiqur Rahman, Hiroshi Hasegawa, Tomoki Ogoshi, Yasufumi Takahashi, Yuri E. Korchev, Atsushi Hirao, Yanjun Zhang, Katsuhiro Maeda
Analyzing 1-methylnicotinamide (1-MNA), a nicotinamide metabolite implicated in metabolic disorders, in biological systems is challenging owing to its trace-level concentrations and matrix effects. Herein, we report an electrochemical sensor featuring a micropipette functionalized with charge-tunable nanomembranes consisting of carboxylated pillar[6]arene-modified poly(vinyl alcohol) (CAP6A-PVA) for rapid metabolite detection. The covalently cross-linked CAP6A-PVA nanomembrane demonstrates exceptional 1-MNA detection capability with a LOD of approximately 1.16 nM,400-fold higher than that of conventional fluorescence-based detection methods. We also achieved real-time 1-MNA detection over a wide concentration range (10 nM-1000 μM) at a broad range of physiologically relevant pH (6.0-9.0). The CAP6A-PVA platform was successfully used to quantify 1-MNA in unprocessed mouse urine samples, demonstrating its real clinical utility by eliminating the need for sample pretreatment.