Interfacial Host–Guest Recognition at Poly(sulfobutyl-β-cyclodextrin)-Macroporous Carbon: A Supramolecular Electrochemical Protocol for Nitrophenol Isomers Sensing

Owing to their inherent stability, nitrophenol isomers (NPs) persist and accumulate in the environment, posing critical ecosystem risks through bioaccumulation and endocrine disruption, and thus advanced detection methods are urgently needed. Herein, we describe the fabrication of poly(sulfobutyl-β-cyclodextrin)-functionalized macroporous carbon (PSBCD-MPC) immobilized on a glassy carbon electrode (GCE), enabling discrimination of ternary nitrophenol isomers in aqueous environmental matrices. The differential pulse voltammetry (DPV) response of PSBCD-MPC interface toward three nitrophenol isomers showed three separated electrochemical signals with distinct linear ranges of 1-180 μM for <i>o</i>-nitrophenol (<i>o</i>-NP), 1-200 μM for both <i>m</i>-nitrophenol (<i>m</i>-NP) and <i>p</i>-nitrophenol (<i>p</i>-NP), and relatively lower detection limits (LOD) of 0.28 μM for <i>o</i>-NP, 0.22 μM for <i>m</i>-NP, and 0.31 μM for <i>p</i>-NP, respectively. The macroporous architectures of MPC establish rapid mass-transfer and electron-transfer highways, while the strategic integration of PSBCD moieties within the conductive matrix enables differentiated host-guest recognition. This synergy facilitates precise discrimination of nitrophenol isomers through a combination of host-guest interactions and electrochemical interfacial microenvironment effects, providing a robust platform for their selective detection. Furthermore, the constructed PSBCD-MPC sensing interface exhibited recoveries of 95.0-104.6% in real aqueous matrices, demonstrating field-applicable potential for simultaneous nitrophenol isomer monitoring.