Bimetallic Porphyrin-Based Metal–Organic Framework for Noninvasive Electrochemical Monitoring of Nitric Oxide in Plants and Fruits

In this study, MX@Fe/NiPor-MOF was constructed at room temperature by assembling a bimetallic porphyrin-based metal–organic framework (Fe/NiPor-MOF) with transition metal carbide nanosheets (MX), and further integrated with screen-printed carbon electrodes (SPCEs) for noninvasive NO detection in plants and fruits.

The cooperative interaction between Fe/Ni bimetallic centers enabled efficient electron redistribution, with Ni acting as an electron reservoir to facilitate rapid and reversible Fe²⁺/Fe³⁺ redox cycling. Meanwhile, the porous MOF structure and highly conductive MX promoted the exposure of Fe–N₄/Ni–N₄ active sites and established efficient electron transport pathways. Benefiting from these structural and electronic advantages, the MX@Fe/NiPor-MOF/SPCE electrochemical sensor exhibited excellent electrocatalytic performance toward NO detection, including a wide linear range (0.5–565.5 μM), a low detection limit (0.14 μM), a high sensitivity (1.95 μA·μM^–1·cm^–2), and excellent anti-interference capability.