In situ self-assembled cationic lanthanide metal organic framework membrane sensor for effective MnO₄⁻ and ascorbic acid detection

Developing portable membrane sensors to accurately detect the biomolecule ascorbic acid (AA) is extremely important for food safety and human health. Herein, we successfully design and synthesize a novel cationic metal organic framework (Eu-pbmc, Hpbmc = 2-(pyridine-2-yl)-1H-benzimidazole-5-carboxylic acid) and assemble polyacrylonitrile/Eu-pbmc membrane (PEM) by an in-situ growth strategy. Benefiting from the appreciable loading of Eu-pbmc nanoparticles and high water permeation flux, PEM possesses effective detection for MnO₄⁻ with a limit of detection (LOD) of 17 nM. Utilizing the cationic porous framework, we load MnO₄⁻ into PEM and construct a “on-off-on” system for effective AA detection. The oxidative MnO₄⁻ can be reduced by AA and the resulting turn-on luminescence can reflect the concentration of AA. Compared with pure Eu-pbmc crystals, PEM exhibits improved AA detection performance with LOD of 48 nM and detection time of 1 min via a concise detection operation. The stable membrane sensor realizes an accurate detection in real biological samples, meeting the practical requirement. Moreover, an IMP logic gate is helpful to analyze MnO₄⁻ and AA in water. The proposed novel luminescence platform as well as reasonable “on-off-on” luminescence mode provide a promising method for AA detection.