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

Highlights: • A portable membrane sensor is prepared via in situ growth of novel cationic MOF. • An on-off-on luminescent mode is proposed to replace previous AA detection methods. • The PEM sensor displays effective MnO₄⁻ and AA detection performance. • Based on IMP logic gate, PEM realizes dual-component analysis (MnO₄⁻, AA) in water. 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.