Bioinspired hierarchical porous membrane for efficient enrichment and quantitative analysis of the environmental metabolite 3,5-dichlorosalicylic acid.

3,5-Dichlorosalicylic acid (3,5-DiClSA) serves as a metabolite for some pharmaceuticals or pesticides entering the environmental media, such as water and soil, leading to environmental pollution, inhibiting crop growth, and exerting toxic effects on aquatic organisms. Therefore, the quantitative analysis of 3,5-DiClSA is of great significance for protecting the environment and promoting the green development of agriculture. Inspired by the hierarchical structure and selective reabsorption mechanism of renal tubules in the kidney, we modified nanochannels with amino-functionalized pillar[6]arene (AP6) to fabricate a bioinspired hierarchical porous membrane (AP6 membrane). This membrane possesses a multiscale porous structure; the nanopores enable efficient enrichment of 3,5-DiClSA and selective interception of interfering substances, while AP6, with angstrom-scale pores, achieves specific binding of 3,5-DiClSA through host-guest interactions. The AP6 membrane specifically recognizes 3,5-DiClSA via its ionic current response, and a good linear relationship is observed between 3,5-DiClSA concentration and the change in ionic current over the range of 5 × 10-7 M to 1 × 10-3 M. The limit of detection (LOD) is as low as 3.1 × 10-7 mol/L. The spike and recovery analysis of 3,5-DiClSA in agricultural and environmental samples demonstrates that the proposed AP6 membrane can quantitatively detect 3,5-DiClSA at micromolar concentrations, with spike recovery rates ranging from 92.00% to 108.00% and relative standard deviations (RSDs) below 5%. The AP6 membrane exhibits excellent detection performance, anti-interference capability, and reusability, making it an effective nanofluid sensor for analyzing environmental metabolites and demonstrating promising application potential in environmental monitoring, agricultural safety assessment, and related fields.