Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
Analyst. 2020 Aug 21;145(16):5594-5602. doi: 10.1039/d0an00830c. Epub 2020 Jul 7.
Core-shell modified nanofiber mats were used as ion-selective membranes for the first time. Keeping the overall macroscopic size of the sensing element the same as for classical plasticized poly(vinyl chloride) membranes, herein the proposed nanofiber based systems resulted in ultrathin (<10 nm) recognition layers with the total area nearly 3 orders of magnitude larger and the surface to volume ratio close to 7.5 × 10. Thus, for the first time close to 2D potentiometric receptors were obtained. Formation of thin and continuous liquid recognition layers on nanofibers was confirmed by XPS studies. The nanofiber based ion-selective mats used in the classical internal-solution arrangement were characterized with analytical parameters - the slope and detection limit well comparable to those for classical plasticized poly(vinyl chloride) based membranes. Despite the novel arrangement of the ion-selective layer and its nanometric thickness, the reproducibility of the recorded potentials, studied for more than 30 days, was high. Using confocal microscopy it was shown that electrolyte transport through porous nanofibers' mat phase is the rate limiting step in conditioning of the receptor layer. The estimated electrolyte diffusion coefficients for the nanofiber phase are close to 10 cm s, and thus are orders of magnitude lower compared to values characterizing ion transport through classical poly(vinyl chloride) based membranes. The truly nanostructural character of nanofiber ion-selective mats is visible in chronoamperometric experiments. It was shown that a core-shell nanofiber mat behaves as an array of nanoelectrodes - individual nanofibers. Thus, the novel nanofiber based architecture of ion-selective mats brings also a new quality to the current based electrochemistry of ion-selective sensors.
核壳修饰纳米纤维垫首次被用作离子选择性膜。在保持与经典的增塑聚氯乙烯膜相同的整体宏观尺寸的情况下，本文提出的基于纳米纤维的系统导致了超薄(<10nm)的识别层，其总面积大近 3 个数量级，比表面积接近 7.5×10。因此，首次获得了接近二维的电位型受体。XPS 研究证实了在纳米纤维上形成薄而连续的液体识别层。使用经典内溶液布置的基于纳米纤维的离子选择性垫具有分析参数-斜率和检测限与经典的增塑聚氯乙烯基膜相当。尽管离子选择性层的新排列及其纳米级厚度，但记录电位的重现性高，研究超过 30 天。使用共焦显微镜表明，通过多孔纳米纤维垫相的电解质传输是受体层调节的限速步骤。估计的纳米纤维相的电解质扩散系数接近 10cm/s，因此与通过经典聚氯乙烯基膜表征的离子传输值相比低几个数量级。纳米纤维离子选择性垫的真正纳米结构特征在计时安培实验中可见。结果表明，核壳纳米纤维垫表现为纳米电极阵列-单个纳米纤维。因此，新型基于纳米纤维的离子选择性垫结构为离子选择性传感器的电流电化学带来了新的品质。
