Biomimetic NaK Channel Membrane Enabled by a Crown Ether-Coordinated Metal-Organic Framework

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Biomimetic Engineering

Background:

• Biological NaK channels are crucial for life processes, offering high ion selectivity and dynamic gating.
• Replicating these multifunctional properties in synthetic ion channels presents significant challenges.

Purpose of the Study:

• To design and fabricate a novel metal-organic framework (MOF) channel membrane that mimics the selectivity and gating functions of biological NaK channels.
• To investigate the ion transport properties and selectivity of the synthesized hybrid MOF membrane.

Main Methods:

• A one-step coordination strategy was employed to assemble UiO-66-COOH and carboxybenzo-15-crown-5 (15C5-COOH) into a hybrid MOF channel membrane.
• Ion selectivity (M+/Mg2+ and Na+/K+) and dynamic gating by Mg2+ were characterized using electrochemical and transport measurements.

Main Results:

• The hybrid MOF membrane demonstrated ultrahigh monovalent cation selectivity over Mg2+ (M+/Mg2+ > 10^2).
• Unprecedented Na+/K+ selectivity (> 10^3) was achieved under mixed-ion conditions.
• Mg2+ ions dynamically gated Na+ and K+ transport with significant on-off ratios (~30).

Conclusions:

• The synergistic interplay of crown ether and carboxyl groups within subnanometer MOF pores is responsible for the observed high performance.
• This work presents a versatile strategy for designing multifunctional artificial ion channels.
• The developed MOF membrane shows potential for advanced ionic devices in artificial cells and biomedical technologies.