Cesium-Induced Ionic Conduction through a Single Nanofluidic Pore Modified with Calixcrown Moieties.

Area of Science:

• Nanofluidics
• Chemical Sensing
• Host-Guest Chemistry

Background:

• Selective ion detection is crucial for environmental monitoring and chemical analysis.
• Nanofluidic devices offer unique platforms for ion recognition due to confined geometries.
• Host-guest interactions provide a basis for molecular recognition and sensing.

Purpose of the Study:

• To develop a nanofluidic device for the selective recognition of cesium ions.
• To exploit host-guest interactions within a confined nanopore geometry for ion sensing.
• To demonstrate electrical rectification as a readout mechanism for cesium ion detection.

Main Methods:

• Synthesis and surface functionalization of amine-terminated p-tert-butylcalix[4]arene-crown (t-BuC[4]C-NH2) on a poly(ethylene terephthalate) (PET) membrane nanopore.
• Carbodiimide coupling chemistry for pore surface modification.
• Electrical current-voltage (I-V) measurements to observe rectification phenomena.
• Theoretical modeling using Nernst-Planck and Poisson equations.

Main Results:

• Successful functionalization of the nanopore surface with the host molecule.
• Observation of electrical rectification in the I-V curves upon exposure to cesium ions, attributed to t-BuC[4]C-Cs+ complex formation.
• Demonstration of selectivity, as other alkali cations did not significantly alter the rectification characteristics.
• Experimental findings validated by theoretical simulations of ion transport.

Conclusions:

• The developed nanofluidic device enables selective detection of cesium ions via host-guest interactions.
• The functionalized nanopore exhibits ion-selective electrical rectification, serving as a sensitive detection method.
• This approach offers a promising strategy for developing advanced nanofluidic sensors.