Gadolinium-Sensitive Artificial Nanochannel Membrane for Information Encryption

Inspired from ion channels in the myelinated axon of <i>Xenopus laevis</i> found to be affected by gadolinium on axonal currents, we present a solid nanochannel membrane sensitive to gadolinium (Gd³⁺), which can be achieved via the use of the macrocyclic triacetic acid derivative in the host-guest chemistry approach. The macrocyclic nanochannel has good responsiveness toward Gd³⁺, even at the nanomolar concentration level, evidenced by discernible changes in rectification, ionic conductance, and XPS analyses. Notably, the Gd³⁺-sensitive nanochannel membrane can be switched by the addition of a diethylenetriaminepentaacetic acid (DTPA) derivative. Further studies have indicated that the gated behavior of Gd³⁺ in the nanochannel can be attributed to the strong binding strength between DO3A and Gd³⁺, which induces a surface charge reversal within the nanochannel. The mechanism has been confirmed through several experimental techniques, including isothermal titration calorimetry (ITC) experiments, fluorescence titration experiments, and finite element analysis. Based on its Gd³⁺ responsiveness of the constructed ion channel, we successfully developed an advanced multilevel information encryption application of the artificial solid nanochannel membrane. Furthermore, it is anticipated that a more effective encryption system will be built by utilizing the bionic ion channel system's ease of use and straightforward functionalization.