Rectified
ion transport in nanochannels is the basis of ion channels
in biological cells and has inspired emerging nanochannel applications
in ion separation, Coulter counters, and biomolecule detection and
nanochannel energy harvesters. In this work we fabricated a polyethylene
terephthalate (PET) conical nanochannel using latent ion track etching
technique and then systematically studied the ion transport and influence
of cation species on the nanochannel surface with cyclic I–V measurement. We discovered the electrical
regulation of the reversible and irreversible modification of the
nanochannel transportation by bivalent and trivalent cations, revealing
the existence of the switching threshold voltage which can control
the current rectification in bivalent solution. The proposed mechanism
of the transport state transition in the PET nanochannel mimics behaviors
of voltage-gated biological ion channels. These findings provide new
insight into the understanding of the ion channel signaling and translocation
control of charged particles in nanochannel applications.
Nanochannel gating exists extensively in biological systems and has wide applications in nanofluidic studies. Magnetic control is non‐contact and penetrative compared to chemical or electrical gating. This work introduces the fabrication of magnetically gated single nanochannels by grafting superparamagnetic nanoparticles, via bridging of DNA single strands, onto the inner surface of the PET nanochannels which were prepared by single ion hit and ion track etching. The nanochannel showed sub‐second magnetic response with an ON/OFF ratio of 18 measured by ionic conductance under control with a permanent magnet. These magnetically gated single PET nanochannel are speficically advantageous for superficial drug‐delivery and non‐contact control in nanofluidic applications.
The lateral scattering of ions in solids can induce beam broadening and range uncertainty in the application of high‐energy heavy ions to cancer treatment, ion beam imaging, and nanofabrication. Herein, using membranes of polyethylene terephthalate (PET), polyimide (PI), and diallyl glycol carbonates (CR‐39) of 25 μm–1.6 mm as nuclear track detectors, the lateral scattering of heavy ions with energy of 5.5–80.5 MeV u−1 Kr and C beams in solids are measured. The linear functional relationship between experimental and stopping and range of ions in matter (SRIM)‐simulated lateral scattering in these solid samples is established with determination coefficients R2 of 0.9979, through which the lateral scattering of ion penetrating through solids obtained from experiments can be reliably evaluated by the SRIM simulation results. The results also demonstrated that the resolution of the single ion localization system is better than 300 nm with the lateral scattering as the main limitation.
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