Self-Assembly of Size-Controlled m-Pyridine-Urea Oligomers and Their Biomimetic Chloride Ion Channels

A hollow Ag/AgCl nanoelectrode for single-cell chloride detection

This work reports the construction of a miniaturized Ag/AgCl nanoelectrode on a nanopipette, which is capable of dual-functions of single-cell drug infusion and chloride detection and is envisioned to promote the study of chloride-correlated therapeutic effects.

Phase Behavior and Aggregate Transition Based on Co-assembly of Negatively Charged Carbon Dots and a pH-Responsive Tertiary Amine Cationic Surfactant

We studied the co-assembly of an oppositely changed binary mixture of selenium-doped carbon quantum dots (Se-CQDs) and N,N-dimethyl octylamide-propyl tertiary amine (DOAPA) through turbidity, ζ potential measurement, and cryogenic transmission electron microscopy (cryo-TEM) with the aim of fabricating supramolecular assemblies with multiple dimensions and novel morphologies. The Se-CQD/DOAPA binary mixture exhibited abundant phase behavior, in which an isotropic phase (I₁) was first observed, followed by turbidity (T), precipitation (P), and a second isotropic phase (I₂), as the DOAPA concentration increased. Then we focused on investigating the morphologies of samples. In cryo-TEM observations, spherical aggregates were observed in all phase sequences, whereas the aggregates have different ζ potentials and sizes. In the I₂ phase, interesting nanocapsule-like aggregates and spindle-like aggregates can be identified in addition to spherical aggregates. In combination with the rheological behaviors of the I₂ phase solution and the detailed structure of the aggregates from enlarged cryo-TEM images, it is possible that the Se-CQDs and DOAPA co-assemble with novel network-like building blocks. The turbid solutions were found to be responsive to pH in phase P, and spherical aggregates were obtained at pH 6.5 but turned into vesicles when the pH reached 5.0. On the basis of these findings, CQDs and surfactants can be good structural building blocks for supramolecular structures, and the diverse morphologies of aggregates offer the prospect of multiple applications in the future.

Supramolecular chemistry in lipid bilayer membranes

Lipid bilayer membranes form compartments requisite for life. Interfacing supramolecular systems, including receptors, catalysts, signal transducers and ion transporters, enables the function of the membrane to be controlled in artificial and living cellular compartments. In this perspective, we take stock of the current state of the art of this rapidly expanding field, and discuss prospects for the future in both fundamental science and applications in biology and medicine.

A Synthetic Phospholipid Derivative Mediates Ion Transport Across Lipid Bilayers

Inspired by the natural phospholipid structures for cell membrane, a synthetic phospholipid LC with an ion recognition group benzo-18-crown-6 (B18C6) moiety was prepared which has been demonstrated to be able to transport ions across the lipid bilayers. Fluorescent vesicle assay shows that LC has an excellent transport activity, and the EC₅₀ value for K⁺ is 11.2 μM. The voltage clamp measurement exhibits regular square-like current signals with considerably long opening times, which indicates that LC achieves efficient ion transport through a channel mechanism and its single channel conductivity is 17 pS. Both of the vesicle assay and patch clamp tests indicate that LC has selectivity for Rb⁺, whose ionic radius is larger than the cavity of crown ether. It suggests that the sandwich interaction may play a key role in the ion transport across lipid bilayers. All these results help us to speculate that LC transports ions via a channel mechanism with a tetrameric aggregate as the active structure. In addition, LC had obvious toxicity to HeLa cells, and the IC₅₀ was 100.0 μM after coculture for 36 h. We hope that this simple synthetic phospholipid will offer novel perspectives in the development of more efficient and selective ion transporters.