Self-assembly of Janus dendrimers into uniform dendrimersomes and other complex architectures.

Self-assembled nanostructures obtained from natural and synthetic amphiphiles serve as mimics of biological membranes and enable the delivery of drugs, proteins, genes, and imaging agents. Yet the precise molecular arrangements demanded by these functions are difficult to achieve. Libraries of amphiphilic Janus dendrimers, prepared by facile coupling of tailored hydrophilic and hydrophobic branched segments, have been screened by cryogenic transmission electron microscopy, revealing a rich palette of morphologies in water, including vesicles, denoted dendrimersomes, cubosomes, disks, tubular vesicles, and helical ribbons.

Self-assembled ionophores from isoguanosine: diffusion NMR spectroscopy clarifies cation's and anion's influence on supramolecular structure.

Cation-templated self-assembly of the lipophilic isoguanosine (isoG 1) with different monovalent cations (M(+)=Li(+), Na(+), K(+), NH(4) (+), and Cs(+)) was studied in solvents of different polarity by using diffusion NMR spectroscopy. Previous studies that did not use diffusion NMR techniques concluded that isoG 1 forms both pentamers (isoG 1)(5)M(+) and decamers (isoG 1)(10)M(+) in the presence of alkali-metal cations. The present diffusion NMR studies demonstrate, however, that isoG 1 does not form (isoG 1)(5)M(+) pentamers.

Cation exchange in lipophilic G-quadruplexes: not all ion binding sites are equal.

Lipophilic guanosine derivatives that form G-quadruplexes are promising building blocks for ionophores and ion channels. Herein, cation exchange between solvated cations (K+ and NH4+) and bound cations in the G-quadruplex [G1]16.4Na+.

A unimolecular G-quadruplex that functions as a synthetic transmembrane Na+ transporter.

We describe the covalent post-modification of a hydrogen-bonded assembly with the subsequent formation of a potent transmembrane Na+ ion transporter. Olefin metathesis is used to cross-link all 16 guanosine subunits in a lipophilic G-quadruplex. The resulting unimolecular G-quadruplex folds in the environment of a phospholipid membrane and functions as a Na+ ion transporter as judged by fluorescence and 23Na NMR transport assays.

Using diffusion NMR to characterize guanosine self-association: insights into structure and mechanism.

This paper presents results from a series of pulsed field gradient (PFG) NMR studies on lipophilic guanosine nucleosides that undergo cation-templated assembly in organic solvents. The use of PFG-NMR to measure diffusion coefficients for the different aggregates allowed us to observe the influences of cation, solvent and anion on the self-assembly process. Three case studies are presented.

Water-mediated association provides an ion pair receptor.

In this paper, we report on the formation and properties of a water-stabilized dimer comprising calix[4]arene-guanosine conjugate cG 2. The 1,3-alternate calixarene cG 2 was poorly soluble in dry CDCl(3) and gave an ill-resolved NMR spectrum, consistent with its nonspecific aggregation. The compound was much more soluble in water-saturated CDCl(3).