High-fidelity noncovalent synthesis of hydrogen-bonded macrocyclic assemblies.

A hydrogen-bonded cyclic tetramer is assembled with remarkably high effective molarities from a properly designed dinucleoside monomer. This self-assembled species exhibits an impressive thermodynamic and kinetic stability and is formed with high fidelities within a broad concentration range.

Synthesis of Phosphoramidite Monomers Equipped with Complementary Bases for Solid-Phase DNA Oligomerization.

We describe the preparation of two monomers that bear complementary nucleobases at the edges (guanine-2'-deoxycytidine and 2-aminoadenine-2'-deoxyuridine) and that are conveniently protected and activated for solid-phase automated DNA synthesis. We report the optimized synthetic routes leading to the four nucleobase derivatives involved, their cross-coupling reactions into dinucleobase-containing monomers, and their oligomerization in the DNA synthesizer.

Multifunctional Albumin-Stabilized Gold Nanoclusters for the Reduction of Cancer Stem Cells.

Controlled delivery of multiple chemotherapeutics can improve the effectiveness of treatments and reduce side effects and relapses. Here in, we used albumin-stabilized gold nanoclusters modified with doxorubicin and SN38 (AuNCs-DS) as combined therapy for cancer. The chemotherapeutics are conjugated to the nanostructures using linkers that release them when exposed to different internal stimuli (Glutathione and pH). This system has shown potent antitumor activity against breast and pancreatic cancer cells. Our studies indicate that the antineoplastic activity observed may be related to the reinforced DNA damage generated by the combination of the drugs. Moreover, this system presented antineoplastic activity against mammospheres, a culturing model for cancer stem cells, leading to an efficient reduction of the number of oncospheres and their size. In summary, the nanostructures reported here are promising carriers for combination therapy against cancer and particularly to cancer stem cells.

G-arylated hydrogen-bonded cyclic tetramer assemblies with remarkable thermodynamic and kinetic stability.

The preparation and self-assembly of novel G-C dinucleoside monomers that are equipped with electron-poor aryl groups at the G-N(2) amino group have been studied. Such monomers associate via Watson-Crick H-bonding into discrete unstrained tetrameric macrocycles that arise as a thermodynamically and kinetically stabilized product in a wide variety of experimental conditions, including very polar solvent environments and low concentrations. G-arylation produces an increased stability of the cyclic assembly, as a result of a subtle interplay between enthalpic and entropic effects involving the solvent coordination sphere.