Formation of a Ligand‐Assisted Complex of Two RNA Hairpin Loops

The hairpin structure is one of the most common secondary structures in RNA and holds a central position in the stream of RNA folding from a non‐structured RNA to structurally complex and functional ribonucleoproteins. Since the RNA secondary structure is strongly correlated to the function and can be modulated by the binding of small molecules, we have investigated the modulation of RNA folding by a ligand‐assisted formation of loop–loop complexes of two RNA hairpin loops. With a ligand (NCT6), designed based on the ligand binding to the G–G mismatches in double‐stranded DNA, we successfully demonstrated the formation of both inter‐ and intra‐molecular NCT6‐assisted complex of two RNA hairpin loops. NCT6 selectively bound to the two hairpin loops containing (CGG)₃ in the loop region. Native polyacrylamide gel electrophoresis analysis of two doubly‐labeled RNA hairpin loops clearly showed the formation of intermolecular NCT6‐assisted loop–loop complex. Förster resonance energy‐transfer studies of RNA constructs containing two hairpin loops, in which each hairpin was labeled with Alexa488 and Cy3 fluorophores, showed the conformational change of the RNA constructs upon binding of NCT6. These experimental data showed that NCT6 simultaneously bound to two hairpin RNAs at the loop region, and can induce the conformational change of the RNA molecule. These data strongly support that NCT6 functions as molecular glue for two hairpin RNAs.     

Inorganic‐Macroion‐Induced Formation of Bicontinuous Block Copolymer Nanocomposites with Enhanced Conductivity and Modulus

A facile and electrostatically driven approach has been developed to prepare bicontinuous polymer nanocomposites that is based on the polyoxometalate (POM) macroion induced phase transition of PS‐b ‐P2VP from an initial lamellar phase to a stable bicontinuous phase. The multi‐charged POMs can electrostatically cross‐link P2VP blocks and give rise to bicontinuous phases in which the POM hybrid conductive domains occupy a large volume fraction of more than 50 %. Furthermore, the POMs can give rise to high proton conductivity and serve as nanoenhancers, endowing the bicontinuous nanocomposites with a conductivity of 0.1 mS cm⁻¹ and a Young's modulus of 7.4 GPa at room temperature; these values are greater than those of pristine PS‐b ‐P2VP by two orders of magnitude and a factor of 1.8, respectively. This approach can provide a new concept based on electrostatic control to design functional bicontinuous polymer materials.