The encapsulation and delivery of short interfering RNA (siRNA) has been realized using lipid nanoparticles1,2, cationic complexes3,4, inorganic nanoparticles5–8, RNA nanoparticles9,10 and dendrimers11. Still, the instability of RNA and the relatively ineffectual encapsulation process of siRNA remain critical issues towards the clinical translation of RNA as a therapeutic1,12,13. Here we report the synthesis of a delivery vehicle that combines carrier and cargo: RNA interference (RNAi) polymers that self-assemble into nanoscale pleated sheets of hairpin RNA, which in turn form sponge-like microspheres. The RNAi-microsponges consist entirely of cleavable RNA strands, and are processed by the cell’s RNA machinery to convert the stable hairpin RNA to siRNA only after cellular uptake, thus inherently providing protection for siRNA during delivery and transport to the cytoplasm. More than half a million copies of siRNA can be delivered to a cell with the uptake of a single RNAi-microsponge. The approach could lead to novel therapeutic routes for siRNA delivery.

The realization of highly flexible and all-solid-state energy-storage devices strongly depends on both the electrical properties and mechanical integrity of the constitutive materials and the controlled assembly of electrode and solid electrolyte. Herein we report the preparation of all-solid-state flexible supercapacitors (SCs) through the easy assembly of functionalized reduced graphene oxide (f-RGO) thin films (as electrode) and solvent-cast Nafion electrolyte membranes (as electrolyte and separator). In particular, the f-RGO-based SCs (f-RGO-SCs) showed a 2-fold higher specific capacitance (118.5 F/g at 1 A/g) and rate capability (90% retention at 30 A/g) compared to those of all-solid-state graphene SCs (62.3 F/g at 1A/g and 48% retention at 30 A/g). As proven by the 4-fold faster relaxation of the f-RGO-SCs than that of the RGO-SCs and more capacitive behavior of the former at the low-frequency region, these results were attributed to the facilitated ionic transport at the electrical double layer by means of the interfacial engineering of RGO by Nafion. Moreover, the superiority of all-solid-state flexible f-RGO-SCs was demonstrated by the good performance durability under the 1000 cycles of charging and discharging due to the mechanical integrity as a consequence of the interconnected networking structures. Therefore, this research provides new insight into the rational design and fabrication of all-solid-state flexible energy-storage devices as well as the fundamental understanding of ion and charge transport at the interface.

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We introduce a novel and versatile approach for preparing self-assembled nanoporous multilayered films with tunable optical properties. Protonated polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and anionic polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer micelles (BCM) were used as building blocks for the layer-by-layer assembly of BCM multilayer films. BCM film growth is governed by electrostatic and hydrogen-bonding interactions between the opposite BCMs. Both film porosity and film thickness are dependent upon the charge density of the micelles, with the porosity of the film controlled by the solution pH and the molecular weight (M(w)) of the constituents. PS(7K)-b-P4VP(28K)/PS(2K)-b-PAA(8K) films prepared at pH 4 (for PS(7K)-b-P4VP(28K)) and pH 6 (for PS(2K)-b-PAA(8K)) are highly nanoporous and antireflective. In contrast, PS(7K)-b-P4VP(28K)/PS(2K)-b-PAA(8K) films assembled at pH 4/4 show a relatively dense surface morphology due to the decreased charge density of PS(2K)-b-PAA(8K). Films formed from BCMs with increased PS block and decreased hydrophilic block (P4VP or PAA) size (e.g., PS(36K)-b-P4VP(12K)/PS(16K)-b-PAA(4K) at pH 4/4) were also nanoporous. This is attributed to a decrease in interdigitation between the adjacent corona shells of the low M(w) BCMs, thus creating more void space between the micelles. Multilayer films with antireflective and photochromic properties were obtained by incorporating a water-insoluble photochromic dye (spiropyran) into the hydrophobic PS core of the BCMs assembled in the films. The optical properties of these films can be modulated by UV irradiation to selectively and reversibly control the transmission of light. Light transmission of higher than 99% was observed with accompanying photochromism in the (PS(7K)-b-P4VP(28K)/PS(2K)-b-PAA(8K)) multilayer films assembled at pH 4/6. Our approach highlights the potential to incorporate a range of materials, ranging from conventional hydrophilic materials with specific interactions to hydrophobic compounds, into the assembled BCMs to yield multifunctional nanoporous films.