PSS-Te nanowires. This technique is shown to provide tunability of thermoelectric and electronic properties, providing up to 22% enhancement of the system's power factor in the low-doping regime, consistent with preferential scattering of low energy carriers. This work provides an exciting platform for rational design of multiphase nanocomposites and highlights the potential for engineering of carrier filtering within hybrid thermoelectrics via introduction of interfaces with controlled structural and energetic properties.

Targeted RNA delivery to lung endothelial cells has the potential to treat conditions that involve inflammation, such as chronic asthma and obstructive pulmonary disease. To this end, chemically modified dendrimer nanomaterials were synthesized and optimized for targeted small interfering RNA (siRNA) delivery to lung vasculature. Using a combinatorial approach, the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length. The top performing materials from in vivo screens were found to primarily target Tie2-expressing lung endothelial cells. At high doses, the dendrimer–lipid derivatives did not cause chronic increases in proinflammatory cytokines, and animals did not suffer weight loss due to toxicity. We believe these materials have potential as agents for the pulmonary delivery of RNA therapeutics.

Hybrid (organic-inorganic) materials have emerged as a promising class of thermoelectric materials, achieving power factors (S2σ) exceeding those of either constituent. The mechanism of this enhancement is still under debate, and pinpointing the underlying physics has proven difficult. In this work, we combine transport measurements with theoretical simulations and first principles calculations on a prototypical PEDOT:PSS-Te(Cux) nanowire hybrid material system to understand the effect of templating and charge redistribution on the thermoelectric performance. Further, we apply the recently developed Kang-Snyder charge transport model to show that scattering of holes in the hybrid system, defined by the energy-dependent scattering parameter, remains the same as in the host polymer matrix; performance is instead dictated by polymer morphology manifested in an energy-independent transport coefficient. We build upon this language to explain thermoelectric behavior in a variety of PEDOT and P3HT based hybrids acting as a guide for future work in multiphase materials.

This article is protected by copyright. All rights reserved.Soft thermoelectric materials, including conjugated polymers and organic-inorganic hybrids, now demonstrate figures of merit approaching those of inorganic materials. These materials development breakthroughs enable the design of thermoelectric devices that exhibit appropriate efficiencies for commercial use, while simultaneously leveraging the unique processing and mechanical advantages of soft materials. Such technology opens the door to a suite of new thermoelectric applications, including power generation for biomedical implants and the Internet of Things, or wearable heating and cooling devices. In order to realize deployment of such technologies, there is a fundamental need for deeper understanding of the complex transport physics underlying thermoelectric transport in soft materials. This progress report discusses the current state-of-the-art in soft thermoelectrics materials and highlight outstanding challenges specific to organic and organic-inorganic hybrid systems.

A library of dendrimers was synthesized and optimized for targeted small interfering RNA (siRNA) delivery to different cell subpopulations within the liver. Using a combinatorial approach, a library of these nanoparticle-forming materials was produced wherein the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length, and evaluated for their ability to deliver siRNA to liver cell subpopulations. Interestingly, two lead delivery materials could be formulated in a manner to alter their tissue tropism within the liver -with formulations from the same material capable of preferentially delivering siRNA to (i) endothelial cells, (ii) endothelial cells and hepatocytes, or (iii) endothelial cells, hepatocytes and tumor cells in vivo. The ability to broaden or narrow the cellular destination of siRNA within the liver may provide a useful tool to address a range of liver diseases. Graphical AbstractDendrimer derivatives optimized for in vivo siRNA delivery to liver endothelial cells, hepatocellular carcinoma cells and/or hepatocytes are prepared using a combinatorial approach.Correspondence to: Daniel G. Anderson, dgander@mit.edu. Supporting information for this article is given via a link at the end of the document. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptThe free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers are substituted with alkyl chains of increasing length. Through formulation changes, these materials have the ability to broaden or narrow their targeted cellular subpopulation within the liver. Keywordsnanomaterial; RNA; dendrimers; amphiphiles; drug delivery RNA interference (RNAi) is the process whereby a small interfering RNA (siRNA) induces the degradation of complimentary mRNA gene transcripts, thus silencing genes. [1] A key need to the broad application of RNAi is the development of safe and effective delivery systems capable of silencing genes in specific cells within the body. This type of selectivity has the potential to focus therapy, and thereby decrease side effects. Nanoformulation of siRNA is one approach towards this end, and to date the most advanced strategies are hepatocyte-specific, having both selectivity and potency in non-human primates and clinical trials. [2] There is an increasing collection of reports of siRNA delivery to tissues other than hepatocytes including tumors, [3] immune cells [4] and the endothelium. [5] However, delivery to these other tissues is often non-specific, with siRNA functionally delivered to more than just the target tissue. Here we report on the development of formulations based on dendrimeric materials where the targeting is tuned through modifying formulation parameters. Particular focus was placed on developing new delivery materials capable of silencing genes in different liver cell subpopulations, with special emphasis placed on blood vessel endothelial cells.The chemically-modif...

A novel core/shell porous crystalline structure was prepared using a large pore metal organic framework (MOF, UiO-66-NH, pore size, ∼ 0.6 nm) as core surrounded by a small pore zeolitic imidazolate framework (ZIF, ZIF-8, pore size, ∼ 0.4 nm) through a layer-by-layer deposition method and subsequently used as an engineered filler to construct hybrid polysulfone (PSF) membranes for CO capture. Compared to traditional fillers utilizing only one type of porous material with rigid channels (either large or small), our custom designed core/shell fillers possess clear advantages via pore engineering: the large internal channels of the UiO-66-NH MOFs create molecular highways to accelerate molecular transport through the membrane, while the thin shells with small pores (ZIF-8) or even smaller pores generated at the interface by the imperfect registry between the overlapping pores of ZIF and MOF enhance molecular sieving thus serving to distinguish slightly larger N molecules (kinetic diameter, 0.364 nm) from smaller CO molecules (kinetic diameter, 0.33 nm). The resultant core/shell ZIF@MOF and as-prepared hybrid PSF membranes were characterized by transmission electron microscopy, X-ray diffraction, wide-angle X-ray scattering, scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, and contact angle tests. The dependence of the separation performance of the membranes on the MOF/ZIF ratio was also studied by varying the number of layers of ZIF coatings. The integrated PSF-ZIF@MOF hybrid membrane (40 wt % loading) with optimized ZIF coating cycles showed improved hydrophobicity and excellent CO separation performance by simultaneously increasing CO permeability (CO permeability of 45.2 barrer, 710% higher than PSF membrane) and CO/N selectivity (CO/N selectivity of 39, 50% higher than PSF membrane), which is superior to most reported hybrid PSF membranes. The strategy of using dual-channel molecular sieving core/shell porous crystals in hybrid membranes thus provides a promising means for CO capture from flue gas.

Herein, we present a scalable approach for the synthesis of a hydrogen-bonded organic–inorganic framework via coordination-driven supramolecular chemistry, for efficient remediation of trace heavy metal ions from water. In particular, using copper as our model ion of interest and inspired by nature’s use of histidine residues within the active sites of various copper binding proteins, we design a framework featuring pendant imidazole rings and copper-chelating salicylaldoxime, known as zinc imidazole salicylaldoxime supramolecule. This material is water-stable and exhibits unprecedented adsorption kinetics, up to 50 times faster than state-of-the-art materials for selective copper ion capture from water. Furthermore, selective copper removal is achieved using this material in a pH range that was proven ineffective with previously reported metal–organic frameworks. Molecular dynamics simulations show that this supramolecule can reversibly breathe water through lattice expansion and contraction, and that water is initially transported into the lattice through hopping between hydrogen-bond sites.

Demand for pragmatic alternatives to carbon-intensive fossil fuels is growing more strident. Hydrogen represents an ideal zero-carbon clean energy carrier with high energy density. For hydrogen fuel to compete with alternatives, safe and high capacity storage materials that are readily cycled are imperative. Here, development of such a material, comprised of nickel-doped Mg nanocrystals encapsulated by molecular-sieving reduced graphene oxide (rGO) layers, is reported. While most work on advanced hydrogen storage composites to date endeavor to explore either nanosizing or addition of carbon materials as secondary additives individually, methods to enable both are pioneered: "dual-channel" doping combines the benefits of two different modalities of enhancement. Specifically, both external (rGO strain) and internal (Ni doping) mechanisms are used to efficiently promote both hydriding and dehydriding processes of Mg nanocrystals, simultaneously achieving high hydrogen storage capacity (6.5 wt% in the total composite) and excellent kinetics while maintaining robustness. Furthermore, hydrogen uptake is remarkably accomplished at room temperature and also under 1 bar-as observed during in situ measurements-which is a substantial advance for a reversible metal hydride material. The realization of three complementary functional components in one material breaks new ground in metal hydrides and makes solid-state materials viable candidates for hydrogen-fueled applications.