Hydrogenase enzymes use first-row transition metals to interconvert H2 with protons and electrons, reactions that are important for the storage and recovery of energy from intermittent sources such as solar, hydroelectric, and wind. Here we present Ni(P(Cy)2N(Gly)2)2, a water-soluble molecular electrocatalyst with the amino acid glycine built into the diphosphine ligand framework. Proton transfer between the outer coordination sphere carboxylates and the second coordination sphere pendant amines is rapid, as observed by cyclic voltammetry and FTIR spectroscopy, indicating that the carboxylate groups may participate in proton transfer during catalysis. This complex oxidizes H2 (1-33 s(-1)) at low overpotentials (150-365 mV) over a range of pH values (0.1-9.0) and produces H2 under identical solution conditions (>2400 s(-1) at pH 0.5). Enzymes employ proton channels for the controlled movement of protons over long distances-the results presented here demonstrate the effects of a simple two-component proton channel in a synthetic molecular electrocatalyst.

In order to understand the unique solvation and conduction properties of ionic liquids (ILs), we explore their interionic associations modulated by hydration level and ionic medium. Pulsed-field-gradient NMR allows sensitive measurement of separate cation and anion diffusion coefficients, which combine to reflect ionic aggregation. With increasing hydration of ILs, the anomalous ratio of cation to anion diffusion coefficients reverses, then plateaus to values consistent with expected hydrodynamic radii ratios (r(cation)/r(anion) = 1.4 for [C(2)mim][BF(4)]). When ILs diffuse inside an ionic polymer, ion associations are modulated by ionic interactions between mobile cations and anions, and drag from fixed -SO(3)(-) lining the polymer's hydrophilic channels. Surprisingly, cations diffuse substantially faster (≤3×) at low hydration inside membranes, revealing prevalent anionic aggregates. At high hydration, isolated anions diffuse faster (≤4×) than cations. Probing ionic interactions provides pivotal insight into these subtle fluids, with quantitative implications for electrolyte applications such as batteries and "artificial muscle" mechanical actuators.

Designing tailored block copolymers represents a viable strategy for building polymer membranes with fruitful combinations of properties, such as the high ionic or small molecule conductivity and high mechanical strength needed for applications such as fuel cells and reverse-osmosis water purification. Here we present a systematic study of water transport and morphological alignment in a class of poly(arylene ether sulfone) hydrophilic−hydrophobic multiblock copolymer membranes and compare these with Nafion 212. Multiaxis pulsed-field-gradient NMR yields diffusion anisotropy, the ratio of diffusion coefficients measured both in plane (D ∥) and through plane (D ⊥), as a function of water uptake and block lengths. As block mass increases, diffusion anisotropy exhibits an increasing dependence on water uptake, in contrast to Nafion 212, where diffusion is isotropic and displays no dependence on water uptake. 2H NMR spectroscopy on absorbed D2O further probes membrane alignment modes. Both types of measurements corroborate uniformly ordered planar structures oriented through the membrane plane in accordance with a lamellar morphology previously observed locally with microscopy. The combination of these two measurements also provides insights into average defect distributions.

We compare diffusion activation energy measurements in a hydrated perfluorosulfonate ionomer and aqueous solutions of triflic acid. These measurements provide insight into water transport dynamics on sub-nm length scales, and gauge the contribution of the polymer sidechain terminal group. Future membrane materials design will hinge on detailed understanding of transport dynamics.

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The fastest synthetic molecular catalysts for H production and oxidation emulate components of the active site of hydrogenases. The critical role of controlled structural dynamics is recognized for many enzymes, including hydrogenases, but is largely neglected in designing synthetic catalysts. Our results demonstrate the impact of controlling structural dynamics on H production rates for [Ni(P N ) ] catalysts (R=n-hexyl, n-decyl, n-tetradecyl, n-octadecyl, phenyl, or cyclohexyl). The turnover frequencies correlate inversely with the rates of chair-boat ring inversion of the ligand, since this dynamic process governs protonation at either catalytically productive or non-productive sites. These results demonstrate that the dynamic processes involved in proton delivery can be controlled through modification of the outer coordination sphere, in a manner similar to the role of the protein architecture in many enzymes. As a design parameter, controlling structural dynamics can increase H production rates by three orders of magnitude with a minimal increase in overpotential.

Changes to the medium results in remarkable increases in the rate of electrocatalytic production of H2 without increases in overpotential.

Lung cancer is the most common cause of cancer deaths all over the world, in which non-small cell lung cancer (NSCLC) accounts for ~85% of cases. It is well known that microRNAs (miRNAs) play a critical role in various cellular processes, mediating post-transcriptional silencing either by mRNA degradation through binding the 3′ UTR of target mRNA or by translational inhibition of the protein. In the past decade, miRNAs have also been increasingly identified in biological fluids such as human serum or plasma known as circulating or cell-free miRNAs, and may function as non-invasive diagnostic markers for various cancer types including NSCLC. Circulating tumor cells (CTCs) are those cells that are shed from solid tumors and then migrate into the circulation. However, reports concerning the roles of CTCs are quite rare, which may be attributed to the difficulties in the enrichment and detection of CTCs in the circulation. Although, there have been reassuring advances in identifying circulating miRNA-panels, which are assumed to be of diagnostic value in NSCLC early stage, some issues remain concerning the reliability of using miRNA panels as a diagnostic tool for NSCLC. In the current review, we are aiming at providing insights into the miRNAs biology, the mechanisms of miRNAs release into the bloodstream, cell-free miRNAs as the diagnostic markers for NSCLC and the current limitations of CTCs as diagnostic markers in NSCLC.