Here, an integrated cascade nanozyme with a formulation of Pt@PCN222-Mn is developed to eliminate excessive reactive oxygen species (ROS). This nanozyme mimics superoxide dismutase by incorporation of a Mn–[5,10,15,20-tetrakis(4-carboxyphenyl)porphyrinato]–based metal-organic framework compound capable of transforming oxygen radicals to hydrogen peroxide. The second mimicked functionality is that of catalase by incorporation of Pt nanoparticles, which catalyze hydrogen peroxide disproportionation to water and oxygen. Both in vitro and in vivo experimental measurements reveal the synergistic ROS-scavenging capacity of such an integrated cascade nanozyme. Two forms of inflammatory bowel disease (IBD; i.e., ulcerative colitis and Crohn’s disease) can be effectively relieved by treatment with the cascade nanozyme. This study not only provides a new method for constructing enzyme-like cascade systems but also illustrates their efficient therapeutic promise in the treatment of in vivo IBDs.

Safe, effective, and convenient administration of therapeutic nanomaterials is one of the greatest difficulties in nanomedicine. To tackle this challenge, a system which couples multi-enzyme mimicking CeO 2 nanoparticles with clinically approved montmorillonite (MMT) for inflammatory bowel disease (IBD) therapy is reported. CeO 2 exhibits superoxide dismutase-and catalase-like activities, and hydroxyl radical scavenging activity, making it more efficient at scavenging reactive oxygen species (ROS) than noncatalytic antioxidants while being more stable than free enzymes. In addition, negatively-charged MMT can be orally administered and specifically adsorbed onto positively-charged inflamed colon tissue via electrostatic interactions for targeted delivery. When the two are assembled together by in situ growth of CeO 2 onto MMT, the optimized CeO 2 @MMT(1:9) is stable in the stomach for oral delivery, targets the inflamed colon through electrostatic interactions, and reduces inflammation through ROS scavenging, all without any significant systemic exposure as demonstrated by the relief of murine IBD in vivo.

An abiotic formation of meso- and dl-tartrates in 80% yield via the cyanide-catalyzed dimerization of glyoxylate under alkaline conditions is demonstrated. A detailed mechanism for this conversion is proposed, supported by NMR evidence and 13C-labeled reactions. Simple dehydration of tartrates to oxaloacetate and an ensuing decarboxylation to form pyruvate are known processes that provide a ready feedstock for entry into the citric acid cycle. While glyoxylate and high hydroxide concentration are atypical in the prebiotic literature, there is evidence for natural, abiotic availability of each. It is proposed that this availability, coupled with the remarkable efficiency of tartrate production from glyoxylate, merits consideration of an alternative prebiotic pathway for providing constituents of the citric acid cycle.

Contents1. Introduction1.1. A workshop and this document1.2. Framing origins of life science1.2.1. What do we mean by the origins of life (OoL)?1.2.2. Defining life1.2.3. How should we characterize approaches to OoL science?1.2.4. One path to life or many?2. A Strategy for Origins of Life Research2.1. Outcomes—key questions and investigations2.1.1. Domain 1: Theory2.1.2. Domain 2: Practice2.1.3. Domain 3: Process2.1.4. Domain 4: Future studies2.2. EON Roadmap2.3. Relationship to NASA Astrobiology Roadmap and Strategy documents and the European AstRoMap Appendix I Appendix II Supplementary Materials References

It is widely believed that the origin of life depended on environmentally driven complexification of abiotically produced organic compounds. Polymerization is one type of such complexification, and it may be important that many diverse polymer sequences be produced for the sake of selection. Not all compound classes are easily polymerized under the environmental conditions present on primitive planets, and it is possible that life's origin was aided by other monomers besides those used in contemporary biochemistry. Here we show that alpha-hydroxy acids, which are plausibly abundant prebiotic monomers, can be oligomerized to generate vast, likely sequence-complete libraries, which are also stable for significant amounts of time. This occurs over a variety of reaction conditions (temperature, concentration, salinity, and presence of congeners) compatible with geochemical settings on the primitive Earth and other solar system environments. The high-sequence heterogeneity achievable with these compounds may be useful for scaffolding the origin of life.

We have identified a series of positive allosteric NMDA receptor (NMDAR) modulators derived from a known class of GluN2C/D-selective tetrahydroisoquinoline analogues that includes CIQ. The prototypical compound of this series contains a single isopropoxy moiety in place of the two methoxy substituents present in CIQ. Modifications of this isopropoxy-containing scaffold led to the identification of analogues with enhanced activity at the GluN2B subunit. We identified molecules that potentiate the response of GluN2B/GluN2C/GluN2D, GluN2B/GluN2C, and GluN2C/GluN2D-containing NMDARs to maximally effective concentrations of agonist. Multiple compounds potentiate the response of NMDARs with submicromolar EC50 values. Analysis of enantiomeric pairs revealed that the S-(−) enantiomer is active at the GluN2B, GluN2C, and/or GluN2D subunits, whereas the R-(+) enantiomer is only active at GluN2C/D subunits. These results provide a starting point for the development of selective positive allosteric modulators for GluN2B-containing receptors.

Metal–semiconductor contacts are key components of nanoelectronics and atomic-scale integrated circuits. In these components Schottky diodes provide a low forward voltage and a very fast switching rate but suffer the drawback of a high reverse leakage current. Improvement of the reverse bias characteristics without degrading performance of the diode at positive voltages is deemed physically impossible for conventional silicon-based Schottky diodes. However, in this work we propose that this design challenge can be overcome in the organic-based diodes by utilizing reversible transitions between distinct adsorption states of organic molecules on metal surfaces. Motivated by previous experimental observations of controllable adsorption conformations of anthradithiophene on Cu(111), herein we use density functional theory simulations to demonstrate the distinct Schottky barrier heights of the two adsorption states. The higher Schottky barrier of the reverse bias induced by a chemisorbed state results in low leakage current, while the lower barrier of the forward bias induced by a physisorbed state yields a larger output current. The rectifying behaviors are further supported by nonequilibrium Green’s function transport calculations.

Hydrogen tautomerization molecular switches, a promising class of molecular components for the construction of complex nanocircuits, have been extensively studied using low-temperature scanning tunneling microscopy. However, these molecules are generally only reliably controllable in cryogenic environments, obstructing their utility in real devices. Here, we use dispersion-inclusive density functional theory and systematically investigate the adsorption and tautomerization behaviors of porphycene on six transition-metal surfaces. Among these surfaces, we found that hydrogen tautomerization on the Pt(110) surface corresponds to the largest switching barrier, allowing a controllable transition at high temperature. The switching behavior is closely related to the exceptional degree of charge transfer in the HOMO−2 orbital, illustrating the important role of deep orbital−surface interactions in porphycene molecular switching. Our work provides an in-depth understanding of the porphycene tautomerization mechanism and highlights new research avenues toward the practical application of molecular switches.