Coherent wavepackets in the Fenna-Matthews-Olson complex are robust to excitonic-structure perturbations caused by mutagenesis. Maiuri Margherita,Ostroumov Evgeny E,Saer Rafael G,Blankenship Robert E,Scholes Gregory D Nature chemistry Femtosecond pulsed excitation of light-harvesting complexes creates oscillatory features in their response. This phenomenon has inspired a large body of work aimed at uncovering the origin of the coherent beatings and possible implications for function. Here we exploit site-directed mutagenesis to change the excitonic level structure in Fenna-Matthews-Olson (FMO) complexes and compare the coherences using broadband pump-probe spectroscopy. Our experiments detect two oscillation frequencies with dephasing on a picosecond timescale-both at 77 K and at room temperature. By studying these coherences with selective excitation pump-probe experiments, where pump excitation is in resonance only with the lowest excitonic state, we show that the key contributions to these oscillations stem from ground-state vibrational wavepackets. These experiments explicitly show that the coherences-although in the ground electronic state-can be probed at the absorption resonances of other bacteriochlorophyll molecules because of delocalization of the electronic excitation over several chromophores. 10.1038/nchem.2910
    Pyonitrins A-D: Chimeric Natural Products Produced by . Mevers Emily,Saurí Josep,Helfrich Eric J N,Henke Matthew,Barns Kenneth J,Bugni Tim S,Andes David,Currie Cameron R,Clardy Jon Journal of the American Chemical Society Bacterial symbionts frequently provide chemical defenses for their hosts, and such systems can provide discovery pathways to new antifungals and structurally intriguing metabolites. This report describes a small family of naturally occurring small molecules with chimeric structures and a mixed biosynthesis that features an unexpected but key nonenzymatic step. An insect-associated strain's activity in an murine candidiasis assay led to the discovery of a family of highly hydrogen-deficient metabolites. Bioactivity- and mass-guided fractionation led to the pyonitrins, highly complex aromatic metabolites in which 10 of the 20 carbons are quaternary, and 7 of them are contiguous. The genome revealed that the production of the pyonitrins is the result of a spontaneous reaction between biosynthetic intermediates of two well-studied metabolites, pyochelin and pyrrolnitrin. The combined discovery of the pyonitrins and identification of the responsible biosynthetic gene clusters revealed an unexpected biosynthetic route that would have prevented the discovery of these metabolites by bioinformatic analysis alone. 10.1021/jacs.9b09739
    Spin-Dependent Electron Transport through Bacterial Cell Surface Multiheme Electron Conduits. Mishra Suryakant,Pirbadian Sahand,Mondal Amit Kumar,El-Naggar Mohamed Y,Naaman Ron Journal of the American Chemical Society Multiheme cytochromes, located on the bacterial cell surface, function as long-distance (>10 nm) electron conduits linking intracellular reactions to external surfaces. This extracellular electron transfer process, which allows microorganisms to gain energy by respiring solid redox-active minerals, also facilitates the wiring of cells to electrodes. While recent studies have suggested that a chiral induced spin selectivity effect is linked to efficient electron transmission through biomolecules, this phenomenon has not been investigated in extracellular electron conduits. Using magnetic conductive probe atomic force microscopy, Hall voltage measurements, and spin-dependent electrochemistry of the decaheme cytochromes MtrF and OmcA from the metal-reducing bacterium MR-1, we show that electron transport through these extracellular conduits is spin-selective. Our study has implications for understanding how spin-dependent interactions and magnetic fields may control electron transport across biotic-abiotic interfaces in both natural and biotechnological systems. 10.1021/jacs.9b09262
    Rational design of quinones for high power density biofuel cells. Milton Ross D,Hickey David P,Abdellaoui Sofiene,Lim Koun,Wu Fei,Tan Boxuan,Minteer Shelley D Chemical science Enzymatic fuel cells (EFCs) are devices that can produce electrical energy by enzymatic oxidation of energy-dense fuels (such as glucose). When considering bioanode construction for EFCs, it is desirable to use a system with a low onset potential and high catalytic current density. While these two properties are typically mutually exclusive, merging these two properties will significantly enhance EFC performance. We present the rational design and preparation of an alternative naphthoquinone-based redox polymer hydrogel that is able to facilitate enzymatic glucose oxidation at low oxidation potentials while simultaneously producing high catalytic current densities. When coupled with an enzymatic biocathode, the resulting glucose/O EFC possessed an open-circuit potential of 0.864 ± 0.006 V, with an associated maximum current density of 5.4 ± 0.5 mA cm. Moreover, the EFC delivered its maximum power density (2.3 ± 0.2 mW cm) at a high operational potential of 0.55 V. 10.1039/c5sc01538c
    Metal-Organic-Framework-Assisted In Vivo Bacterial Metabolic Labeling and Precise Antibacterial Therapy. Mao Duo,Hu Fang,Kenry ,Ji Shenglu,Wu Wenbo,Ding Dan,Kong Deling,Liu Bin Advanced materials (Deerfield Beach, Fla.) Bacterial infection is one of the most serious physiological conditions threatening human health. There is an increasing demand for more effective bacterial diagnosis and treatment through noninvasive theranostic approaches. Herein, a new strategy is reported to achieve in vivo metabolic labeling of bacteria through the use of MIL-100 (Fe) nanoparticles (NPs) as the nanocarrier for precise delivery of 3-azido-d-alanine (d-AzAla). After intravenous injection, MIL-100 (Fe) NPs can accumulate preferentially and degrade rapidly within the high H O inflammatory environment, releasing d-AzAla in the process. d-AzAla is selectively integrated into the cell walls of bacteria, which is confirmed by fluorescence signals from clickable DBCO-Cy5. Ultrasmall photosensitizer NPs with aggregation-induced emission characteristics are subsequently designed to react with the modified bacteria through in vivo click chemistry. Through photodynamic therapy, the amount of bacteria on the infected tissue can be significantly reduced. Overall, this study demonstrates the advantages of metal-organic-framework-assisted bacteria metabolic labeling strategy for precise bacterial detection and therapy guided by fluorescence imaging. 10.1002/adma.201706831
    Orbital-exchange and fractional quantum number excitations in an f-electron metal, Yb₂Pt₂Pb. Wu L S,Gannon W J,Zaliznyak I A,Tsvelik A M,Brockmann M,Caux J-S,Kim M S,Qiu Y,Copley J R D,Ehlers G,Podlesnyak A,Aronson M C Science (New York, N.Y.) Exotic quantum states and fractionalized magnetic excitations, such as spinons in one-dimensional chains, are generally expected to occur in 3d transition metal systems with spin 1/2. Our neutron-scattering experiments on the 4f-electron metal Yb2Pt2Pb overturn this conventional wisdom. We observe broad magnetic continuum dispersing in only one direction, which indicates that the underlying elementary excitations are spinons carrying fractional spin-1/2. These spinons are the emergent quantum dynamics of the anisotropic, orbital-dominated Yb moments. Owing to their unusual origin, only longitudinal spin fluctuations are measurable, whereas the transverse excitations such as spin waves are virtually invisible to magnetic neutron scattering. The proliferation of these orbital spinons strips the electrons of their orbital identity, resulting in charge-orbital separation. 10.1126/science.aaf0981
    High-power hybrid biofuel cells using layer-by-layer assembled glucose oxidase-coated metallic cotton fibers. Kwon Cheong Hoon,Ko Yongmin,Shin Dongyeeb,Kwon Minseong,Park Jinho,Bae Wan Ki,Lee Seung Woo,Cho Jinhan Nature communications Electrical communication between an enzyme and an electrode is one of the most important factors in determining the performance of biofuel cells. Here, we introduce a glucose oxidase-coated metallic cotton fiber-based hybrid biofuel cell with efficient electrical communication between the anodic enzyme and the conductive support. Gold nanoparticles are layer-by-layer assembled with small organic linkers onto cotton fibers to form metallic cotton fibers with extremely high conductivity (>2.1×10 S cm), and are used as an enzyme-free cathode as well as a conductive support for the enzymatic anode. For preparation of the anode, the glucose oxidase is sequentially layer-by-layer-assembled with the same linkers onto the metallic cotton fibers. The resulting biofuel cells exhibit a remarkable power density of 3.7 mW cm, significantly outperforming conventional biofuel cells. Our strategy to promote charge transfer through electrodes can provide an important tool to improve the performance of biofuel cells. 10.1038/s41467-018-06994-5
    Chemically Controlled Helical Polymorphism in Protein Tubes by Selective Modulation of Supramolecular Interactions. Li Zhen,Chen Shuyu,Gao Chendi,Yang Zhiwei,Shih Kuo-Chih,Kochovski Zdravko,Yang Guang,Gou Lu,Nieh Mu-Ping,Jiang Ming,Zhang Lei,Chen Guosong Journal of the American Chemical Society Polymorphism has been the subject of investigation across different research disciplines. In biology, polymorphism could be interpreted in such a way that discrete biomacromolecules can adopt diversiform specific conformations/packing arrangement, and this polymorph-dependent property is essential for many biochemical processes. For example, bacterial flagellar filament, composed of flagellin, switches between different supercoiled state allowing the bacteria to swim and tumble. However, in artificial supramolecular systems, it is often challenging to achieve polymorph control and prediction, and in most cases, two or more concomitant polymorphs of similar formation energies coexist. Here, we show that a tetrameric protein with properly oriented binding sites on its surface can arrange into diverse protein tubes with distinct helical parameters by adding specifically designed inducing ligands. We examined several parameters of the ligand that would influence the protein tube formation and found that the flexibility of the ligand linker and the dimerization pose of the ligand complex is critical for the successful production of the tubes and eventually influence the specific helical polymorphs of the formed tubes. A surface lattice accommodation model was further developed to rationalize the geometrical relationship between each helical tube type. Molecular simulation was used to elucidate the interactions between ligands and SBA and molecular basis for polymorphic switching of the protein tubes. Moreover, the kinetics of structural formation was studied and the ligand design was found that can affect the kinetics of the protein polymerization pathway. In short, our designed protein tubes serves as an enlightening system for understanding how a protein polymer composed of a single protein switches among different helical states. 10.1021/jacs.9b10505
    Real-time infrared detection of cyanide flip on silver-alumina NOx removal catalyst. Thibault-Starzyk Frédéric,Seguin Etienne,Thomas Sébastien,Daturi Marco,Arnolds Heike,King David A Science (New York, N.Y.) Spectroscopic studies of the mechanistic steps that occur on supported precious metal catalysts used in industrial and automotive applications are hampered by a dearth of suitable experimental methods. We used femtosecond laser excitation followed by nanosecond time-resolved in situ Fourier-transform infrared spectroscopy to initiate a catalytic reaction on alumina-supported silver catalysts, which are of interest in minimizing nitrogen oxide emissions from fuel-efficient lean-burn engines. We found that the key intermediate step in the reaction between carbon monoxide and nitric oxide is the flip of a cyanide group from a silver nanoparticle to the alumina support (with a lifetime of 2 microseconds), which indicates the central role played by the interface between the metal particle and the oxide support. 10.1126/science.1169041
    Taking the "waste" out of "wastewater" for human water security and ecosystem sustainability. Grant Stanley B,Saphores Jean-Daniel,Feldman David L,Hamilton Andrew J,Fletcher Tim D,Cook Perran L M,Stewardson Michael,Sanders Brett F,Levin Lisa A,Ambrose Richard F,Deletic Ana,Brown Rebekah,Jiang Sunny C,Rosso Diego,Cooper William J,Marusic Ivan Science (New York, N.Y.) Humans create vast quantities of wastewater through inefficiencies and poor management of water systems. The wasting of water poses sustainability challenges, depletes energy reserves, and undermines human water security and ecosystem health. Here we review emerging approaches for reusing wastewater and minimizing its generation. These complementary options make the most of scarce freshwater resources, serve the varying water needs of both developed and developing countries, and confer a variety of environmental benefits. Their widespread adoption will require changing how freshwater is sourced, used, managed, and priced. 10.1126/science.1216852
    Biomimetic Platelet-Camouflaged Nanorobots for Binding and Isolation of Biological Threats. Li Jinxing,Angsantikul Pavimol,Liu Wenjuan,Esteban-Fernández de Ávila Berta,Chang Xiaocong,Sandraz Elodie,Liang Yuyan,Zhu Siyu,Zhang Yue,Chen Chuanrui,Gao Weiwei,Zhang Liangfang,Wang Joseph Advanced materials (Deerfield Beach, Fla.) One emerging and exciting topic in robotics research is the design of micro-/nanoscale robots for biomedical operations. Unlike industrial robots that are developed primarily to automate routine and dangerous tasks, biomedical nanorobots are designed for complex, physiologically relevant environments, and tasks that involve unanticipated biological events. Here, a biologically interfaced nanorobot is reported, made of magnetic helical nanomotors cloaked with the plasma membrane of human platelets. The resulting biomimetic nanorobots possess a biological membrane coating consisting of diverse functional proteins associated with human platelets. Compared to uncoated nanomotors which experience severe biofouling effects and hence hindered propulsion in whole blood, the platelet-membrane-cloaked nanomotors disguise as human platelets and display efficient propulsion in blood over long time periods. The biointerfaced nanorobots display platelet-mimicking properties, including adhesion and binding to toxins and platelet-adhering pathogens, such as Shiga toxin and Staphylococcus aureus bacteria. The locomotion capacity and platelet-mimicking biological function of the biomimetic nanomotors offer efficient binding and isolation of these biological threats. The dynamic biointerfacing platform enabled by platelet-membrane cloaked nanorobots thus holds considerable promise for diverse biomedical and biodefense applications. 10.1002/adma.201704800
    Enzymatic glucose/oxygen biofuel cells: Use of oxygen-rich cathodes for operation under severe oxygen-deficit conditions. Jeerapan Itthipon,Sempionatto Juliane R,You Jung-Min,Wang Joseph Biosensors & bioelectronics A glucose/oxygen biofuel cell (BFC) that can operate continuously under oxygen-free conditions is described. The oxygen-deficit limitations of metabolite/oxygen enzymatic BFCs have been addressed by using an oxygen-rich cathode binder material, polychlorotrifluoroethylene (PCTFE), which provides an internal oxygen supply for the BFC reduction reaction. This oxygen-rich cathode component mitigates the potential power loss in oxygen-free medium or during external oxygen fluctuations through internal supply of oxygen, while the bioanode employs glucose oxidase-mediated reactions. The internal oxygen supply leads to a prolonged energy-harvesting in oxygen-free solutions, e.g., maintaining over 90% and 70% of its initial power during 10- and 24-h operations, respectively, in the absence of oxygen. The new strategy holds considerable promise for energy-harvesting and self-powered biosensing applications in oxygen-deficient conditions. 10.1016/j.bios.2018.09.063
    Tracking the popularity and outcomes of all bioRxiv preprints. Abdill Richard J,Blekhman Ran eLife The growth of preprints in the life sciences has been reported widely and is driving policy changes for journals and funders, but little quantitative information has been published about preprint usage. Here, we report how we collected and analyzed data on all 37,648 preprints uploaded to bioRxiv.org, the largest biology-focused preprint server, in its first five years. The rate of preprint uploads to bioRxiv continues to grow (exceeding 2,100 in October 2018), as does the number of downloads (1.1 million in October 2018). We also find that two-thirds of preprints posted before 2017 were later published in peer-reviewed journals, and find a relationship between the number of downloads a preprint has received and the impact factor of the journal in which it is published. We also describe Rxivist.org, a web application that provides multiple ways to interact with preprint metadata. 10.7554/eLife.45133
    Reticulated vitreous carbon as a scaffold for enzymatic fuel cell designing. Kizling Michal,Dzwonek Maciej,Olszewski Bartłomiej,Bącal Paweł,Tymecki Łukasz,Więckowska Agnieszka,Stolarczyk Krzysztof,Bilewicz Renata Biosensors & bioelectronics Three - dimensional (3D) electrodes are successfully used to overcome the limitations of the low space - time yield and low normalized space velocity obtained in electrochemical processes with two - dimensional electrodes. In this study, we developed a three - dimensional reticulated vitreous carbon - gold (RVC-Au) sponge as a scaffold for enzymatic fuel cells (EFC). The structure of gold and the real electrode surface area can be controlled by the parameters of metal electrodeposition. In particular, a 3D RVC-Au sponge provides a large accessible surface area for immobilization of enzyme and electron mediators, moreover, effective mass diffusion can also take place through the uniform macro - porous scaffold. To efficiently bind the enzyme to the electrode and enhance electron transfer parameters the gold surface was modified with ultrasmall gold nanoparticles stabilized with glutathione. These quantum sized nanoparticles exhibit specific electronic properties and also expand the working surface of the electrode. Significantly, at the steady state of power generation, the EFC device with RVC-Au electrodes provided high volumetric power density of 1.18±0.14mWcm (41.3±3.8µWcm) calculated based on the volume of electrode material with OCV 0.741±0.021V. These new 3D RVC-Au electrodes showed great promise for improving the power generation of EFC devices. 10.1016/j.bios.2017.03.070
    Biochemical and Spectroscopic Observation of Mn(II) Sequestration from Bacterial Mn(II) Transport Machinery by Calprotectin. Hadley Rose C,Gagnon Derek M,Brophy Megan Brunjes,Gu Yu,Nakashige Toshiki G,Britt R David,Nolan Elizabeth M Journal of the American Chemical Society Human calprotectin (CP, S100A8/S100A9 oligomer) is a metal-sequestering host-defense protein that prevents bacterial acquisition of Mn(II). In this work, we investigate Mn(II) competition between CP and two solute-binding proteins that Staphylococcus aureus and Streptococcus pneumoniae, Gram-positive bacterial pathogens of significant clinical concern, use to obtain Mn(II) when infecting a host. Biochemical and electron paramagnetic resonance (EPR) spectroscopic analyses demonstrate that CP outcompetes staphylococcal MntC and streptococcal PsaA for Mn(II). This behavior requires the presence of excess Ca(II) ions, which enhance the Mn(II) affinity of CP. This report presents new spectroscopic evaluation of two Mn(II) proteins important for bacterial pathogenesis, direct observation of Mn(II) sequestration from bacterial Mn(II) acquisition proteins by CP, and molecular insight into the extracellular battle for metal nutrients that occurs during infection. 10.1021/jacs.7b11207
    Cyclodextrin-Based Peptide Self-Assemblies (Spds) That Enhance Peptide-Based Fluorescence Imaging and Antimicrobial Efficacy. Jiao Jin-Biao,Wang Guan-Zhen,Hu Xi-Le,Zang Yi,Maisonneuve Stéphane,Sedgwick Adam C,Sessler Jonathan L,Xie Juan,Li Jia,He Xiao-Peng,Tian He Journal of the American Chemical Society As a result of their high specificity for their corresponding biological targets, peptides have shown significant potential in a range of diagnostic and therapeutic applications. However, their widespread use has been limited by their minimal cell permeability and stability in biological milieus. We describe here a hepta-dicyanomethylene-4-pyran appended β-cyclodextrin () that acts as a delivery enhancing "host" for 1-bromonaphthalene-modified peptides, as demonstrated with peptide probes . Interaction between the fluorescent peptides and results in the hierarchical formation of unique supramolecular architectures, which we term supramolecular-peptide-dots (). Each (, , and ) was found to facilitate the intracellular delivery of the constituent fluorescent probes (), thus allowing spatiotemporal imaging of an apoptosis biomarker (caspase-3) and mitosis. , incorporating the antimicrobial peptide , was found to provide an enhanced therapeutic benefit against both Gram-positive and Gram-negative bacteria relative to alone. In addition, a fluorescent was prepared, which revealed greater bacterial cellular uptake compared to the peptide alone () in . (ATCC 25922) and (ATCC 25923). This latter observation supports the suggestion that the platform reported here has the ability to facilitate the delivery of a therapeutic peptide and provides an easy-to-implement strategy for enhancing the antimicrobial efficacy of known therapeutic peptides. The present findings thus serve to highlight a new and effective supramolecular delivery approach that is potentially generalizable to overcome limitations associated with functional peptides. 10.1021/jacs.9b11207
    Engineered Bacterial Bioreactor for Tumor Therapy via Fenton-Like Reaction with Localized H O Generation. Fan Jin-Xuan,Peng Meng-Yun,Wang He,Zheng Hao-Ran,Liu Zong-Lin,Li Chu-Xin,Wang Xia-Nan,Liu Xin-Hua,Cheng Si-Xue,Zhang Xian-Zheng Advanced materials (Deerfield Beach, Fla.) Synthetic biology based on bacteria has been displayed in antitumor therapy and shown good performance. In this study, an engineered bacterium Escherichia coli MG1655 is designed with NDH-2 enzyme (respiratory chain enzyme II) overexpression (Ec-pE), which can colonize in tumor regions and increase localized H O generation. Following from this, magnetic Fe O nanoparticles are covalently linked to bacteria to act as a catalyst for a Fenton-like reaction, which converts H O to toxic hydroxyl radicals (•OH) for tumor therapy. In this constructed bioreactor, the Fenton-like reaction occurs with sustainably synthesized H O produced by engineered bacteria, and severe tumor apoptosis is induced via the produced toxic •OH. These results show that this bioreactor can achieve effective tumor colonization, and realize a self-supplied therapeutic Fenton-like reaction without additional H O provision. 10.1002/adma.201808278
    The Open Circuit Voltage in Biofuel Cells: Nernstian Shift in Pseudocapacitive Electrodes. Conzuelo Felipe,Marković Nikola,Ruff Adrian,Schuhmann Wolfgang Angewandte Chemie (International ed. in English) In the development of biofuel cells great effort is dedicated to achieving outstanding figures of merit, such as high stability, maximum power output, and a large open circuit voltage. Biofuel cells with immobilized redox mediators, such as redox polymers with integrated enzymes, show experimentally a substantially higher open circuit voltage than the thermodynamically expected value. Although this phenomenon is widely reported in the literature, there is no comprehensive understanding of the potential shift, the high open circuit voltages have not been discussed in detail, and hence they are only accepted as an inherent property of the investigated systems. We demonstrate that this effect is the result of a Nernstian shift of the electrode potential when catalytic conversion takes place in the absence or at very low current flow. Experimental evidence confirms that the immobilization of redox centers on the electrode surface results in the assembled biofuel cell delivering a higher power output because of charge storage upon catalytic conversion. Our findings have direct implications for the design and evaluation of (bio)fuel cells with pseudocapacitive elements. 10.1002/anie.201808450
    Signalling and differentiation in emulsion-based multi-compartmentalized in vitro gene circuits. Dupin Aurore,Simmel Friedrich C Nature chemistry Multicellularity enables the growth of complex life forms as it allows for the specialization of cell types, differentiation and large-scale spatial organization. In a similar way, modular construction of synthetic multicellular systems will lead to dynamic biomimetic materials that can respond to their environment in complex ways. To achieve this goal, artificial cellular communication and developmental programs still have to be established. Here, we create geometrically controlled spatial arrangements of emulsion-based artificial cellular compartments containing synthetic in vitro gene circuitry, separated by lipid bilayer membranes. We quantitatively determine the membrane pore-dependent response of the circuits to artificial morphogen gradients, which are established via diffusion from dedicated organizer cells. Utilizing different types of feedforward and feedback in vitro gene circuits, we then implement artificial signalling and differentiation processes, demonstrating the potential for the realization of complex spatiotemporal dynamics in artificial multicellular systems. 10.1038/s41557-018-0174-9
    Electrical Conductivity, Selective Adhesion, and Biocompatibility in Bacteria-Inspired Peptide-Metal Self-Supporting Nanocomposites. Guterman Tom,Ing Nicole L,Fleischer Sharon,Rehak Pavel,Basavalingappa Vasantha,Hunashal Yamanappa,Dongre Ramachandra,Raghothama Srinivasarao,Král Petr,Dvir Tal,Hochbaum Allon I,Gazit Ehud Advanced materials (Deerfield Beach, Fla.) Bacterial type IV pili (T4P) are polymeric protein nanofibers that have diverse biological roles. Their unique physicochemical properties mark them as a candidate biomaterial for various applications, yet difficulties in producing native T4P hinder their utilization. Recent effort to mimic the T4P of the metal-reducing Geobacter sulfurreducens bacterium led to the design of synthetic peptide building blocks, which self-assemble into T4P-like nanofibers. Here, it is reported that the T4P-like peptide nanofibers efficiently bind metal oxide particles and reduce Au ions analogously to their native counterparts, and thus give rise to versatile and multifunctional peptide-metal nanocomposites. Focusing on the interaction with Au ions, a combination of experimental and computational methods provides mechanistic insight into the formation of an exceptionally dense Au nanoparticle (AuNP) decoration of the nanofibers. Characterization of the thus-formed peptide-AuNPs nanocomposite reveals enhanced thermal stability, electrical conductivity from the single-fiber level up, and substrate-selective adhesion. Exploring its potential applications, it is demonstrated that the peptide-AuNPs nanocomposite can act as a reusable catalytic coating or form self-supporting immersible films of desired shapes. The films scaffold the assembly of cardiac cells into synchronized patches, and present static charge detection capabilities at the macroscale. The study presents a novel T4P-inspired biometallic material. 10.1002/adma.201807285
    In Situ Engineering of Intracellular Hemoglobin for Implantable High-Performance Biofuel Cells. Chen Huifeng,Bai Zhengyu,Dai Xianqi,Zeng Xiaoqiao,Cano Zachary P,Xie Xiaoxiao,Zhao Mingyu,Li Matthew,Wang He,Chen Zhongwei,Yang Lin,Lu Jun Angewandte Chemie (International ed. in English) The key challenge for the broad application of implantable biofuel cells (BFCs) is to achieve inorganic-organic composite biocompatibility while improving the activity and selectivity of the catalysts. We have fabricated nanoengineered red blood cells (NERBCs) by an environmentally friendly method by using red blood cells as the raw material and hemoglobin (Hb) embedded with ultrasmall hydroxyapatite (HAP, Ca (PO ) (OH) ) as the functional BFC cathode material. The NERBCs showed greatly enhanced cell performance with high electrocatalytic activity, stability, and selectivity. The NERBCs maintained the original biological properties of the natural cell, while enhancing the catalytic oxygen reduction reaction (ORR) through the interaction between -OH groups in HAP and the Hb in RBCs. They also enabled direct electron transportation, eliminating the need for an electron-transfer mediator, and showed catalytic inactivity for glucose oxidation, thus potentially enabling the development of separator-free BFCs. 10.1002/anie.201902073
    Semi-artificial Photosynthetic CO Reduction through Purple Membrane Re-engineering with Semiconductor. Chen Zhaowei,Zhang He,Guo Peijun,Zhang Jingjing,Tira Gregory,Kim Yu Jin,Wu Yimin A,Liu Yuzi,Wen Jianguo,Rajh Tijana,Niklas Jens,Poluektov Oleg G,Laible Philip D,Rozhkova Elena A Journal of the American Chemical Society The engineering of biological pathways with man-made materials provides inspiring blueprints for sustainable fuel production. Here, we leverage a top-down cellular engineering strategy to develop a new semi-artificial photosynthetic paradigm for carbon dioxide reduction via enveloping purple membrane-derived vesicles over Pd-deposited hollow porous TiO nanoparticles. In this biohybrid, the membrane protein, bacteriorhodopsin, not only retains its native biological function of pumping protons but also acts as a photosensitizer that injects light-excited electrons into the conduction band of TiO. As such, the electrons trapped on Pd cocatalysts and the protons accumulated inside the cytomimetic architecture act in concert to reduce CO via proton-coupled multielectron transfer processes. This study provides an alternative toolkit for developing robust semi-artificial photosynthetic systems for solar energy conversion. 10.1021/jacs.9b05564
    Gold-Coated M13 Bacteriophage as a Template for Glucose Oxidase Biofuel Cells with Direct Electron Transfer. Blaik Rita A,Lan Esther,Huang Yu,Dunn Bruce ACS nano Glucose oxidase-based biofuel cells are a promising source of alternative energy for small device applications, but still face the challenge of achieving robust electrical contact between the redox enzymes and the current collector. This paper reports on the design of an electrode consisting of glucose oxidase covalently attached to gold nanoparticles that are assembled onto a genetically engineered M13 bacteriophage using EDC-NHS chemistry. The engineered phage is modified at the pIII protein to attach onto a gold substrate and serves as a high-surface-area template. The resulting "nanomesh" architecture exhibits direct electron transfer (DET) and achieves a higher peak current per unit area of 1.2 mA/cm(2) compared to most other DET attachment schemes. The final enzyme surface coverage on the electrode was calculated to be approximately 4.74 × 10(-8) mol/cm(2), which is a significant improvement over most current glucose oxidase (GOx) DET attachment methods. 10.1021/acsnano.5b04580
    Bioelectrocatalytic NAD/NADH inter-conversion: transformation of an enzymatic fuel cell into an enzymatic redox flow battery. Quah Timothy,Milton Ross D,Abdellaoui Sofiene,Minteer Shelley D Chemical communications (Cambridge, England) Diaphorase and a benzylpropylviologen redox polymer were combined to create a bioelectrode that can both oxidize NADH and reduce NAD. We demonstrate how bioelectrocatalytic NAD/NADH inter-conversion can transform a glucose/O enzymatic fuel cell (EFC) with an open circuit potential (OCP) of 1.1 V into an enzymatic redox flow battery (ERFB), which can be rapidly recharged by operation as an EFC. 10.1039/c7cc03842a
    In Situ Capture of Bacterial Toxins for Antivirulence Vaccination. Wei Xiaoli,Gao Jie,Wang Fei,Ying Man,Angsantikul Pavimol,Kroll Ashley V,Zhou Jiarong,Gao Weiwei,Lu Weiyue,Fang Ronnie H,Zhang Liangfang Advanced materials (Deerfield Beach, Fla.) Antivirulence vaccination is a promising strategy for addressing bacterial infection that focuses on removing the harmful toxins produced by bacteria. However, a major challenge for creating vaccines against biological toxins is that the vaccine potency is often limited by lack of antigenic breadth, as most formulations have focused on single antigens, while most bacteria secrete a plethora of toxins. Here, a facile approach for generating multiantigenic nanotoxoids for use as vaccines against pathogenic bacteria by leveraging the natural affinity of virulence factors for cellular membranes is reported. Specifically, multiple virulent toxins from bacterial protein secretions are concurrently and naturally entrapped using a membrane-coated nanosponge construct. The resulting multivalent nanotoxoids are capable of delivering virulence factors together, are safe both in vitro and in vivo, and can elicit functional immunity capable of combating live bacterial infections in a mouse model. Despite containing the same bacterial antigens, the reported nanotoxoid formulation consistently outperforms a denatured protein preparation in all of the metrics studied, which underscores the utility of biomimetic nanoparticle-based neutralization and delivery. Overall this strategy helps to address major hurdles in the design of antivirulence vaccines, enabling increased antigenic breadth while maintaining safety. 10.1002/adma.201701644
    Reversible and Selective Interconversion of Hydrogen and Carbon Dioxide into Formate by a Semiartificial Formate Hydrogenlyase Mimic. Sokol Katarzyna P,Robinson William E,Oliveira Ana R,Zacarias Sonia,Lee Chong-Yong,Madden Christopher,Bassegoda Arnau,Hirst Judy,Pereira Inês A C,Reisner Erwin Journal of the American Chemical Society The biological formate hydrogenlyase (FHL) complex links a formate dehydrogenase (FDH) to a hydrogenase (Hase) and produces H and CO from formate via mixed-acid fermentation in . Here, we describe an electrochemical and a colloidal semiartificial FHL system that consists of an FDH and a Hase immobilized on conductive indium tin oxide (ITO) as an electron relay. These systems benefit from the efficient wiring of a highly active enzyme pair and allow for the reversible conversion of formate to H and CO under ambient temperature and pressure. The hybrid systems provide a template for the design of synthetic catalysts and surpass the FHL complex by storing and releasing H on demand by interconverting CO/H and formate with minimal bias in either direction. 10.1021/jacs.9b09575
    Mechanically and biologically skin-like elastomers for bio-integrated electronics. Chen Shuo,Sun Lijie,Zhou Xiaojun,Guo Yifan,Song Jianchun,Qian Sihao,Liu Zenghe,Guan Qingbao,Meade Jeffries Eric,Liu Wenguang,Wang Yadong,He Chuanglong,You Zhengwei Nature communications The bio-integrated electronics industry is booming and becoming more integrated with biological tissues. To successfully integrate with the soft tissues of the body (eg. skin), the material must possess many of the same properties including compliance, toughness, elasticity, and tear resistance. In this work, we prepare mechanically and biologically skin-like materials (PSeD-U elastomers) by designing a unique physical and covalent hybrid crosslinking structure. The introduction of an optimal amount of hydrogen bonds significantly strengthens the resultant elastomers with 11 times the toughness and 3 times the strength of covalent crosslinked PSeD elastomers, while maintaining a low modulus. Besides, the PSeD-U elastomers show nonlinear mechanical behavior similar to skins. Furthermore, PSeD-U elastomers demonstrate the cytocompatibility and biodegradability to achieve better integration with tissues. Finally, piezocapacitive pressure sensors are fabricated with high pressure sensitivity and rapid response to demonstrate the potential use of PSeD-U elastomers in bio-integrated electronics. 10.1038/s41467-020-14446-2
    "Uphill" cation transport: A bioinspired photo-driven ion pump. Zhang Zhen,Kong Xiang-Yu,Xie Ganhua,Li Pei,Xiao Kai,Wen Liping,Jiang Lei Science advances Biological ion pumps with active ionic transport properties lay the foundation for many life processes. However, few analogs have been produced because extra energy is needed to couple to this "uphill" process. We demonstrate a bioinspired artificial photo-driven ion pump based on a single polyethylene terephthalate conical nanochannel. The pumping process behaving as an inversion of zero-volt current can be realized by applying ultraviolet irradiation from the large opening. The light energy can accelerate the dissociation of the benzoic acid derivative dimers existing on the inner surface of nanochannel, which consequently produces more mobile carboxyl groups. Enhanced electrostatic interaction between the ions traversing the nanochannel and the charged groups on the inner wall is the key reason for the uphill cation transport behavior. This system creates an ideal experimental and theoretical platform for further development and design of various stimuli-driven and specific ion-selective bioinspired ion pumps, which anticipates wide potential applications in biosensing, energy conversion, and desalination. 10.1126/sciadv.1600689
    Three-Dimensional, Enzyme Biohydrogel Electrode for Improved Bioelectrocatalysis. Ghimire Ananta,Pattammattel Ajith,Maher Charles E,Kasi Rajeswari M,Kumar Challa V ACS applied materials & interfaces Higher loading of enzymes on electrodes and efficient electron transfer from the enzyme to the electrode are urgently needed to enhance the current density of biofuel cells. The two-dimensional nature of the electrode surface limits the enzyme loading on the surface, and unfavorable interactions with electrode surfaces cause inactivation of the enzyme. Benign biohydrogels are designed here to address enzyme degradation, and the three-dimensional nature of the biohydrogel enhanced the enzyme density per unit area. A general strategy is demonstrated here using a redox active enzyme glucose oxidase embedded in a bovine serum albumin biohydrogel on flexible carbon cloth electrodes. In the presence of ferricyanide as a mediator, this bioelectrode generated a maximum current density (j) of 13.2 mA·cm at 0.45 V in the presence of glucose with a sensitivity of 67 μA·mol·cm and a half-life of >2 weeks at room temperature. A strong correlation of current density with water uptake by the biohydrogel was observed. Moreover, a soluble mediator (sodium ferricyanide) in the biohydrogel enhanced the current density by ∼1000-fold, and citrate-phosphate buffer has been found to be the best to achieve the maximum current density. A record 2.2% of the loaded enzyme was electroactive, which is greater than the highest value reported (2-fold). Stabilization of the enzyme in the biohydrogel resulted in retention of the enzymatic activity over a wide range of pH (4.0-8.0). We showed here that biohydrogels are excellent media for enzymatic electron transfer reactions required for bioelectronics and biofuel cell applications. 10.1021/acsami.7b13606
    pH Dependency in Anode Biofilms of Thermincola ferriacetica Suggests a Proton-Dependent Electrochemical Response. Lusk Bradley G,Peraza Isaias,Albal Gaurav,Marcus Andrew K,Popat Sudeep C,Torres Cesar I Journal of the American Chemical Society Monitoring the electrochemical response of anode respiring bacteria (ARB) helps elucidate the fundamental processes of anode respiration and their rate limitations. Understanding these limitations provides insights on how ARB create the complex interfacing of biochemical metabolic processes with insoluble electron acceptors and electronics. In this study, anode biofilms of the thermophilic (60 °C) Gram-positive ARB Thermincola ferriacetica were studied to determine the presence of a proton-dependent electron transfer response. The effects of pH, the presence of an electron donor (acetate), and biofilm growth were varied to determine their influence on the electrochemical midpoint potential ( E) and formal redox potential ( E°') under nonturnover conditions. The E and E°' are associated with an enzymatic process within ARB's metabolism that controls the rate and energetic state of their respiration. Results for all conditions indicate that pH was the major contributor to altering the energetics of T. ferriacetica anode biofilms. Electrochemical responses measured in the absence of an electron donor and with a minimal proton gradient within the anode biofilms resulted in a 48 ± 7 mV/pH unit shift in the E°', suggesting a proton-dependent rate-limiting process. Given the limited energy available for anode respiration (<200 mV when using acetate as electron donor), our results provide a new perspective in understanding proton-transport limitations in ARB biofilms, one in which ARB are thermodynamically limited by pH gradients. Since the anode biofilms of all ARB that perform direct extracellular electron transfer (EET) investigated thus far exhibit an n = 1 Nernstian behavior, and because this behavior is affected by changes in pH, we hypothesize that the Nernstian response is associated with membrane proteins responsible for proton translocation. Finally, this study shows that the E and E°' are a function of pH within the physiological range of ARB, and thus, given the significant effect pH has on this parameter, we recommend reporting the E and E°' of ARB biofilms at a specific bulk pH. 10.1021/jacs.8b01734
    Multiheme Cytochrome Mediated Redox Conduction through Shewanella oneidensis MR-1 Cells. Xu Shuai,Barrozo Alexandre,Tender Leonard M,Krylov Anna I,El-Naggar Mohamed Y Journal of the American Chemical Society Multiheme cytochromes function as extracellular electron transfer (EET) conduits that extend the metabolic reach of microorganisms to external solid surfaces. These conduits are also proposed to facilitate long-distance electron transport along cellular membranes and across multiple cells. Here we report electrochemical gating measurements of Shewanella oneidensis MR-1 cells linking interdigitated electrodes. The dependence of the source-drain current on gate potential demonstrates a redox conduction mechanism, which we link to the presence of multiheme cytochromes of the Mtr pathway. We also find that the measured thermal activation energy of 0.29 ± 0.03 eV is consistent with these obtained from electron hopping calculations through the S. oneidensis Mtr outer-membrane decaheme cytochromes. Our measurements and calculations have implications for understanding and controlling micrometer-scale electron transport in microbial systems. 10.1021/jacs.8b05104
    A Biocompatible Heterogeneous MOF-Cu Catalyst for In Vivo Drug Synthesis in Targeted Subcellular Organelles. Wang Faming,Zhang Yan,Liu Zhengwei,Du Zhi,Zhang Lu,Ren Jinsong,Qu Xiaogang Angewandte Chemie (International ed. in English) As a typical bioorthogonal reaction, the copper-catalyzed azide-alkyne cycloaddition (CuAAC) has been used for drug design and synthesis. However, for localized drug synthesis, it is important to be able to determine where the CuAAC reaction occurs in living cells. In this study, we constructed a heterogeneous copper catalyst on a metal-organic framework that could preferentially accumulate in the mitochondria of living cells. Our system enabled the localized synthesis of drugs through a site-specific CuAAC reaction in mitochondria with good biocompatibility. Importantly, the subcellular catalytic process for localized drug synthesis avoided the problems of the delivery and distribution of toxic molecules. In vivo tumor therapy experiments indicated that the localized synthesis of resveratrol-derived drugs led to greater antitumor efficacy and minimized side effects usually associated with drug delivery and distribution. 10.1002/anie.201901760
    Selection of DNA-Encoded Libraries to Protein Targets within and on Living Cells. Cai Bo,Kim Dongwook,Akhand Saeed,Sun Yixing,Cassell Robert J,Alpsoy Aktan,Dykhuizen Emily C,Van Rijn Richard M,Wendt Michael K,Krusemark Casey J Journal of the American Chemical Society We report the selection of DNA-encoded small molecule libraries against protein targets within the cytosol and on the surface of live cells. The approach relies on generation of a covalent linkage of the DNA to protein targets by affinity labeling. This cross-linking event enables subsequent copurification by a tag on the recombinant protein. To access targets within cells, a cyclic cell-penetrating peptide is appended to DNA-encoded libraries for delivery across the cell membrane. As this approach assesses binding of DELs to targets in live cells, it provides a strategy for selection of DELs against challenging targets that cannot be expressed and purified as active. 10.1021/jacs.9b08085
    Engineering Secretory Amyloids for Remote and Highly Selective Destruction of Metastatic Foci. Céspedes María Virtudes,Cano-Garrido Olivia,Álamo Patricia,Sala Rita,Gallardo Alberto,Serna Naroa,Falgàs Aïda,Voltà-Durán Eric,Casanova Isolda,Sánchez-Chardi Alejandro,López-Laguna Hèctor,Sánchez-García Laura,Sánchez Julieta M,Unzueta Ugutz,Vázquez Esther,Mangues Ramón,Villaverde Antonio Advanced materials (Deerfield Beach, Fla.) Functional amyloids produced in bacteria as nanoscale inclusion bodies are intriguing but poorly explored protein materials with wide therapeutic potential. Since they release functional polypeptides under physiological conditions, these materials can be potentially tailored as mimetic of secretory granules for slow systemic delivery of smart protein drugs. To explore this possibility, bacterial inclusion bodies formed by a self-assembled, tumor-targeted Pseudomonas exotoxin (PE24) are administered subcutaneously in mouse models of human metastatic colorectal cancer, for sustained secretion of tumor-targeted therapeutic nanoparticles. These proteins are functionalized with a peptidic ligand of CXCR4, a chemokine receptor overexpressed in metastatic cancer stem cells that confers high selective cytotoxicity in vitro and in vivo. In the mouse models of human colorectal cancer, time-deferred anticancer activity is detected after the subcutaneous deposition of 500 µg of PE24-based amyloids, which promotes a dramatic arrest of tumor growth in the absence of side toxicity. In addition, long-term prevention of lymphatic, hematogenous, and peritoneal metastases is achieved. These results reveal the biomedical potential and versatility of bacterial inclusion bodies as novel tunable secretory materials usable in delivery, and they also instruct how therapeutic proteins, even with high functional and structural complexity, can be packaged in this convenient format. 10.1002/adma.201907348
    Cross-Linked Artificial Enzyme Crystals as Heterogeneous Catalysts for Oxidation Reactions. Lopez Sarah,Rondot Laurianne,Leprêtre Chloé,Marchi-Delapierre Caroline,Ménage Stéphane,Cavazza Christine Journal of the American Chemical Society Designing systems that merge the advantages of heterogeneous catalysis, enzymology, and molecular catalysis represents the next major goal for sustainable chemistry. Cross-linked enzyme crystals display most of these essential assets (well-designed mesoporous support, protein selectivity, and molecular recognition of substrates). Nevertheless, a lack of reaction diversity, particularly in the field of oxidation, remains a constraint for their increased use in the field. Here, thanks to the design of cross-linked artificial nonheme iron oxygenase crystals, we filled this gap by developing biobased heterogeneous catalysts capable of oxidizing carbon-carbon double bonds. First, reductive O activation induces selective oxidative cleavage, revealing the indestructible character of the solid catalyst (at least 30 000 turnover numbers without any loss of activity). Second, the use of 2-electron oxidants allows selective and high-efficiency hydroxychlorination with thousands of turnover numbers. This new technology by far outperforms catalysis using the inorganic complexes alone, or even the artificial enzymes in solution. The combination of easy catalyst synthesis, the improvement of "omic" technologies, and automation of protein crystallization makes this strategy a real opportunity for the future of (bio)catalysis. 10.1021/jacs.7b09343
    Bioresponsive Nanoparticles Targeted to Infectious Microenvironments for Sepsis Management. Zhang Can Yang,Gao Jin,Wang Zhenjia Advanced materials (Deerfield Beach, Fla.) Sepsis is a life-threatening disease resulted from a dysregulated host immune response to bacterial infections, continuing to cause high morbidity and mortality worldwide. Despite discoveries of many potential therapeutic targets, effective treatments of sepsis are lacking. Here, a strategy is reported to target infectious microenvironments (IMEs) via bioresponsive nanoparticles that simultaneously eliminate bacteria and alleviate the host inflammation response, thus managing sepsis in mice. The nanoparticle is made of copolymers sensitive to pH and bacterial enzymes to self-assemble into a micelle loaded with both an antibiotic (ciprofloxacin) and an anti-inflammatory agent ((2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide). In addition, the nanoparticle is conjugated with intercellular adhesion molecule-1 antibodies to target IMEs. Nanoparticle targeting to IMEs and local cues as triggers to deliver therapeutics in on-demand manners is demonstrated using an acute lung bacterial infection mouse model. In the sepsis mouse model induced by peritonitis at a lethal dose of bacterial invasion, it is shown that concurrently targeting pathogens and excessive inflammation pathways is valuable to manage the sepsis. The study illustrates not only the development of a new delivery system but also the mechanism-based therapy of nanomedicine for infectious diseases. 10.1002/adma.201803618
    Construction of CPs@MnO-AgNPs as a multifunctional nanosensor for glutathione sensing and cancer theranostics. Wang Qi,Wang Chunyan,Wang Xiaodong,Zhang Yuan,Wu Yuehuan,Dong Chuan,Shuang Shaomin Nanoscale A multifunctional nanosensor of CPs@MnO-AgNPs was constructed for sensitive and selective sensing of GSH and cancer theranostics in this work. The CPs@MnO nanocomposite was synthesized by capping MnO onto carbon nanoparticles through an in situ redox reaction under ultrasonication. AgNPs with fluorescence were obtained through a silver-mirror-like reaction using BSA as both a template and reductant and further anchored onto the surface of CPs@MnO through electrostatic interaction to construct the CPs@MnO-AgNP nanocomposite. The fluorescence of AgNPs was effectively quenched by MnO through an inner filter effect and a static quenching effect and further recovered by GSH owing to the unique redox reaction between GSH and MnO. Therefore, a novel fluorescent turn-on nanosensor was established for GSH sensing in vitro and in vivo. For GSH sensing, a satisfactory linear range of 0.8-80 μM with a detection limit of 0.55 μM was obtained under optimal conditions. Moreover, by integrating the GSH-responsive fluorescence imaging capacity, the photothermal activity of carbon nanoparticles and the anticancer effect of AgNPs, the CPs@MnO-AgNP nanocomposite was successfully applied for cancer theranostics. The fluorescence recognition of cancer was achieved by overexpressing GSH in cancer, meanwhile the photothermal therapy from CPs and chemotherapy from AgNPs jointly produced an enhanced therapeutic effect. This redox-responsive nanocomposite of CPs@MnO-AgNPs improves the MnO nanomaterial-based applications in GSH sensing and cancer theranostics. 10.1039/c9nr06443e
    Correction to Lancet Infect Dis 2020; published online March 11, https://doi.org/10.1016/ S1473-3099(20)30144-4. The Lancet. Infectious diseases 10.1016/S1473-3099(20)30251-6
    High-Performance Respiration-Based Biocell Using Artificial Nanochannel Regulation. Zhang Qianqian,Li Xiulin,Chen Yang,Zhang Qian,Liu Huixue,Zhai Jin,Yang Xiaoda Advanced materials (Deerfield Beach, Fla.) Based on electron and proton transfer events occurring in biological respiration, a mitochondria-based biocell is constructed by combining with artificial nanochannels. In this biocell, mitochondria transfer electrons to the working electrode and pump protons into the electrolyte through the tricarboxylic acid cycle. The nanochannels provide passages for protons to transport along the transmembrane concentration gradient to consume electrons on the counter electrode, forming a continuous and stable current. Furthermore, the proton transmembrane transport behavior could be modulated by regulating the permeability area and surface charge of nanochannels. A high-performance biocell is obtained when equipped with the optimized nanochannels, which produces a current of ≈3.1 mA cm , a maximum power of ≈0.91 mW cm , and a lifetime over 60 h. This respiratory-based biocell shows great potential for the efficient utilization of bioelectricity. 10.1002/adma.201606871
    An "On-Site Transformation" Strategy for Treatment of Bacterial Infection. Qi Guo-Bin,Zhang Di,Liu Fu-Hua,Qiao Zeng-Ying,Wang Hao Advanced materials (Deerfield Beach, Fla.) To date, numerous nanosystems have been developed as antibiotic replacements for bacterial infection treatment. However, these advanced systems are limited owing to their nontargeting accumulation and the consequent side effects. Herein, transformable polymer-peptide biomaterials have been developed that enable specific accumulation in the infectious site and long-term retention, resulting in enhanced binding capability and killing efficacy toward bacteria. The polymer-peptide conjugates are composed of a chitosan backbone and two functional peptides, i.e., an antimicrobial peptide and a poly(ethylene glycol)-tethered enzyme-cleavable peptide (CPC-1). The CPC-1 initially self-assembles into nanoparticles with pegylated coronas. Upon the peptides are cleaved by the gelatinase secreted by a broad spectrum of bacterial species, the resultant compartments of nanoparticles spontaneously transformed into fibrous nanostructures that are stabilized by enhanced chain-chain interaction, leading to exposure of antimicrobial peptide residues for multivalent cooperative electrostatic interactions with bacterial membranes. Intriguingly, the in situ morphological transformation also critically improves the accumulation and retention of CPC-1 in infectious sites in vivo, which exhibits highly efficient antibacterial activity. This proof-of-concept study demonstrates that pathological environment-driven smart self-assemblies may provide a new idea for design of high-performance biomaterials for disease diagnostics and therapeutics. 10.1002/adma.201703461
    Large-scale tight-binding simulations of quantum transport in ballistic graphene. Calogero Gaetano,Papior Nick R,Bøggild Peter,Brandbyge Mads Journal of physics. Condensed matter : an Institute of Physics journal Graphene has proven to host outstanding mesoscopic effects involving massless Dirac quasiparticles travelling ballistically resulting in the current flow exhibiting light-like behaviour. A new branch of 2D electronics inspired by the standard principles of optics is rapidly evolving, calling for a deeper understanding of transport in large-scale devices at a quantum level. Here we perform large-scale quantum transport calculations based on a tight-binding model of graphene and the non-equilibrium Green's function method and include the effects of p-n junctions of different shape, magnetic field, and absorptive regions acting as drains for current. We stress the importance of choosing absorbing boundary conditions in the calculations to correctly capture how current flows in the limit of infinite devices. As a specific application we present a fully quantum-mechanical framework for the '2D Dirac fermion microscope' recently proposed by Bøggild et al (2017 Nat. Commun. 8 10.1038), tackling several key electron-optical effects therein predicted via semiclassical trajectory simulations, such as electron beam collimation, deflection and scattering off Veselago dots. Our results confirm that a semiclassical approach to a large extend is sufficient to capture the main transport features in the mesoscopic limit and the optical regime, but also that a richer electron-optical landscape is to be expected when coherence or other purely quantum effects are accounted for in the simulations. 10.1088/1361-648X/aad6f1