Polychromatic solar energy conversion in pigment-protein chimeras that unite the two kingdoms of (bacterio)chlorophyll-based photosynthesis

Natural photosynthesis can be divided between the chlorophyll-containing plants, algae and cyanobacteria that make up the oxygenic phototrophs and a diversity of bacteriochlorophyll-containing bacteria that make up the anoxygenic phototrophs. Photosynthetic light harvesting and reaction centre proteins from both kingdoms have been exploited for solar energy conversion, solar fuel synthesis and sensing technologies, but the energy harvesting abilities of these devices are limited by each protein’s individual palette of pigments. In this work we demonstrate a range of genetically-encoded, self-assembling photosystems in which recombinant plant light harvesting complexes are covalently locked with reaction centres from a purple photosynthetic bacterium, producing macromolecular chimeras that display mechanisms of polychromatic solar energy harvesting and conversion. Our findings illustrate the power of a synthetic biology approach in which bottom-up construction of photosystems using naturally diverse but mechanistically complementary components can be achieved in a predictable fashion through the encoding of adaptable, plug-and-play covalent interfaces

Discussion on Electric Power Supply Systems for All Electric Aircraft

The electric power supply system is one of the most important research areas within sustainable and energy-efcient aviation for more- and especially all electric aircraft. This paper discusses the history in electrication, current trends with a broad overview of research activities, state of the art of electrication and an initial proposal for a short-range aircraft. It gives an overviewof the mission prole, electrical sources, approaches for the electrical distribution system and the required electrical loads. Current research aspects and questions are discussed, including voltage levels, semiconductor technology, topologies and reliability. Because of the importance for safety possible circuit breakers for the proposed concept are also presented and compared, leading to a initial proposal. Additionally, a very broad review of literature and a state of the art discussion of the wiring harness is given, showing that this topic comes with a high number of aspects and requirements. Finally, the conclusion sums up the most important results and gives an outlook on important future research topics

Sustaining Electron Transfer Pathways Extends Biohybrid Photoelectrode Stability to Years

The exploitation of natural photosynthetic enzymes in semi-artificial devices constitutes an attractive and potentially sustainable route for the conversion of solar energy into electricity and solar fuels. However, the stability of photosynthetic proteins after incorporation in a biohybrid architecture typically limits the operational lifetime of biophotoelectrodes to a few hours. Here, we demonstrate ways to greatly enhance the stability of a mesoporous electrode coated with the RC-LH1 photoprotein from Rhodobacter sphaeroides. By preserving electron transfer pathways, we extended operation under continuous high-light to 33 days, and operation after storage to over two years. Coupled with large photocurrents that reached peak values of 4.6 mA cm−2, the optimized biophotoelectrode produced a cumulative output of 86 C cm−2, the largest reported performance to date. Our results demonstrate that the factor limiting stability is the architecture surrounding the photoprotein, and that biohybrid sensors and photovoltaic devices with operational lifetimes of years are feasible

Just Bone Tired: Equine Bone Stress

The field of biophotoelectrochemistry and its application in biophotovoltaics and biosensors has gained more and more attention in recent years. Knowledge of the redox potentials of the catalytically active protein cofactors in biophotovoltaic devices is crucial for accurate modelling and in discerning the mechanisms of their operation. Here, for the first time, we used spectroelectrochemical methods to investigate thermodynamic parameters of a biophotoelectrode in situ. We determined redox potentials of two elements of the system: the primary electron donor in photosynthetic reaction centers (RCs) of the bacterium Rhodobacter sphaeroides and osmium-complex based redox mediators that are bound to a hydrogel matrix. We observe that the midpoint potential of the primary donor is shifted towards more positive potentials in comparison to literature data for RCs solubilized in buffered water solution, likely due to interaction with the polymer matrix. We also demonstrate that the osmium-complex modified redox polymer efficiently wires the RCs to the electrode, maintaining a high Internal Quantum Efficiency with approximately one electron per two photons generated (IQE=50±12%). Overall, this biophotoelectrode may be attractive for controlling the redox state of the protein when performing other types of experiments, e.g. time resolved absorption or fluorescence measurements, in order to gain insights into kinetic limitations and thereby help in the rational design of bioelectronic devices

Rapid nitric oxide–induced desensitization of the cGMP response is caused by increased activity of phosphodiesterase type 5 paralleled by phosphorylation of the enzyme

Most of the effects of the signaling molecule nitric oxide (NO) are mediated by cGMP, which is synthesized by soluble guanylyl cyclase and degraded by phosphodiesterases. Here we show that in platelets and aortic tissue, NO led to a biphasic response characterized by a tremendous increase in cGMP (up to 100-fold) in less than 30 s and a rapid decline, reflecting the tightly controlled balance of guanylyl cyclase and phosphodiesterase activities. Inverse to the reported increase in sensitivity caused by NO shortage, concentrating NO attenuated the cGMP response in a concentration-dependent manner. We found that guanylyl cyclase remained fully activated during the entire course of the cGMP response; thus, desensitization was not due to a switched off guanylyl cyclase. However, when intact platelets were incubated with NO and then lysed, enhanced activity of phosphodiesterase type 5 was detected in the cytosol. Furthermore, this increase in cGMP degradation is paralleled by the phosphorylation of phosphodiesterase type 5 at Ser-92. Thus, our data suggest that NO-induced desensitization of the cGMP response is caused by the phosphorylation and subsequent activity increase of phosphodiesterase type 5

Demonstration of asymmetric electron conduction in pseudosymmetrical photosynthetic reaction centre proteins in an electrical circuit

Photosynthetic reaction centres show promise for biomolecular electronics as nanoscale solar-powered batteries and molecular diodes that are amenable to atomic-level re-engineering. In this work the mechanism of electron conduction across the highly tractable Rhodobacter sphaeroides reaction centre is characterized by conductive atomic force micro-scopy. We find, using engineered proteins of known structure, that only one of the two cofactor wires connecting the positive and negative termini of this reaction centre is capable of conducting unidirectional current under a suitably oriented bias, irrespective of the magnitude of the bias or the applied force at the tunnelling junction. This behaviour, strong functional asymmetry in a largely symmetrical protein–cofactor matrix, recapitulates the strong functional asymmetry characteristic of natural photochemical charge separation, but it is surprising given that the stimulus for electron flow is simply an externally applied bias. Reasons for the electrical resistance displayed by the so-called B-wire of cofactors are explored

Nutzerintegration bei der Produktentwicklung am Beispiel der Medizintechnik

Aus der Einführung: "Eine systematische Vorgehensweise entsprechend der Konstruktionsmethodik gilt als zielführender Ansatz bei der Findung von technischen Lösungen und der Entwicklung von Produkten. In der Literatur finden sich dazu zahlreiche Veröffentlichungen z. B. Feldhusen & Grote 2013; Ehrlenspiel 2014; Ehrlenspiel 2009; Roth 1994 und Livotov 2013. Die VDI Richtlinie 2221 „Methodik zum Entwickeln und Konstruieren technischer Systeme und Produkte“ (VDI 1993) beschreibt ebenfalls allgemeingültige Regeln bei der systematischen Lösungsfindung. Iterativ wird in mehreren Teilschritten eine zuvor definierte Aufgabe in eine Lösung überführt. Dabei werden die Phasen der Planung, der Konzeption, des Entwurfes und der Ausarbeitung durchschritten. In der Literatur und den Richtlinien ist jedoch keine explizite Rückkopplung mit dem Nutzer gefordert oder angedacht. Gerade vor dem Hintergrund der voranschreitenden Individualisierung der Produkte und kann hierin ein entscheidender Vorteil liegen. Entwicklungszyklen und die Zeit bis zur Markteinführung von Produkten können reduziert werden. Zudem ist von einer höheren Akzeptanz durch den Kunden auszugehen. ...

A Versatile Macromer-Based Glycosaminoglycan (sHA3) Decorated Biomaterial for Pro-Osteogenic Scavenging of Wnt Antagonists

High serum levels of Wnt antagonists are known to be involved in delayed bone defect healing. Pharmaceutically active implant materials that can modulate the micromilieu of bone defects with regard to Wnt antagonists are therefore considered promising to support defect regeneration. In this study, we show the versatility of a macromer based biomaterial platform to systematically optimize covalent surface decoration with high-sulfated glycosaminoglycans (sHA3) for efficient scavenging of Wnt antagonist sclerostin. Film surfaces representing scaffold implants were cross-copolymerized from three-armed biodegradable macromers and glycidylmethacrylate and covalently decorated with various polyetheramine linkers. The impact of linker properties (size, branching) and density on sHA3 functionalization efficiency and scavenging capacities for sclerostin was tested. The copolymerized 2D system allowed for finding an optimal, cytocompatible formulation for sHA3 functionalization. On these optimized sHA3 decorated films, we showed efficient scavenging of Wnt antagonists DKK1 and sclerostin, whereas Wnt agonist Wnt3a remained in the medium of differentiating SaOS-2 and hMSC. Consequently, qualitative and quantitative analysis of hydroxyapatite staining as a measure for osteogenic differentiation revealed superior mineralization on sHA3 materials. In conclusion, we showed how our versatile material platform enables us to efficiently scavenge and inactivate Wnt antagonists from the osteogenic micromilieu. We consider this a promising approach to reduce the negative effects of Wnt antagonists in regeneration of bone defects via sHA3 decorated macromer based macroporous implants. © 2020 by the authors. Licensee MDPI, Basel, Switzerland