Low-dimensional perovskites

Abstract

The conductance of a classical metallic cable is inversely proportional to its length. In contrast, molecular wires usually act as tunnelling barriers where the conductance decays exponentially with length. Algethami and co-workers now show theoretically that, in some cases, the conductance can actually increase with the length of the molecular wire. Density functional theory-based simulation is used to explore the electronic transport through fused porphyrin oligomers. The molecules, which are known for their good electron transmission, are anchored to either graphene or gold electrodes. The researchers compare the conductance of different oligomers as a function of the Fermi level alignment. When using gold electrodes, the conductance can either increase or decrease with the length, depending on the anchoring group used to couple the molecule to the electrode. For graphene electrodes, however, the conductance increases with the length, independent of the molecule-electrode bonding. Algethami et al. attribute this to the strong coupling between the porphyrin units which yields a sizeable reduction of the gap between the highest occupied and the lowest unoccupied molecular orbital. The reduced transport gap overcompensates the decay of tunnelling conductance with length, at least up to six fused porphyrin units. BH https://doi. By spatially isolating specific reactions, compartmentalization has allowed eukaryotic cells to achieve their high level of complexity. Artificial orthogonal compartments built via protein self-assembly might offer a similar level of control over engineered, non-native metabolic pathways for the generation of valuable products that need to be segregated from the rest of the cell. However, contrary to prokaryotes, eukaryotes do not possess proteins that can spontaneously perform such a task. To tackle this issue, Sigmund and colleagues express the bacterial encapsulin shell and cargo protein system in human embryonic kidney cells. Even in this unfamiliar cellular environment, the system behaves as predicted, with the shell protein self-assembling into nanocompartments that encapsulate the native cargo proteins, with no apparent cytotoxicity. The system lends itself to different applications. By targeting native ferritin-like cargos the nanocompartments can sequester iron, functioning as genetically expressed contrast agents for magnetic resonance imaging, or as markers for electron microscopy. A modified version of the encapsulin nanocompartment can target destabilized proteins, shielding them from proteosomal degradation. Finally, the nanocompartments can be exploited to perform enclosed enzymatic reactions, such as the one producing melanin, a toxic metabolite used for cell imaging. CP https://doi.