Activity

Many strategies for meeting mankind’s future energy demands through the exploitation of plentiful solar energy have been influenced by the efficient and sustainable processes of natural photosynthesis. A limitation affecting solar energy conversion based on photosynthetic proteins is the selective spectral coverage that is the consequence of their particular natural pigmentation. Here we demonstrate the bottom-up formation of semisynthetic, polychromatic photosystems in mixtures of the chlorophyll-based LHCII major light harvesting complex from the oxygenic green plant Arabidopsis thaliana, the bacteriochlorophyll-based photochemical reaction center (RC) from the anoxygenic purple bacterium Rhodobacter sphaeroides and synthetic quantum dots (QDs). Polyhistidine tag adaptation of LHCII and the RC enabled predictable self-assembly of LHCII/RC/QD nanoconjugates, the thermodynamics of which could be accurately modeled and parametrized. The tricomponent biohybrid photosystems displayed enhanced solar energy conversion via either direct chlorophyll-to-bacteriochlorophyll energy transfer or an indirect pathway enabled by the QD, with an overall energy transfer efficiency comparable to that seen in natural photosystems.Novel pH probes based on 2-(6-methoxynaphthalen-2-yl)-3,3-dimethyl-3H-indole have been synthesized and characterized. These compounds display excellent “off-on” fluorescence responses to acidic pH especially under two-photon (TP) excitation conditions as well as strong selectivity and sensitivity toward H+. These features are supported by fluorescence quantum yields over 35%, TP cross sections ∼60 GM, and good resistance to photodegradation under acidic conditions. The synthetic versatility of this model allows subcellular targets to be tuned through minor scaffold modifications without affecting its optical characteristics. The effectiveness of the probes’ innate photophysical properties and the structural modifications for different pH-related applications are demonstrated in mouse embryonic fibroblast cells.The therapeutic effect of traditional chemodynamic therapy (CDT) agents is severely restricted by their weakly acidic pH and glutathione (GSH) overexpression in the tumor microenvironment. Here, fusiform-like copper(II)-based tetrakis(4-carboxy phenyl)porphyrin (TCPP) nanoscale metal-organic frameworks (nMOFs) were designed and constructed for the first time (named PCN-224(Cu)-GOD@MnO2). The coated MnO2 layer can not only avoid conjugation of glucose oxidase (GOD) to damage normal cells but also catalyzes the generation of O2 from H2O2 to enhance the oxidation of glucose (Glu) by GOD, which also provides abundant H2O2 for the subsequent Cu+-based Fenton-like reaction. Meanwhile, the Cu2+ chelated to the TCPP ligand is converted to Cu+ by the excess GSH in the tumor, which reduces the tumor antioxidant activity to improve the CDT effect. see more Next, the Cu+ reacts with the plentiful H2O2 by enzyme catalysis to produce a toxic hydroxyl radical (•OH), and singlet oxygen (1O2) is synchronously generated from combination with Cu+, O2, and H2O via the Russell mechanism. Furthermore, the nanoplatform can be used for both TCPP-based in vivo fluorescence imaging and Mn2+-induced T1-weighted magnetic resonance imaging. In conclusion, fusiform-like PCN-224(Cu)-GOD@MnO2 nMOFs facilitate the therapeutic efficiency of chemodynamic and starvation therapy via combination with relief hypoxia and GSH depletion after acting as an accurate imaging guide.The biaryl scaffold, often showing axial chirality, is a common feature of various fungal natural products. Their biosynthesis requires an oxidative phenol-coupling reaction usually catalyzed by laccases, cytochrome P450 enzymes, or peroxidases. The combination of a laccase and a fasciclin domain-containing (fas) protein is encoded in many biosynthetic gene clusters of biaryls from ascomycetes. However, such phenol-coupling systems including their regio- and stereoselectivity have not been characterized so far. Elucidating the biosynthesis of the antiparasitic binaphthalene sporandol from Chrysosporium merdarium, we demonstrate the combination of a laccase and a fas protein to be crucial for the dimerization reaction. Only the heterologous coproduction of the laccase and the fas protein led to a functional phenol-coupling system, whereas the laccase alone showed no coupling activity. Thus, the laccase/fas protein combination forms an independent group of phenol-coupling enzymes that determines the coupling activity and selectivity of the reaction concurrently and applies to the biosynthesis of many fungal natural products with a biaryl scaffold.The desulfurization property of conventional mixed matrix membranes (MMMs) cannot meet the necessary demand due to particles aggregation and interface defects. Here, we put forward a layer-by-layer (LBL) approach to make a novel PEG@ZIF-8/poly(vinylidene difluoride)(PVDF) composite membrane for pervaporation desulfurization. In this way, a ZIF-8 layer is covered on the surface of the PVDF porous membrane via an in situ growth method. Then, a PEG layer is covered on the ZIF-8 layer by a casting method. Compared with pristine PEG membranes, the separation performance of the ZIF-8@PEG/PVDF nanocomposite membrane increased significantly. This can be attributed to the homogeneous ZIF-8 particle layer and better compatibility between the poly(ethylene glycol) (PEG) matrix and ZIF-8 particles. The membrane achieves a maximum total flux of 3.08 kg·m-2·h-1 at the third in situ growth cycles of ZIF-8 particles and a maximum sulfur enrichment factor of 7.6 at the sixth in situ growth cycles of ZIF-8 particles.Working organic-inorganic lead halide perovskite-based devices are notoriously sensitive to surface and interface effects. Using a combination of density functional theory (DFT) and time-dependent DFT methods, we report a comprehensive study of the changes (with respect to the bulk) in geometric and electronic structures going on at the (001) surface of a (tetragonal phase) methylammonium lead iodide perovskite slab, in the dark and upon photoexcitation. The formation of a hydrogen bonding pattern between the -NH3 groups of the organic cations and the iodine atoms of the outer inorganic layout is found to critically contribute to the relative thermodynamic stability of slabs with varying surface compositions and terminations. Most importantly, our results show that the hydrogen bond locking effects induced by the MA groups tend to protect the external two-dimensional lattice against large local structural deformations, i.e., the formation of a small exciton-polaron, at variance with purely inorganic lead halide perovskites.