MnO2‐Modified Persistent Luminescence Nanoparticles for Detection and Imaging of Glutathione in Living Cells and In Vivo

Persistent luminescence nanoparticles (PLNPs) hold great promise for the detection and imaging of biomolecules. Herein, we have demonstrated a novel nanoprobe, based on the manganese dioxide (MnO₂)‐modified PLNPs, that can detect and image glutathione in living cells and in vivo. The persistent luminescence of the PLNPs can be efficiently quenched by the MnO₂ nanosheets. In the presence of glutathione (GSH), MnO₂ was reduced to Mn²⁺ and the luminescence of PLNPs can be restored. The persistent luminescence property can allow detection and imaging without external excitation and avoid the background noise originating from the in situ excitation. This strategy can offer a promising platform for detection and imaging of reactive species in living cells or in vivo.     

A New Class of Tunable Dendritic Diphosphine Ligands: Synthesis and Applications in the Ru‐Catalyzed Asymmetric Hydrogenation of Functionalized Ketones

A series of tunable G₀–G₃ dendritic 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP) ligands was prepared by attaching polyaryl ether dendrons onto the four phenyl rings on the P atoms. Their ruthenium complexes were employed in the asymmetric hydrogenation of β‐ketoesters, α‐ketoesters, and α‐ketoamides to reveal the effects of dendron size on the catalytic properties. The second‐ and third‐generation catalysts exhibited excellent enantioselectivities, which are remarkably higher than those obtained from the small molecular catalysts and the first‐generation catalyst. Molecular modeling indicates that the incorporation of bulky dendritic wedges can influence the steric environments around the metal center. In addition, the ruthenium catalyst bearing a second‐generation dendritic ligand could be recycled and reused seven times without any obvious decrease in enantioselectivity.     

Electroactive shape memory effect of radiation cross-linked SBS/LLDPE composites filled with carbon black

The poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer and linear low-density polyethylene (LLDPE) were blended and irradiated by γ rays to prepare shape memory polymer (SMP). Different weight fractions of conductive carbon black (CB) were filled into SMP to form a novel electroactive shape memory CB/SBS/LLDPE composite. The CB reinforced radiation cross-linked SBS/LLDPE blends for the improvement of the mechanical weakness and conductivity of SBS/LLDPE bulk and for wide practical engineering uses. The electroactive shape memory CB/SBS/LLDPE composites were investigated by electrical properties, mechanical, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and electroactive shape memory effects. It is found that the tensile strength, storage modulus, and resistance against mechanical and thermal mechanical cycle loading in the developed composites increased due to the role of reinforcement of CB. The melting temperatures and volume resistance of the composites decreased with the increment of CB for excellent electrical conductivity of CB. The electroactive shape memory effects of developed CB/SBS/LLDPE composites were affected by CB weight fractions and applied voltage, while good shape recovery could be obtained in the shape recovery test. When the CB fraction is more than 5 wt%, full recovery can be observed after tens of seconds and shape recovery speed increased with CB fractions and voltage increasing. However, the shape recovery rate decreases slightly with increment of cycle times.     

Near-infrared aminocyanine dyes: synthesis,optical properties,and application to the preparation of fluorescent microspheres

Several near-infrared (NIR) fluorescent dyes based on aminocyanine have been designed, synthesized, and used for preparation of NIR fluorescent microspheres. Their spectral properties and pH-dependent optical characteristics were investigated. It was found that different substitution at the central position of the dyes led to diverse optical properties, with especially large effects on their spectroscopic properties. Spectroscopic responses of the fluorescent dyes to changes of pH were different. Under acidic conditions, the wavelengths of maximum absorption of the N-substituted cyanine dyes were clearly red shifted. Dyes with an N-substituted piperazidine ring were the most sensitive. The fluorescent microspheres retained the properties of the parent dyes, making them suitable for applications in biological studies.     

Redox Dyshomeostasis Strategy for Hypoxic Tumor Therapy Based on DNAzyme-Loaded Electrophilic ZIFs

Redox homeostasis is one of the main reasons for reactive oxygen species (ROS) tolerance in hypoxic tumors, limiting ROS-mediated tumor therapy. Proposed herein is a redox dyshomeostasis (RDH) strategy based on a nanoplatform, FeCysPW@ZIF-82@CAT Dz, to disrupt redox homeostasis, and its application to improve ROS-mediated hypoxic tumor therapy. Once endocytosed by tumor cells, the catalase DNAzyme (CAT Dz) loaded zeolitic imidazole framework-82 (ZIF-82@CAT Dz) shell can be degraded into Zn²⁺ as cofactors for CAT Dz mediated CAT silencing and electrophilic ligands for glutathione (GSH) depletion under hypoxia, both of which lead to intracellular RDH and H₂O₂ accumulation. These “disordered” cells show reduced resistance to ROS and are effectively killed by ferrous cysteine-phosphotungstate (FeCysPW) induced chemodynamic therapy (CDT). In vitro and in vivo data demonstrate that the pH/hypoxia/H₂O₂ triple stimuli responsive nanocomposite can efficiently kill hypoxic tumors. Overall, the RDH strategy provides a new way of thinking about ROS-mediated treatment of hypoxic tumors.     

Pressure-Suppressed Carrier Trapping Leads to Enhanced Emission in Two-Dimensional Perovskite (HA)2(GA)Pb2I7

A remarkable PL enhancement by 12 fold is achieved using pressure to modulate the structure of a recently developed 2D perovskite (HA)₂(GA)Pb₂I₇ (HA=n-hexylammonium, GA=guanidinium). This structure features a previously unattainable, extremely large cage. In situ structural, spectroscopic, and theoretical analyses reveal that lattice compression under a mild pressure within 1.6 GPa considerably suppresses the carrier trapping, leading to significantly enhanced emission. Further pressurization induces a non-luminescent amorphous yellow phase, which is retained and exhibits a continuously increasing band gap during decompression. When the pressure is released to 1.5 GPa, emission can be triggered by above-band gap laser irradiation, accompanied by a color change from yellow to orange. The obtained orange phase could be retained at ambient conditions and exhibits two-fold higher PL emission compared with the pristine (HA)₂(GA)Pb₂I₇.     

Current Status of COVID-19 (Pre)Clinical Vaccine Development

The current COVID-19 pandemic has a tremendous impact on daily life world-wide. Despite the ability to dampen the spread of SARS-CoV-2, the causative agent of the diseases, through restrictive interventions, it is believed that only effective vaccines will provide sufficient control over the disease and revert societal live back to normal. At present, a double-digit number of efforts are devoted to the development of a vaccine against COVID-19. Here, we provide an overview of these (pre)clinical efforts and provide background information on the technologies behind these vaccines. In addition, we discuss potential hurdles that need to be addressed prior to mass scale clinical translation of successful vaccine candidates.     

Quantification of imatinib and related compounds using capillary electrophoresis-tandem mass spectrometry with field-amplified sample stacking

A quantification method for imatinib (IM), its major metabolite N-desmethyl imatinib (NDI), and a degradation by-product was developed using CE–MS combined with an online concentration technique. The use of multiple reaction monitoring (MRM)–MS/MS further improved the sensitivity of this technology. Liquid–liquid extraction (LLE) using tertiary butyl methyl ether yielded high recovery and reproducibility for the pretreatment of serum samples. The recovery rate exceeded 83% for all three analytes, and was 90% for IM. To improve quantification results, a conductivity-induced online analyte concentration technique, field-amplified sample stacking (FASS), was used. The S/N ratios were improved at least 10-fold when compared with conventional capillary zone electrophoresis. The detection limits were 0.2 ng/mL for IM, 0.4 ng/mL for NDI, and 4 ng/mL for the degradation by-product. These results are superior to those previously obtained by other reported methods. The new method was validated in terms of its selectivity, intra- and interday repeatability and accuracy, and sample storage stability, following the guidelines issued by the European Medicines Agency. Considering the convenient pretreatment procedure (LLE), superior sensitivity, and fast analysis speed (<15 min), this method can be useful in the determination of imatinib levels in blood.     

Accurate prediction of relative binding affinities of a series of HIV-1 protease inhibitors using semi-empirical quantum mechanical charge

A major challenge in computer-aided drug design is the accurate estimation of ligand binding affinity. Here, a new approach that combines the adaptive steered molecular dynamics (ASMD) and partial atomic charges calculated by semi-empirical quantum mechanics (SQMPC), namely ASMD-SQMPC, is suggested to predict the ligand binding affinities, with 24 HIV-1 protease inhibitors as testing examples. In the ASMD-SQMPC, the relative binding free energy (ΔG) is reflected by the average maximum potential of mean force (<PMF>_max) between bound and unbound states. The correlation coefficient (R²) between the <PMF>_max and experimentally determined ΔG is 0.86, showing a significant improvement compared with the conventional ASMD (R² = 0.52). Therefore, this study provides an efficient approach to predict the relative ΔG and reveals the significance of precise partial atomic charges in the theoretical simulations.     

Thermoelectric Properties of Nano-grained Mooihoekite Cu9Fe9S16

Cu-Fe-S-based compounds gain the interest from thermoelectric community because all the consisting elements, Cu, Fe, and S, are non-toxic and earth-abundant. Comparing with CuFeS₂ and Cu₅FeS₄, the investigation on Cu₉Fe₉S₁₆ is very rare. In this work, a series of Cu_9–xFe_9+xS₁₆ samples were fabricated by means of melting-annealing process. Their phase composition, microstructure, electrical and thermal transport properties were systematically investigated. X-ray measurement confirms that all samples are phase pure. Transmission electron microscopy characterization indicates that the fabricated Cu₉Fe₉S₁₆ has a natural nanostructure. Cu₉Fe₉S₁₆ shows semiconducting-like electrical transport behavior and intrinsically low lattice thermal conductivity. Beyond the numerous boundaries between nanosized grains, the existence of low-frequency optical phonons is also responsible for the intrinsically low lattice thermal conductivity. Doping Fe at the Cu-sites in Cu₉Fe₉S₁₆ significantly alters the electrical transport properties by introducing extra carriers. A peak dimensionless figure of merit zT value of 0.21 is obtained at 800 K for pure Cu₉Fe₉S₁₆, which is comparable with that for CuFeS₂.