Latest ArticlesLead-free double perovskite nanocrystals (NCs) have emerged as a promising candidate in the optical field, owing to their non-toxic, good moist heat and chemical stability. However, their poor optical properties limited their application. To improve the optical properties of lead-free double perovskite NCs, metal ion doping or alloying had been suggested as a promising strategy. Here, we prepared monodisperse, uniformly sized, cubic morphology of Cs2AgBiCl6 NCs with different Na+ incorporation amounts via a simple hot-injection method. The Na+ incorporation broke the parity-forbidden transition by reducing the inversion symmetry of the electron wave function at the Ag site, which changed the parity of the self-trapped exciton wave function and thus allowed radiative recombination. As a result, the photoluminescence quantum yield (PLQY) of Na+-alloyed Cs2AgBiCl6 NCs (12.1%) was higher than that of Cs2AgBiCl6 NCs (2.4%), and the exciton lifetime of Na+-alloyed Cs2AgBiCl6 NCs increased to 36.98 ns from 17.58 ns for Cs2AgBiCl6 NCs. By adjusting the amount of Na+ incorporation, the band gap of Cs2AgBiCl6 NCs can be significantly tuned from ~2.90 eV to ~3.50 eV. Furthermore, the temperature-dependent photoluminescence spectra indicated that the Na+-alloyed Cs2AgBiCl6 NCs possessed higher longitudinal optical phonon energy and exciton binding energy compared to Cs2AgBiCl6 NCs. This suggested that there were strong exciton-phonon interactions during exciton recombination, a reduced probability of non-radiative processes, and excellent thermal stability. It offers a promising strategy for improving the optical properties of lead-free double perovskite NCs, and have the potential to replace traditional lead halide perovskite NCs in future optoelectronic applications.
Tuberculosis (TB) is a chronic infectious disease, which is caused by the pathogen Mycobacterium tuberculosis (Mtb) and reemerged as a global health risk with a significant proportion of multi-drug resistant and extensively drug resistant TB cases. It is very urgent to find some novel high-confidence drug targets in Mtb for discovering the effective anti-TB agents. Thioredoxin reductase (TrxR) has been identified to be a highly viable target for anti-TB drugs for its important role in protecting the pathogen from thiol-specific oxidizing stress, regulating intracellular dithiol/disulfide homeostasis and DNA replication and repair. In the present work, a near-infrared (NIR) fluorescent probe DDAT was developed for the detection of TrxR activity and used to high-throughput screen the TrxR inhibitors from natural products. Two screened TrxR inhibitors from Sappan Lignum and microbial metabolites that were further used to inhibit Mycobacterium tuberculosis. All the results indicate that DDAT is a practical fluorescent molecular tool for the discovery of potential anti-TB drugs.
Fungal symbionts co-evolve with hosts and microbial co-inhabitants to acquire an unpredictable potential for producing novel bioactive metabolites, but the knowledge about the topic remains patchy and superficial. Here we present the chemical characterization of acatulides A−G (1−7) as architecturally unprecedented macrolides from the solid-state culture of Acaulium album H-JQSF, an arthropod-associated fungus. The acatulide structures were elucidated by spectroscopic analysis, modified Mosher's method and single-crystal X-ray diffraction. The plausible biosynthetic pathways for compounds 1−4 are proposed. Interestingly, acatulides B−D (2−4) and G (7) were demonstrated to be neuroprotective against the 1-methyl-4-phenylpyridinium (MPP+)-induced damage to SH-SY5Y cells and nematode Caenorhabditis elegans (C. elegans).
Early pathogenesis of ischemia-reperfusion (I/R)-induced acute kidney injury (AKI) is dominated by intracellular calcium overload, which induces oxidative stress, intracellular energy metabolism disorder, inflammatory activation, and a series of pathologic cascaded reactions that are closely intertwined with self-amplifying and interactive feedback loops, ultimately resulting in cell damage and kidney failure. Currently, most nanomedicines originate from the perspective of antioxidant stress, which can only quench existing reactive oxide species (ROS) but cannot prevent the continuous production of ROS, resulting in insufficient efficacy. As a safe and promising drug, BAPTA-AM is hydrolyzed into BAPTA by intracellular esterase upon entering cells, which can rapidly chelate with overloaded Ca2+, restoring intracellular calcium homeostasis, thus inhibiting ROS regeneration at the source. Here, we designed a KTP-targeting peptide-modified yolk-shell structure of liposome–poly(ethylene glycol)methyl ether-block-poly (l-lactide-co-glycolic) (mPLGA) hybrid nanoparticles (<100 nm), with the characteristics of high encapsulation rate, high colloid stability, facile modification, and prolonged blood circulation time. Once the BA/mPLGA@Lipo-KTP was targeted to the site of kidney injury, the cholesteryl hemisuccinate (CHEMS) in the phospholipid bilayer, as an acidic cholesterol ester, was protonated in the simulated inflammatory slightly acidic environment (pH 6.5), causing the liposomes to rupture and release the BA/mPLGA nanoparticles, which were then depolymerized by intracellular esterase. The BAPTA-AM was diffused and hydrolyzed to produce BAPTA, which can rapidly cut off the malignant loop of calcium overload/ROS generation at its source, blocking the endoplasmic reticulum (ER) apoptosis pathway (ATF4–CHOP–Bax/Bcl-2, Casp-12–Casp-3) and the inflammatory pathway (TNF-α–NF-κB–IL-6 axes), thus alleviating pathological changes in kidney tissue, thereby inhibiting the expression of renal tubular marker kidney injury molecule 1 (Kim-1) (reduced by 82.9%) and also exhibiting prominent anti-apoptotic capability (TUNEL-positive ratio decreased from 40.2% to 8.3%), significantly restoring renal function. Overall, this research holds huge potential in the treatment of I/R injury-related diseases.
Developing new functional explosives that display high stability, good energy performance, and low sensitivity are one of the key directions of energetic materials research. In this work, two-dimensional (2D) Schiff-based energetic covalent organic frameworks (COFs) are prepared based on triaminoguanidine salts with different anions as building blocks. Benefiting from the robust covalent bond in 2D extended polygons and strong π-π interactions in the eclipsed interlayers, the synthesized energetic COFs showed higher thermal stability and lower mechanical sensitivity than their precursor salts. More importantly, incorporating triaminoguanidine salts into COFs effectively increase the corrosion resistance to metal under high humidity conditions, which is due to the imine moieties in COFs functioning as π acceptors and offering strong bonding with metallic ions. This work provides a new pathway for the development of high-performance energetic materials.
Catalytic Michael addition reaction represents a fundamental importance in organic synthetic chemistry. Whereas corresponding conversions toward intrinsically low reactive enamide remains an ongoing challenging. We herein report a copper-catalyzed conjugate addition of allenes to β-substituted alkenyl amides, one of the most challenging Michael acceptors. The present method utilizes readily available allenes as the latent carbon-based nucleophiles and simple, common β-substituted alkenyl amides as starting materials, unlike previous methods that usually preinstall an activating group to improve the reactivity of amide or uses highly reactive stoichiometric quantities of organometallics. Hence, this approach shows good functional group compatibility and can be implemented under mild reaction conditions with excellent level of chemo- and regioselectivities.
The Wnt signaling pathway plays a critical role in bone homeostasis, and the related protein therapy strategies have been reported to have great potential in osseointegration; however, they face formidable challenges such as complex external environments and unavoidable protein denaturation. In this work, we report a novel approach combining the synthesis of metal–organic frameworks (MOFs) and protein encapsulation in a one-pot process based on zeolitic imidazolate framework-8 (ZIF-8) and Wnt3a protein, with improved biomechanical behavior and enhanced protein biological response. This combination was designed to enhance the Wnt3a protein function through the improved chemical stability provided by the ZIF-8 crystals. Additionally, the zinc ions contained in the ZIF-8 crystals induced bone homeostasis, further favoring the osteogenesis. The results showed that the Wnt3a protein-loaded ZIF-8 crystals served as efficient drug delivery vehicles to promote osteogenesis, preventing protein denaturation. In particular, Wnt3a-loaded ZIF-8 nanoparticles (Wnt3a@ZIF-8 NPs) had higher efficacy on bone marrow mesenchymal stem cells (BMSCs) than ZIF-8 NPs or Wnt3a proteins, contributing to the osteogenesis through ZIF-8 crystals and intracellular Wnt3a proteins released from Wnt3a@ZIF-8 NPs. Furthermore, polymerase chain reaction (PCR) analysis showed that the osteogenic pathways were upregulated. Overall, the present one-pot process can open up new avenues to develop signaling protein-delivery systems for applications in protein therapy strategies.
A facile chemical method for the development of photocatalytic coating products was proposed based on practical application perspective for the Hong Kong roadside nitrogen oxides (NOx) mitigation. TiO2-based photocatalytic coating PC-C film with crystallized size of around 5–6 nm was synthesized with the peptization of H2O2. The PC-C coating possesses a super-hydrophilicity surface and is proven to have a NOx degradation rate of 46.8% with an optimum pH level of 7. In addition, the PC-C coating presents a promising photocatalytic NOx degradation compared with other commercially available coating products and P25 when applied on two building materials of poly-methyl methacrylate (PMMA) and concrete surface. A weather resistance simulation and a 180-day on-site field trial were carried out the attenuation effects of photocatalytic coating applied in outdoor exposure. Based on epidemiological estimation and field investigation, hospital admissions for respiratory diseases (HARD) and mortality cases (MC) could be reduced with the application of PC-C coating along the street canyon. This work demonstrates the feasibility of air pollution control measures for the local roadside NOx using photocatalytic technology, offering promising health benefits with environmental remediation.
Thrombosis remains a major global health concern mainly characterized by high rates of morbidity and mortality. Animal models serve as an indispensable tool to understand the underlying pathogenesis of thrombosis and assess the efficacy of novel antithrombotic drugs. Currently, zebrafish has emerged as a valuable model organism for thrombosis research. However, the traditional method of studying zebrafish thrombosis requires a laborious and time-consuming procedure, including anesthesia and manual immobilization of zebrafish. In this study, based on hydrodynamic force, a lateral-immobilization zebrafish microfluidic chip (LIZMC) was designed to evaluate the cardiovascular system of multiple larvae within a single microscope field of view. Specifically, coupling with microscope imaging, real-time monitoring of the peripheral blood circulation in the tail of phenylhydrazine (PHZ)-induced zebrafish thrombosis was enabled. Furthermore, the reliability of LIZMC for in vivo evaluation of antithrombotic agents in zebrafish was verified using aspirin. Collectively, this novel LIZMC-based system can be used for in vivo zebrafish thrombosis studies and rapid screening of antithrombotic agents.
Manganese oxides (MnOx), as low-toxicity and high-abundance catalysts, have been demonstrated to hold great promise for application in advanced oxidation processes (AOPs). However, further application of this material is restricted due to its unsatisfactory oxidant activation efficiency. Fortunately, recently remarkable research on deep activation mechanisms and modification of MnOx have been undertaken to improve its reactivity. Herein, modification enhancement mechanisms of MnOx to efficiently degrade various organic contaminants were discussed and highlighted, including metal doping, coupling with other metal oxides, composite with carbonaceous material, and compounding with other support. The activation mechanisms of different MnOx and derivative-modified material (such as doped MnOx, metal oxide-MnOx hybrids, and MnOx-carbonaceous material hybrids) were summarized in great details, which was specifically categorized into both radical and non-radical pathways. The effects of pH, inorganic ions, and natural organic matter on degradation reactions are also discussed. Finally, future research directions and perspectives are presented to provide a clear interpretation on the MnOx initiated AOPs.
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