Latest ArticlesThe low drug bioavailability of eye drops challenges the therapy of ocular disorders with high efficacy. One of solutions is to extend the corneal retention and enhance the penetration of drug into cornea. Here we synthesize two fluorophore-conjugated peptide based analogs rich in positive charges (i.e., NBD-FFKK) and with a specific ligand (i.e., NBD-FFRGD), respectively, to visualize their performances in vitro and in vivo. The peptides both can self-assemble into supramolecular hydrogels with the microstructure of nanofibers. The in vitro experiments exhibit that two peptides are both uniformly distributed in cytoplasm, and the intracellular amount of peptide rich in positive charges is significantly larger than that of peptide with a specific ligand. The living corneal fluorescence shows that two peptides enter the corneal stroma within 15 min, and the peptide rich in positive charges is accumulated more extensively throughout the entire cornea, revealing that the supramolecular hydrogel eye drops penetrate the cornea more efficiently via electrostatic interaction than that via ligand-receptor interaction. This work, as a comparative study of supramolecular hydrogel eye drops on penetrating efficiency, indicates a possible direction for the design of eye drops with efficient corneal penetration.
Nitrogen-doped carbon (N–C) materials have demonstrated exceptional performances in activating peroxymonosulfate (PMS) for environmental remediation. However, accommodating higher nitrogen contents remains challenging in N–C due to the thermodynamic instability of C–N skeleton. In this study, we proposed an innovative epitaxial growth approach to synthesize two-dimensional N–C nanosheets. Leveraging the abundant amino groups supplied by the polymer dots as growing sites, we successfully attained a high nitrogen level and spontaneously introduced abundant structural defects in the carbon framework. The resulting N–C nanosheets exhibited outstanding catalytic activity for the activation of PMS toward selective oxidation of diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate (1,4-DHP) into diethyl 2,6-dimethylpyridine-3,5-dicarboxylate, which serves as a valuable intermediate in the synthesis of various pharmaceutical compounds. Comprehensive experimental and characterization investigations verified that the nitrogen sites and defects are the primary active sites for PMS activation and selective oxidation of 1,4-DHP. This work offered an efficient approach for the fabrication of high-nitrogen-loading carbon materials for catalytic oxidation reactions.
Water-soluble inorganic ions (WSIIs) play a pivotal role in atmospheric chemical reactions, particularly influencing the formation of secondary particulate matter. A comprehensive grasp of the vertical distribution of atmospheric pollutants holds immense significance in understanding the diffusion and transportation of these pollutants. This study investigates the WSIIs of PM2.5 and size-segregated particles at the top (~2060 m a.s.l.) and foot of Mt. Hua during the winter of 2020. All the measured ions present significant higher concentrations (1.9~6.9 times) at the foot than the top. Cl− and K+ at the foot are more than 4 times of those at the top, whereas Ca2+ and Mg2+ are only 1.3–1.9 times higher. The particle size distribution of NO3−, SO42−, K+ and Cl− demonstrate a single peak distribution (0.7–1.1 µm) at the foot, but with a bimodal distribution (0.7–1.1 µm and 4.7–5.8 µm) at the top. These differences suggest that the aerosol at the alpine region is mainly transported via long-distance from Northwest/North China, but limited influenced by vertical transport through valley breeze. The changes of concentration and size distribution of WSIIs in dust event and non-dust period indicate that the effects of dust event on aerosols at ground surface were weaker than that of the free troposphere of Guanzhong Plain. Notably, our study underscores the dominant influence of NO3− in shaping the gas-particle distribution of ammonia within the winter free troposphere. Our results highlight the significant role of long-range transport on aerosols in the free troposphere in Guanzhong Plain, Northwest China.
Reactive oxygen species (ROS) are essential in various pathological and physiological processes. Developing nanosystems that generate ROS in a controlled manner is of great interest for nanomedicine. DNA nanotechnology offers a promising approach to constructing programmable ROS-generating platforms. By incorporating photosensitizers or metal ions, DNA nanostructures can be designed to produce ROS in a spatially and temporally desired fashion. DNA-based ROS-generating nanosystems hold great potential in intracellular homeostasis regulation, drug release, and cancer therapy. This review summarizes recent advances in developing DNA-based ROS-generating nanosystems, highlights their emerging biomedical applications, and discusses the opportunities and challenges for further applications. DNA nanotechnology provides a versatile toolkit to construct biocompatible ROS-generating platforms for next-generation nanomedicines.
In this study, the environmentally friendly precursor, tartaric acid (TA), was employed for the generation of CO2 anion radical (CO2•−) in an advanced UV/TA/Fe3+ system to reduce the hazardous -N in wastewater. To optimize this process, various factors, including the dosage of Fe3+, TA, and pH, were systematically investigated for their impact on the reduction process. Under the conditions of 3 mmol/L Fe3+ dosage, 10 mmol/L TA dosage, and a pH of 2.5, -N was effectively removed from the water within 60 min, selectively transformed into N2, with a remarkable N2 selectivity of 91.2%. In the optimal conditions, the -N reduction mechanism in the UV/TA/Fe3+ system and the critical role of were illustrated. Finally, this study explored the reduction of real nitrified seawater using the UV/TA/Fe3+ system. The results demonstrated that the UV/TA/Fe3+ system could completely eliminate -N and achieve a N2 selectivity of up to 90%, with minimal interference from coexisting ions. This work holds promising implications for the environmentally benign treatment of nitrite-polluted wastewater.
Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized. Compound 1 [Th6(HPyC)8(HCOO)4] is formed by replacing formate ligands of preassembled thorium cluster [Th6O4(OH)4(H2O)6(HCOO)12] with eight H2PyC (4-pyrazolecarboxylic acid) under solvothermal conditions. Each of the HPyC− ligands is coordinated with one Cu2+ to form the (4,8)-connected -net structure of compound 2 [(CuCl2)2Th6(HPyC)8(HCOO)4]. In compound 3 [(CuCl2)2Th6(HPyC)10(HCOO)4], ten of the formate ligands of preassembled Th6 cluster are replaced by HPyC− ligands. Compared with compound 2, the two extra HPyC− ligands in the equatorial plane of the Th6 cluster in compound 3 are not further connected to copper ions. Therefore, the topology structure of compound 3 is same with that of compound 2. Compound 4 [(Cu3Cl2)(CuCl2)Th6(PyC)3(HPyC)4(HCOO)5] contains three kinds of metal nodes, Th6 cluster, Cu3 cluster and mononuclear Cu2+, and exhibits a novel (5,7)-connected net structure, which was first discovered in actinide MOFs. Furthermore, considering the satisfactory stability of compound 4 and its unsaturated metal nodes and Lewis acid sites, the catalysis of cycloaddition of CO2 was further studied. We found that this thorium-copper heterometallic cluster organic framework can be used as a potential actinide functional material for catalyzing the efficient CO2 conversion to value-added products.
Aliphatic C(sp3)–H moieties are ubiquitous in numerous organic compounds. Direct functionalization of inert C(sp3)–H bonds is a powerful and straightforward approach for the efficient construction of diverse carbon–carbon or carbon–heteroatom bonds. Chelating group directed metal-catalyzed remote functionalization of readily available alkenes has emerged as an appealing strategy for rapidly accessing various value-added aliphatic molecules. With the aid of directing groups, various α-, β- and γ-functionalized alkanes could be synthesized smoothly with excellent regioselectivity. The preferred formation of a stable five- or six-membered metallacycle intermediate terminates the chain-walking at a specific methylene site, which serves as the driving force for excellent site-selective migratory functionalization. This review herein is aimed at summarizing the recent progress on the metal-catalyzed regiodivergent functionalization of unactivated alkenes by merging alkene isomerization and cross-coupling with the assistance of directing auxiliary. Last but not least, the current situations and future directions in this field are highlighted and discussed.
Constructing more stable self-assembled organic nanotubes has been one of the focuses of scientists in recent decades. Hexakis(m-phenylene ethynylene) (m-PE) benzene macrocycles can form stable tubular self-assemblies in nonpolar or weakly polar solvents through the π-π interaction of the main skeleton and the hydrogen bonding of the side chain amide. We covalently linked two macrocyclic units at the para position of the macrocycles using two oligo(β-alanine) linkers through an efficient synthetic route. UV–visible spectroscopy, fluorescence spectroscopy, and circular dichroism spectroscopy were employed to demonstrate that the incorporation of two peptide chains significantly enhances the stability of the self-assemblies. Meanwhile, the average open time of the ion channel formed by the macrocyclic dimer in the lipid bilayer was significantly better than that of the ion channel formed by a single macrocycle. This study shows that this strategy effectively improves the efficiency of self-assembly and the stability of its formed self-assemblies, providing a feasible strategy for constructing organic self-assembled nanotubes in highly polar solvents.
Microbial fabrication of metal nanoparticles (MNPs) has received significant attention due to the advantages of low toxicity, energy efficiency and ecological safety. Diverse groups of MNPs can be synthesized intracellularly or extracellularly by various wild-type microorganisms, including bacteria, fungi, algae and viruses. Synthetic biology approaches, represented by genetic engineering, have been applied to overcome the shortcomings in productivity, stability, and controllability of biosynthetic MNPs. Scanning electron microscope (SEM), transmission electron microscope (TEM) and other characterization techniques assist in deciphering their unique properties. In addition, biosynthetic MNPs have been widely explored for the utilization in environmental remediation and contaminant detection. And machine learning contains a great potential for designing targeted MNPs and predicting their toxicity. This review provides a comprehensive overview of the research progress in the microbial synthesis of MNPs. An outlook on the current challenges and future prospects in the biologically controllable synthesis and engineering environmental applications of MNPs is also provided in this review.
Parkinson’s disease (PD) is an aging-associated neurodegenerative movement disorder with increasing morbidity and mortality rates. The current gold standard for diagnosing PD is clinical evaluation, which is often challenging and inaccurate. Metabolomics and lipidomics approaches have been extensively applied because of their potential in discovering valuable biomarkers for medical diagnostics. Here, we used comprehensive untargeted metabolomics and lipidomics methodologies based on liquid chromatography-mass spectrometry to evaluate metabolic abnormalities linked with PD. Two well-characterized cohorts of 288 plasma samples (143 PD patients and 145 control subjects in total) were used to examine metabolic alterations and identify diagnostic biomarkers. Unbiased multivariate and univariate studies were combined to identify the promising metabolic signatures, based on which the discriminant models for PD were established by integrating multiple machine learning algorithms. A 6-biomarker predictive model was constructed based on the omics profile in the discovery cohort, and the discriminant performance of the biomarker panel was evaluated with an accuracy over 81.6% both in the discovery cohort and validation cohort. The results indicated that PC (40:7), eicosatrienoic acid were negatively correlated with severity of PD, and pentalenic acid, PC (40:6p) and aspartic acid were positively correlated with severity of PD. In summary, we developed a multi-metabolite predictive model which can diagnose PD with over 81.6% accuracy based on this unique metabolic signature. Future clinical diagnosis of PD may benefit from the biomarker panel reported in this study.
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