Latest ArticlesThe wide-spreading SARS-CoV-2 virus has put the world into boiling water for more than a year, however pharmacological therapies to act effectively against coronavirus disease 2019 (COVID-19) remain elusive. Chloroquine (CQ), an antimalarial drug, was found to exhibit promising antiviral activity in vitro and in vivo at a high dosage, thus CQ was approved by the FDA for the emergency use authorization (EUA) in the fight against COVID-19 in the US, but later was revoked the EUA status due to the severe clinical toxicity. Herein, we show that supramolecular formulation of CQ by a macrocyclic host, curcurbit[7]uril (CB[7]), reduced its non-specific toxicity and improved its antiviral activity against coronavirus, working in synergy with CB[7]. CB[7] was found to form 1:1 host-guest complexes with CQ, with a binding constant of ~104 L/mol. The CQ-CB[7] formulation decreased the cytotoxicity of CQ against Vero E6 and L-02 cell lines. In particular, the cytotoxicity of CQ (60 μmol/L) against both Vero E6 cell line and L-02 cell lines was completely inhibited in the presence of 300 μmol/L and 600 μmol/L CB[7], respectively. Furthermore, the CB[7] alone showed astonishing antiviral activity in SARS-CoV-2 infected Vero E6 cells and mouse hepatitis virus strain A59 (MHV-A59) infected N2A cells, and synergistically improved the antiviral activity of CQ-CB[7], suggesting that CB[7]-based CQ formulation has a great potential as a safe and effective antiviral agent against SARS-CoV-2 and other coronavirus.
The successful applications of two-dimensional (2D) transition metal dichalcogenides highly rely on rational regulation of their electronic properties. The nondestructive and controllable doping strategy is of great importance to implement 2D materials in electronic devices. Herein, we propose a straightforward and effective method to realize controllable n-type doping in WSe2 monolayer by electron beam irradiation. Electrical measurements and photoluminescence (PL) spectra verify the strong n-doping in electron beam-treated WSe2 monolayers. The n-type doping arises from the generation of Se vacancies and the doping degree is precisely controlled by irradiation fluences. Due to the n-doping-induced narrowing of the Schottky barrier, the current of back-gated monolayer WSe2 is enhanced by an order of magnitude and a ~8 × increase in the electron filed-effect mobility is observed. Remarkably, it is a moderate method without significant reduction in electrical performance and severe damage to lattice structures even under ultra-high doses of irradiation.
Carbon-based fluorescent nanomaterials have gained much attention in recent years. In this work, green-photoluminescent carbon nanodots (CNDs; also termed carbon dots, CDs) with amine termination were synthesized via the hydrothermal treatment of amine-containing spermine and rose bengal (RB) molecules. The CNDs have an ultrasmall size of ~2.2 nm and present bright photoluminescence with a high quantum yield of ~80% which is possibly attributed to the loss of halogen atoms (Cl and I) during the hydrothermal reaction. Different from most CNDs which have multicolor fluorescence emission, the as-prepared CNDs possess excitation-independent emission property, which can avoid fluorescence overlap with other fluorescent dyes. Moreover, the weakly basic amine-terminated surface endows the CNDs with the acidotropic effect. As a result, the CNDs can accumulate in the acidic lysosomes after cellular internalization and can serve as a favorable agent for lysosome imaging. Besides, the CNDs have a negligible impact on the lysosomal morphology even after 48 h incubation and exhibit excellent biocompatibility in the used cell models.
Advanced chemotherapy strategies are in urgent demand for improving anticancer efficacy. Herein, a water-soluble pillar[6]arene (WP6A) was used to load chemotherapeutic agent pemetrexed (PMX) by forming direct host-guest inclusion, which is beneficial for decreasing cytotoxicity of PMX on BEAS-2B cells. NMR and florescence titration served to confirm the complexation between WP6A and ATP with higher affinity [(5.67 ± 0.31) × 105 L/mol], favoring competitive replacement of PMX. Complexation ATP by WP6A effectively prevented ATP from being hydrolyzed in presence of alkaline phosphatase. The formed host-guest complex was further used to block the efflux pump by cutting off energy source from ATP hydrolysis, which was accompanied with releasing PMX to produce synergistic enhancement of anticancer performance towards A549 cells. This supramolecular strategy would also be extended to other clinical chemotherapeutic agents and it was expected to provide salutary profits for cancer patients.
Soft and wet actuator systems have attracted great attention in some applications, such as assistive technologies for rehabilitation, training and regenerative biomedicines. Three-dimensional (3D) printing methods have realized the rapid fabrication of complex structures without the need for expensive dies or post processing. In this review, a comprehensive description is presented on stimuli-responsive hydrogels fabricated by light-responsive and extrusion-based 3D printing technologies. Mechanisms of actuations have been introduced based on stimuli types. As the most common method for 3D printed hydrogel actuators, direct-ink-writing has been discussed, including the two printing parameters of resolution and rheology. In addition, applications of 3D printed hydrogel actuators are presented followed by introductions of recent contributions on enhancing the toughness of 3D printed hydrogel and robust design tools, such as finite element analysis and artificial intelligence.
Trimethoprim (TMP) is a typical antibiotic to treat infectious disease, which is among the most commonly detected antibacterial agents in natural waters and municipal wastewaters. In the present study, the impacts of dissolved oxygen (DO) on the oxidation efficiency and pathways of TMP by reaction with sulfate radicals (SO4·−) were investigated. Our results revealed that the presence of DO was favourable for TMP degradation. Specifically, TMP would react initially with SO4·− via electron-transfer process to form a carbon-centered radical. In the absence of oxygen, the carbon-centered radical could undergo hydrolysis to produce α-hydroxytrimethoprim (TMP−OH), followed by the further oxidation which generated α-ketotrimethoprim (TMP = O). However, in the presence of oxygen, the carbon-centered radical would alternatively combine with oxygen, leading to a sequential reaction in which peroxyl radical and a tetroxide were formed, and finally generated TMP−OH and TMP=O simultaneously. The proposed pathways were further confirmed by density functional theory (DFT) calculations. The results obtained in this study would emphasize the significance of DO on the oxidation of organic micro-pollutants by SO4·−.
Nanozymes are nanomaterials with enzyme-like activities that efficiently overcome the drawbacks of natural enzymes in biosensing, detection, and biomedical fields, and they are the most widely used artificial enzymes. Owing to their excellent catalytic characteristics, biocompatibility, and environmental favorability, carbon-dots-based (CDs) nanozymes have inspired a research upsurge. However, no review focusing on CDs nanozymes has been published, even though substantial advances have been achieved. Herein, the advances, catalytic activities, and applications of CDs nanozymes are highlighted and summarized. In addition, the critical issues and challenges of researching nanozymes are discussed. We hope that this review will broaden the horizons of nanozymes and CDs nanozymes, as well as promote their development.
Gastric ulcers are one of the most common stomach diseases that often accompanied by inflammation, congestion, edema, scar tissue formation, and pyloric obstruction. Fiberoptic endoscopy and X-ray analysis of the upper GI tract have become the diagnostic procedure of choice for patients. However, conventional diagnosis technology is either invasive or radioactive. Herein, a novel CD-MOF NIR-II fluorophore (GPs-CH1055) was developed. The relative fluorophore intensity was largely consistent at various media and pH buffers, and it can swell into gel particles in solvents and be completely expelled from the gastrointestinal tract without being assimilated. GPs-CH1055 has been further evaluated in vivo, and exhibited strong retention effect on the gastric ulcer sites, bright NIR-II signals with high spatial and temporal resolution. Therefore, GPs-CH1055 shows great promise for realizing real-time gastric ulcer imaging and diagnosis.
Density functional theory calculations have been performed to investigate the nickel-catalyzed [3 + 2] cycloaddition of cyclopropenones and α, β-unsaturated ketones. The computations show that the overall catalytic cycle consists of four major steps, including: (1) C-C oxidative addition of the cyclopropenone to afford the four-membered nickelacycle, (2) isomerization, (3) migratory insertion via a 4, 1-insertion fashion, and (4) C-C reductive elimination to deliver the [3 + 2] cycloaddition product. The enantioselectivity is mainly attributed to the π-π interaction between the diphenylcyclopropenone moiety and the phenyl substituent of the oxazoline ring of the ligand. The chemoselectivity of the C = O versus C = C insertion was rationalized in terms of the steric effect.
A convenient colorimetric approach for visual detection of melamine in raw milk was realized by using gold nanoparticles (AuNPs) stabilized by an unsymmetrical terpyridyl zinc complex with a thymine fragment at one terminal and a quaternary ammonium salt at the other. Even without pre-addition of melamine or relative additives, obvious color change from red to blue was observed by naked eye in the presence of trace amount of melamine, which was attributed to the alternation of aggregation state of AuNPs caused by the selective binding between the thymine fragment and melamine via triple hydrogen-bonding interactions. Remarkably, the detection limit for melamine was as low as 2.4 ppb, providing a highly sensitive and efficient approach for the visual detection of melamine.
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