Latest ArticlesA new charge transfer cocrystal of 1, 2, 4, 5-tetracyanobenzene (TCNB)-phenazine (PTC) was prepared by solvent evaporation method. The donor and acceptor molecules of cocrystal are stacked face to face with a mixed-stacking, implying a strong charge transfer (CT) interactions in the cocrystal system. The spectroscopic studies, single-crystal X-ray diffraction structure, density functional theory (DFT) and Hirschfield surfaces calculations are carried out to explore the relationship between structure and properties of cocrystal system, which show that the intermolecular interactions in PTC are stronger than those of single components, leading to the stability and photophysical behaviors of cocrystal different from their constitute units. This study will be helpful for the design and preparation of multifunctional cocrystal materials.
A facile and efficient strategy was established for the construction of RC-529 and its derivatives. Four conjugates of RC-529 derivatives with Tn antigen were synthesized and all elicited strong and T cell-dependent immune responses in mice without requiring external adjuvants. In addition, all antisera induced by these conjugates could specifically recognize, bind to and kill Tn-overexpressing cancer cells. Thus, RC-529 shows promise as a useful platform for the development of new vaccine carriers with self-adjuvanting properties for the treatment of cancer. Moreover, preliminary structure-activity relationship analysis provides convincing support for further optimization of, and additional investigation into, RC-529.
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.
The 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.
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.
We have developed a versatile, mild protocol for trifluoromethylthiolation reactions of aldehydes with catalysis by a decatungstate hydrogen atom transfer photocatalyst under redox-neutral conditions. The protocol is highly selective, operationally simple, and compatible with a wide array of sensitive functional groups. It can be used for late-stage functionalization of bioactive molecules, which makes it convenient for drug discovery.
A new synthesis of the bridged [6-6-6] ABE tricyclic ring analogues of methyllycaconitine with the C-1 oxygenated substituents has been developed using an efficient aza-annulation of β-enamino ketone followed by a facile decarboxylation to form BE rings. Subsequent elaboration to form the A ring was achieved by a transannular acyl radical cyclization with concomitant equipment of the key C-1 oxygen functionality.
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.
A series of probes KJ-x (x = 1−3) with carbon chains of different lengths based on the matrix of rhodamine B were engineered to detect Ag+ in aqueous solution in this work. Among them, KJ-1 is selected as the best option after in vitro investigation in view of its most sensitive and rapid response to Ag+, whose possible sensing mechanism is studied by experimental investigation and theoretical calculation. To identify the practical application of the probe, the detection of Ag+ in nonantibiotic fungicide Silver & Health and differentiation between normal hepatocytes and hepatoma cells using confocal imaging was conducted.
Codelivery of drugs by drug carriers is a promising strategy against several diseases such as infections and cancer. However, traditional drug carriers are typically characterized by low drug payload, limiting their treatment efficacy. Using nanocrystals of insoluble drug as carriers, a carrier free platform was developed previously to deliver a second insoluble drug for codelivery. To extend the concept, we hypothesized, herein, that the platform allows for codelivery of hydrophobic and hydrophilic drugs using a cocrystalization-like strategy. To obtain proof-of-concept, paclitaxel (PTX), an insoluble chemotherapeutic agent, and dichloroacetic acid (DCA), a water-soluble inhibitor of pyruvate dehydrogenase kinase, were utilized as model drugs. PTX-DCA hybrid nanocrystals (PTX-DCA NCs) were prepared by anti-solvent precipitation and characterized. Their in vitro antitumor activity against cancer cells was evaluated. PTX-DCA NCs prepared from the optimized formulation had a diameter of 160 nm and a rod-shape morphology and possessed encapsulated efficacy of approximately 30% for DCA. The use of the hybrid crystals enabled synergy to kill cancer cells, in particular in PTX-resistant cells in a dose-dependent pattern. In conclusion, by using a cocrystalization-like strategy, a hydrophilic drug can be formulated into a drug's nanocrystal for codelivery.
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