Latest ArticlesIrradiated by visible light, the recyclable (PhTe)2-catalyzed oxidative deoximation reaction could occur under mild conditions. In comparison with the thermo reaction, the method employed reduced catalyst loading (1 mol% vs. 2.5 mol%), but afforded elevated product yields with expanded substrate scope. This work demonstrated that for the organotellurium-catalyzed reactions, visible light might be an even more precise driving energy than heating because it could break the Te-Te bond accurately to generate the active free radical catalytic intermediates without damaging the fragile substituents (e.g., heterocycles) of substrates. The use of O2 instead of explosive H2O2 as oxidant affords safer reaction conditions from the large-scale application viewpoint.
An electrochemical amino-azidation of 2-aminostyrene with sodium azide (NaN3) was developed, which can be carried out smoothly in water under metal-free condition, affording a series of 3-azido indolines with high yields.
Luminescent conjugated network polymer is one of the most promising chemo-sensors owing to their good chemical/optical stability and multiple functionalization. Herein, three conjugated network polymers were prepared by using aggregation-induced emission active 1, 1, 2, 2-tetrakis(4-formyl-(1, 1'-biphenyl))-ethane (TFBE) unit as monomer and hydrazine as linker. Through regulating the synthetical condition, the polymeric network can form either uniform two-dimensional azine-linked nanosheets (A-NS), conjugated microporous polymers (A-CMP) or covalent organic frameworks (A-COF). All of these polymers exhibited good stability and high fluorescence quantum efficiency with the quantum yield of 6.31% for A-NS, 5.26% for A-CMP, and 5.80% for A-COF, as well as fast and selective fluorescence quenching response to 2, 4, 6-trinitrophenol (TNP). And the best TNP sensing performance with the Stern-Volmer constants (Ksv) values up to 8×105 L/mol and a detection limit of 0.09 μmol/L was obtained for A-NS. The study explores various strategies to construct conjugated polymers with different nanoarchitectures based on the same building block for sensitive detection of explosives.
Structure-efficacy effect of small molecular drug attracts wide attentions, but it has always been ignored in nanomedicine research. To reveal the efficacy modulation of nanomedicine, we developed a new type of paclitaxel (PTX)-conjugated gold nanoparticles (PTX-conjugated GNPs) to investigate the influence of drug position in controlling their in vitro properties and in vivo performance. Two therapeutic ligands (TA-PEG-NH-N=PTX and TA-PTX=N-NH-PEG) were synthesized to conjugate PTX on the surface of GNPs at different positions, locating on the surface of gold conjugate and inserting between GNPs and polyethylene glycol (PEG, molecular weight 1000 Da), respectively. It was found that PEG-PTX@GNPs with PTX located between GNP and PEG exhibited higher aqueous solubility, biocompatibility, and stability. In addition, an acid sensitive hydrazone bond has been inserted between PTX and PEG in both ligands for drug release of PTX and PTX-PEG segment, respectively, at the tumor site. Further release of PTX from PTX-PEG segment is based on the esterase hydrolysis of an ester bond between PTX and PEG. This two-step drug release mechanism offers PEG-PTX@GNPs effective and sustained release behavior for desirable anticancer activity, enhanced therapeutic efficacy, and lower systematic toxicity in Heps-bearing animal models.
Celastrol, a Chinese herbal medicine, has exhibited anticancer activity in many types of cancer cells. However, the further clinical application of celastrol is restricted by its poor water solubility and serious side effects. Furthermore, the apoptosis mechanism of tumor cells induced by celastrol has not been exhausted yet. In this study, we developed a reduction sensitive polymeric vector for tumor-targeted celastrol delivery. And our researches indicated that the celastrol could be delivered by reduction-sensitive nanomedicine (RSNMs) with a controlled release strategy. Meanwhile, the cell uptake results indicated that excellent reduction-sensitive behavior of RSNMs could effectively accelerate celastrol into the human retinoblastoma (RB) cell. The cell cytotoxicity assay demonstrated that celastrol inhibited proliferation of human RB Y79 cells growth in a dose-dependent manner. Furthermore, the results of flow cytometry and terminal dUTP nick-end labeling (TUNEL) staining showed that celastrol induced apoptosis of the RB Y79 cells, and revealed a time-dependent increase in apoptosis induction of RB Y79 cells. The results of western blotting showed that celastrol induced the apoptosis of human RB Y79 cells involving the activation of caspase-3 and caspase-9. In conclusion, our results revealed that RSNMs may be utilized as a novel therapy for retinoblastoma.
Herein, copper ion doped calcium alginate (Cu2+/CaAlg) composite hydrogel filtration membranes were prepared by using natural polymer sodium alginate (NaAlg) as raw material. The thermal stability and structure of the composite membranes were characterized by thermogravimetric analysis and infrared spectroscopy. The mechanical strength, anti-fouling performance, hydrophilicity and filtration performance of the membrane were studied. The results show that Cu2+/CaAlg hydrogel membrane has excellent mechanical properties and thermal stability. The anti-swelling ability of the membrane was greatly enhanced by doping Cu2+. After three alternate filtration cycles, the flux recovery rate of Cu2+/CaAlg hydrogel membrane can still reach 85%, indicating that the membrane has good anti-pollution performance. When the operation pressure was 0.1 MPa, the rejection of coomassie brilliant blue G250 reached 99.8% with a flux of 46.3 L m-2 h-1, while the Na2SO4 rejectionwas less than 10.0%. The Cu2+/CaAlg membrane was recycled after 24 h in the filtration process, and its flux and rejection rate did not decrease significantly, indicating that the hydrogel membrane has long-term application potential. The Cu2+/CaAlg membrane has a wide range of applications prospect in dye desalination, fine separation and biopharmaceutical technology fields.
Most recently, cobalt sulfide (CoS) nanospheres (NSs) have been demonstrated as an ideal high-efficient photothermal agent for tumor elimination. However, the surface of CoS NSs is lack of functional chemical groups or active radicals to incorporate therapeutic agents, which tremendously hinders their versatile utilization in medical field. Here, surface activation of CoS NSs was realized through the growth of polydopamine (PDA) in situ via alkaline-triggered polymerization. Upon the formation of CoS@PDA NSs, thiol-polyethylene glycol (SH-PEG) and chemotherapeutic agent of doxorubicin (DOX) were loaded onto the particle surface by means of π-π electrostatic interaction and Michael addition reactions. As-synthesized CoS@PDA/PEG/DOX (CoPPD) NSs exhibited an admirable photothermal property and high loading capacity of DOX (44.6%). Furthermore, drug release can be accelerated under a more acidic pH condition mimicking tumor microenvironment (TME), ascribed to the protonation of amino group in DOX molecules. Finally, a strong chemotherapeutic-enhanced photothermal therapeutic effect was demonstrated toward solid tumor under near-infrared (NIR) light irradiation without causing significant systemic toxicity. In this regard, this paradigm may offer valuable guidance for the design of multifunctional CoS-based nanoagents for medical treatment.
By pairing two fluorophores according to their optical properties such as absorption spectral overlap and absorptivity, fluorescent quantum yield and emission spectral separation, a bifunctional fluorescent probe, TQBF-NBD, was rationally designed and synthesized to discriminatively sense Hcy/Cys and GSH with good selectivity and sensitivity. It is noted that this probe could work under a single-wavelength excitation and displayed a mega-large Stokes shift. TQBF-NBD reacted with Hcy/Cys to give a mixed green-red fluorescence and displayed a red fluorescence upon the treatment with GSH. Distinguishable imaging of intracellular Hcy/Cys from GSH with the help of TQBF-NBD was realized in living cells and zebrafish.
The abnormal aggregation of amyloid-beta (Aβ) has been widely believed to play an important role in the pathogenesis of Alzheimer's disease (AD), which is also recognized as one of the main biomarkers for AD diagnosis. The peptide sequence Lys-Leu-Val-Phe-Phe (KLVFF) is considered as the main driver of the fibrillation of Aβ, which also can be utilized to target Aβ and inhibit its aggregation. In this study, KLVFF and Fmoc-KLVFF fluorescent nanoparticles were self-assembled through zinc coordination and π-π stacking. The recognition of Aβ aggregates including oligomers and fibrils by fluorescent nanoparticles can be realized through aromatic, hydrophobic, and hydrogen-bond interactions. The fluorescent nanoprobes can distinguish Aβ aggregation formats and detect Aβ at the limit of 1 pg/mL (S/N = 3). Hence, the detection of Aβ aggregates by fluorescent peptide nanoparticles has great potential for AD diagnosis and progression prediction.
Azithromycin loaded fumaryl diketopiperazine (FDKP) dry powder inhalationwas designed and prepared for the treatment of community-acquired pneumonia. The solubility of FDKP and stability of azithromycin solution was investigated. Formulation of azithromycin loaded FDKP microparticle was investigated and optimized by the single factor experiment. High-pressure homogenization and spray drying conditions were also optimized to prepare the particles by spray drying azithromycin dissolved FDKP microparticle suspension at pH 4.5. The in vitro antibacterial efficiency and in vitro dispersion performance was also investigated to confirm the antibacterial efficiency, dispersion and deposition behavers. FDKP/azithromycin mass ratio (3:2) was the optimized formulation of azithromycin loaded FDKP microparticle with the maximal drug loading efficiency. High-pressure homogenization and spray drying conditions were also optimized. The in vitro antibacterial results indicated that only with the antibiotic concentration higher than mutant prevention concentration could totally inhibit the reproduction of bacteria. In vitro dispersion performance of azithromycin loaded FDKP microparticles (AZM@FDKP-MPs) also shows remarkable improvement of dispersion and deposition behavers of AZM. AZM@FDKP-MPs dry powder inhalation as a targeting delivery route has better potential for lung infection treatment.
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