Nickel-Catalyzed Enantioselective Coupling of Acid Chlorides with α-Bromobenzoates: An Asymmetric Acyloin Synthesis.

The reaction of common acyl-metal species (acyl anion) with aldehydes to furnish acyloins has received much less attention and specifically was restricted to using preformed stoichiometric acyl-metal reagents. Moreover, the (catalytic) enantioselective variants remain unexplored, and the asymmetric synthesis of chiral acyloins has met significant challenges in organic synthesis. Here, we uncover the highly enantioselective coupling of acid chlorides with α-bromobenzoates by nickel catalysis for producing enantioenriched protected α-hydroxy ketones (acyloins, >60 examples) with high enantioselectivities (up to 99% ee). The successful execution of this enantioselective coupling protocol enables the formation of a key ketyl radical from α-bromoalkyl benzoate in situ generated from corresponding aldehyde and acyl bromide, which finally is captured by chiral acyl-Ni species catalytically in situ formed from acyl chlorides, thus avoiding the use of preformed acyl-metal reagents. The synthetic utility of this chemistry is demonstrated in the downstream synthetic elaboration toward a diverse set of synthetically valuable chiral building blocks and biologically active compounds.

Prediction and New Insight for the Drag Reduction of Turbulent Flow with Polymers and Its Degradation Mechanism.

A physicochemical understanding of the mechanism of turbulent flow drag reduction with polymer and its degradation is of great interest from both science and industry perspectives. Although the correlation based on the Fourier series has been proposed to predict the drag reduction and its degradation, its physical meaning was not clear until now. This letter aims to clarify this issue. We develop a comprehensive model to predict the drag reduction and degradation of polymers in turbulent flow from a chemical thermodynamics and kinetics viewpoint. We demonstrate that the Fourier series employed to predict the drag reduction and its degradation is due to the viscoelastic property of drag-reducing polymer solution, and the phase angle in the model, in physical nature, represents the hysteresis of the polymer in turbulent flow. Besides, our new insight of drag reduction with flexible polymers can also explain why a maximum drag reduction in rotational flow appears before degradation happens.

One-step fabrication and characterization of Fe3O4/HBPE-DDSA/INH nanoparticles with controlled drug release for treatment of tuberculosis.

In this study, Fe3O4/hyperbranched polyester-(2-dodecen-1-yl)succinic anhydride2-Dodecen-1-/isoniazid magnetic nanoparticles (Fe3O4/HBPE-DDSA/INH MNPs) with controlled drug release characteristics were synthesized successfully by a simple one-step method. Orthogonal experiments were performed to optimize the loading capacity and encapsulation efficiency of the MNPs. The structure of the Fe3O4/HBPE-DDSA/INH MNPs was characterized by 1H nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization mass spectrometry, Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, and superconducting quantum interference device measurements, while their properties were characterized based on swelling behavior observations, in-vitro release experiments, and cytotoxicity analysis. The results indicated that the fabricated Fe3O4/HBPE-DDSA/INH MNPs had a high drug-loading capacity and encapsulation efficiency. Further, the drug-release rate of the MNPs was higher in an acidic buffer, indicating that the MNPs were pH-responsive. Swelling studies revealed that the MNPs exhibited diffusion-controlled drug release, while in-vitro release studies revealed that the drug-release properties could be controlled readily, owing to the high encapsulation efficiency of the MNPs and the uniform dispersion of the drug in them. These results collectively suggest that this multifunctional nontoxic drug delivery system, which exhibits good magnetic properties and pH-triggered drug-release characteristics, should be suitable for the treatment of tuberculosis.

A novel near-infrared fluorescent probe for highly selective detection of cysteine and its application in living cells.

A novel red-emitting fluorescent probe (DDNA) for cysteine has been rationally designed and synthesized, which exhibited a low limit of detection to Cys (0.26 µM) as well as a favorable large stokes shift (λEm-λEx = 128 nm). This novel fluorophore (HDM), which features a large π-conjugation system and typical intramolecular charge transfer (ICT) process, has a long emission wavelength at 631 nm. Besides that, as a turn-on fluorescent probe, it shows high selectivity and sensitivity for Cys over other metal ions and amino acids including the similar structured homocysteine (Hcy) and glutathione (GSH). Finally, the probe DDNA was successfully applied to bioimage intracellular Cys in Hela cells with low cytotoxicity.

A facile one-step method for preparation of Fe3O4/CS/INH nanoparticles as a targeted drug delivery for tuberculosis.

In this paper, Fe3O4/chitosan/isoniazid magnetic nanoparticles (Fe3O4/CS/INH-MNPs) were prepared as an environmental stimuli-responsive drug-delivery system by automated in situ click technology, in which Fe3O4 magnetic nanoparticles, chitosan and isoniazid were simultaneously in situ crystallized by one-step method. The Fe3O4 magnetic nanoparticles and tripolyphosphate act as stable crosslinkers to produce numerous intermolecular crosslinkages for the mobility of the chitosan chains. Characterization results indicated that the multifunctional drug delivery system with optimized size, excellent loading capacity, well magnetic properties, nontoxicity and pH triggered drug release property is expected to be applied in tuberculosis treatment with excellent magnetic sensitivity and sustained release.

Biocompatible hyperbranched polyester magnetic nanocarrier for stimuli-responsive drug release.

A novel biocompatible magnetic nanocomposite drug carrier was developed by first chemically modifying a hyperbranched polyester (HBPE) with dodecenyl succinic anhydride (DDSA) functional groups to produce HBPE-DDSA. The magnetic nanocomposite Fe3O4/HBPE-DDSA was then synthesized by dispersing superparamagnetic iron oxide (Fe3O4) nanoparticles within HBPE-DDSA. The structure and magnetic properties of the nanocomposite were characterized by 1H NMR, MALDI-MS, XRD, FTIR, TEM, and SQUID analyses. Isoniazid (INH) was selected as a model antituberculosis drug to investigate the in vitro drug release properties of Fe3O4/HBPE-DDSA/INH. The cytotoxicity of the magnetic nanocomposites was assessed by CCK-8 assay. The results indicated that Fe3O4/HBPE-DDSA is a promising potential drug carrier for a magnetic-targeted drug delivery system.

Preparation and Biosafety Assessment of Water-Soluble Hyperbranched Polyester Nanoparticles with Carboxylic Acid Functional Groups.

Biosafety assessment of nanoparticles has been of great interest in the development of nanoscience and nanotechnology. Here, the water-soluble hyperbranched polyester nanoparticles with carboxylic acid functional group (HBPE-CA NPs) are synthesized and characterized. They have amphiphilic structure that include hydrophobic hyperbranched polyester (HBPE) core and hydrophilic carboxylated terminal groups. Biosafety assessment tests of the HBPE-CA NPs include coagulation times, hemolysis, complement activation, platelet activation and cytotoxicity (MTT) are performed. The results show that the HBPE-CA NPs exhibit good hemocompatibility that strongly depend on the amphiphilic structure. Moreover, the results also indicate the non-cytotoxicity of the HBPE-CA NPs. So the HBPE-CA NPs provide a promising platform of blood circulation system for illness therapy with the help of the drug-loaded capacity of-HBPE.

A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection.

In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN)6](3-/4-). Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10fM-100nM) and a detection limit on the order of 0.90fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health.

Preparation of water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups and their micelles behavior, anticoagulant effect and cytotoxicity.

Biocompatibility of nanoparticles has been attracting great interest in the development of nanoscience and nanotechnology. Herein, the aliphatic water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups (HBPE-SO3 NPs) were synthesized and characterized. They are amphiphilic polymeric nanoparticles with hydrophobic hyperbranched polyester (HBPE) core and hydrophilic sulfonic acid terminal groups. Based on our observations, we believe there are two forms of HBPE-SO3 NPs in water under different conditions: unimolecular micelles and large multimolecular micelles. The biocompatibility and anticoagulant effect of the HBPE-SO3 NPs were investigated using coagulation tests, hemolysis assay, morphological changes of red blood cells (RBCs), complement and platelet activation detection, and cytotoxicity (MTT). The results confirmed that the sulfonic acid terminal groups can substantially enhance the anticoagulant property of HBPE, and the HBPE-SO3 NPs have the potential to be used in nanomedicine due to their good bioproperties.

Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique.

Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO3H) nanoparticles and their biomedical application. The H30-SO3H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy ((1)H NMR). The good hemocompatibility of H30-SO3H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO3H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO3H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2-20 mM), a low detection limit 1.2×10(-5) M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood.