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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.

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.

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 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.

To understand the fracture behavior during different perforation modes on horizontal wells, laboratory-scale hydraulic fracturing experiments with acoustic emission monitoring were conducted on tight concrete samples. The experimental results indicated that the breakdown pressure could be greatly reduced and that a simple fan-like structure was created with in-plane perforations on a horizontal well under the same fracturing treatment conditions. Furthermore, there was a positive relationship between treatment parameters and breakdown pressure for helical perforations. Because of the small pressurization rate and large stress interaction, the breakdown pressure with in-plane perforations is smaller than that of helical perforations. However, the treatment parameters were not sensitive to the breakdown pressure but correlated with the shut-in pressure for the in-plane perforation mode. In general, increasing the pump rate and fracturing fluid viscosity can slightly increase the breakdown pressure and substantially increase the shut-in pressure. The increase in fracture extension pressure in the in-plane perforation mode refers to different fracture initiation orders of individual perforations. Although the deviation and failure of fracture initiation of some perforations can be observed due to the strong stress interaction of in-plane perforations, the existence of perforation tunnels can guide hydraulic fracture propagation within one plane. Thus, hydraulic fractures can connect and create large-scale fractures because of the close perforation spacing. The results of trace length and microscale fracture demonstrate that twisted and curved fractures with smaller widths can be significantly created by the helical perforation mode, but large-scale fractures can be created by the in-plane perforation mode, which is beneficial to sand plugging mitigation.

Developing drilling fluid materials from modified biomass to meet drilling and environmental requirements has always been of concern. This paper reports for the first time the use of polyampholyte hydrophobically modified by epoxidized soybean oil (ESO), as a potential shale inhibitor. It (AADE) was prepared by micellar polymerization of acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and methacrylatoethyl trimethyl ammonium chloride (DMC) with pre-prepared ESO-derived methacrylate monomer (ESO-MA). Its molecular structure was confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. A comparative study of obtained AADE and the polyampholyte without hydrophobic modification (AAD) was carried out through thermal properties, rheological properties, inhibition performance and drilling fluid compatibility tests. The results showed that AADE possessed higher thermal stability due to the presence of hydrophobic associative ability and crosslinkable epoxy groups, and the hydrophobic interaction between AADE chains dominated the shear-thinning behavior and lowered the viscosity-temperature and viscosity-salt dependence. Also, AADE at a lower concentration more effectively prevented clay hydration swelling and inhibited shale disintegration than AAD and conventional inhibitors. Meanwhile, AADE was well compatible with bentonite dispersion in both fresh water and brine, and improved rheological properties and decreased API and high temperature high pressure (HTHP) fluid loss before and after hot rolling. The inhibition mechanism of AADE was revealed to be the synergetic actions of physical plugging of hydrophobic associated multipolymer aggregates in micro-pores of shale, chemical film with a hydrophobic shell formed on clay surface, and the surface activity to reduce capillary driven force. This research might provide an insight for the application of hydrophobically modified polymer, particularly plant oil-based, as shale inhibitor in water-based drilling fluid.

The near-infrared (NIR) fluorescent probe for rapid, highly sensitive and selective detection of cysteine (Cys) has great significance in both biological and environment sciences. In this work, a novel and specific dicyanoisophorone-based NIR probe for Cys was developed. This probe features remarkably large Stokes shift, with turn-on fluorescence property for highly sensitive and selective detection of Cys over other amino acids including the similar structured homocysteine (Hcy) and glutathione (GSH). The probe based on the conjugate addition-cyclization reaction, and has low detection limit of Cys. Furthermore, this probe shows great potential for Cys detection, which was successfully applied to bioimage Cys in living cells with low cytotoxicity.

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.

Hyperbranched aromatic-aliphatic polyester HBPE-BBA was synthesized by modifying the periphery of a second-generation hyperbranched polyester (HBPE) with benzimidazole (BBA) end groups. HBPE-BBA showed interesting self-assembly behaviors, and retained one-dimensional nano bead-on-string fibers and two-dimensional helical nanocoil morphologies in different solvents. The fluorescence results indicated that HBPE-BBA exhibited remarkable selectivity for Fe3+ and fused ring compounds.

As an important reactive carbonyl compound, formaldehyde (FA) existing in various parts of the organism and plays an important role in cognitive ability and memory formation. However, abnormal concentrations of FA could cause many diseases. Herein, a novel 1,8-naphthalimide derivative fluorescent probe (NID) for detecting FA was rationally designed and synthesized. Probe NID showed a rapid response (within 8 s) towards FA with visual detection. More importantly, NID can be used to image FA in MCF-7 cells, which demonstrated its suitability for practical applications of biological systems with low cytotoxicity.

A novel and simple method has been proposed to prepare magnetic Fe 3 O 4 –chitosan nanoparticles loaded with isoniazid (Fe 3 O 4 /CS/INH nanocomposites). Efforts have been made to develop isoniazid (INH) loaded chitosan (CS) nanoparticles by ionic gelation of chitosan with tripolyphosphate (TPP). The factors that influence the preparation of chitosan nanoparticles, including the TPP concentration, the chitosan/TPP weight ratio and the chitosan concentration on loading capacity and encapsulation efficiency of chitosan nanoparticles were studied. The magnetic Fe 3 O 4 nanoparticles were prepared by co-precipitation method of Fe 2+ and Fe 3+ . Then the magnetic Fe 3 O 4 /CS/INH nanocomposites were prepared by ionic gelation method. The magnetic Fe 3 O 4 nanoparticles and magnetic Fe 3 O 4 /CS/INH nanocomposites were characterized by XRD, TEM, FTIR and SQUID magnetometry. The in vitro release of Fe 3 O 4 /CS/INH nanocomposites showed an initial burst release in the first 10 h, followed by a more gradual and sustained release for 48 h. It is suggested that the magnetic Fe 3 O 4 /CS/INH nanocomposites may be exploited as potential drug carriers for controlled-release applications in magnetic targeted drugs delivery system.

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.

The structurally controllable hyperbranched HBPE–CIDAs (HBPE modified with CIDA units) were synthesized by modifying the periphery of the second generation hyperbranched polyester (HBPE) with 1-cyanoindolizine-3-carboxylic acid (CIDA) groups via a one-pot synthesis. The structures and self-assembly behaviors of HBPE–CIDAs were established by combined studies of FFT-IR, NMR, TEM, SEM, AFM and XRD. Furthermore, host–guest recognition of HBPE–CIDAs was investigated by fluorescence studies. The results indicated that the HBPE–CIDA4 nanospindles have weaker response to various metal ions while having better selectivity to anthracene through π–π stacking interactions than the HBPE–CIDA1 nanospheres.

In this study, Fe

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 (10 fM–100 nM) and a detection limit on the order of 0.90 fM 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.

Some new 4H-pyrrolo[1,2-a]benzimidazoles(2a–2f) have been synthesized. The structures of these compounds were confirmed by IR, 1H NMR, mass spectroscopy and elemental analysis. Compound 2a was further confirmed by X-ray diffraction. The in vitro antimicrobial activities of these compounds were determined against some gram-positive bacteria, gram-negative bacteria and fungi and their drug-resistant isolates in comparison with standard drugs. Antimicrobial results indicate that compounds 2c, 2d and 2e show moderately active antibacterial properties, their minimum inhibitory concentrations are from 12.5 μg/mL to 125 μg/mL. In the series, the most active compound against C. albicans is compound 2f with an MIC value of 31.25 μg/mL.

In this study, new carbon nanomaterial N-doped carbon dots (NCDs) were obtained via a one-step hydrothermal method using isoleucine and citric acid as carbon precursors. TEM results showed that the NCD diameters were not uniform but distributed in the 6–15 nm range, with an average value of 10 nm. The maximum emission wavelength of the obtained NCDs was 415 nm with an excitation wavelength of 370 nm. Under optimal conditions, the nanoparticle can be used as sensors and exhibited a ‘turn-off’ fluorescence response to Fe 3+ , with a good linear relationship of ( F / F 0 ) versus Fe 3+ over the concentration range of 0–20 μmol/L.

Herein, we reported the synthesis of hyperbranched aromatic–aliphatic co-polyester nanorods HBPE-CICA6 and HBPE-CICA2 by modifying the periphery of second generation hyperbranched polyester (HBPE) with 1-cyano-pyrrolo[2,1-a]isoquinoline-3-carboxylic acid (CICA) groups. Structures of the HBPE-CICAs were confirmed by combined studies of Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The potential application of HBPE-CICAs in ion recognition was investigated; in particular, HBPE-CICA2 exhibited remarkable selectivity for Fe3+.

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.

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.

In this paper, Fe

p-Aminophenol was synthesized by catalytic hydrogenation of p-nitrophenol on Ni nanoparticles prepared by a chemical reduction method using polyamidoamine (PAMAM) dendrimers as templates. The as-prepared Ni nanoparticles were characterized by XRD, LRS, EDS, FTIR, FESEM, HRTEM and N2 sorption analysis. Smaller-sized, better-dispersed and more active Ni nanoparticles can be successfully achieved using PAMAM dendrimers as templates. Analysis results show the as-prepared Ni nanoparticles are pure f.c.c. nickel. In hydrogenation reactions of p-nitrophenol, Ni nanoparticles show higher catalytic activity than that of Ni nanoparticles prepared in the absence of PAMAM dendrimers. The weight ratio of PAMAM/Ni2+ is proved to be an important parameter on the catalytic activity of Ni nanoparticles and the optimal ratio is 15%. The reason proposed for higher catalytic activity of Ni nanoparticles is a combination effect of smaller particle size, better dispersion and more active Ni nanoparticles.

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-SO 3 H) nanoparticles and their biomedical application. The H30-SO 3 H 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-SO 3 H 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-SO 3 H 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-SO 3 H 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.