Hyaluronic acid is a naturally ionic polysaccharide with cancer cell selectivity. It is an ideal candidate material for delivery of anticancer agents. In this study, hyaluronic acid (HA) micro-hydrogel loaded with anticancer drugs was prepared by the biotin–avidin system approach. Firstly, carboxyl groups on HA were changed into amino groups with adipic acid dihydrazide (ADH) to graft with biotin by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride named as HA–biotin. When HA–biotin solution mixed with doxorubicin hydrochloride (DOX·HCl) was blended with neutravidin, the micro-hydrogels would be formed with DOX loading. If excess biotin was added into the microgel, it would be disjointed, and DOX will be released quickly. The results of the synthesis procedure were characterized by 1H-NMR and FTIR; ADH and biotin have been demonstrated to graft on the HA molecule. A field emission scanning electron microscope was used to observe morphologies of HA micro-hydrogels. Furthermore, the in vitro DOX release results revealed that the release behaviors can be adjusted by adding biotin. Therefore, the HA micro-hydrogel can deliver anticancer drugs efficiently, and the rate of release can be controlled by biotin-specific bonding with the neutravidin. Consequently, the micro-hydrogel will perform the promising property of switching in the specific site in cancer therapy. 相似文献
Reported herein is an iridium‐catalyzed, regioselective silylation of the aromatic C H bonds of benzylamines and the benzylic C H bonds of 2,N‐dialkylanilines. In this process, (hydrido)silyl amines, generated in situ by dehydrogenative coupling of benzylamine or aniline with diethylsilane, undergo selective silylation at the C H bond γ to the amino group. The products of this silylation are suitable for subsequent oxidation, halogenation, and cross‐coupling reactions to deliver benzylamine and arylamine derivatives. 相似文献
We have revisited the synthesis of a series of ICT fluorophores, which were reported to have a core structure of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile. However, based on the 2D NMR and X-ray diffraction analysis, their core structure was corrected as 1-oxo-1H-phenalene-2,3-dicarbonitrile (1). Compound 1 shows a highly electron-deficient nature and can easily undergo oxidative SNArH reaction on the naphthyl ring to produce a series of novel ICT fluorophores. The regioselectivity of this substitution reaction was studied by introduction of representative nucleophiles. Moreover, due to the strong rigidity and efficient ICT nature, the obtained fluorescent dyes display very good spectroscopic properties even in an aqueous environment. 相似文献
Transition-metal free direct C–H arylation of benzene with aryl halides was achieved by meso-aryl-substituted [14]triphyrins(2.1.1) catalysts in an air atmosphere. Various aryl halides underwent successful direct C–H arylation of benzene to give moderate to high yields of biaryls. A radical mechanism is proposed for this triphyrin catalyzed C–H arylation reaction. 相似文献
Several approaches to quantifying measurement uncertainty in k0-based neutron activation analysis (k0-NAA) are reviewed, comprising the original approach, the spreadsheet approach, the dedicated computer program involving analytical calculations and the two k0-NAA programs available on the market. Two imperfectness in the dedicated programs are identified, their impact assessed and possible improvements presented for a concrete experimental situation. The status of uncertainty assessment in k0-NAA is discussed and steps for improvement are recommended. It is concluded that the present magnitude of measurement uncertainty should further be improved by making additional efforts in reducing uncertainties of the relevant nuclear constants used. 相似文献
Developing artificial enzyme mimetics for the detection of small biomolecules are a current research interest because natural enzymes bear some serious disadvantages, such as their catalytic activity can be easily inhibited and they can be digested by proteases. Herein, a heteropoly acids (HPA) encapsulating metal–organic framework (MOF) with metal-carbene structure, [Cu10(H3trz)4(Htrz)4][PMo12VO41] (PMA-MOF) as bifunctional enzyme-mimetic catalyst for colorimetric detection of hydrogen peroxide (H2O2) and ascorbic acid (AA) was designed and synthesized. Thanks to the good stability and the synergistic effect of PMA and MOF, PMA-MOF exhibits the lower limit of detection (0.222 μM towards H2O2 and 0.0046 μM to AA), and the smaller Km value (0.0138 mM for H2O2 and 0.136 mM for o-phenylenediamine) compared to most reported MOF- and HPA-based enzyme-mimetic catalyst, to the best our knowledge.
Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of~(25)Mg(p,γ)~(26)Al,~(19)F(p,α)~(16)O,~(13)C(α,n)~(16)O and ~(12)C(α,γ)~(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given. 相似文献
We propose a method to produce a definite number of ground-state atoms by adiabatic reduction of the depth of a potential well that confines a degenerate Bose gas with repulsive interactions. Using a variety of methods, we map out the maximum number of particles that can be supported by the well as a function of the well depth and interaction strength, covering the limiting case of a Tonks gas as well as the mean-field regime. We also estimate the time scales for adiabaticity and discuss the recent observation of atomic number squeezing [Chuu, Phys. Rev. Lett. 95, 260403 (2005)10.1103/PhysRevLett.95.260403]. 相似文献
The structure of uleine type alkaloids is characterized by the presence of a bridged tetracyclic hexahydro-1H-1,5-methanoazocino[4,3-b]indole ring system 1 . Various strategies have been developed to access this polycyclic structural motif. We report herein a one-step conversion of appropriately functionalized 1,3,4-trisubstituted cyclopent-1-ene to 1 by way of an integrated oxidation/reduction/cyclization (iORC) process. This domino sequence, initiated by oxidative cleavage of cyclopentene ring, generated subsequently a cyclohexenone, an indole and a 1,3-bridged piperidine ring through formation of one C−C and two C−N bonds. Compound 1 is subsequently converted to nordasycarpidone, dasycarpidone and uleine. The chirality of the molecule was introduced by enzymatic desymmetrization of commercially available meso cis-3,5-diacetoxy-1-cyclopentene. 相似文献