Publications (1295) View all
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Article: Enhanced brain targeting of curcumin by intranasal administration of a thermosensitive poloxamer hydrogel.
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ABSTRACT: The aim of this study was to develop a curcumin intranasal thermosensitive hydrogel and to improve its brain targeting efficiency. The hydrogel gelation temperature, gelation time, drug release and mucociliary toxicity characteristics as well as the nose-to-brain transport in the rat model were evaluated. The developed nasal hydrogel, composed of Pluronic F127 and Poloxamer 188, had shorter gelation time, longer mucociliary transport time and produced prolonged curcumin retention in the rat nasal cavity at body temperature. The hydrogel release mechanism was diffusion-controlled drug release, evaluated by the dialysis membrane method, but dissolution-controlled release when evaluated by the membraneless method. A mucociliary toxicity study revealed that the hydrogel maintained nasal mucosal integrity until 14 days after application. The drug-targeting efficiencies for the drug in the cerebrum, cerebellum, hippocampus and olfactory bulb after intranasal administration of the curcumin hydrogel were 1.82, 2.05, 2.07 and 1.51 times that after intravenous administration of the curcumin solution injection, respectively, indicating that the hydrogel significantly increased the distribution of curcumin into the rat brain tissue, especially into the cerebellum and hippocampus. A thermosensitive curcumin nasal gel was developed with favourable gelation, release properties, biological safety and enhanced brain-uptake efficiency.The Journal of pharmacy and pharmacology. 06/2013; 65(6):807-16. -
Article: Mass acquisition of Dirac fermions in Cr-doped topological insulator Sb2Te3 films
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ABSTRACT: We introduce time-reversal-symmetry breaking by doping Cr atoms into the topmost quintuple layer or into the bulk of Sb2Te3 thin films. We find that even at a high Cr-doping level the Landau level spectrum keeps a good quality, enabling the first demonstration of deviation of the zero-mode Landau level, induced by the acquisition of a mass term in the surface states in the presence of surface or bulk magnetic doping. The magnitude of the mass term in the surface states increases with increasing Cr-doping level. Our observation suggests Cr-doped Sb2Te3 is a promising candidate for the realization of the proposed novel magnetoelectric effects.05/2013; -
Article: Donor substrate promiscuity of the N-acetylglucosaminyltransferase activities of Pasteurella multocida heparosan synthase 2 (PmHS2) and Escherichia coli K5 KfiA.
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ABSTRACT: The biological activities of heparan sulfate (HS) and heparin (HP) are closely related to their molecular structures. Both Pasteurella multocida heparosan synthase 2 (PmHS2) and Escherichia coli K5 KfiA have been used for enzymatic and chemoenzymatic synthesis of HS and HP oligosaccharides and their derivatives. We show here that cloning using the pET15b vector and expressing PmHS2 as an N-His6-tagged fusion protein improve its expression level in E. coli. Investigation of the donor substrate specificity of the N-acetylglucosaminyltransferase activities of P. multocida heparosan synthase 2 (PmHS2) and E. coli K5 KfiA indicates the substrate promiscuities of PmHS2 and KfiA. Overall, both PmHS2 and KfiA can use uridine 5'-diphosphate-N-acetylglucosamine (UDP-GlcNAc) and some of its C2'- and C6'-derivatives as donor substrates for their α1-4-GlcNAcT activities. Nevertheless, PmHS2 has a broader tolerance towards substrate modifications. Other than the UDP-sugars that can be used by KfiA, additional C6'-derivatives of UDP-GlcNAc, UDP-glucose, and UDP-N-acetylgalactosamine (UDP-GalNAc) are tolerable substrates for the α1-4-GlcNAcT activity of PmHS2. The substrate promiscuities of PmHS2 and KfiA will allow efficient chemoenzymatic synthesis of diverse HS and HP oligosaccharide derivatives which may have improved or altered activities compared to their natural counterparts.Applied Microbiology and Biotechnology 05/2013; · 3.42 Impact Factor -
Article: Non-enzymatic oxalic acid sensor using platinum nanoparticles modified on graphene nanosheets.
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ABSTRACT: An enzyme-free oxalic acid (OA) electrochemical sensor was assembled using a platinum nanoparticle-loaded graphene nanosheets (PtNPGNs)-modified electrode. The PtNPGNs, with a high yield of PtNPs dispersed on the graphene nanosheets, were successfully achieved by a green, rapid, one-step and template-free method. The resulting PtNPGNs were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and an X-ray diffraction technique. Electrochemical oxidation of OA on the PtNPGNs-modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry methods. Based on the results, the modified electrode exhibited high electrochemical activity with well-defined peaks of OA oxidation and a notably decreased overpotential compared to the bare or even the GNs-modified electrode. Under optimized conditions, a good linear response was observed for the concentration of OA and its current response was in the range of 0.1-15 mM and 15-50 mM with a detection limit (S/N = 3) of 10 μM. Furthermore, the electrochemical sensor presented good characteristics in terms of stability and reproducibility, promising the applicability of the sensor in practical analysis.Nanoscale 05/2013; · 5.91 Impact Factor -
Article: Vaccine-induced plasma IgA specific for the C1 region of the HIV-1 envelope blocks binding and effector function of IgG.
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ABSTRACT: Analysis of correlates of risk of infection in the RV144 HIV-1 vaccine efficacy trial demonstrated that plasma IgG against the HIV-1 envelope (Env) variable region 1 and 2 inversely correlated with risk, whereas HIV-1 Env-specific plasma IgA responses directly correlated with risk. In the secondary analysis, antibody-dependent cellular cytotoxicity (ADCC) was another inverse correlate of risk, but only in the presence of low plasma IgA Env-specific antibodies. Thus, we investigated the hypothesis that IgA could attenuate the protective effect of IgG responses through competition for the same Env binding sites. We report that Env-specific plasma IgA/IgG ratios are higher in infected than in uninfected vaccine recipients in RV144. Moreover, Env-specific IgA antibodies from RV144 vaccinees blocked the binding of ADCC-mediating mAb to HIV-1 Env glycoprotein 120 (gp120). An Env-specific monomeric IgA mAb isolated from an RV144 vaccinee also inhibited the ability of natural killer cells to kill HIV-1-infected CD4(+) T cells coated with RV144-induced IgG antibodies. We show that monomeric Env-specific IgA, as part of postvaccination polyclonal antibody response, may modulate vaccine-induced immunity by diminishing ADCC effector function.Proceedings of the National Academy of Sciences 05/2013; · 9.68 Impact Factor
