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ABSTRACT: It is well known that combination therapy can significantly enhance the cytotoxicity and bypass some resistance mechanisms. However, the different solubility and pharmacokinetics of drugs limit the applications of combination therapy. In this study, novel glucose-functionalized polymeric micelle nanoparticles containing multidrugs were successfully fabricated and characterized. Two chemotherapeutic agents, cytarabine (Ara-C) and fluorodeoxyuridine (FUDR), were conjugated to a glucose-functionalized amphiphilic random terpolymer to create a novel nanocarrier for the delivery of multiple drugs simultaneously with an identical pharmacokinetic profile. The incorporation of D-glucose markedly increased the dispersity and biocompatibility of the novel polymeric micelles. In vitro drug release studies showed the two anticancer agents could be simultaneously released from multidrug-conjugating nanoparticles. Cellular uptake assay observed by confocal laser scanning microscopy and cytotoxicity tests performed by MTT assay against hepG2 human hepatoma cells indicated that glucose-functionalized multidrug-conjugating nanoparticles could be effectively internalized by HepG2 cells and showed much more effective growth-inhibitory activity than two single-drug-conjugating polymer aggregates or free drugs. This finding, therefore, illustrated that the D-glucose functionalized nanoparticles could be used as a novel potential multidrug delivery vehicle.
International journal of pharmaceutics 11/2012; · 2.96 Impact Factor
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ABSTRACT: Candida antarctica lipase B (Cal-B) is one of the most recognized biocatalysts because of its high degree of selectivity in a broad range of synthetic applications of industrial importance. Herein, the substituent effects involved in transesterification catalyzed by Cal-B are explored in detail using a combination of experimental analysis and theoretical modeling. The transesterification ability of Cal-B was experimentally determined with 22 vinyl ester analogs and ribavirin as substrates and, on this basis, a series of quantitative structure-activity relationship (QSAR) models are developed using various structural parameters characterizing the variation in substituent groups of the substrate molecules. The resulting models exhibit a good stability and predictive power, from which five most important properties are highlighted and engaged to ascertain the structural basis and reaction mechanism underlying the transesterification. From the modeling analysis it is seen that the size, geometry, and charge distributions of substrate exert a significant effect on reaction yield, where, the size of the substituent group was the most significant impact factor on the reaction yield, the charge distribution was the second, and then the topological structure of the substrate.
Journal of Molecular Modeling 08/2012; · 1.80 Impact Factor
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ABSTRACT: Substituted triazolinones were prepared by a three-component reaction of aldehydes, hydrazines and azodicarboxylates using
TFA as a catalyst. The procedure was convenient and efficient, utilizing readily available substrates. A plausible mechanism
for the cascade process is proposed.
Keywordstriazolinones-cascade reactions-multicomponent reactions (MCRs)-azodicarboxylates
Chinese Science Bulletin 04/2012; 55(25):2879-2884. · 1.32 Impact Factor
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ABSTRACT: A novel amperometric immunosensor for the determination of carcinoembryonic antigens (CEA) was developed. Firstly, ordered multilayer films of Prussian blue (PB) and multiwalled-carbon nanotube/polyethylenimine/Au (MWNT-PEI-Au) nanocomposite were fabricated onto the surface of a glassy carbon electrode via alternate electrodeposition and self-assembly. Then a layer of chitosan mixed with gold nanoparticles was cast onto the surface of the electrode. Subsequently, the electrode was coated with antibody (Ab(1)) and blocked with BSA. The morphology of the MWNT-PEI-Au nanocomposite was characterized by transmission electron microscopy (TEM). The fabrication process of the ordered multilayer structure and immunosensor were characterized by scanning electron microscopy (SEM) and electrochemical measurements, respectively. The proposed fabrication strategy effectively ensured the stability of the Prussian blue as electron mediator. Under optimal conditions, the fabricated immunosensor exhibited a good response to CEA, with a detection range from 0.5 to 160 ng/mL and a detection limit of 0.08 ng/mL at 3δ. The current fabricated immunosensor exhibited good sensitivity, selectivity, and long-term stability. Furthermore, current study demonstrated the promising application of the alternate strategy based on electrodeposition and self-assembly for the construction of biosensor.
Biosensors & bioelectronics 03/2012; 35(1):277-83. · 5.43 Impact Factor
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ABSTRACT: A simple and controllable one-step electrodeposition method for the preparation of a chitosan-carbon nanotubes-gold nanoparticles (CS-CNTs-GNPs) nanocomposite film was used to fabricate an immunosensor for detection of carcinoembryonic antigen (CEA). The porous three-dimensional CS-CNTs-GNPs nanocomposite film, which offered a large specific surface area for immobilization of antibodies, exhibited improved conductivity, high stability and good biocompatibility. The morphology of the formed nanocomposite film was investigated by scanning electron microscopy (SEM), and the electrochemical behaviors of the immunosensor were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Under the optimal conditions, the proposed immunosensor could detect CEA in two linear ranges from 0.1 to 2.0 ng mL(-1) and from 2.0 to 200.0 ng mL(-1), with a detection limit of 0.04 ng mL(-1). The immunosensor based on CS-CNTs-GNPs nanocomposite film as the antibody immobilization matrix could exhibit good sensitivity, stability, and reproducibility for the determination of CEA.
Talanta 09/2011; 85(4):1980-5. · 3.79 Impact Factor
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ABSTRACT: The influence of reaction media on the racemic temperature (T(r)) in the lipase-catalyzed resolution of ketoprofen vinyl ester was investigated. An effective approach to the control of the enzymatic enantioselectivity and the prediction of the increasing tendency was developed based on the T(r) influenced by reaction media. The T(r) for the resolution catalyzed by Candida rugosa lipase (CRL) was found at 29 °C in aqueous and S-ketoprofen was obtained predominantly at 40 °C. However, CRL showed R-selectivity at 40 °C in diisopropyl ether because the T(r) was changed to 56 °C. CRL, lipase from AYS Amano(®) and Mucor javanicus lipase were further applied for the investigation of the enzymatic enantioselectivity in dioxane, DIPE, isooctane and their mixed media with water. The effects of the reaction medium on T(r) could be related to the solvent hydrophobicity, the lipase conformational flexibility and the interaction between the enantiomers and the lipase.
Enzyme and microbial technology. 05/2011; 48(6-7):454-7.
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ABSTRACT: A new amperometric immunosensor for the determination of carcinoembryonic antigen (CEA) was constructed. First, the uniform nanomultilayer film was fabricated via layer-by-layer (LBL) assembly of positively charged carbon nanotubes wrapped by poly(diallyldimethylammonium chloride) and negatively charged poly(sodium-p-styrene-sulfonate), which could provide a high accessible surface area and a biocompatible microenvironment. Subsequently, gold nanoclusters were electrodeposited on the electrode to immobilize anti-CEA. The fabricated process and electrochemical behaviors of the immunosensor were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Under optimal conditions, the proposed immunosensor could detect CEA in two linear ranges from 0.1 to 2.0 ng mL(-1) and from 2.0 to 160.0 ng mL(-1), with a detection limit of 0.06 ng mL(-1).
Analytical Biochemistry 03/2011; 414(1):70-6. · 3.00 Impact Factor
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ABSTRACT: This paper reported the modulation of enzyme activity by organic small molecule. The esterification activity of Penicillin G acylase (PGA) was improved more than 70-fold by the addition of 10% N-methylimidazole. Some control experiments have been designed to demonstrate the catalytic specificity of PGA. The structure and the amount of additive were optimized to improve the product yield. The influence of N-methylimidazole on the PGA conformation was investigated by FTIR and autodock simulation. Seven substrates were used to evaluate the effect of structure on the PGA-catalyzed transesterification. A series of products were successfully synthesized with the yield ranged from 56% to 84% and PGA showed specific recognition on the substrate with phenyl group in the presence of 10% N-methylimidazole.
Journal of biotechnology 03/2011; 153(3-4):111-5. · 2.88 Impact Factor
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ABSTRACT: A series of novel designed mexiletine derivatives and its analogs were prepared, the structures were confirmed by Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), and Electrospray Ionization-Mass Spectrometry (ESI-MS), and the enantioseparations were performed on polysaccharide-based chiral stationary phase (CSP), Chiralcel OD-H, and Chiralcel OJ-H, under normal-phase mode. The effects of the concentration of isopropanol in the mobile phase were studied, seven of the eight enantiomers got baseline separation on Chiralcel OD-H, and five of the eight enantiomers got successfully separation on Chiralcel OJ-H. The effects of structural features were also discussed.
Chirality 02/2011; 23(2):99-104. · 2.35 Impact Factor
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ABSTRACT: Comparative studies of enzymatic acylation of troxerutin by the alkaline protease from Bacillus subtilis under ultrasound and shaking were carried out in nonaqueous media. Using divinyl dicarboxylates (CH(2)CH-OOC-(CH(2))(n)-COO-CHCH(2), n=2, 3, 4, 7, 8, 11) featuring different chain length as acyl donors, troxerutin was regioselectively acylated at B ethoxyl group, whether under ultrasound or shaking. Ultrasonic treatment increased the reaction rate and led to high conversion. Several factors, such as pre-irradiation on the enzyme, the power and frequency of the ultrasound, operation manner, as well as the length of the acyl donors were investigated. Using enzyme pre-irradiated for 8 h, the conversion of troxerutin was increased to 87.3% compared with 56.3% obtained from the untreated enzyme. Experimental results also showed that continual ultrasound caused greater rate acceleration than interval ultrasound. Powers of 100, 150 and 200 W, frequencies of 40, 80 and 100 kHz all showed significant improvement on the transesterification, with the greatest effect observed at 150 W, 80 kHz. The acceleration effect increased as the chain length of the acyl donors decreased from C(13) to C(4).
Ultrasonics Sonochemistry 01/2011; 18(1):303-9. · 3.57 Impact Factor
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ABSTRACT: The molecular weight, degree of deacetylation and the acetic acid concentration of chitosan solutions were modulated to change the structures and properties of the chitosan membranes, including chemical structures, ionic conductivity and hydrophobicity, which were analyzed by FTIR-ATR, electrochemical impedance and water contact angle measurement, respectively. Consequently, the adsorption of horseradish peroxidase (HRP, as a model) was controlled by the structural and natural changes of chitosan membranes, exhibiting different adsorbed amount and activity. A HRP-based electrode coated with the chitosan membrane was further constructed to investigate the influence of the chitosan membrane properties on the electrochemical performance. Therefore, this work offered a fundamental understanding of the control of the enzyme adsorption and performance through changing the chitosan membrane structures and properties for the more extensive applications, especially in the construction of the highly efficient bioelectrodes.
Carbohydrate Polymers - CARBOHYD POLYM. 01/2011; 85(4):786-791.
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ABSTRACT: Eleven shikonin glycosides were synthesized and evaluated for their antitumor activity in vitro. Some of them were found to exhibit cytotoxic activities against both drug sensitive cell lines (K562, MCF-7 and HL60) and their drug resistant cell sublines (K562/ADR, MCF-7/ADR and HL60/ADR).
European journal of medicinal chemistry 07/2010; 45(7):2713-8. · 3.27 Impact Factor
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ABSTRACT: Bienzyme bionanomultilayer electrode for glucose biosensing was constructed based on functional carbon nanotubes and sugar-lectin biospecific interaction through layer-by-layer (LBL) assembly. After being functionalized by wrapping with polyelectrolyte, multiwalled carbon nanotubes (MCNTs) were water soluble and positively charged. MCNT-bienzyme bionanomultilayer electrode was then fabricated by LBL assembly of horseradish peroxidase (HRP) and glucose oxidase (GOD) on functional MCNT modified electrode. The attachment of the MCNT-bienzyme bionanomultilayer with the underlying electrode and each layer in the bionanomultilayer was based on reliably electrostatic or sugar-lectin biospecific interaction. The developed bienzyme biosensor exhibited fast amperometric response for the determination of glucose. The linear response of the developed biosensor for the determination of glucose ranged from 2.0 x 10(-6) to 1.7 x 10(-4) M with a detection limit of 2.5 x 10(-7) M. The biosensor can be used directly to determine glucose in serum. The construction of the bienzyme biosensor showed potential for the preparation of MCNT-enzyme nanocomposite with controllability and high performance.
Analytical Biochemistry 04/2010; 403(1-2):36-42. · 3.00 Impact Factor
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ABSTRACT: A simple layer-by-layer (LBL) assembly strategy was established for constructing a novel reagentless biosensor based on a nanocomposite of methylene blue multiwalled carbon nanotubes (MB-MWNTs). A nanocomposite of MB-MWNTs was obtained by direct premixing and possessed good dispersion in barbital-HCl buffer. Through electrostatic interactions, the nanocomposite of MB-MWNTs could alternately be assembled with horseradish peroxidase (HRP) on the Au electrode modified with precursor films. UV/Vis spectra and scanning electron microscopy (SEM) were applied to reveal the formation of the nanocomposite of MB-MWNTs. The LBL assembly process was also verified by electrochemical impedance spectroscopy (EIS). The MB is a well-established mediator and efficiently facilitated the electron shuttle between the HRP and the electrode, as demonstrated by the cyclic voltammetry (CV) measurements. The as-prepared reagentless biosensor exhibited a fast response for the determination of hydrogen peroxide (H2O2) and reached 95% of the steady-state current within 3 s. It was found that the linear response range of the reagentless biosensor for H2O2 was from 4.0 μM to 3.78 mM with a detection limit of 1.0 μM and a sensitivity of 22.5 μA mM−1. The biosensor exhibited a high reproducibility and stability.
Electroanalysis 12/2009; 22(3):277 - 285. · 2.87 Impact Factor
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ABSTRACT: Novel hepatoma-targeting azacitidine-conjugating microdisks were successfully fabricated by hydrogen bond-assisted self-assembly of an amphiphilic random copolymer with galactose and azacitidine as pendants, poly(5'-O-vinyladipyl-azacitidine-co-6-O-vinylsebacyl-galactose). The random copolymer was easily prepared by a two-step chemoenzymatic synthetic route, and the possibility of its self-assembly was verified by ultraviolet-visible and fluorescence spectroscopy using pyrene as the hydrophobic probe. Transmission electron microscopy and scanning electron microscopy indicated that aggregation morphologies of these self-assemblies were thin disks with radii from 250 to 500nm. Section analysis of atomic force microscopy for a thin disk gave a thickness of approximately 16nm. The existence of hydrogen bonds among the pendants was investigated by infrared spectra and Gaussian calculation. Cellular uptake assay observed by confocal laser scanning microscopy and cell cytotoxicity tests by MTT dye reduction method showed that the self-assemblies had an evident hepatoma-targeting function to hepG2 human hepatoma cells and could effectively realize cellular internalization of azacitidine.
Acta biomaterialia 08/2009; 6(2):511-8. · 3.98 Impact Factor
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ABSTRACT: A simple and controllable electrodeposition approach was established for one-step construction of novel reagentless biosensors by in situ formation of chitosan-carbon nanotubes-nile blue-horseradish peroxidase (CS-CNTs-NB-HRP) biocomposite film on electrode surface. The mediator effect of NB, conducting performance of CNTs and the biocompatible microenvironment of CS were combined by such one-step non-manual process. NB could interact with CNTs and resulted in good dispersion of CNTs-NB nanocomposites in aqueous solution. Cyclic voltammetry measurements demonstrated that electrons were efficiently shuttled between HRP and the electrode mediated by NB. The developed reagentless biosensor exhibited a fast amperometric response for the determination of H(2)O(2) and 95% of the steady-state current was obtained within 2s. The linear response of the reagentless biosensor for the determination of H(2)O(2) ranged from 1.0 x 10(-6) to 2.4 x 10(-4)mol l(-1) with a detection limit of 1.2 x 10(-7)mol l(-1). The biosensor exhibited high reproducibility and long-time storage stability. The as-prepared biosensor also showed effective anti-interference capability. The ease of the one-step non-manual technique and the promising feature of the biocomposite could serve as a versatile platform for fabricating electrochemical biosensors.
Talanta 06/2009; 78(3):1077-82. · 3.79 Impact Factor
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ABSTRACT: Artemisinin (ART) crystals were encapsulated with chitosan, gelatin, and alginate for the purpose of controlled release. These polyelectrolytes were alternatively deposited on ART crystals sized about 766 nm through the layer-by-layer technique. Size distribution, zeta potential, and swelling property of ART nanocapsules were measured. The morphology of ART nanocapsules was observed by transmission electron microscopy after dissolution. Release property of ART nanocapsules was measured in phosphate buffer solution (pH 7.4). It was proved that the ART nanocapsules dispersed well in aqueous solutions. Hydrophilicity of ART crystals was improved after encapsulation. The ART drug release rate was tuned by the properties of polyelectrolyte solutions, such as polyelectrolyte type, number of polyelectrolyte multilayers, sodium chloride concentration, and ethanol concentration in polyelectrolyte solution, and so on. Our research provides a feasible method of achieving prolonged drug release through self-assembly of polyelectrolytes on natural drug crystals. FROM THE CLINICAL EDITOR: Artemisinin (ART) crystals were encapsulated with chitosan, gelatin, and alginate for the purpose of controlled release of this anticancer drug. The reported method is feasible for achieving prolonged drug release through self-assembly of polyelectroytes on natural drug crystals.
Nanomedicine: nanotechnology, biology, and medicine 02/2009; 5(3):316-22. · 5.44 Impact Factor
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ABSTRACT: A simple and controllable electrodeposition approach was established for one-step construction of hydrogen peroxide (H(2)O(2)) biosensors by in situ formation of chitosan-ionic liquid-horseradish peroxidase (CS-IL-HRP) biocomposite film on electrode surface. A highly porous surface with orderly three-dimensional network was revealed by scanning electron microscopy (SEM) investigation. The biocomposite provided improved conductivity and biocompatible microenvironment. The developed biosensor exhibited a fast amperometric response for the determination of H(2)O(2) and 95% of the steady-state current was obtained within 2s. The linear response of the developed biosensor for the determination of H(2)O(2) ranged from 6.0 x 10(-7) to 1.6 x 10(-4)M with a detection limit of 1.5 x 10(-7)M. Performance of the biosensor was evaluated with respect to possible interferences and a good selectivity was revealed. The fabricated biosensor exhibited high reproducibility and long-time storage stability. The ease of the one-step non-manual technique and the promising feature of biocomposite could serve as a versatile platform for the fabrication of electrochemical biosensors.
Biosensors and Bioelectronics 10/2008; 24(1):29-34. · 5.60 Impact Factor
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ABSTRACT: A highly sensitive biosensor was developed based on bionanomultilyer with water-soluble carbon nanotubes (CNTs). The water-soluble poly(allylamine hydrochloride)-wrapped multiwall carbon nanotubes (PAH-MWNTs) can be obtained for the first time relying on the function of barbiturates, which provides a useful avenue for CNT application in material science and biosensor technology. Based on this, the PAH-MWNTs/horseradish peroxidase (HRP) bionanomultilayer was prepared via layer-by-layer (LBL) assembly. Electrochemical impedance spectroscopy, atomic force microscopy and UV-vis spectra were adopted to monitor the uniform LBL assembly of the homogeneous bionanomultilayer. The bionanomultilayer was used to construct a phenolic biosensor. Under the optimal conditions, the biosensor presented a linear response for catechol from 0.1 to 20.4 microM, with a detection limit of 0.06 microM. A series of phenolics were detected by the bionanomultilayer biosensor. The introduced MWNTs in the biosensor provided a suitable microenvironment to retain the HRP activity and acted as a transducer for amplifying the electrochemical signal of the product of the enzymatic reaction. So the developed bionanomultilayer biosensor exhibited a fast, sensitive and stable detection.
Biosensors and Bioelectronics 05/2008; 24(2):306-12. · 5.60 Impact Factor
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Journal of Polymer Science Part A Polymer Chemistry 03/2008; 46(8):2734 - 2744. · 3.92 Impact Factor
