Huijuan Yan

Northeast Institute of Geography and Agroecology, Beijing, Beijing Shi, China

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Publications (7)15.18 Total impact

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    ABSTRACT: l-asparaginase (l-Asnase) can suppress the growth of malignant cells by rapid depletion of two essential amino acids, l-glutamine (l-Gln) and l-asparagine (l-Asn). To study the cytotoxic effect and the secondary complications of l-Asnase in the treatment of acute lymphoblastic leukemia, the development of a novel enzyme reactor of l-Asnase for the hydrolysis of l-Gln, employing the enzyme-gold nanoparticle conjugates in capillary, was reported in this work. Firstly, a microchip electrophoresis-laser induced fluorescence method (MCE-LIF) was established for the separation of l-amino acids (l-Gln and l-glutamic acid) and the hydrolysis of l-Gln by using l-Asnase enzyme reactor. Then, using l-Gln as target analyte, the enzyme kinetics of l-Asnase in free solution (E-F), enzyme-gold nanoparticle conjugates (E-GNP) and the enzyme-gold nanoparticle conjugates immobilized in capillary (E-GNP-C) were investigated in detail with the proposed MCE-LIF method. Moreover, for optimizing the enzymatic reaction efficiency, three important parameters, including the length of capillary, the enzyme concentration reacted with gold nanoparticle and the amount of l-Asnase immobilized on the gold nanoparticle, have been studied. Owing to the high specific activity, the E-GNP-C enzyme reactor exhibited the best performance for the hydrolysis of l-Gln.
    Electrophoresis 11/2012; · 3.26 Impact Factor
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    ABSTRACT: A novel series of diblock copolymers, poly(butyl methacrylate)(n) -block-poly(glycidyl methacrylate)(m) [P(BMA)(n) -b-P(GMA)(m) ], were synthesized by atom transfer radical polymerization and developed as covalent coating of capillaries. The excellent performance of this coating in separation of three 1,4-dihydropyridines (DHPs) derivatives (amlodipine, nicardipine, nitrendipine) was achieved when the diblock copolymers self-assembled into micelles, which was confirmed by transmission electron microscopy, dynamic light scattering, and atom force microscopy. Meanwhile, the effects of block ratio n/m, pH value, buffer concentration, and organic solvents on the separation of 1,4-DHPs were investigated in detail. Then, the relationship between the morphologies of copolymers and the separation resolutions of 1,4-DHPs was discussed. Furthermore, the proposed method exhibited good run-to-run and column-to-column precision with relative standard deviations of electroosmotic flow less than 3.0%. It was also validated with linearity of three 1,4-DHPs in the range of 0.01-1.80 mM (r(2) ≥ 99.7%), efficient recovery (94-103%), and good repeatability (≤ 3.8%). In addition, three 1,4-DHPs were successfully separated in the spiked human serum sample, which indicated the potential utility of this method in biological sample analysis.
    Electrophoresis 07/2012; 33(13):2019-27. · 3.26 Impact Factor
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    ABSTRACT: A new amphipathic block copolymer, poly(tert-butyl acrylate)(127)-block-poly(glycidyl methacrylate)(86), was developed for the coating in open tubular capillary electrochromatography. The self-assembly characters of the coating, which could form micelle-like aggregates under proper conditions, were observed by atomic force microscopy. Compared with bare capillary, this coating could act as surfactant and lead to improve the separation of steroids. In addition, the influence of pH, buffer concentration and organic solvents on the separation was investigated. The best separation of the three model steroid analytes could be achieved using 20.0mM borate buffer at pH 10.5. For covalent bonding, the coating showed good repeatability and stability with RSD of u(EOF) less than 3.3%. Then, this proposed method was well validated with good linearity (≥ 0.999), recovery (91.0-94.0%) and repeatability, and was successfully used for separation of steroids in spiked serum samples, which indicated that this new OT-CEC method could provide a potential tool to determine steroids in real biological system without interference.
    Talanta 04/2011; 84(2):501-7. · 3.50 Impact Factor
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    ABSTRACT: The adsorption and adlayer structures of tetrathiofulvalene (TTF), tetracyanoquinodimethane (TCNQ) and TTF-TCNQ on Au(111) have been systematically investigated by in situ electrochemical scanning tunneling microscopy (ECSTM) and cyclic voltammetry in 0.1 mol L−1 HClO4. All the three molecules were found to form well-ordered adlayers in the double-layer potential region of Au(111). For TTF and TCNQ adlayers, (6×3) and (4×7) structures have been observed, respectively. A structural transition was observed on TCNQ adlayer at potential negative of 0.08 V vs. the reversible hydrogen electrode (RHE), and induced a new phase with (3$ \sqrt 3 $ \sqrt 3 × 12) structure. On the other hand, the charge transfer complex, TTF-TCNQ, self-organized into ordered domains with a lamellar structure different from those of the pure TTF and TCNQ adlayers on Au(111). Its packing arrangement was comparable to surface structures of either single crystal or thin film of TTF-TCNQ.
    Science in China Series B Chemistry 01/2009; 52(5):559-565. · 1.20 Impact Factor
  • JiQun Lu, CunJi Yan, HuiJuan Yan, LiJun Wan
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    ABSTRACT: Two-dimensional (2D) self-assembly of two 1,3,2-dioxaborine derivatives was investigated by STM. The molecules consist of π system and steric end groups. A droplet of toluene solution containing the molecules was deposited onto HOPG for preparing the assemblies. STM images showed that the molecular structures affect the assembly structure. The dipole-dipole interaction and steric repulsion played important roles in the formation of the self-assembled monolayers.
    Chinese Science Bulletin 01/2007; 52(18):2486-2490. · 1.32 Impact Factor
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    ABSTRACT: The composite material of poly-(L-lactide) (PLLA) and carbon nanotubes (CNTs) were prepared. Its surface morphologies and property were worked out by using atomic force microscopy (AFM) and contact angle measurement. Moreover, the prime cytocompatibility was used to investigate the biocompatibility of the composite material containing CNTs and the effects of CNTs on one aspect of cell function, cell affinity. The results obtained indicate that the composite material of PLLA and CNTs possesses good bio-compatibility for both the 3T3 fibroblasts and Oct-1 osteoblast-like cells. The addition of CNTs will greatly affect cell affinity of the material, which may be disadvantage for the cell adhesion. Keywordscarbon nanotube-composite material-cell-poly-(L-lactide)-biocompatibility
    Chinese Science Bulletin 01/2004; 49(20):2126-2128. · 1.32 Impact Factor
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    ABSTRACT: We have fabricated hybrid molecular chain structures formed by electron acceptor compound 1 and electron donor molecules 2 and 3 at the liquid/solid interface of graphite surface. The structural details of the mono-component and the binary assemblies are revealed by high resolution scanning tunneling microscopy (STM). Compound 1 can form two well-ordered lamellar patterns at different concentrations. In the co-adsorption structures, compounds 2 and 3 can insert into the space between molecular chains of compound 1 and form large area well-ordered nanoscale phase separated lamellar structures. The unit cell parameters for the coassemblies can be “flexibly” adjusted to make the electron donors and acceptors perfectly match along the molecular chains. Scanning tunneling spectroscopy (STS) results indicate that the electronic properties of individual molecular donors and acceptors are preserved in the binary self-assembly. These results provide molecular insight into the nanoscale phase separation of organic electron acceptors and donors on surfaces and are helpful for the fabrication of surface supramolecular structures and molecular devices.
    Science China-Chemistry 56(1). · 1.33 Impact Factor

Publication Stats

12 Citations
382 Views
15.18 Total Impact Points

Institutions

  • 2011
    • Northeast Institute of Geography and Agroecology
      • Institute of Chemistry
      Beijing, Beijing Shi, China
  • 2009
    • Chinese Academy of Sciences
      • Institute of Chemistry
      Peping, Beijing, China
  • 2007
    • Technical Institute of Physics and Chemistry
      Peping, Beijing, China