Zhichun Chen

Amperometric immunosensor for carcinoembryonic antigen detection with carbon nanotube-based film decorated with gold nanoclusters.

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).

One-step construction of reagentless biosensor based on chitosan-carbon nanotubes-nile blue-horseradish peroxidase biocomposite formed by electrodeposition

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.

One step electrochemically deposited nanocomposite film of chitosan-carbon nanotubes-gold nanoparticles for carcinoembryonic antigen immunosensor application.

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.

A novel immunosensor based on an alternate strategy of electrodeposition and self-assembly.

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.

Thermal treatment of galactose-branched polyelectrolyte microcapsules to improve drug delivery with reserved targetability

A novel multilayered drug delivery system by LbL assembly of galactosylated polyelectrolyte, which is possible to have the potential in hepatic targeting by the presence of galactose residues at the microcapsules surface, is designed. Thermal treatment was performed on the capsules and a dramatic thermal shrinkage up to 60% decrease of capsule diameter above 50 degrees C was observed. This thermal behavior was then used to manipulate drug loading capacity and release rate. Heating after drug loading could seal the capsule shell, enhancing the loading capacity and reducing the release rate significantly. Excellent affinity between galactose-binding lectin and heated galactose-containing microcapsules were observed, indicating a stable targeting potential even after high temperature elevating up to 90 degrees C.

Regio- and stereo-selective synthesis of vinyl glucose ester catalyzed by an alkaline protease of Bacillus subtilis

The transesterification of α-d-glucose with divinylsuccinate, divinyladipate and divinylsebacate in pyridine at 55 °C for 3 days was catalyzed by an alkaline protease from Bacillus subtilis to give corresponding 6-O-vinyl glucose esters at 30%, 53% and 35% yield, respectively. The stereo-selectivity of the alkaline protease toward the α-anomer was affected by the acyl donor chain length. 6-O-Vinylsuccinyl-d-glucose was mixture of α- and β-anomers (α/β=44/56), the other two products were the pure α-d-glucose derivatives.