Xianfu Lin

One-step construction of biosensor based on chitosan-ionic liquid-horseradish peroxidase biocomposite formed by electrodeposition.

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.

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).

Promiscuous zinc-dependent acylase-mediated carbon–carbon bond formation in organic media

A zinc-dependent acylase, D-aminoacylase from Escherichia. Coli, displays a promiscuous activity to catalyze the carbon-carbon bond formation reaction of 1,3-dicarbonyl compounds to methyl vinyl ketone in organic media.

Hydrolase-catalyzed fast Henry reaction of nitroalkanes and aldehydes in organic media

Nitroalkanes underwent fast additions to a variety of structurally diverse aldehydes under the catalysis of d-aminoacylase in DMSO. The influences of reaction conditions including solvents, temperature, enzyme concentration and molar ratio of substrates were systematically investigated. Seventeen products were obtained in short time with moderate to high yields. It is the first report on hydrolase-catalyzed fast Henry reaction in organic solvent.

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 green protocol for synthesis of benzo-fused N,S-, N,O- and N,N-heterocycles in water

A fast and efficient protocol which is associated with readily available starting materials, mild conditions, excellent yields, and a broad range of the products in synthetic chemistry, was established for synthesis of quinoxaline, benzoxazine, and benzothiazine derivatives in water under catalyst-free conditions.

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.

Highly sensitive biosensor based on bionanomultilayer with water-soluble multiwall carbon nanotubes for determination of phenolics.

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.

N-Methylimidazole significantly improves lipase-catalysed acylation of ribavirin

N-methylimidazole, a molecular solvent, but also, in cationic form, a component of 1-alkyl-3-methylimidazolium ([C(n)MIM]+) ionic liquids, showed promise as an additive in accelerating remarkably transesterification catalyzed by lipase acrylic resin from Candida antarctica (CAL-B).