Youming Shen

Electrochemical immunosensor based on Pd-Au nanoparticles supported on functionalized PDDA-MWCNT nanocomposites for aflatoxin B1 detection.

This paper reports a label-free electrochemical immunosensor for the determination of aflatoxin B1 (AFB1), which is based on a gold electrode modified by a biocompatible film of carbon nanotubes/poly(diallyldimethylammoniumchloride)/Pd-Au nanoparticles (CNTs/PDDA/Pd-Au). The nanocomposite was characterized by transmission electron microscopy and the electrochemical behavior of modified electrodes was investigated by cyclic voltammetry. The CNTs/PDDA/Pd-Au nanocomposites film showed good electron transfer ability, which ensured high sensitivity to detect AFB1 in a range from 0.05 to 25 ng mL(-1) with a detection limit of 0.03 ng mL(-1) obtained at 3σ (where σ is the standard deviation of the blank solution, n = 10). The proposed immunosensor provides a simple tool for AFB1 detection. This strategy can be extended to any other antigen detection by using the corresponding antibodies.

One-step immobilization of antibodies for α-1-fetoprotein immunosensor based on dialdehyde cellulose/ionic liquid composite.

A novel immunosensor for α-1-fetoprotein based on dialdehyde cellulose/ionic liquid composite film as a matrix has been developed. Microcrystalline cellulose was activated by sodium metaperiodate to produce dialdehyde cellulose. Antibodies can be immobilized on the electrode by a one-step method through covalent bonding of the aldehyde groups of dialdehyde cellulose with the amino groups of antibodies, in which no additional chemical cross-linking step is required. Moreover, ionic liquid added can improve the conductivity of the sensing interface and, therefore, can enhance the electrochemical signal. In this work, α-1-fetoprotein was detected within the range from 0.1 to 60ngml(-1) with a detection limit of 0.07ngml(-1) (signal/noise=3). The proposed immunosensor had good specificity and reproducibility. It was used to determine real samples with satisfactory results.

Direct immobilization of antibodies on a new polymer film for fabricating an electrochemical impedance immunosensor.

A new polymer bearing aldehyde groups was designed and synthesized by grafting 4-pyridinecarboxaldehyde onto poly(epichlorohydrin). Antibodies can be directly immobilized on the surface of the polymer film through the covalent bonding of aldehyde groups of the film with amino groups of antibodies. In this study, human immunoglobulin G (IgG) was used as a model analyte for the fabrication of an electrochemical impedance immunosensor. Using the proposed immunosensor, IgG in the range from 0.1 to 80 ng ml(-1) was detected with a detection limit of 0.07 ng ml(-1) (signal/noise [S/N]=3). In addition, the electrochemical impedance immunosensor displays good stability and reproducibility.

Fabrication of three-dimensional porous cobalt network-supported cobalt oxides nanoflake arrays for electrochemical energy storage

Smart combination of porous metal with metal oxides is important for the construction of high-performance electrochemical devices. Herein, we report three-dimensional Co network-supported Co3O4 nanoflake arrays by a facile electrodeposition and following hydrothermal process. 3D Co networks with porous branches and interconnected pores are well formed and used as the skeleton for the growth of porous Co3O4 nanoflake arrays. High porosity and integrated growth are combined in the composite electrode. As an anode material for lithium ion batteries, the Co network-supported Co3O4 nanoflake array electrode exhibits a high first discharge capacity (1164 mAh g−1 at 0.5 A g−1), good cycling stability (714 mAh g−1 after 100 cycles) and enhanced rate capability. The proposed method is useful for the construction of other porous metal/metal oxide composite films for application in electrochemical energy storage and catalysis.

The development of an electrochemical immunosensor using a thiol aromatic aldehyde and PAMAM-functionalized Fe3O4@Au nanoparticles

In this work, a novel thiol aromatic aldehyde was synthesized. It can be used as a substrate to directly immobilize antibodies on a gold electrode, for which no additional chemical cross-linker is required. It was also applied as a linker to prepare Fe3O4@Au/PAMAM/Ab2-horseradish peroxidase bioconjugates, which introduced multiple enzymes onto a sensing interface owing to the high surface-to-volume ratio of Fe3O4@Au nanoparticles and many functional groups of the poly(amidoamine) dendrimer (PAMAM). The introduced multiple enzymes greatly improved the detection signal. Under optimal conditions, the proposed electrochemical immunosensor exhibited desirable performance for detection of IgG in the range 0.005-50 ng ml(-1) with a detection limit of 3 pg ml(-1) based on a signal-to-noise ratio of 3. It has great potential application in the area of clinical analysis.

A label-free electrochemical immunosensor based on a new polymer containing aldehyde and ferrocene groups

In this work, a novel and convenient strategy for synthesis of a well-defined polymer containing both aldehyde and ferrocene functional groups by grafting 4-hydroxybenzaldehyde and ferrocenecarboxylhydrazide onto linear poly (vinylbenzyl chloride) was developed. The designed polymer film (polymer CAF) could be used as a new support matrix for fabrication of a label-free electrochemical immunosensor with high sensitivity, good stability and repeatability. With human IgG as an analyte model, the proposed electrochemical immunosensor showed a linear concentration range from 0.1 to 20ngmL-1 with a detection limit of 0.07ngmL-1 (S/N=3). Moreover, interfering proteins including HSA, IgM, and IgE were added into the analyte, the developed immnnosensor can detect human IgG with high specificity.

A versatile matrix of an ionic liquid functionalized with aldehyde and ferrocene groups for label-free electrochemical immunosensors

A novel ionic liquid functionalized with aldehyde and ferrocene groups was successfully synthesized. It was used to develop a label-free electrochemical immunosensor for the detection of human immunoglobulin G by casting this multifunctional ionic liquid entrapped in a Nafion matrix on a gold electrode. This multifunctional material was redox-active because of the introduction of ferrocene on the surface of the electrode through the covalent attachment of ferrocene to the ionic liquid, which avoided the use of other redox species in the electrolyte solution. In the meantime, the covalent attachment also avoided signal decrease resulting from the leakage of ferrocene into solution. In addition, the versatile ionic liquid can be used as a substrate for direct antibody immobilization due to the existence of the aldehyde group, which greatly simplified the process of sensor fabrication. The proposed sensor exhibited a good performance in a linear range from 0.05 to 35 ng mL−1 with a detection limit of 0.03 ng mL−1 based on 3σ and provided a novel strategy for clinical detection due to its satisfactory stability, selectivity and reproducibility.