Electrochemical Immunosensor for a-Fetoprotein Based on Gold Nanoparticles/Graphene-Prussian Blue

The electrochemical immunosensor for a-fetoprotein （AFP） was fabricated based on the platform of gold nanoparticles （GNP）/graphene （Gr）-prussian blue （PB）. By electrodeposition, GNP were modified on the surface of the prepared Gr-PB. The anti-AFP-1, l＇-ferrocenedicarboxylic acid （FcDA） as label was directly immobilized on the platform of GNP/Gr-PB. And after the immunoreactions, the formed complex inhibited the electron transfer and decreased the catalytic current of FcDA toward the reduction of H2O2. And in the range of 10-3200 pgomL^-1, the decreased current is linear with the concentration of AFP, with a detection limit of 3 pg.mL-1. The developed im- munoassay method showed good precision, high sensitivity, acceptable stability and reproducibility, and could be used for the detection of real samples with consistent results in comparison with those obtained by the enzyme linked immunosorbent assay （ELISA） method.

Comparison of chemiluminescence enzyme immunoassay based on magnetic microparticles with traditional colorimetric ELISA for the detection of serum α-fetoprotein

A chemiluminescence enzyme immunoassay based on magnetic microparticles (MmPs-CLEIA) was developed to evaluate serum a-fetoprotein (AFP) in parallel with traditional colorimetric enzyme-linked immunosorbent assay (ELISA).A systematic comparison between the MmPs-CLEIA and colorimetric ELISA concluded that the MPs-CLEIA exhibited fewer dosages of immunoreagents,less total assay time,and better linearity,recovery,precision,sensitivity and validity.AFP was detected in forty human serum samples by the proposed MPs-CLEIA and ELISA,and the results were compared with commercial electrochemiluminescence immunoassay (ECLIA) kit.The correlation coefficient between MPs-CLEIA and ELISA was obtained with R 2 0.6703;however,the correlation between MPs-CLEIA and ECLIA (R 2 0.9582) was obviously better than that between colorimetric ELISA and ECLIA (R 2 0.6866).

Construction of plasmid vector pAFP-HSVtk-IRES2-EGFP and its effect on the cytotoxicity of ganciclovir to hepatocellular carcinoma

Background Herpes simplex virus thymidine kinase phosphorylates ganciclovir to ganciclovir monophosphate,which is then converted to ganciclovir triphosphate by endogenous cellular nucleoside kinases.The ganciclovir triphosphate acts as a DNA chain terminator due to the lack of a functional 3＇-OH group and terminates the process of DNA replication,hence leading to cell apoptosis.At present,HSVtk gene usually acts as suicide gene to kill tumor cells.The aim of this study was to investigate the selective cytotoxicity of the herpes simplex virus thymidine kinase/ganciclovir （HSVtK/GCV） suicide gene system controlled by the α-fetoprotein （AFP） promoter on hepatocellular carcinoma （HCC） cells in vitro.Methods pAFP-HSVtk-IRES2-EGFP recombinant plasmid vectors driven by the AFP promoter were constructed.HL-7702 liver cells,HUH-7 HCC,and HepG2 HCC were transfected with the recombinant plasmids.HSVtK gene expression was detected using Western blotting analysis.HepG2 cells line stably expressing HSVtk gene was selected by G418 reagent.The cytotoxicity of HSVtK/GCV suicide gene system on hepatoma cells was measured by CCK-8 reagents when different doses of ganciclovir were added.Results Plasmid pAFP-TK-IRES2-EGFP-expressed HSVtk gene was constructed successfully.HSVtk gene expression level was significantly higher in AFP-positive hepatoma cells than in AFP-negative liver cells.After G418 selection,a HepG2 cells line stably expressing HSVtk gene was acquired.With the increase of the dose of ganciclovir the optical density at 450 nm of HepG2 cells stably expressing HSVtk gene gradually decreased （P ＜0.05）.Conclusion The HSVtK gene-specific expression in hepatoma cells as well as the cytotoxicity of the suicide gene system in HepG2 cells provided the basis for the targeted gene therapy of HCC.

Highly sensitive and selective electrochemical immunosensors by substrate-enhanced electroless deposition of metal nanoparticles onto three-dimensional graphene@Ni foams

In this study, we have for the first time preformed the facile substrate-enhanced electroless deposition(SEED) of metal nanoparticles onto monolithic graphene@Ni foams for construction of disposable three-dimensional(3 D) electrochemical immunosensors. Specifically, we firstly used the SEED method to deposit gold nanoparticles(AuNPs) onto the graphene@Ni foam for immobilization of antibody(Ab1). This is followed by a second step SEED deposition to produce silver nanoparticles(AgNPs) for electrochemical stripping detection. Using a-fetoprotein antigen(AFP) as a module analyte, the newly-developed sensor showed a wide linear response, ranging from 5.0 pg/mL to 5.0 ng/mL and a low detection limit down to 2.3 pg/mL. The newly-developed 3 D-immunosensor is sensitive, reliable,and easy to be fabricated, showing great potential for clinic applications.