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He X.,Hunan University | He X.,Key Laboratory for Bio Nanotechnology and Molecule Engineering of Hunan Province | Chen Z.,Hunan University | Chen Z.,Key Laboratory for Bio Nanotechnology and Molecule Engineering of Hunan Province | And 8 more authors.
Biosensors and Bioelectronics | Year: 2012

In this paper, a novel label-free electrochemical strategy has been developed for assay of casein kinase II (CK2) activity and inhibition using TiO 2/MWNTs nanocomposites. This detection system takes advantage of specific binding of the phosphate groups with TiO 2 nanoparticles and fast electron transfer rate of MWNTs. In this strategy, the synthesized TiO 2/MWNTs nanocomposite was firstly deposited on the surface of a glassy carbon electrode (GCE). The presence of MWNTs not only increased the surface area of the electrode but also promoted electron-transfer reaction. In the presence of CK2, the kinase reaction resulted in the phosphorylation of peptide substrates. The phosphorylated peptides were subsequently captured to the surface of GCE modified with TiO 2/MWNTs nanocomposite through specific binding of the phosphate groups with TiO 2 nanoparticles. Then the access of redox probe [Fe(CN) 6] 3-/4- to electrode surface was blocked. As a result, the decrease peak currents were related to the concentrations of the CK2, providing a sensing mechanism for monitoring peptides phosphorylation. The electrochemical strategy can be employed to assay CK2 activity with a low detection limit of 0.07U/mL. The linear range of the assay for CK2 was 0-0.5U/mL. Furthermore, the interferences experiments of PKA and inhibition of CK2 have been also studied by using this strategy. © 2012 Elsevier B.V.


Shi H.,Hunan University | Shi H.,Key Laboratory for Bio Nanotechnology and Molecule Engineering of Hunan Province | Cui W.,Hunan University | Cui W.,Key Laboratory for Bio Nanotechnology and Molecule Engineering of Hunan Province | And 10 more authors.
PLoS ONE | Year: 2013

Background:Carcinomas make up the majority of cancers. Their accurate and specific diagnoses are of great significance for the improvement of patients' curability.Methodology/Principal Findings:In this paper, we report an effectual example of the in vivo fluorescence molecular imaging of carcinomas with extremely high specificity based on whole cell-SELEX aptamers. Firstly, S6, an aptamer against A549 lung carcinoma cells, was adopted and labeled with Cy5 to serve as a molecular imaging probe. Flow cytometry assays revealed that Cy5-S6 could not only specifically label in vitro cultured A549 cells in buffer, but also successfully achieve the detection of ex vivo cultured target cells in serum. When applied to in vivo imaging, Cy5-S6 was demonstrated to possess high specificity in identifying A549 carcinoma through a systematic comparison investigation. Particularly, after Cy5-S6 was intravenously injected into nude mice which were simultaneously grafted with A549 lung carcinoma and Tca8113 tongue carcinoma, a much longer retention time of Cy5-S6 in A549 tumor was observed and a clear targeted cancer imaging result was presented. On this basis, to further promote the application to imaging other carcinomas, LS2 and ZY8, which are two aptamers selected by our group against Bel-7404 and SMMC-7721 liver carcinoma cells respectively, were tested in a similar way, both in vitro and in vivo. Results showed that these aptamers were even effective in differentiating liver carcinomas of different subtypes in the same body.Conclusions/Significance:This work might greatly advance the application of whole cell-SELEX aptamers to carcinomas-related in vivo researches. © 2013 Shi et al.

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