A novel aptamer biosensor for cancer cell assay has been reported on the basis of ultrasensitive electrochemical detection. Cancer cell capturing is first accomplished via aptamer-aided recognition, and the cell-aptamer binding events then mediate an alkaline phosphatase-catalyzed silver deposition reaction which can be probed by electrochemical detection. Following biocatalytic silver deposition, an efficient amplification approach for sensitive electrochemical measurements is demonstrated, for cell detection with high sensitivity. Ramos cell are used as a model case, a typical biomarker of the acute blood cell cancer, Burkitt's lymphoma. The results reveal that the developed technique displays desirable selectivity in Ramos cell discrimination, and linear response range from 10 to 10(6) cells with a detection limit as low as 10 cells. Due to the simple procedures, label-free and electrochemistry based detection format, this technique is simple and cost-effective, and exhibits excellent compatibility with miniaturization technologies. The electrochemical cell detection strategy may create an intrinsically specific and sensitive platform for cancer cell assay and associated studies.
BACKGROUND: To study the effects of quercetin on the functionality of myofibrillar proteins (MPs), various levels of quercetin (0, 10, 50, 100 and 200 ∼mol g −1 protein) were added to MP solution and the structure and gel properties of MPs were determined.RESULTS: Compared with the control MPs not treated with quercetin, adding 10, 50 and 100 ∼mol g −1 quercetin caused a significant (P < 0.05) loss of sulfhydryls; 10 and 50 ∼mol g −1 quercetin enhanced the surface hydrophobicity significantly (P < 0.05), and 50, 100 and 200 ∼mol g −1 quercetin reduced the fluorescence intensity of tryptophan. Additions of 50, 100 and 200 ∼mol g −1 quercetin resulted in a significant (P < 0.05) reduction in MP solubility. Adding 10, 50 and 100 ∼mol g −1 quercetin did not significantly (P > 0.05) change the gel strength and water-holding ability of MPs than control, but 200 ∼mol g −1 quercetin declined the gel properties significantly (P < 0.05). The microstructure and dynamic rheological properties confirmed the results of the gel properties of MPs affected by various levels of quercetin.
CONCLUSION:The results obtained in the present study show that mildly high levels of quercetin can maintain the gel properties of MPs, which may be a result of the moderate MP cross-linkage and aggregation caused by the covalent and non-covalent interactions of MPs.
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