Detection system using elecrochemical glucose sensor system and the change of nano-structure of aptamers

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We develped the Gq-switch by connecting the glucose dehydrogenase (GDH)-binding aptamer and the vascular endothelial growth factor (VEGF)-binding aptamer. Gq-switch forms huge 3D network structure sicne it has a lot of G-quadruplex (Gq) structure forming parts and it can be the juction of the multiple aptamers. We observed its structural change upon its binding to VEGF and checked it can also bind to GDH. The GDH used in this study can directly transfer electron to the electrode, therefore if the distance between the GDH bound to Gq-swithch and the electrode changes, we can expect the change of electric current generated by the glucose oxidation catalyzed by the GDH.We immoblized the GDH-Gq-switch complex onto the gold electrode and obseved the change of electric current generated from the glucose addition upon the addition of VEGF. That current change was dependent on the concentration of VEGF and therefore we were able to detect VEGF with this electrochemical detection system.