A turn-on graphene quantum dot and graphene oxide based
fluorometric aptasensor for the determination of telomerase activity
Elahe Kazemi, Habib Bagheri, Dariush Norouzian
Microchimica Acta 186 (2019) 785
doi: 10.1007/s00604-019-3956-x
A turn-on fluorometric assay is described for determination of the activity of enzyme telomerase. For this purpose, graphene quantum dots (GQDs) were first modified with the telomeric sequence (5′-amino-AATCCGTCGAGCAGAGTT-3′) via a condensation reaction. Injection of graphene oxide causes instant quenching of the blue fluorescence of the GQDs. Addition of cell
extract containing telomerase, triggers the extension of telomer via addition of specific sequence (TTAGGG)n to its 3′ end.
Fluorescence, best measured at excitation/emission wavelengths of 390/446 nm, is subsequently restored due to folding of the
extended telomeric sequence into G-quadruplex structure. The method was applied to the determination of telomerase activity in
crude cell extracts of as little as 10 HeLa cells. The linear dynamic range extends from 10 to 6500 cells.