Portable glucose meter-utilized label-free and washing-free telomerase assay

We herein describe a portable glucose meter (PGM)-utilized label-free and washing-free method for the facile determination of telomerase activity, which relies on the kinase-catalyzed cascade enzymatic reaction (KCER) that transduces the telomerase activity to the glucose level. In the sensor, the telomerase that elongates telomere sequences ((TTAGGG)n) from the 3'-terminus of telomerase substrate primer (TSP) consumes deoxynucleoside triphosphate (dNTP) that serves as a phosphate source for KCER promoted by hexokinase and pyruvate kinase. Thus, the presence of telomerase protects KCER from working effectively, resulting in the maintenance of initial, high glucose level that is readily determined by using hand-held PGM. With this strategy, the telomerase activities in various types of cell lines were successfully determined with the high sensitivity. Furthermore, the capability of this method to screen candidate inhibitors for the telomerase activity was also verified.