A Graphene Oxide Nanoprobe for Sensitive Fluorescent Telomerase Activity Analysis

A novel fluorescent biosensor with ultra-sensitivity and selectivity for telomerase detection has been designed based on oligonucleotide-adsorption to graphene oxide (GO). This PCR-free method employs fluorescent ssDNA as a probe, which exhibits minimal background fluorescence in the present of GO. In the test procedure, telomeric primer DNA was incubated with cancer cell extract and dNTP molecules for 18 hours and then added to the fluorescent probe solution. If telomerase is present and active, this telomeric primer will be elongated and hybridised with the fluorescent DNA probe, causing strong fluorescence emission due to the formation of double helix DNA and its detachment from the surface of GO. If telomerase is absent or inactive (e.g. due to heating in the incubation solution), the telomeric primer will not be elongated, preventing hybridisation with the fluorescent DNA probe. Therefore, in the absence of telomerase, fluorescence is quenched by GO, enabling detection of telomerase activity with a high signal-to-background ratio. Using this GO-based fluorescence method, the telomerase activity detection limits were 5 cells and 50 cells under 0.2 mg•mL-1 and 0.5 mg•mL-1 GO concentration, respectively.