Single living cell detection of telomerase over-expression for cancer detection by an optical fiber nanobiosensor.

An optical fiber nanobiosensor was constructed to successfully detect a general cancer biomarker, telomerase at single cell level with its nanoscale tip. The nanotip immobilized with a specific antibody was inserted into a MCF-7 breast cancer cell nucleus to capture telomerases directly, after which an in vitro enzymatic sandwich immunoassay was performed to achieve sensitive single living cell detection. The nanotip inserted into MCF-7 cell nucleus provides significantly higher average (F-F(0))/F(0) ratio than that of human mesenchymal stem cell (hMSC) nucleus, demonstrating the successful detection of the telomerase over-expression in cancer cells as compared to normal cells. The detection in the cytoplasm shows much smaller average ratio than that in the nucleus of MCF-7 cells while clearly verifies the nuclear localization of telomerase. The successful detection of telomerase over-expression in a single living cell for the first time may provide a potential method for cancer detection, and also demonstrate a universal approach that can be used to detect other low expression proteins in a single living cell.