Ultra-sensitive and chemiluminescent detection of telomerase activity via handheld luminometer

Abstract

The point-of-care testing (POCT) of disease biomarker is crucial and in great demand. Herein, the activity of tumor biomarker, telomerase, was simply and sensitively detected via handheld luminometer based on the horseradish peroxidase (HRP) catalyzed luminol/H2O2 chemiluminescence (CL) reaction. Biotinylated telomerase substrate (TS) primer was loaded onto the streptavidin-modified magnetic beads (MBs) surface via biotin-avidin interaction. In the presence of telomerase, TTAGGG repeated units were progressively added to the 3′ end of TS to form a long telomeric DNA elongation product (TEP) which will hybridize with multiple short HRP-labeled complementary DNA (HRP-cDNA), leading to the enrichment of HRP on the surface of MBs. An obvious chemiluminescence was observed when MBs complexes were mixed with luminol/H2O2/p-Iodophenol (PIP) mixture. The CL intensity was linearly related with the logarithm of the number of HeLa cells in the range of 10–1000 cells. By combining the self-amplification of telomerase with the high sensitivity of CL, the ultra-sensitive detection of telomerase activity was achieved, and the detection limit was estimated down to 9 cells. Detection of telomerase activity in serum achieved satisfactory results. The replacement of the commercial fluorescein-luciferase test swab by luminol/H2O2/PIP solution led to a more stable and cheaper POC assay, which holds great potential for exploring facile, sensitive and reliable POCT.