PCR-free paper-based nanobiosensing platform for visual detection of telomerase activity via gold enhancement

© 2020 Elsevier B.V. Telomerase activity has been demonstrated in a wide variety of most solid tumors and considered as a well-known cancer biomarker. The commonly utilized method for its detection is polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP). However, the TRAP technique suffers from false-negative results caused by the failure of PCR step. Moreover, it requires advanced equipment with a tedious and time-consuming procedure. Herein, we presented a portable nitrocellulose paper-based nanobiosensing platform for ultrafast and equipment-free detection of telomerase activity based on a simple colorimetric assay that enabled naked-eye visualization of the color change in response to enzyme activity. In this platform, hybridization was initially performed between telomere complementary oligonucleotide immobilized on gold nanoparticles (GNPs) and telomerase elongated biotinylated probe. Thereafter, the assembly was attached on activated paper strip via avidin-biotin interaction. The signal amplification was carried out by enlargement of the attached GNPs on the paper strip, forming tightly compact rod-shaped submicron structures of gold representing a visual color formation. Thanks to significant sensitivity enhancement, the color change was occurred for down to 6 cells, which can be easily observed by the naked eye. Due to the desired aspects of the developed assay including PCR-free, low cost, simple, and high sensitivity, it can be used for evaluation of telomerase activity in cell extracts for future clinical applications. Furthermore, this design has the ability to be easily integrated into lab-on-chip devices for point-of-care telomerase sensing