Optical, Electrical and Surface Plasmon Resonance Methods for Detecting Telomerase Activity

Abstract

Three different sensing platforms for the analysis of telomerase activity in human cells are described. One sensing platform involves the label-free analysis of the telomerase activity by a field-effect-transistor (FET) device. The telomerase-induced extension of a primer associated with the gate of the FET device, in the presence of the nucleotide mixture dNTPs, alters the gate potential, and this allows the detection of telomerase extracted from 65 ± 10 293T (transformed human embryonic kidney) cells/μL. The second sensing platform involves the optical detection of telomerase using CdSe/ZnS quantum dots (QDs). The telomerase-stimulated telomerization of the primer-functionalized QDs in the presence of the nucleotide mixture dNTPs results in the synthesis of the G-rich telomeres. The stacking of hemin on the self-organized G-quadruplexes found on the telomers results in the electron transfer quenching of the QDs, thus providing an optical readout signal. This method enables the detection of telomerase originating from 270 ± 20 293T cells/μL. The third sensing method involves the amplified surface plasmon resonance (SPR) detection of telomerase activity. The telomerization of a primer associated with Au film-coated glass slides, in the presence of telomerase and the nucleotide mixture (dNTPs), results in the formation of telomeres on the surface, and these alter the dielectric properties of the surface resulting in a shift in the SPR spectrum. The hybridization of Au NPs functionalized with nucleic acids complementary to the telomere repeat units with the telomeres amplifies the SPR shifts due to the coupling between the local plasmon of the NPs and the surface plasmon wave. This method enables the detection of telomerase extracted from 18 ± 3 293T cells/μL.