Sensitive Electrochemical Detection of Telomerase Activity Using Spherical Nucleic Acids Gold Nanoparticles Triggered Mimic-Hybridization Chain Reaction Enzyme-Free Dual Signal Amplification

Abstract

We report an electrochemical sensor for telomerase activity detection based on spherical nucleic acids gold nanoparticles (SNAs AuNPs) triggered mimic-hybridization chain reaction (mimic-HCR) enzyme-free dual signal amplification. In the detection strategy, SNAs AuNPs and two hairpin probes were employed. SNAs AuNPs as the primary amplification element, not only hybridized with the telomeric repeats on the electrode to amplify signal but also initiated the subsequent secondary amplification, mimic-hybridization chain reaction of two hairpin probes. If the cells' extracts were positive for telomerase activity, SNAs AuNPs could be captured on the electrode. The carried initiators could trigger an alternative hybridization reaction of two hairpin probes that yielded nicked double helices. The signal was further amplified enzyme-free by numerous hexaammineruthenium(III) chloride ([Ru(NH3)6](3+), RuHex) inserting into double-helix DNA long chain by electrostatic interaction, each of which could generate an electrochemical signal at appropriate potential. With this method, a detection limit of down to 2 HeLa cells and a dynamic range of 10-10,000 cells were achieved. Telomerase activities of different cell lines were also successfully evaluated.

Sensing telomerase: From in vitro detection to in vivo imaging

“…This assay can sensitively measure telomerase activity with a detection limit of as low as 10 HeLa cells per mL. Recently, a series of electrochemical methods have been reported for telomerase assay using Methylene Blue 42 and hexaammineruthenium( iii ) chloride 43 as the reporters. In addition, metal–organic frameworks have been used in the development of electrochemical methods for telomerase assays.…”

Advances in the detection of telomerase activity using isothermal amplification

“…Zhu et al captured spherical nucleic acids AuNPs through hybridization with the telomeric repeats on the gold electrode surface 28. The hairpin probe alternated hybridization by the specific initiator on AuNPs to generate a nicked double helix for dual signal amplification.…”

Zero‐Background Helicase‐Dependent Amplification and Its Application to Reliable Assay of Telomerase Activity in Cancer Cell by Eliminating Primer–Dimer Artifacts

“…Accordingly,t elomerase is regarded as ac ommon cancer marker for early diagnosis and prognosis.W eu sed telomerase substrate (TS) primert op erform telomerase-catalyzed extension reactions. [42][43][44][45] As mall number of TS primers are extended with 3' telomericr epeatsi nt he presence of telomerase (Scheme 1B). These extension products can act as templates for DNA amplification by zero-background HDA.…”