Sensitive electrochemiluminescent detection of telomerase activity based on nicking enzyme assisted signal amplification

Abstract

Abstract Herein, an ultrasensitive biosensor for the detection of telomerase activity was constructed by utilizing gold@Carbon dots nanohybrids (Au@CDs) as a high efficiency electrochemiluminescence (ECL) emitter and nicking enzyme assisted signal amplification (NESA) technology. Firstly, the self-enhanced Au@CDs was synthesized from the reduction of HAuCl4 with carbon dots (CDs), which served as reductant and stabilizer. The prepared hybrids exhibited significant enhancement in the ECL emission compared to the single CDs. Enhanced sensitivity was thus achieved by using these Au@CDs as ECL labels. Next, an isothermal amplification with nicking enzyme (Nb.BbvcI)-assisted recycle was employed to convert a small amount of telomerase to numerous output signal DNA (sDNA). The obtained sDNA was then linked with Au@CDs and immobilized on a capture DNA (cDNA), and connected to the working electrode through oligonucleotide hybridization, resulting in a quantitative ECL reading. As a consequence, by employment of the dual signal amplification strategy, the proposed biosensor exhibited excellent sensitivity for telomerase activity detection with a detection limit down to 1 HeLa cell, which is comparable or even better than the most reported methods. The method also displayed a wide linear response ranges and good reproducibility. This work not only expanded the application of high-efficiency ECL indicators Au@CDs, but also offered a novel PCR-free ECL sensing platform for detecting telomerase activity that is helpful for real-time monitoring, point-of-care testing and on-site analysis.