Magnetic bead and nanoparticle based electrochemiluminescence amplification assay for direct and sensitive measuring of telomerase activity.

The broad-spectrum expression of telomerase in most malignancies makes it a promising target for a cancer diagnostic and prognostic tool. Conventional polymerase chain reaction (PCR)-based telomerase activity assay is highly sensitive but susceptible to amplification-related errors. Here, we present a novel approach to telomerase activity detection. The detection of telomerase activity is accomplished by the hybridization of electrochemiluminescence (ECL) nanoprobes to telomerase reaction products, subsequent capture by magnetic beads, and in situ measurement of the light signal from ECL nanoprobes. The ECL intensity directly reflects the quantity of telomerase reaction products, thus telomerase activity. The high sensitivity afforded by the current magnetic bead and nanoparticle based ECL detection platform allows measuring of telomerase activity from as little as 500 cultured cancer cells in crude cell extracts without the PCR amplification of telomerase reaction products. In addition, a comparative study of the ECL nanoprobe and linear telomere antisense ECL probe was executed. By the employment of the ECL nanoprobe, a gain of about 100-fold elevation of sensitivity was determined. The method described here is ideal for telomerase activity analysis due to its reliability and high sensitivity.