Journal
ANALYST
Volume 144, Issue 20, Pages 5959-5964Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9an01271k
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Funding
- National Natural Science Foundation of China [21375086]
- Fundamental Research Funds for the Central Universities [GK201701002]
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It is of great importance to achieve facile and reliable detection of telomerase because it is an important cancer biomarker. The complex components of cell extracts and ultra-low concentration of telomerase makes it more difficult to realize a simple and sensitive visual detection of telomerase activity. Herein, a facile and sensitive visual strategy was developed for the detection of telomerase based on the telomerase-controlled in situ formation of a G-quadruplex-hemin DNAzyme. To avoid the influence of the complex components of cell extracts, a telomerase substrate (TS) was immobilized onto the surface of magnetic beads (MBs) to form a MB/TS complex. MB/TS incubated with telomerase can add several TTAGGG repeat units to the 3 ' terminal of TS. After magnetic separation and washing, these G-rich elongated DNA folded into numerous G-quadruplex-hemin DNAzymes under the aid of K+ and hemin, which efficiently catalysed the TMB/H2O2 reaction. Magnetic separation basically eliminated the non-specific background interference from other cell extracts and redundant hemin. Taking full advantage of the in situ formation of multiple catalysts, the telomerase activity could be sensitively evaluated by a color change of the TMB/H2O2 solution. The telomerase activity down to 1 HeLa cell per mu L and 0.5 HeLa cell per mu L can be measured by the naked eye and UV-vis spectroscopy, respectively. Due to the magnetic separation and enrichment, the sensitivity was obviously improved compared with the previous colorimetric assay. Meanwhile, the telomerase activity of 5 HeLa cells per mu L in human serum can be visually detected. Therefore, this study provides a facile, cost-effective and robust colorimetric assay for the visual detection of telomerase activity, which holds great potential in telomerase-based cancer clinical diagnostics.
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