Spatiotemporal control of DNAzyme activity for fluorescent imaging of telomerase RNA in living cells.

Background: Human telomerase is a ribonucleoprotein complex that includes proteins and human telomerase RNA (hTR). Emerging evidence suggested that the expression level of hTR was high related with the development of tumor, so it is important to accurately detect the content of hTR. Optical control of DNAzyme activity shows a promising strategy for precise biosensing, biomedical imaging and modulation of biological processes. Although DNAzyme-based sensors can be controlled spatiotemporally by light, its application in the detection of hTR in living cells is still rare. Therefore, designing DNAzyme activity spatiotemporal controllable sensors for hTR detection is highly needed.

Results: We developed a UV light-activated DNAzyme-based nanoprobe for spatially accurate imaging of intracellular hTR. The proposed nanoprobe was named MDPH, which composed of an 8-17 DNAzyme (D) inactivated by a protector strand (P), a substrate strand (H), and MnO nanosheets. The MnO nanosheets can enhance the cellular uptake of DNA strands, so that MDPH probe can enter cells autonomously through endocytosis. Under the high concentration of GSH in cancer cells, MnO nanosheets can self-generate cofactors to maintain the catalytic activity of DNAzyme. When exposing UV light and in presence of target hTR, DNAzyme could cleave substrate H, resulting in the recovery of fluorescence of the system. The cells imaging results show that MDPH probe could be spatiotemporally controlled to image endogenous hTR in cancer cells.

Significance: With this design, telomerase RNA-specific fluorescent imaging was achieved by MDPH probe in both cancer and normal cells. Our probe made a promising new platform for spatiotemporal controllable intracellular hTR monitoring. This current method can be applied to monitor a variety of other biomarkers in living cells and perform medical diagnosis, so it may has broad applications in the field of medicine.