Label-free palindromic DNA nanospheres as naked-eye colorimetric assay platform for detection of telomerase activity

A versatile naked-eye colorimetric assay platform is a desirable format for rapid analysis of disease-specific biomarkers, but is constrained by a complicated labeling process and false-positive signal readout. Target-triggered label-free palindromic DNA nanospheres (P-DNANS) were developed for the first time for the visual detection of telomerase activity. Telomerase recognition and extension trigger a hybridization event that yields Y-shaped double helices as core motifs. Y-shaped DNAs were linked by their palindromic sticky ends and P-DNANS were subsequently assembled with SYBR Green I (SG) in the helix. The SG-induced aggregation of gold nanoparticles is inhibited, and thus the red color can be observed by the naked eye. This label-free platform offers a cost-effective method for the cancer diagnosis and identification of breast cancer phenotypes. •Target-guided assembly provides an effective way avoiding “false-positives” results.•Palindromic DNA nanospheres enable discernible color changes by the naked eye.•This label-free platform offers a cost-effective method for the cancer diagnosis.