In Vitro Selection of a DNA Aptamer by Cell-SELEX as a Molecular Probe for Cervical Cancer Recognition and Imaging.

Aptamers have become the most promising recognition reagents in terms of early diagnosis and effective treatment of cancers. In this study, using cervical cancer as a model, we have identified a DNA aptamer specifically binding to cervical cancer cells with high affinity using the cell-SELEX (systematic evolution of ligands by exponential enrichment) method, in which a negative selection was carried out using normal epithelial cells as control. The binding abilities of 6 selected truncated aptamers were determined by laser confocal fluorescence microscopy and flow cytometry, while most of them only recognize the target cells and do not bind the control cells, and the aptamer C-9S with 51-mer shows the best binding affinity to Ca Ski cells (target cells) with a dissociation constant value of 19.3 ± 2.9 nM. Moreover, at physiological temperature, C-9S remains its specific recognition capability to Ca Ski cells as well. Meanwhile, C-9S shows a similar binding ability to another cervical cancer cells (HeLa). Therefore, on the basis of its excellent targeting properties and inherent functional versatility of aptamer, C-9S holds great potential to be a molecular probe for early detection, in vivo imaging, and targeted delivery for further researches in cancer.