Study On Tumor Cell Detection And Enrichment Using Aptamer

Development of tumor cell detection methods has significant meaning in early cancer diagnosis and prevention. Traditional tumor detection mainly relies on the morphological characterization, which is insensitive and often leads to false positive results. As a novel molecular probe, aptamer could not only be used as a recognition probe to target specific tumor cells, but also be used as a signal generation probe. Moreover, aptamer is greatly potential for tumor cell detection and enrichment because of its unique advantages, such as high affinity, high specificity, facile selection, and easy modification and so on. In this article, by choosing CCRF-CEM tumor cells and Hela tumor cells as the target models, aptamer has been applied in the development of tumor cell detection and enrichment methods.1. Study on the tumor cell detection using aptamer G qua-folate complexAptamer G qua-Hemin complex has been chosen as a signal generation probe. Through an amino-carboxyl reaction, G-quadruplex was covalently linked to the folate molecule, and then the Hemin-G qua-folate complex was prepared for detection of tumor cells with highly expressed folate receptors. Because of the specific binding ability of folate to folate receptor, the Hemin-G qua-folate complex could be bound to target tumor cells. By further combining its ability to catalyze ATBS oxidation in the presence of H2O2, target tumor cells could be detected by measuring the absorption of catalyzed products at 414nm using a microplate reader. It was shown that the specific quantitative detection of Hela cells with a detection limit of 103 cells could be successfully achieved. This method would be potential to be applied as a universal method for detecting tumor cells that possess a high expression of folate receptors.2. Study on the tumor cell detection using aptamer and signal DNA functionalized AuNPsThe study on the tumor cell detection using aptamer and signal DNA functionalized AuNPs was performed, employing aptamer sgc8c, a specific recognition probe for CCRF-CEM tumor cells as the target molecule, a short sequence DNA as the signal generation probe, which could hybridize with the extension sequence of sgc8c and trigger the molecular beacon's fluorescence restoration. In this method, by using AuNPs as the carrier, thiol-modified sgc8c was linked to AuNPs and then hybridized with the signal DNA, thus leading to the aptamer and signal DNA functionalized AuNPs for tumor cell detection. After incubation of the functionalized AuNPs and tumor cells, by further releasing the signal DNA, tumor cells could be detected with molecular beacons. It was shown that CCRF-CEM cells could be specifically detected. Without any DNA amplification process, 104 target tumor cells could produce a significant signal.3. Study on tumor cell magnetic separation and enrichment using aptamer functionalized magnetic beadsAptamer sgc8c, a specific recognition probe for CCRF-CEM tumor cells,was chosen as the target molecule. Through the biotin-streptavidin crosslinking, sgc8c was modified to the magnetic microbeads, thus leading to the aptamer functionalized magnetic beads for tumor cell separation and enrichment. After specific capture, target tumor cells could be easily separated and enriched from a mixed cell system through a simple magnetic separation. Results showed that the capturing limit of CCRF-CEM cells was 102 cells and the separation purity was over 95%. This method not only could be used as a pretreatment method, but also could serve as a direct detection manner.