A novel sensing platform using aptamer and RNA polymerase-based amplification for detection of cancer cells

Cancer is one of the most serious and lethal diseases around the world. Its early detection has become a challenging goal. To address this challenge, we developed a novel sensing platform using aptamer and RNA polymerase-based amplification for the detection of cancer cells. The assay uses the aptamer as a capture probe to recognize and bind the tumor marker on the surface of the cancer cells, forming an aptamer-based sandwich structure for collection of the cells in the microplate wells, and uses SYBR Green II dye as a tracer to produce strong fluorescence signal. The tumor marker interacts first with the recognition probes which were composed of the aptamer and single-stranded T7 RNA polymerase promoter. Then, the recognition probe hybridized with template probes to form a double-stranded T7 RNA polymerase promoter. This dsDNA region is extensively transcribed by T7 RNA polymerase to produce large amounts of RNAs, which are easily monitored using the SYBR Green II dye and a standard fluorometer, resulting in the amplification of the fluorescence signal. Using MCF-7 breast cancer cell as the model cell, the present sensing platform showed a linear range from 5.0 × 10² to 5.0 × 10⁶ cells mL⁻¹ with a detection limit of 5.0 × 10² cells mL⁻¹. This work suggested a strategy to use RNA signal amplification combining aptamer recognition to develop a highly sensitive and selective method for cancer cells detection.