An aptamer for recognizing the transmembrane protein PDL-1 (programmed death-ligand 1), and its application to fluorometric single cell detection of human ovarian carcinoma cells

Programmed death-ligand 1 (PD-L1) is overexpressed in a variety of cancer cells. Using protein SELEX, aptamers against PD-L1 were identified. After 10 rounds of selection, 2 aptamers (Apt5 and Apt33) were chosen. Due to the higher specificity and affinity of Apt5 for PDL-1, this aptamer was characterized in detail. The ATTO 647 N-labeled aptamer readily internalizes into PD-L1 positive A2780 cells where it can detect human ovarian carcinoma. Hence, fluorometry provides a rapid and sensitive quantitative tool for the detection of these cancer cells with limit of detection (LOD) as low as 10 cells.mL(-1) and linear response in the range between 50 and 1000 cells.mL(-1). In our perception, the Apt 5 aptamer holds great promise for use in cancer diagnosis and therapy.