A fluorescein labeled aptamer switch for thrombin with fluorescence decrease response

We developed a simple fluorescent switch for rapid thrombin detection by using a high-binding affinity 27-mer aptamer with fluorescein (FAM) labeled at the 3' end. This FAM-labeled aptamer showed remarkable fluorescence quenching upon thrombin binding. This assay enabled the detection of thrombin ranging from 0.062 nM to 2 nM. The assay was selective, and other tested proteins and diluted serum did not interfere with thrombin analysis.