Fluorescence sensing strategy based on aptamer recognition and mismatched catalytic hairpin assembly for highly sensitive detection of alpha-fetoprotein.

At present, alpha fetoprotein (AFP) is mainly used as a serum marker of primary Hepatocellular carcinoma. A simple, enzyme-free sensing strategy is introduced for highly sensitive fluorescence detection of AFP. This detection strategy is based on aptamer recognition and mismatched catalytic hairpin assembly (MCHA). At first, Trigger is locked by aptamer before the introduction of AFP in this aptamer-MCHA system. The aptamer preferentially combines with AFP via powerful attraction in the presence of AFP. This results in the release of trigger and initiation of MCHA cycle, thus forming the H1 and H2 double chain complexes (denoted as H1@H2). Finally, H1@H2 and double chain structure containing fluorophore and its quenched group- BHQ1 (denoted as F@Q) initiated displacement reaction, which caused double chain separation and fluorescence recovery. This assay produces a wide detection range, which is from 0.1 ng mL-1 to 10 μg mL-1 and the limit of detection as 0.033 ng mL-1. The whole detection process was performed at 37 °C for 60 min. In addition, this assay had high anti-interference ability and could be used to detect AFP in clinical serum. This novel AFP detection strategy is able to screen of Hepatocellular carcinoma.