Fluorometric detection of cancer marker FEN1 based on double-flapped dumbbell DNA nanoprobe functionalized with silver nanoclusters.

Flap endonuclease 1 (FEN1), a ubiquitous enzyme involved in DNA repair and replication, is overexpressed in highly proliferative cancer cells. FEN1 has been recognized as a promising diagnostic marker of cancers; however, very few analytical techniques have been developed for the convenient detection of FEN1. To realize the simplified quantification of FEN1, we developed a FEN1-responsive fluorescent nanoprobe based on DNA-silver nanoclusters (DNA-AgNCs). The nanoprobe was rationally designed with a double-flapped dumbbell conformation, where its 5' flap was produced with DNA-AgNCs, and the 3' flap was elongated by a guanine-rich enhancer sequence (GRS). Rigidified by the DNA scaffold, DNA-AgNCs and the GRS are in close proximity, resulting in high fluorescence because of the GRS-induced activation of DNA-AgNCs. Upon the addition of FEN1, the 5' flap of the nanoprobe is cleaved due to the structure-specific endonuclease activity of FEN1. This cleavage released the DNA-AgNCs from the nanoprobe, broke the proximity between DNA-AgNCs and the GRS, and caused decreased fluorescence. This nanoprobe can be applied in the sensitive detection of FEN1 with a detection limit of 40 fM, and it showed high specificity for the monitoring of FEN1 in clinical samples. As the first attempt to develop biosensors targeting FEN1 based on DNA-AgNCs, this work provided a potent platform for monitoring FEN1 and screening FEN1 inhibitors. Copyright © 2021 Elsevier B.V. All rights reserved.

Citation

Bingzhi Li, Peng Zhang, Bin Zhou, Siying Xie, Anqi Xia, Tiying Suo, Shuang Feng, Xing Zhang. Fluorometric detection of cancer marker FEN1 based on double-flapped dumbbell DNA nanoprobe functionalized with silver nanoclusters. Analytica chimica acta. 2021 Mar 01;1148:238194

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PMID: 33516385

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