posted on 2021-06-30, 16:41authored byXianyi Cheng, Yaofei Bao, Shuo Liang, Bo Li, Yunlong Liu, Haiping Wu, Xueping Ma, Yanan Chu, Yang Shao, Qi Meng, Guohua Zhou, Qinxin Song, Bingjie Zou
DNA
walkers have shown superior performance in biosensing due to
their programmability to design molecular walking behaviors with specific
responses to different biological targets. However, it is still challenging
to make DNA walkers capable of distinguishing DNA targets with single-base
differences, so that DNA walkers that can be used for circulating
tumor DNA sensing are rarely reported. Herein, a flap endonuclease
1 (FEN 1)-assisted DNA walker has been proposed to achieve mutant
biosensing. The target DNA is captured on a gold nanoparticle (AuNP)
as a walking strand to walk by hybridizing to the track strands on
the surface of the AuNP. FEN 1 is employed to report the walking events
by cleaving the track strands that must form a three-base overlapping
structure recognized by FEN 1 after hybridizing with the captured
target DNA. Owing to the high specificity of FEN 1 for structure recognition,
the one-base mutant DNA target can be discriminated from wild-type
DNA. By constructing a sensitivity-enhanced DNA walker system, as
low as 1 fM DNA targets and 0.1% mutation abundance can be sensed,
and the theoretical detection limits for detecting the DNA target
and mutation abundance achieve 0.22 fM and 0.01%, respectively. The
results of epidermal growth factor receptor (EGFR) L858R mutation
detection on cell-free DNA samples from 15 patients with nonsmall
cell lung cancer were completely consistent with that of next-generation
sequencing, indicating that our DNA walker has potential for liquid
biopsy.