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Nuclease-free target recycling signal amplification for ultrasensitive multiplexing DNA biosensing
Zhihan Zhao1, Shixing Chen2, Jianbang Wang2
1NEST Lab, Department of Chemistry, Shanghai University, Shanghai 200444, China; Division of Physical Biology and Bioimaging Center, Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 2019 Jialuo Road, Shanghai 201800, China.
Abstract:
Ultrasensitive biosensing technologies without gene amplification held great promise for direct detection of DNA. Herein we report a novel biosensing method, combining target recycling signal-amplification strategy and a homemade electrochemical device. Especially, the target recycling was achieved by a strand displacement process, no needing the help of any nucleases. In the presence of target DNA, the recycling system could be activated to generate a cascade of assembly steps with three hairpin DNA segments. Each recycling process were accompanied by a disassembly step that the last hairpin DNA segment displaces target DNA from the complex at the end of each circulation, freeing targets to activate the self-assembly of more trefoil DNA structures. This biosensing method could detect target DNA at aM level and can distinguish target DNA from interfering DNAs, demonstrating its high sensitivity and high selectivity. Importantly, the biosensing method could work well with serum samples.