期刊
ANALYTICAL CHEMISTRY
卷 92, 期 9, 页码 6229-6234出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.analchem.0c00005
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资金
- National Natural Science Foundation of China (NSFC) [21573024]
- Beijing Natural Science Foundation [2182026]
- Natural Sciences and Engineering Research Council (NSERC) of Canada
In terms of how the signal varies in response to increased concentration of an analyte, sensors can be classified as either signal-on or signal-off format. While both types hold potentials to be sensitive, selective, and reusable, in many situations signal-on sensors are preferred for their low background signal and better selectivity. In this study, with the detection of lysozyme using its DNA aptamer as a trial system, for the first time we demonstrated that such an aptamer-based electrochemical biosensor can be converted from intrinsically signal-off to signal-on with the aid of a DNA exonuclease. The fact that the stepwise cleavage of antilysozyme aptamer catalyzed by Exonuclease I (Exo I) is entirely inhibited upon binding lysozyme leads to the selective removal of unbound DNA probes (thiolate anti-lysozyme DNA aptamer strands immobilized on gold electrode) upon the introduction of Exo Ito the sensor. With the aid of electrostatically bound redox cations ([Ru(NH3)(6)](3+)), we were able to quantitate the number of aptamer strands that are bound with lysozymes via conventional cyclic voltammetry (CV) measurements. We demonstrated that Exo I-assisted signal-on conversion protocol not only improves the sensing performance (10 times better limit of detection) but also promises a versatile strategy for DNA-based biosensor design, i.e., it can be readily adapted to other aptamer-protein binding systems (thrombin, as another example).
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