| The accuracy and integrity of genomic DNA is vital to all living organisms,but it often suffers from persistent oxidative damage,leading to mutations,aging,and diseases.8-OxoGuanine?8-OxoG?is the most important one.In order to maintain the stability of genome,cells have evolved a base excision repair?BER?system to respond to the above damages.Human 8-oxoGuanine DNA glycosylase?hOGG1?initiates the first step of BER pathway by specifically recognizing and repairing 8-oxoG.Dysregulation of hOGG1 may cause various diseases such as lung cancer,bladder cancer and autoimmune inflammation.Therefore,the sensitive detection of hOGG1 is essential for oxidative DNA damage repair research.Molecular self-replication is a fundamental function of all living organisms with the capability of templating and catalysing its own synthesis,and it plays important roles in prebiotic chemical evolution and effective synthetic machineries.However,the construction of self-replication system in vitro remains a great challenge and its application for biosensing is rare.Here,we demonstrate the construction of an in vitro enzymatic nucleic acid self-replication system and its application for amplified sensing of hOGG1.In this strategy,hOGG1 excises8-oxoG to unfold the hairpin substrate,activating autonomous biocatalytic process with molecular beacons?MBs?as both the fuels for producing nucleic acid templates and the generators for signal output,leading to the continuously replication of biocatalytic nucleic acid templates and the repeatedly cleavage of MBs for an enhanced fluorescence signal.This strategy exhibits an extremely low detection limit of 4.3×10-7 U/?L and a large dynamic range of 5 orders of magnitude from 1.0×10-6 to 0.05 U/?L.Importantly,it can be applied for the detection of enzyme kinetic parameters,the screening of hOGG1 inhibitors,and the quantification of hOGG1 activity in even 1 single lung cancer cell,providing a new approach for biomedical research and clinical diagnosis. |
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