title: Exonuclease III-based target recycling for ultrasensitive homogeneous monitoring of HIV DNA using Ag(+)-coordinated hairpin probe.
abstract: A new homogeneous electrochemical sensing strategy based on exonuclease III-assisted target recycling amplification was utilized for simple, rapid and highly sensitive detection of human immunodeficiency virus (HIV) DNA on an immobilization-free Ag(I)-assisted hairpin DNA through the cytosine-Ag(+)-cytosine coordination chemistry. The assay involved target-induced strand-displacement reaction accompanying dissociation of the chelated Ag(+) in the hairpins and exonuclease III-triggered target recycling. Initially, the added target DNA hybridized with hairpin DNA to disrupt the Ag(I)-coordinated hairpin probe and releases the coordinated Ag(+) ion. Then, the newly formed DNA double-stranded DNA could be cleaved by exonuclease III, and released target HIV DNA, which retriggered the strand-displacement reaction with the hairpin for target recycling, thereby resulting in formation of numerous free Ag(+) ions in the detection cell. The released Ag(+) ions can be readily captured by the negatively charged electrode, and subsequent anodic-stripping voltammetric detection of the captured Ag(+) ions are conducted to form the anodic current for the production of the electronic signal within the applied potential. Under optimal conditions, the exonuclease III-based sensing system exhibited good electrochemical responses for the detection of HIV DNA at a concentration as low as 23 fM.
authors.affiliation: Department of Chemistry and Chemical Engineering, Xinxiang University, Xinxiang 453000, PR China. Electronic address: sunaili77@yeah.net.
authors.forename: Ai-Li
authors.initials: AL
authors.lastname: Sun
authors.affiliation: Laboratory of the Clinical Experimental Base of Biosensor and Microarray, Center of Molecule and Gene Diagnosis, Southwest Hospital, Third Military Medical University, Chongqing 400042, PR China.
authors.forename: Kun
authors.initials: K
authors.lastname: Deng
authors.affiliation: Laboratory of the Clinical Experimental Base of Biosensor and Microarray, Center of Molecule and Gene Diagnosis, Southwest Hospital, Third Military Medical University, Chongqing 400042, PR China.
authors.forename: Wei-Ling
authors.initials: WL
authors.lastname: Fu
mesh_terms: D001483:Base Sequence; D015374:Biosensing Techniques; D056831:Coordination Complexes / Q000737:chemistry; D003596:Cytosine / Q000737:chemistry*; D015342:DNA Probes / Q000737:chemistry* / Q000378:metabolism; D004279:DNA, Viral / Q000032:analysis* / Q000378:metabolism; D055664:Electrochemical Techniques; D005090:Exodeoxyribonucleases / Q000378:metabolism; D006678:HIV / Q000302:isolation & purification*; D015658:HIV Infections / Q000821:virology; D006801:Humans; D057230:Limit of Detection; D009693:Nucleic Acid Hybridization; D012834:Silver / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D015342:DNA Probes; D004279:DNA, Viral; D012834:Silver; D003596:Cytosine; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III
keywords: Cytosine-Ag(+)-cytosine coordination chemistry; Electrochemical DNA sensor; Exonuclease III-assisted target recycling; Human immunodeficiency virus DNA; Immobilization-free