title: An ultrasensitive fluorescent aptasensor for adenosine detection based on exonuclease III assisted signal amplification.
abstract: We report here a graphene oxide (GO)-based fluorescent aptasensor for adenosine detection by employing exonuclease III (Exo III) as a signal amplifying element. In the absence of adenosine, the adenosine aptamers hybridized with the complementary DNA (cDNA), and the Exo III could not cleave the single-strand signal probes labeled with carboxylfluorescein (FAM) at its 5' ends. When the graphene oxide was finally added, it could strongly adsorb the single-strand signal probes and quenched the fluorophore effectively. In the presence of adenosine, the aptamers associated with the targets, which led to the formation of duplex DNAs between the cDNAs and the signal probes. The Exo III thereafter could digest the duplex DNAs from 3' blunt terminus of signal probes, liberating the fluorophore. Upon adding the GO, the fluorophore could not be adsorbed and quenched. By coupling cyclic enzymatic cleavage, a remarkable fluorescent increase was obtained. Due to the specific recognition ability of the aptamer for the target and the powerful quenching property of GO for signal probe, this proposed approach has a good selectivity and high sensitivity for adenosine. In the optimum conditions described, >100% signal enhancement was achieved and a limit of detection as low as 1 nM was obtained, which is lower than those of commonly used fluorescent aptamer sensors. Moreover, the biosensor exhibited an ultrahigh sensitivity and held a versatile platform for clinical diagnostics, molecular biology and drug developments.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, PR China.
authors.forename: Peng
authors.initials: P
authors.lastname: Hu
authors.forename: Chengzhou
authors.initials: C
authors.lastname: Zhu
authors.forename: Lihua
authors.initials: L
authors.lastname: Jin
authors.forename: Shaojun
authors.initials: S
authors.lastname: Dong
mesh_terms: D000241:Adenosine / Q000737:chemistry* / Q000302:isolation & purification; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D018076:DNA, Complementary / Q000737:chemistry; D055664:Electrochemical Techniques; D005090:Exodeoxyribonucleases / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*
chemical_list: D052157:Aptamers, Nucleotide; D018076:DNA, Complementary; D005456:Fluorescent Dyes; D006108:Graphite; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D000241:Adenosine