title: A fluorescent aptasensor using double-stranded DNA/graphene oxide as the indicator probe.
abstract: We developed a fluorescent aptasensor based on the making use of double-stranded DNA (dsDNA)/graphene oxide (GO) as the signal probe and the activities of exonuclease I (Exo I). This method takes advantage of the stronger affinity of the aptamer to its target rather than to its complementary sequence (competitor), and the different interaction intensity of dsDNA, mononucleotides with GO. Specifically, in the absence of target, the competitor hybridizes with the aptamer, preventing the digestion of the competitor by Exo I, and thus the formed dsDNA is adsorbed on GO surface, allowing fluorescence quenching. When the target is introduced, the aptamer preferentially binds with its target. Thereby, the corresponding nuclease reaction takes place, and slight fluorescence change is obtained after the introduction of GO due to the weak affinity of the generated mononucleotides to GO. Adenosine (AD) was chosen as a model system and tested in detail. Under the optimized conditions, smaller dissociation constant (Kd, 311.0 µM) and lower detection limit (LOD, 3.1 µM) were obtained in contrast with traditional dye-labeled aptamer/GO based platform (Kd=688.8 µM, LOD=21.2 µM). Satisfying results were still obtained in the evaluation of the specificity and the detection of AD in human serum, making it a promising tool for the diagnosis of AD-relevant diseases. Moreover, we demonstrated the effect of the competitor on the LOD, and the results reveal that the sensitivity could be enhanced by using the rational competitor. The present design not only constructs a label-free aptamer based platform but also extends the application of dsDNA/GO complex in biochemical and biomedical studies.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, China; College of Chemistry and Pharmaceutical Engineering, Nanyang Normal University, Nanyang 473061, China.
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Xing
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, China.
authors.forename: Wan-Lu
authors.initials: WL
authors.lastname: Xiao
authors.affiliation: Department of Biology and Chemical Engineering, Nanyang Institute of Technology, Nanyang 473004, China.
authors.forename: Xue-Guo
authors.initials: XG
authors.lastname: Liu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, China.
authors.forename: Dai-Wen
authors.initials: DW
authors.lastname: Pang
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, China. Electronic address: hwtang@whu.edu.cn.
authors.forename: Hong-Wu
authors.initials: HW
authors.lastname: Tang
mesh_terms: D000241:Adenosine / Q000737:chemistry / Q000302:isolation & purification*; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques; D004247:DNA / Q000737:chemistry; D005090:Exodeoxyribonucleases / Q000737:chemistry; D005456:Fluorescent Dyes; D006108:Graphite / Q000737:chemistry*; D006801:Humans
chemical_list: D052157:Aptamers, Nucleotide; D005456:Fluorescent Dyes; D006108:Graphite; D004247:DNA; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I; D000241:Adenosine
keywords: Exonuclease I; Fluorescent aptasensor; Graphene oxide