title: A competitive strategy coupled with endonuclease-assisted target recycling for DNA detection using silver-nanoparticle-tagged carbon nanospheres as labels.
abstract: A simple competitive strategy was designed for the sensitive detection of sequence-specific DNA by combining endonuclease-assisted target recycling and electrochemical stripping analysis of silver nanoparticles (AgNPs). The AgNP-tagged carbon nanospheres were synthesized by means of in situ reduction of Ag(+) adsorbed onto a negatively charged polyelectrolyte layer and functionalized with streptavidin for binding biotin-labeled DNA strands. The labeled strand was captured on the DNA sensor surface by competitive hybridization of biotinated primer 1 and its cleaved product. The cleaved product could be amplified in homogeneous solution by endonuclease-assisted target recycling with a Y-shaped junction DNA structure, thus leading to the correlation of the stripping signal to the target concentration. The functionalized nanosphere was characterized with X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The proposed method showed a linear range from 0.1 to 1000 fM with a limit of detection of 0.066 fM (3σ) and good selectivity for base discrimination. The designed strategy provided a sensitive tool for DNA analysis and could be widely applied in bioanalysis and biomedicine.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, PR China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Zhu
authors.forename: Fenglei
authors.initials: F
authors.lastname: Gao
authors.forename: Jianping
authors.initials: J
authors.lastname: Lei
authors.forename: Haifeng
authors.initials: H
authors.lastname: Dong
authors.forename: Huangxian
authors.initials: H
authors.lastname: Ju
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004247:DNA / Q000032:analysis*; D055664:Electrochemical Techniques; D004720:Endonucleases / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D054118:Nanospheres / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D019809:Streptavidin / Q000737:chemistry / Q000378:metabolism
chemical_list: D012834:Silver; D002244:Carbon; D004247:DNA; D019809:Streptavidin; D004720:Endonucleases