title: Dendrimer-encapsulated copper as a novel oligonucleotides label for sensitive electrochemical stripping detection of DNA hybridization.
abstract: This paper describes the synthesis and characterization of a novel electrochemical label for sensitive electrochemical stripping detection of DNA hybridization based on dendrimer-encapsulated copper. The generation 4.5 (G 4.5) carboxyl-terminated poly(amidoamine) dendrimer with a trimesyl core was used as a template for synthesis of Cu²⁺/dendrimer nanocomposites (Cu-DNCs). Ratios of Cu²⁺/dendrimer were optimized in order to obtain stable nanocomposites with maximal copper loading in the interior of a polymeric shell. Cu-DNCs labeled DNA probe was employed for determining a target ssDNA immobilized on multi-walled carbon nanotubes-modified glassy carbon electrode (GCE) based on a specific hybridization reaction. The hybridization events were monitored by electrochemical detection of Cu anchored on the hybrids after the release in a diluted nitric acid by anodic stripping differential pulse voltammetry (ASDPV). The results showed that only a complementary sequence could form a dsDNA with the Cu-DNCs DNA probe and give an obvious electrochemical signal. The non-complementary sequence exhibited negligible signal change compared with the blank measurement (means: the electrode containing no target DNA incubating in hybridization buffer solution containing Cu-DNCs DNA probe for a certain time). The use of Cu encapsulated-dendrimer as tags and ASDPV for the detection of the released Cu ions could enhance the hybridization signal, and result in the increase of the sensitivity for the target DNA. Under the conditions employed here, the detection limit for measuring the full complementary sequence is down to pM level.
authors.affiliation: Department of Chemistry, College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Gao
authors.forename: Xue
authors.initials: X
authors.lastname: Jiang
authors.forename: Yang-Jun
authors.initials: YJ
authors.lastname: Dong
authors.forename: Wan-Xin
authors.initials: WX
authors.lastname: Tang
authors.forename: Cong
authors.initials: C
authors.lastname: Hou
authors.forename: Ning-Ning
authors.initials: NN
authors.lastname: Zhu
mesh_terms: D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000032:analysis*; D015342:DNA Probes / Q000737:chemistry; D050091:Dendrimers / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods; D004566:Electrodes; D057230:Limit of Detection; D009693:Nucleic Acid Hybridization / Q000379:methods*; D009841:Oligonucleotides / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D015342:DNA Probes; D050091:Dendrimers; D009841:Oligonucleotides; D003300:Copper; D004247:DNA