title: Enzyme-free colorimetric detection of DNA by using gold nanoparticles and hybridization chain reaction amplification.
abstract: A novel, high sensitive, and specific DNA assay based on gold nanoparticle (AuNP) colorimetric detection and hybridization chain reaction (HCR) amplification has been demonstrated in this article. Two hairpin auxiliary probes were designed with single-stranded DNA (ssDNA) sticky ends which stabilize AuNPs and effectively prevent them from salt-induced aggregation. The target DNA hybridized with the hairpin auxiliary probes and triggered the formation of extended double-stranded DNA (dsDNA) polymers through HCR. As a result, the formed dsDNA polymers provide less stabilization without ssDNA sticky ends, and AuNPs undergo aggregation when salt concentration is increased. Subsequently, a pale purple-to-blue color variation is observed in the colloid solution. The system is simple in design and convenient in operation. The novel strategy eliminates the need for enzymatic reactions, separation processes, chemical modifications, and sophisticated instrumentation. The detection and discrimination process can be seen with the naked eye. The detection limit of this method is lower than or at least comparable to previous AuNP-based methods. Importantly, the protocol offers high selectivity for the determination between perfectly matched target oligonucleotides and targets with single base-pair mismatches.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Liu
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Yang
authors.forename: Shan
authors.initials: S
authors.lastname: Sun
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
authors.forename: Kemin
authors.initials: K
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Huang
authors.forename: Jianbo
authors.initials: J
authors.lastname: Liu
authors.forename: Leiliang
authors.initials: L
authors.lastname: He
mesh_terms: D001483:Base Sequence; D003124:Colorimetry / Q000379:methods*; D004247:DNA / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles; D046529:Microscopy, Electron, Transmission; D009693:Nucleic Acid Hybridization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D006046:Gold; D004247:DNA