title: Label-free DNA hybridization detection and single base-mismatch discrimination using CE-ICP-MS assay.
abstract: Detecting a specific DNA sequence and discriminating single base-mismatch is critical to clinical diagnosis, paternity testing, forensic sciences, food and drug industry, pathology, genetics, environmental monitoring, and anti-bioterrorism. To this end, capillary electrophoresis (CE) coupled with the inductively coupled plasma mass spectrometry (ICP-MS) method is developed using the displacing interaction between the target ssDNA and the competitor Hg(2+) for the first time. The thymine-rich capture ssDNA 1 is interacted with the competitor Hg(2+), forming an assembled complex in a hairpin-structure between the thymine bases arrangement at both sides of the capture ssDNA 1. In the presence of a target ssDNA with stronger affinity than that of the competitor Hg(2+), the energetically favorable hybridization between capture ssDNA 1 and the target ssDNA destroys the hairpin-structure and releases the competitor as free Hg(2+), which was then read out and accurately quantified by CE-ICP-MS assay. Under the optimal CE separation conditions, free Hg(2+) ions and its capture ssDNA 1 adduct were baseline separated and detected on-line by ICP-MS; the increased peak intensity of free Hg(2+) against the concentration of perfectly complementary target ssDNA was linear over the concentration range of 30-600 nmol L(-1) with a limit of detection of 8 nmol L(-1) (3s, n = 11) in the pre-incubated mixture containing 1 μmol L(-1) Hg(2+) and 0.2 μmol L(-1) capture ssDNA 1. This new assay method is simple in design since any target ssDNA binding can in principle result in free Hg(2+) release by 6-fold Hg(2+) signal amplification, avoiding oligonucleotide labeling or assistance by excess signal transducer and signal reporter to read out the target. Due to element-specific detection of ICP-MS in our assay procedure, the interference from the autofluorescence of substrata was eliminated.
authors: College of Chemistry, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, Tianjin Normal University, Tianjin 300387, China. nkliyan398@gmail.com
authors: Yan
authors: Y
authors: Li
authors: Shao-kai
authors: SK
authors: Sun
authors: Jia-lin
authors: JL
authors: Yang
authors: Yan
authors: Y
authors: Jiang
mesh_terms: D020137:Base Pair Mismatch; D004277:DNA, Single-Stranded / Q000032:analysis* / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D008628:Mercury / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D013054:Spectrophotometry, Atomic / Q000379:methods
chemical_list: D004277:DNA, Single-Stranded; D008628:Mercury