title: Ultrasensitive DNA detection based on two-step quantitative amplification on magnetic nanoparticles.
abstract: Sensitive detection of a specific deoxyribo nucleic acid (DNA) sequence is important for biomedical applications. In this report, a two-step amplification strategy is developed based on magnetic nanoparticles (MNPs) to achieve ultrasensitive DNA fluorescence detection. The first level amplification is obtained from multiple binding sites on MNPs to achieve thousands of probe DNA molecules on one nanoparticle surface. The second level amplification is gained by enzymatic reaction to achieve fluorescence signal enhancement. MNPs functionalized by probe DNA (DNAp) are bound to target DNA (t-DNA) molecules with a ratio of 1:1 on a substrate with capture DNA (DNAc). After the MNPs with DNAp are released from the substrate, alkaline phosphatase (AP) is labelled to MNPs via hybridization reaction between DNAp on MNPs and detection DNAs (DNAd) with AP. The AP on MNPs catalyses non-fluorescent 4-methylumbelliferyl phosphate (4-MUP) to fluorescent 4-methylumbelliferone (4-MU) with high intensity. Finally, fluorescence intensity of the 4-MU is detected by a conventional fluorescence spectrophotometer. With this two-step amplification strategy, the limit of detection (LOD) of 2.8 × 10(-18) mol l(-1) for t-DNA has been achieved.
authors.affiliation: Institute of Electronic paper Displays, Academy of South China Advanced Optoelectronics, South China Normal University, Guangzhou 510006, People's Republic of China.
authors.forename: Mingliang
authors.initials: M
authors.lastname: Jin
authors.forename: Xia
authors.initials: X
authors.lastname: Liu
authors.forename: Albert
authors.initials: A
authors.lastname: van den Berg
authors.forename: Guofu
authors.initials: G
authors.lastname: Zhou
authors.forename: Lingling
authors.initials: L
authors.lastname: Shui
mesh_terms: D015374:Biosensing Techniques; D004247:DNA; D057230:Limit of Detection; D008280:Magnetics; D058185:Magnetite Nanoparticles; D009693:Nucleic Acid Hybridization
chemical_list: D058185:Magnetite Nanoparticles; D004247:DNA