title: Ultrasensitive, high temperature and ionic strength variation-tolerant Cu²⁺ fluorescent sensor based on reconstructed Cu²⁺-dependent DNAzyme/substrate complex.
abstract: A previously reported Cu²⁺-dependent DNAzyme/substrate complex was reconstructed in this work, which makes possible the use of an intramolecular stem-loop structure and is, therefore, a good choice for the design of Cu²⁺ sensors. To demonstrate this, a fluorescent sensor was designed on the basis of the reconstructed complex. In this sensor, the fluorophore/quencher pair was caged tightly in an intramolecular double-helix structure; thus, the background signal was greatly suppressed. Cu²⁺-dependent cleavage of the complex could cause the release of the fluorophore, leading to restoration of the fluorescence signal. High quenching efficiency provides the sensor with three important characteristics: high sensitivity, high temperature variation tolerance and high ionic strength tolerance. The proposed sensor allows specific detection of aqueous Cu²⁺ down to a limit of 0.6 nM, and the performance is independent of temperature and ionic strength in the range of 4-40 °C and 0.8-3.0 M NaCl, respectively. This work identifies a good choice for sensor design on the basis of DNAzymes containing triple-helix structures.
authors.affiliation: State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Xiao-Xi
authors.initials: XX
authors.lastname: Huang
authors.forename: De-Ming
authors.initials: DM
authors.lastname: Kong
authors.forename: Han-Xi
authors.initials: HX
authors.lastname: Shen
authors.forename: Yue
authors.initials: Y
authors.lastname: Liu
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003300:Copper / Q000737:chemistry / Q000302:isolation & purification*; D021881:DNA, Catalytic / Q000737:chemistry*; D005453:Fluorescence; D009994:Osmolar Concentration; D013379:Substrate Specificity
chemical_list: D021881:DNA, Catalytic; D003300:Copper