title: Dual-emission fluorescent silica nanoparticle-based probe for ultrasensitive detection of Cu2+.
abstract: An effective dual-emission fluorescent silica nanoparticle-based probe has been constructed for rapid and ultrasensitive detection of Cu(2+). In this nanoprobe, a dye-doped silica core served as a reference signal, thus providing a built-in correction for environmental effects. A response dye was covalently grafted on the surface of the silica nanoparticles through a chelating reagent for Cu(2+). The fluorescence of the response dye could be selectively quenched in the presence of Cu(2+), accompanied by a visual orange-to-green color switch of the nanoprobe. The nanoprobe provided an effective platform for reliable detection of Cu(2+) with a detection limit as low as 10 nM, which is nearly 2 × 10(3) times lower than the maximum level (∼20 μM) of Cu(2+) in drinking water permitted by the U.S. Environmental Protection Agency (EPA). The high sensitivity was attributed to the strong chelation of Cu(2+) with polyethyleneimine (PEI) and a signal amplification effect. The nanoprobe constructed by this method was very stable, enabling the rapid detection of Cu(2+) in real water samples. Good linear correlations were obtained over the concentration range from 1 × 10(-7) to 8 × 10(-7) (R(2) = 0.99) with recoveries of 103.8-99.14% and 95.5-95.14% for industrial wastewater and lake water, respectively. Additionally, the long-wavelength emission of the response dye can avoid the interference of the autofluorescence of the biosystems, which facilitated their applications in monitoring Cu(2+) in cells. Furthermore, the nanoprobe showed a good reversibility; the fluorescence can be switched "off" and "on" by an addition of Cu(2+) and EDTA, respectively.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China.
authors.forename: Chenghua
authors.initials: C
authors.lastname: Zong
authors.forename: Kelong
authors.initials: K
authors.lastname: Ai
authors.forename: Guo
authors.initials: G
authors.lastname: Zhang
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.forename: Lehui
authors.initials: L
authors.lastname: Lu
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D003300:Copper / Q000032:analysis*; D004305:Dose-Response Relationship, Drug; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000494:pharmacology; D005618:Fresh Water / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide; D003300:Copper