Dual-Emission Fluorescent Silica Nanoparticle-Based Probe for Ultrasensitive Detection of Cu~(2+)

摘要

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 X 10~(3) times lower than the maximum level (approx20 (mu)M) 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 X 10~(-7) to 8 X 10~(-7) (R~(2) velence 0.99) with recoveries of 103.8-99.14percent and 95.5-95.14percent 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.