Long-wavelength emission carbon dots as self-ratiometric fluorescent nanoprobe for sensitive determination of Zn2.

Abstract

Anovel ratiometric fluorescence nanoprobe based on long-wavelength emission carbon dots (CDs) was designed for high sensitive and selective detection of Zn2+. The CDs were conveniently prepared by a one-step solvothermal treatment of formamide and glutathione (GSH). Under single excitation wavelength (420nm), the obtained CDs exhibit three emission peaks at 470, 650, and 685nm, respectively. For the long-wavelength emission region of the CDs, the fluorescence at 685nm can be quenched with different levels upon the addition of most metal ions. However, the presence of Zn2+ not only results in the fluorescence quenching at 685nm effectively but also enhances at 650nm remarkably, which may be due to the formation of CD-Zn2+ chelate complex inducing the dispersion of CDs aggregates and changes in the group distribution on the surface of CDs. Taking the advantage of the unique fluorescence response induced by Zn2+, the prepared CDs were successfully employed as nanoprobe for self-ratiometric fluorescence determination of Zn2+ with F650/F685 as signal output. A good linear relationship in the concentration range 0.01 to 2μM, and a detection limit as low as 5.1nM has beenobtained. Theratiometric nanoprobe was successfully applied to Zn2+ determination in human serum samples.