Fe(3+)-Sensitive Carbon Dots for Detection of Fe(3+) in Aqueous Solution and Intracellular Imaging of Fe(3+) Inside Fungal Cells

In this article, the Fe(3+)-sensitive carbon dots were obtained by means of a microwave-assisted method using glutamic acid and ethylenediamine as reactants. The carbon dots exhibited selective response to Fe(3+) ions in aqueous solution with a turn-off mode, and a good linear relationship was found between (F(0)-F)/F(0) and the concentration of Fe(3+) in the range of 8–80 μM. As a result, the as-synthesized carbon dots can be developed as a fluorescent chemosensor for Fe(3+) in aqueous solution. Moreover, the carbon dots can be applied as a fluorescent agent for fungal bioimaging since the fungal cells stained by the carbon dots were brightly illuminated on a confocal microscopy excited at 405 nm. Furthermore, an increase in the concentration of intracellular Fe(3+) could result in fluorescence quenching of the carbon dots in the fungal cells when incubated in the Tris-HCl buffer solution containing Fe(3+). However, due to EDTA might hinder Fe(III) to enter the fungal cells, incubation in Fe(III)-EDTA complex solution exerted negligible effect on the fluorescence of fungal cells labeled by the carbon dots. Therefore, the carbon dots can serve as a potential probe for intracellular imaging of Fe(3+) inside fungal cells.