Fe3+-Sensitive Carbon Dots for Detection of Fe3+ in Aqueous Solution and Intracellular Imaging of Fe3+ Inside Fungal Cells.

Yanqiu Chen,Wei Pan,Xiaobo Sun,Jinping Wang,Guifeng Yu

doi:10.3389/fchem.2019.00911

Abstract

In this article, the Fe3+-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 Fe3+ ions in aqueous solution with a turn-off mode, and a good linear relationship was found between (F0-F)/F0 and the concentration of Fe3+ in the range of 8–80 μM. As a result, the as-synthesized carbon dots can be developed as a fluorescent chemosensor for Fe3+ 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 Fe3+ could result in fluorescence quenching of the carbon dots in the fungal cells when incubated in the Tris-HCl buffer solution containing Fe3+. 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 Fe3+ inside fungal cells.

Highlights

As the most abundant transition metal in cellular systems, iron with its chemical versatility plays indispensable roles in physiological processes (Gao R. et al, 2019) such as oxygen transport (Aisen et al, 1999), electron transfer (Lucas et al, 2011), and enzymatic catalysis (Eisenstein, 2000)
The Fe3+-sensitive carbon dots can be synthesized by means of a microwave-assisted method using glutamic acid and ethylenediamine as reactants
The as-syntheszied carbon dots have the potential to be developed as a fluorescent chemosensor for detection of Fe3+ ions in aqueous solution because the dots showed selective response to Fe3+ ions in aqueous solution with a turn-off mode, and a good linear relationship was observed between (F0-F)/F0 and the Fe3+ concentrations of in the range of 8–80 μM

Summary

INTRODUCTION

As the most abundant transition metal in cellular systems, iron with its chemical versatility plays indispensable roles in physiological processes (Gao R. et al, 2019) such as oxygen transport (Aisen et al, 1999), electron transfer (Lucas et al, 2011), and enzymatic catalysis (Eisenstein, 2000). A variety of methods based on carbon dots with high sensitivity and selectivity have been reported for chemically sensing Hg2+ (Yan et al, 2016), Cu2+ (Zhu et al, 2017), Fe3+ (Tian et al, 2017), Pb2+ (Xiong et al, 2016), Cr(VI) (Wang et al, 2017), and Ag+ (Jiang et al, 2015) It is of great interest for intracellular imaging, and even quantitatively detecting specific metal ions in cells with high sensitivity and selectivity using carbon dots as fluorescent probes. Thereafter, the selected young vigorous mycelia washed by distilled water for three times were incubated in the Tris-HCl buffer solution containing the as-synthesized carbon dots at a certain concentration for another 36 h in a constant temperature incubator. Three drops of 0.005 M Fe3+, Fe(III)-EDTA, Cu2+, and Ca2+ were added from one side of the chink between the cover glass and the slide glass for intracellular imaging of metal ions

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT