Synthesis of highly photoluminescent carbon dots via citric acid and Tris for iron(III) ions sensors and bioimaging

•Highly fluorescent quantum yield carbon quantum dots (C-QDs) were prepared.•The C-QDs fluorescence was selectively quenched by Fe3+ ions.•The C-QDs acted as sensitive and selective nanoprobes for Fe3+ ions determination.•The C-QDs were applied to optical bioimaging of MCF-7 cells with low cytotoxicity.

In this work, high quantum yield and strong photoluminescent carbon quantum dots (C-QDs) are successfully synthesized via a facile and green hydrothermal method using citric acid and Tris as precursors. The as-synthesized C-QDs with a quantum yield (QY) as high as 52% were characterized by UV, FT-IR, TEM, XPS and fluorescence spectroscope. TEM results show that C-QDs are mono-dispersed spherical particles and the diameter distribution of C-QDs is 2.8±1.1 nm. The extraordinary photoluminescent properties and low cytotoxicity of C-QDs were obtained through optical property characterization and cytotoxicity assay. In addition, we found that the as-prepared C-QDs had a high affinity for Fe3+ ions and the response toward Fe3+ ions was highly linear (R2=0.997) over the concentration range from 2 to 50 μM, which could provide an effective platform for portable detection of Fe3+ ions. Also, it is demonstrated that the photoluminescent C-QDs display hypotoxicity and are biocompatible for use as biosensors in living cells.

Graphical abstractScheme proposed for synthesis of highly photoluminescent carbon dots via citric acid and tris for iron (III) ions sensors and bioimaging application.Figure optionsDownload full-size imageDownload as PowerPoint slide