The Control Of Hydrophilicity And Hydrophobicity Of Carbon Dots Via A One-pot Approach

As a kind of newly emerged fluorescent materials, fluorescent carbon nanoparticles (carbon dots, CDs) have shown promising potential in a wide range of application fields, including sensing, bio-imaging, drug delivery, photocatalysis and electrocatalysis. CDs exhibit tunable fluorescence emission property and chemical stability, in addition to favorable biocompatibility as well as low toxicity, they have shown promises as a new generation of fluorescence probe in the field of bio-imaging or bio-labeling. In most cases, hydrophilic CDs with oxygen-or nitrogen-containing groups, e.g., carboxyl, hydroxyl and amine, are obtained and directly applied to bio-imaging or chemical sensing.In contrast, however, hydrophobic CDs attract little attention at present, due to both the difficulty in their fabrication and the up-to-date limitations in their practical applications attributed to the incompatibility with the aqueous environment. At present, hydrophobic CDs are usually prepared in organic solvents, e.g., octadecene and toluene, with long-chain organic molecules as surface passivation/capping agents including dodecanethiol, hexadecylamine, octadecylamine, and organosilaneIn the present work, we report a facile approach for the regulation of production of either hydrophilic or hydrophobic CDs, or the production of both, with citric acid and cysteamine. A simple control of the citric acid/cysteamine ratio or reaction time facilitates the regulation of the hydrophilicity and/or hydrophobicity of the produced CDs (or their proportions).Fluorescent probes is an important tool, which is very sensitive to useful information in the micro-environment.8-Anilino-l-Naphthalene Sulfonate (ANS) fluorescent probe is taken to research the hydrophilicity or hydrophobicity of two CDs.