An efficient solid-state synthesis of fluorescent surface carboxylated carbon dots derived from C60 as a label-free probe for iron ions in living cells

In order to achieve the simple, easily repeated, and large scale preparation of fluorescent CDs, a new solid-state synthesis (SSS) approach was developed by calcining the mixture of fullerenes (C 60 ) and solid sodium hydroxide. The cage of fullerenes could be opened and the hydroxyl and carboxyl were successfully introduced in the presence of sodium hydroxide under high temperature. The as-prepared surface carboxylated CDs possess many good properties, such as high water solubility, good photostability, salt tolerance, and nontoxicity. Especially, the fluorescence of CDs could be highly quenched by Fe 3+ because of the strong interaction of hydroxyl or carboxyl on the as-obtained CDs with Fe 3+ , which realized a sensitive detection of Fe 3+ in the linear range of 0.02–0.6   μmol/L. What is more, we further applied the obtained CDs into the intracellular imaging of Fe 3+ .