Carbon dots with red-shifted photoluminescence by fluorine doping for optical bio-imaging

Carbon dots (CDs) are environmentally benign alternatives to quantum dots comprised of heavy metals with outstanding photoluminescent (PL) properties and have shown great promise in optical bio-imaging and sensing. However, it remains challenging to rationally design and synthesize CDs with red PL emission. We herein disclose that a red-shifted PL emission could be achieved by doping the electron-withdrawing fluorine atoms into CDs. Moreover, we demonstrate the preparation of fluorine doped CDs with a red PL emission under excitation at 530 nm by an easy, environmental friendly, one-step microwave-assistant carbonation route. A possible mechanism of the red-shifted emission upon fluorine doping is tentatively proposed. In addition, the applicable of these red-emissive fluorine doped CDs as optical nanoprobes for bio-imaging applications, both in vivo and in vitro, was explored. It is indicated that the as-prepared fluorine doped CDs with red-shifted PL emission are promising candidates for tumor bio-imaging/or diagnostics.