Photoluminescent carbon dots synthesized by laser ablation of charcoal in physiological solutions

Quantum carbon dots (QCDs) have been synthesized using an IR ns pulsed Nd:YAG laser ablating an amorphous charcoal target placed in a physiological liquid. The CDs dispersion exhibits high transparency in the visible region and shows photoluminescence under UV excitation at 365 nm. Using a sodium-chlorine-based physiological solution, the CDs' functionalized luminescence is peaked in the red region, while using a glucose-based physiological solution, it is peaked in the blue region. The luminescence is stable and proportional to the dispersion concentration, i.e., to the laser ablation time. The CDs dispersion transmittances and absorbances have been measured in the UV, visible, and near-IR regions. ATR-FTIR spectroscopy was performed on the dried solution drops deposited on a silicon substrate. The CDs dispersions were characterized relatively to some physical parameters, such as density, surface tension, viscosity, refractive index, and wetting ability on different substrates. Synthesized CDs are crystalline as a result of the high energy transferred from the laser beam to the amorphous carbon atoms of the target. The possible use of the biocompatible dispersions in the biomedical field, for bioimaging and therapy, was also presented and discussed.