Luminescent carbon dots structure by charcoal laser ablation in biocompatible liquid

Nanometric Carbon dots (CDs) were synthesized using the laser ablation of vegetable carbon placed in a liquid. A pulsed diode laser operating at a 970 nm wavelength was employed to irradiate a charcoal target placed in a phosphate-buffered saline (PBS) solution with neutral pH. The laser radiation induces carbon ablation and exfoliation, with an ablation yield of the order of 5 ng/laser pulse. Small carbon dots and larger carbon nanoparticles were synthesized in the solution. A 365 nm UV lamp irradiation of the CDs dispersion induces visible luminescence emission at about 478 nm wavelength, with a typical blue-green color. UV-Visible-NIR and FTIR spectroscopies have permitted to evaluation of the dispersion liquid transmittance and absorbance. TEM microscopy has evinced that the synthesized CDs are crystalline with a spherical shape and an average size of the order of 1.5 nm. The CD's properties in terms of luminescence and quantum yield in the biocompatible dispersion are presented and discussed for advanced possible applications to the biological and medical fields.