Carbon dots synthesis by laser ablation of graphene oxide in biocompatible solutions

A biocompatible dispersion of carbon dots (CDs) has been obtained by laser irradiation of graphene oxide (GO) placed in liquids. The CDs synthesis uses a pulsed IR laser operating at 970 nm, 100 ms pulse duration, and 1.1 kJ/cm ² fluence. The carbon target is constituted by GO sheets, containing micrometric GO flakes, immersed in a common phosphate-buffered saline (PBS) solution used in biology. CDs are functionalized by the solution salts and, under UV excitation, produce a high-intensity dispersion luminescence in the visible region. The optical properties and other physical characteristics of the dispersions are presented. The CD's fluorescent emission occurs in the blue region, around 478 nm, upon excitation at 365 nm. The synthesized CDs showed high biocompatibility, stability, and nontoxicity. This study provides an inexpensive and simple method for synthesizing biocompatible CDs in liquids for useful applications in bioimaging, diagnostics, and therapy.