Abstract: The present invention relates to the treatment of photoluminescent silicon nanoparticles in order to give them surface functionalities, for example amine radicals or other radicals, that favor their use especially in biology for labeling applications. A reaction is then applied to the nanoparticles in order to create a surface coating that gives the nanoparticles these functionalities, especially a protection against dissolution in an aqueous medium. The process comprises, prior to this coating reaction, a passivation of the silicon nanoparticles that favors the creation of bonds of Si—OH type at the surface, this type of bond making it possible to obtain a multiplicity of functionalities including, in particular, amines, thiols, polyethylene glycol, as surface radicals.