Institut Charles Sadron Event

Upconversion nanoparticles (UCNPs) are promising platforms for bioimaging and cellular labeling due to their ability to convert near-infrared light into visible or ultraviolet emission. However, their hydrophobic surface limits aqueous dispersibility and thus requires post-synthesis surface modification. Although poly(ethylene glycol) is widely used for this purpose, its potential to induce immune responses has motivated the development of alternative hydrophilic polymers. In this doctoral project, oligosarcosines were studied as a surface modifier for UCNPs. A library of amphiphilic molecules with systematically varied sarcosine and alkyl chain lengths was synthesized. The self-assembly properties of these amphiphiles, particularly their critical micelle concentrations, were investigated to optimize the coating conditions and improve the aqueous dispersibility of UCNPs while preserving their luminescence properties. Keywords : Upconversion nanoparticles; oligosarcosine; amphiphilic molecules; self-assembly in water; surface modification