Lipid nanoparticles (LNP): a new technology for fluorescence contrast agents with improved properties

摘要

Fluorescence imaging is a valuable tool for the study of living systems. It can be used with good resolution from the micro- to the macroscopic range. However, for macroscopic use in living animals or humans, fluorescent probes must overcome several obstacles such as aqueous solubility, suitable circulating lifetime and clearance. Fluorescent probes should also display high molar extinction coefficient and fluorescence quantum yield. In this article, we report the encapsulation of five hydrophobic or amphiphilic fluorophores (DiO, Dil, DiD, DiR and ICG) with emission wavelength ranging from 500 to 800 nm, in long-circulating Lipid NanoParticles (LNP). Loading of these commercially available indocyanines in LNP is highly efficient (from 77 to 97 %), and fluorescence quantum yields range from 7 to 53%, depending on the dye, in the standard formulation (50 nm diameter nanoparticles). Given the wide range of wavelengths covered and the stability of particle dispersion in aqueous buffer, dye-loaded LNP should be a valuable tool for both in vivo and in vitro fluorescence imaging.