Synthesis and charaterization of poly(DL-lactide-co-glycolide) nanoparticles with entrapped organic lanthanides and Yttrium complexes for imaging applications

Abstract

Photoluminescence organic complexes of lanthanide ions show narrow band emission and high quantum yield, which make them interesting materials for fluorescence microscopy; moreover, their lifetime is milli second greater than conventional fluorophores (10-8, 10-9 s) like fluorescein and rhodamine. Their potential application in biological system is limited by low solubility in water and toxicity of the metal. Water molecules are strong chelating agents of the lanthanide ions and cause decomplexation by hydrolysing the ligand with consequent loss of functionality: the mechanism of photoluminescence is based on the antenna effect. PLGA (poly[DL-lactide-co-glycolide]) nanoparticles holding complexes of lanthanide (Eu and Lu) ions have been synthetized to improve the solubility and produce a biocompatible material. PLGA is a co-polymer FDA approved and easily adsorbed by the cells. Also an isostructural organic complex of Yttrium has been encapsulated since this atom exhibits potential use in Positron Emission Tomography (PET), another imaging technique. The goal of the research was to produce PLGA nanoparticles with entrapped photoluminescence lanthanide complex and nanoparticles with Yttrium complex optimized for dimension, thermal stability and emission intensity (in the case of lanthanides), for possible in vitro and in vivo imaging.