Facile fabrication of biodegradable lanthanide ions containing fluorescent polymeric nanoparticles: Characterization, optical properties and biological imaging

Abstract

The fluorescent polymeric nanoparticles (FPNs) with encapsulated europium complexes have recently emerged as one of the most promising luminescent probes for biomedical applications owing to their unique optical properties, biocompatibility and structure designability. Significant progresses have been made for the preparation of biocompatible trivalent lanthanide ions (Ln3+) fluorescent nanoparticles, whereas, only limited attention was focused on the fabrication of europium ion containing FPNs with biodegradability, high sensitivity and deep penetration. In this work, a facile and simple method was developed to construct biodegradable and biocompatible luminescent polyurethanes (PUs) through a two-step polymerization. In this construction system, diisocyanate-terminating polyethylene glycol (NCO-PEG-NCO) was first synthesized and subsequently conjugated with dihydroxyl modified europium (III) chelates (Eu(TTA)3Phen-OH) to obtain these luminescent PUs. These PUs show amphipathic property and can assemble into core-shell FPNs in aqueous solution and exhibit high water dispersibility. Biological evaluation results suggest that Eu(TTA)3Phen-PEG2000 FPNs possess desirable biocompatibility and great potential for biological imaging applications. Therefore, we expect that the fabrication approach will inspire much research enthusiasm and effort for the preparation of biodegradable luminescent probes.