Characterization of fluorescent poly(isobutylcyanoacrylate) nanoparticles obtained by copolymerization of a fluorescent probe during Redox Radical Emulsion Polymerization (RREP)

Fluorescent labeled nanoparticles have been prepared by redox radical emulsion polymerization and characterized. These fluorescent nanoparticles labeled in the core can be used to investigate siRNA delivery into cell cultures and during in vivo experiments. The purpose of the work was to demonstrate that a polymerizable fluorescent labeled was incorporated in the core of chitosan/pluronic® F68-coated Poly(IsobutylCyanoAcrylate) (PIBCA) nanoparticles thanks to a covalent linkage. It was also aimed to show that the labeling did not modify the complement activation capacity of the nanoparticles which are designed as drug carriers for the in vivo delivery of siRNA. Fluorescent nanoparticles were prepared by adding a fluorescent monomer dye, methacryloxyethyl thiocarbamoyl rhodamine B during the preparation of nanoparticles by redox radical emulsion polymerization. The structure and composition of the fluorescent nanoparticles was investigated. The capacity of the fluorescent nanoparticles to activate the complement system was evaluated by 2D immunoelectrophoresis. Results from the analysis of the composition and structure of polymers forming the nanoparticles showed that the fluorescent dye was incorporated in the core of the nanoparticles by formation of a stable covalent linkage with PIBCA. The labeled nanoparticles showed the same surface properties as the corresponding non-labeled nanoparticles based on analysis of the polymer structure, physicochemical properties and evaluation of their capacity to activate the complement system. This work showed that the fluorescent PIBCA nanoparticles were labeled by incorporation of the fluorescent probe in the nanoparticle core and that the fluorescent probe did not modify the nanoparticle surface properties. These fluorescent nanoparticles can be proposed as relevant models to investigate how they deliver siRNA to their biological target in cell cultures and during in vivo experiments.