A new formulation of poly(MAOTIB) nanoparticles as an efficient contrast agent for in vivo X-ray imaging

Polymeric nanoparticles (PNPs) are gaining increasing importance as nanocarriers or contrasting material for preclinical diagnosis by micro-CT scanner. Here, we investigated a straightforward approach to produce a biocompatible, radiopaque, and stable polymer-based nanoparticle contrast agent, which was evaluated on mice. To this end, we used a nanoprecipitation dropping technique to obtain PEGylated PNPs from a preformed iodinated homopolymer, poly(MAOTIB), synthesized by radical polymerization of 2-methacryloyloxyethyl(2,3,5-triiodobenzoate) monomer (MAOTIB). The process developed allows an accurate control of the nanoparticle properties (mean size can range from 140 nm to 200 nm, tuned according to the formulation parameters) along with unprecedented important X-ray attenuation properties (concentration of iodine around 59 mg I/mL) compatible with a follow-up in vivo study. Routine characterizations such as FTIR, DSC, GPC, TGA, 1H and 13C NMR, and finally SEM were accomplished to obtain the main properties of the optimal contrast agent. Owing to excellent colloidal stability against physiological conditions evaluated in the presence of fetal bovine serum, the selected PNPs suspension was administered to mice. Monitoring and quantification by micro-CT showed that iodinated PNPs are endowed strong X-ray attenuation capacity toward blood pool and underwent a rapid and passive accumulation in the liver and spleen