Latex nanoparticles for multimodal imaging and detection in vivo

The aim of the present work was to develop a multimodal imaging and detection approach to study the behaviour of nanoparticles in animal studies. Highly carboxylated 144 nm-sized latex nanoparticles were labelled with ⁶⁸Ga for positron emission tomography, ¹¹¹In for quantitative gamma scintigraphy or Gd³⁺ for magnetic resonance imaging. Following intravenous injection into rats, precise localization was achieved revealing the tracer in the blood compartment with a time-dependent accumulation in the liver. In addition, rhodamine B was also incorporated to examine specific interactions with blood cells. Flow cytometry and fluorescent microscopy show uptake of nanoparticles by leucocytes and, unexpectedly, thrombocytes, but not erythrocytes. Cellular internalization was an active and selective process. Further incorporation of polyethylene glycol into the nanoparticle corona could prevent uptake by thrombocytes but not macrophages or monocytes. Our data demonstrate the feasibility of a multimodal approach and its usefulness to analyse the fate of nanoparticles at the macroscopic and cellular level. It will facilitate the development of functionalized nanocarrier systems and extend their biomedical applications.