Synthesis of cRGD peptide cluster-decorated NIR-fluorescent PISA-RAFT nanoparticles targeting integrin expressing cells

Surface chemistry has a critical influence on the behavior of nanoparticles in biological media. Moreover, the presence, number, location and organization of surface ligands are important parameters for their selective interaction with cells. In this study, we explored the synthesis of "hairy" polymer nanoparticles presenting a cRGD peptide cluster ligand precisely located at the polymer alpha-chain-end of the hairs. These polymer nanoparticles were prepared by polymerization-induced self-assembly mediated by the RAFT process (PISA-RAFT) thanks to the synthesis of an original RAFT control agent functionalized with a cRGD tetravalent peptide cluster. Optimization of the PISA-RAFT synthesis led to 50-60 nm spherical hairy nanoparticles that incorporated in their hydrophobic core a crosslinker for stability and near-infrared fluorophores for optical bioimaging. Finally, cRGDcluster-decorated Cy5.5-fluorescent nanoparticles were prepared and both confocal microscopy and flow cytometry demonstrated their ability to selectively recognize cells over-expressing at their membrane integrins that are the natural protein receptor of cRGD ligands. Biocompatible PISA-RAFT nanoparticles were synthesized with NIR-fluorescent monomers in the core and cRGD peptide clusters at the outer surface. These original nanoprobes selectively labeled integrin-presenting cells.