Application Of Activatable Cell-penetrating Peptide Conjugated Polymer Nanoparticles For Bimodal MR And Fluorescence Imaging

Multi-modal imaging has drawn extensive research interest as multi-modal imagingmodalities can be complementary and overcome the inherent limitations od single imaging modality alone.Combination of magnetic resonance?MR?and fluorescence imaging enables the nanoprobe to obtain superb spatial resolution of MRI and high sensitivity of FI,which has wide application prospect in clinic.In this paper,Gd³⁺chelates,aggregation-induced emission fluorogens?AIEgens?andactivatable cell penetrating peptides?ACPPs?were combined to obtain an active targeted magnetic resonance?MR?and fluorescence bimodal imaging.We synthesized Gd³⁺chelating monomer and AIEgens monomer,linear amphiphilic block copolymers were subsequently obtained by reversible addition fragmentation chain transfer polymerization?RAFT?,and then the active targeting ACPPs were conjugated at end groups of hydrophilic corona.The polymer nanoparticles have been generated by dissolving pre-synthesized linear block copolymers into water directly.The active targeting bimodal probe showed high biocompatibility and low toxicity.The active targeting polymer nanoparticles showed tumor cell penetration which can be characterized by in vitro fluorescence imaging?FI?.Preliminary in vivo experiments of Gd³⁺-chelated nanoparticles,which can achieve maximum enrichment in tumor tissue within 30 min,have promising characteristics as a tumor targeting MRI contrast agent with good biocompatibility.We loaded near infrared?NIR?dye into polymer nanoparticles to show the biodistribution via NIR imaging,the results of in vivo NIR imaging is consistent with the findings of the in vivo MR imaging study.The MRI and FI bimodal probe with active targeting is an obvious contrast agent,which is expected for clinic application.