Multifunctional Core-Shell Tecto Dendrimers Incorporated with Gold Nanoparticles for Targeted Dual Mode CT/MR Imaging of Tumors.

Development of multifunctional nanoprobes with an excellent imaging performance for precision tumor imaging still remains a great challenge. Here, we report the creation of multifunctional core-shell tecto dendrimers (CSTDs) incorporated with gold nanoparticles (Au NPs) as a platform for dual-mode computed tomography (CT)/magnetic resonance (MR) imaging of tumors. In this work, β-cyclodextrin (CD)-modified generation 5 poly(amidoamine) (PAMAM) dendrimers were synthesized and entrapped with Au NPs as the core. Then, adamantine (Ad)-modified generation 3 PAMAM dendrimers acted as a shell to form Au NP-entrapped CSTDs (for short, Au CSTDs) through supramolecular host-guest recognition between CD and Ad. The formed Au CSTDs were sequentially modified with Arg-Gly-Asp (RGD) peptide through a spacer of polyethylene glycol (PEG), Gd chelator, and 1,3-propane sultone, followed by chelating Gd (III) ions. The synthesized multifunctional Au CSTDs with a mean size of 11.61 nm possess good colloidal stability, high X-ray attenuation property and high relaxivity (9.414 mM s), good antifouling property, and desired cytocompatibility. Due to the RGD-mediated targeting specificity to αβ integrin-overexpressing cancer cells, the multifunctional Au CSTDs enable targeted CT/MR dual mode imaging of a breast cancer model and can be cleared out of body through metabolization pathway with good biosafety profile. The developed multifunctional CSTDs may be applied as an effective CT/MR dual mode imaging probe for accurate diagnosis of various αβ integrin-overexpressing cancer types.