Synthesis, Characterization, and Enhanced Cancer-Imaging Application of Trans-activator of Transcription Peptide-conjugated Ultrasmall Gadolinium Oxide Nanoparticles

We prepared gadolinium oxide (Gd₂O₃) nanoparticles (GNPs) coated with a trans-activator of transcription (TAT) peptide with cell-penetrating ability (i.e., TAT-GNPs) through one-pot process. We characterized the particle diameter, surface-coating structure, water proton relaxivities, and in vitro cellular toxicities of the TAT-GNPs. We measured in vivo T₁ magnetic resonance images (MRI) in a model nude mouse with liver cancer prior and posterior to intravenous administration. The average particle diameter of the GNPs was 1.5 nm. The sample solution exhibited a longitudinal water proton relaxivity (r₁) of 18.2/s/mM (r₂/r₁ = 1.6, r₂ = transverse water proton relaxivity), which is four to five times higher than those of commercial Gd-chelates. The in vivo T₁ MRI exhibited positively (or T₁) enhanced contrasts in the mouse liver cancer after intravenous administration, demonstrating that the TAT-GNPs acted as an enhanced cancer-imaging agent similar to the cancer-targeting agent in T₁ MRI.