Target-Specific Magnetic Resonance Imaging of Human Prostate Adenocarcinoma Using NaDyF₄–NaGdF₄ Core–Shell Nanoparticles

We illustrate the development of NaDyF4–NaGdF4 core–shell nanoparticles (NPs) for targeting prostate cancer cells using a preclinical 9.4 T magnetic resonance imaging (MRI) of live animals. The NPs composed of paramagnetic Dy3+ and Gd3+ (T2- and T1-contrast agents, respectively) demonstrate proton relaxivities of r1 = 20.2 mM–1 s–1 and r2 = 32.3 mM–1 s–1 at clinical 3 T and r1 = 9.4 mM–1 s–1 and r2 = 144.7 mM–1 s–1 at preclinical 9.4 T. The corresponding relaxivity values per NP are r1 = 19.4 × 105 mMNP–1 s–1 and r2 = 33.0 × 105 mMNP–1 s–1 at 3 T and r1 = 9.0 × 105 mMNP–1 s–1 and r2 = 147.0 × 105 mMNP–1 s–1 at 9.4 T. In vivo active targeting of human prostate tumors grown in nude mice revealed docking of anti-prostate-specific membrane antigen (PSMA) antibody-tagged NPs at tumor sites post-24 h of their intravenous injection. On the other hand, in vivo passive targeting showed preferential accumulation of NPs at tumor sites only within 2 h of their injection, ascribed to the enhanced permeation and retention effect of the tumor. A biodistribution study employing the harvested organs of mice, post-24 h injection of NPs, quantified active targeting as nearly twice as efficient as passive targeting. These outcomes provide potential opportunities for noninvasive diagnosis using NaDyF4–NaGdF4 core–shell NPs for target-specific MRI.