Herein, we have synthesized Gd(iii)-encapsulated
glycol chitosan nanoparticles (Gd(iii)-CNPs) for
tumor-targeted T1-weighted magnetic resonance (MR) imaging. The T1
contrast agent, Gd(iii), was successfully encapsulated into
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (
DOTA)-modified CNPs to form stable Gd(iii)-encapsulated CNPs (Gd(iii)-CNPs) with an average particle size of approximately 280 nm. The stable nanoparticle structure of Gd(iii)-CNPs is beneficial for liver
tumor accumulation by the enhanced permeation and retention (EPR) effect. Moreover, the
amine groups on the surface of Gd(iii)-CNPs could be protonated and could induce fast cellular uptake at acidic pH in
tumor tissue. To assay the
tumor-targeting ability of Cy5.5-labeled Gd(iii)-CNPs, near-infrared fluorescence (NIRF) imaging and MR imaging were used in a liver
tumor model as well as a subcutaneous
tumor model. Cy5.5-labeled Gd(iii)-CNPs generated highly intense fluorescence and T1 MR signals in
tumor tissues after
intravenous injection, while DOTAREM®, the commercialized control MR
contrast agent, showed very low
tumor-targeting efficiency on MR images. Furthermore, damaged tissues were found in the livers and kidneys of mice injected with DOTAREM®, but there were no obvious adverse effects with Gd(iii)-CNPs. Taken together, these results demonstrate the superiority of Gd(iii)-CNPs as a
tumor-targeting T1 MR agent.