Multimodal Magnetic Resonance and Photoacoustic Imaging of Tumor-Specific Enzyme-Responsive Hybrid Nanoparticles for Oxygen Modulation.

Multimodal imaging contrast agents for cancer that can not only perform diagnostic functions but also serve as tumor microenvironment-responsive biomaterials are encouraging. In this study, we report the design and fabrication of a novel enzyme-responsive T magnetic resonance imaging (MRI) contrast agent that can modulate oxygen in the tumor microenvironment via the catalytic conversion of HO to O. The T contrast agent is a core-shell nanoparticle that consists of manganese oxide and hyaluronic acid (HA)-conjugated mesoporous silica nanoparticle (HA-MnO@MSN). The salient features of the nanoparticle developed in this study are as follows: 1) HA serves as a targeting ligand for CD44-expressing cancer cells; 2) HA allows controlled access of water molecules to the MnO core via the digestion of enzyme hyaluronidase; 3) the generation of O bubbles in the tumor by consuming HO; and 4) the capability to increase the oxygen tension in the tumor. The relaxivity of HA-MnO@MSN was measured to be 1.29 mMs at a magnetic field strength of 9.4 T. results demonstrated the ability of continuous oxygen evolution by HA-MnO@MSN. After intratumoral administration of HA-MnO@MSN to an HCT116 xenograft mouse model, T weighted MRI contrast was observed after 5 h postinjection and retained up to 48 h. In addition, photoacoustic imaging of HA-MnO@MSN demonstrated an increase in the tumor oxygen saturation over time after i. t. administration. Thus, the core-shell nanoparticles developed in this study could be helpful in tumor-targeted T MR imaging and oxygen modulation.