A Macrophages-Targeting and ROS-Responsive Iron-Based T1Magnetic Resonance Imaging Contrast Agent for Inflammation Imaging

Accurate detection of inflammation regions in the body is of immense value to subsequent therapy. Magnetic resonance imaging (MRI) enables noninvasive inflammation detection in situ; however, most MRI contrast agents are limited due to their potential toxicity and low specificity against inflammatory tissues. In this study, we developed a macrophage-targeting and ROS-responsive iron complex (FePM) as a T1-enhanced MRI contrast agent for inflammation imaging. In the presence of a highly concentrated reactive oxygen species (ROS) environment, the Fe(II) centers in FePM undergo rapid oxidation. This process is accompanied by a significant increase in longitudinal relaxivity (r1), allowing the complex to function as an ROS-responsive contrast agent for tumor-specific magnetic resonance imaging (MRI). Cellular studies confirmed that FePM possesses excellent biocompatibility and preferential uptake by macrophages. In vitro MRI experiments further demonstrated significant T1 contrast enhancement in macrophages following FePM treatment. Collectively, these results support FePM as a promising inflammation-specific MRI contrast agent with strong potential for improving diagnostic accuracy in inflammatory diseases.