FAP-Targeted MRI Conjugate for Contrast and Toxicity Trade-off

The MRI agent system is segmented into two functional components: a targeting moiety (FL radical) that specifically binds to FAP-expressing cells, and an MRI agent radical (IA) that provides the imaging function. This segmentation allows the targeting component to direct the agent specifically to diseased tissue while the MRI component provides contrast, thereby improving both contrast and reducing toxicity through selective accumulation at the target site.

The linker L serves as an intermediary component that chemically connects the targeting moiety (FL radical) to the MRI agent radical (IA). This intermediary structure enables the stable integration of the targeting function and imaging function into a single conjugate molecule, allowing the targeted MRI agent to maintain both its specific binding capability and its imaging contrast function simultaneously.

The MRI agent is constructed as a composite conjugate molecule comprising three distinct functional radicals: the FL radical (targeting moiety with specific FAP binding capability), the linker L (connecting structure), and the IA radical (MRI contrast agent). This composite structure integrates targeting specificity and imaging functionality into a single molecular entity, achieving high imaging specificity while the modular design helps manage structural complexity.

The conjugate structure is designed to perform multiple functions simultaneously: the FL radical provides specific targeting to FAP-expressing cells, the linker L provides stable chemical connection, and the IA radical provides MRI contrast. This multi-functionality within a single conjugate molecule achieves both high specificity and broad applicability for imaging various FAP-positive conditions.