Activatable MRI nanoprobes for tumor and immune microenvironment imaging: biological mechanisms and translational implications.
Authors
Affiliations (4)
Affiliations (4)
- Medical Imaging Department, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272007, China.
- Guangzhou Institute of Cancer Research, the Affiliated Cancer Hospital, Guangzhou Medical University, Guangzhou, 510095, China.
- Department of Gastrointestinal Surgery, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272007, China.
- Department of Laboratory Medicine, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong, 272007, China.
Abstract
Although magnetic resonance imaging (MRI) remains indispensable in oncology, conventional contrast agents lack the biological specificity required to resolve cellular-level pathological events. This review critically examines pivotal advances (2023-2026) in activatable biomaterial-based MRI nanoprobes for precision theranostics. These intelligent platforms convert tumor-associated biological cues into high-fidelity imaging signals while simultaneously enabling targeted therapeutic interventions. We dissect key structural and compositional innovations, spanning high-relaxivity metal-chelating assemblies, zero-background <sup>19</sup>F MRI platforms, and inherently biocompatible, metal-free organic radicals, alongside their controlled activation via microenvironment-responsive, logic-gate architectures. Importantly, we delineate a conceptual shift from tumor-centric imaging toward non-invasive mapping of tumor immune microenvironment dynamics-including macrophage polarization and inflammatory responses-to track immunotherapy efficacy and provide real-time theranostic feedback. Furthermore, we explore how machine learning algorithms serve as a transformative toolkit to accelerate de novo probe design, refine signal quantification, and decipher tumor microenvironment heterogeneity. Finally, to bridge the lab-to-clinic chasm, we benchmark clinical precedents such as AGuIX and ferumoxytol to establish translation-ready design principles for engineering nanoprobes as "imaging drugs" that deliver reproducible, clinically actionable endpoints for precision oncology.