Microfluidic Gd³⁺-chelated hydrogel microspheres enable MRI-visible, image-guided photothermal chemotherapy for...

Innovative biomaterials are playing an increasingly important role in biomedicine as drug-delivery carriers, tissue-repair scaffolds, and beyond. However, effective approaches for in situ, longitudinal monitoring of lesion initiation and progression in vivo during biomaterial-based interventions remain limited. Magnetic resonance imaging (MRI) offers high spatial resolution and excellent soft-tissue contrast. Here, gadolinium ions (Gd³⁺) were incorporated into a double-network gelatin methacryloyl (GelMA) hydrogel microsphere platform for photothermal-chemotherapy. Monodisperse microspheres were fabricated via microfluidics and photocrosslinking to construct an MRI-visible biomaterial for pancreatic cancer treatment, enabling non-invasive, real-time tracking of both the material and therapeutic response. The microsphere morphology and photothermal performance were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), spectroscopy, and photothermal measurements, and a pancreatic cancer model was established for in vivo evaluation. Following in-situ injection of the hydrogel microspheres, serial MRI was performed to monitor intratumoral distribution and treatment outcomes. The microspheres exhibited an MRI contrast half-life of 32 h and supported continuous MR monitoring for 15 days, allowing clear visualization of tumor evolution. In addition, the system demonstrated favorable in vivo safety with no evident toxicity.