Biodegradable Citrate-Based Polymers Enable 5D Monitoring of Implant Evolution

Biodegradable tissue engineering scaffolds have garnered increasing interest for their role in providing mechanical support, promoting tissue regeneration, and eliminating the need for removal. However, the in vivo degradation processes remain challenging to track. Here, a novel biodegradable polymer, N-methyldiethanolamine (MDEA) and Gadolinium(III) diethylenetriamine pentaacetate (Gd-DTPA) modified biodegradable photoluminescent polymers (BPLPMGd), which combines near-infrared (NIR) fluorescence and magnetic resonance (MR) dual-modality imaging are introduced to monitor scaffold degradation in vivo. The chemical structure of BPLPMGd is characterized and its dual-imaging properties in vitro are evaluated. Subsequently, non-invasive dual-modality imaging to track the degradation of implanted BPLPMGd scaffolds is performed in a rat model, comparing these results with histological data. This approach reveals that BPLPMGd enables reliable non-invasive tracking of the degradation, where NIR fluorescence imaging offers a qualitative and quantitative analysis of scaffold mass loss, total volume and solid content changes, while magnetic resonance imaging (MRI) details structural and morphological changes, allowing for 5D monitoring of implant degradation, including 3D structure, location, mass, volume, and geometry. The combination of these imaging modalities provides a comprehensive view of scaffold degradation, where the synergistic use of both yields results greater than either modality alone, offering unprecedented 5D information of implantable devices. This innovative approach has potential applications in regenerative engineering and beyond.