Optimizing release dynamics of bone-derived nanoparticles for enhanced <i>in vivo</i> fluorescence monitoring and bone regeneration in craniofacial repair

Craniofacial bone defects, particularly alveolar clefts, pose significant clinical challenges in pediatric patients due to complex anatomy and the limitations of current grafting options. Although autologous bone grafts remain the clinical gold standard, their use is restricted by donor-site morbidity, limited tissue availability, high cost, and risks such as infection, chronic pain, and functional impairment. Decellularized and demineralized bone matrix (DDBM) offers an attractive alternative but lacks controlled drug-release capability and cannot be monitored in real time in patients. To address these limitations, we developed indocyanine green-encapsulated bone-derived nanoparticles (ICG/BPs) from porcine DDBM, combining the intrinsic osteoinductive and osteoconductive properties of DDBM with near-infrared (NIR) imaging functionality. In this study, we fabricated two ICG/BP formulations , crosslinked (X-ICG/BP) and uncrosslinked (UnX-ICG/BP), and compared their in vitro degradation, release profiles, and in vivo performance in a rat model of cavity-type alveolar defects. Crosslinking improved particle stability and prolonged ICG release, and NIR imaging enabled real-time, non-invasive monitoring of particle degradation and retention within the defect. Additionally, both ICG/BP formulations supported bone regeneration, with X-ICG/BPs demonstrating greater regeneration, tissue organization, and vascularization. Overall, these findings highlight the tunability and theranostic potential of ICG/BPs and support their continued development as an image-guided functional biomaterial for craniofacial bone repair.