Photoluminescent biodegradable polyorganophosphazene: A promising scaffold material for application to promote bone regeneration.

Tissue engineering scaffolds made of conventional aliphatic polyesters are inherently non-fluorescent, which results in their degradation hard to be visualized. Photoluminescent biodegradable polyorganophosphazenes (PPOPs) are synthesized by introducing fluorophores onto the polyphosphazene backbone via nucleophilic substitution reaction. In this study, a fluorophore (termed as TPCA), derived from citric acid and 2-aminoethanethiol, was co-substituted with alanine ethyl ester onto the polyphosphazene backbone to obtain a photoluminescent biodegradable POPP (termed as PTA). The scaffolds made of PTA demonstrated non-cytotoxicity and cell affinity, particularly, capacity in promoting osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs). evaluations using the rat calvarial defect model confirmed its strong potential in enhancing osteogenesis, more importantly, the degradation of the PTA scaffold could be monitored via its fluorescence intensity alongside implantation time.