Intrinsically fluorescent bioactive glass-poly(ester amide) hybrid microparticles for dual drug delivery and bone repair

The bone extracellular matrix (ECM) is a composite scaffold having inorganic hydroxyapatite and organic collagen fibers. Synthetic bone repair scaffolds that mimic the chemical composition of the native ECM and capable of delivering therapeutics are beneficial. In this study, we prepared intrinsically fluorescent organicinorganic hybrid microparticle biomaterials by sol-gel process. Unlike the conventional Stober process which requires an alkaline condition for microparticle formation, an acidic condition in the presence of a biodegradable poly(ester amide) (PEA) polymer was used to prepare silica and tertiary bioactive glass hybrids. During their preparation, one or two model drugs were loaded in the microparticles. Our results showed that a gelation temperature between 40 degrees C-60 degrees C and the inclusion of PEA were critical for microparticle formation. Unexpectedly, the hybrid microparticles were fluorescent with tunable emission by changing the excitation wave-lengths ranging from 300 to 565 nm for potential multiplex imaging. Gene expression studies showed that the hybrid materials induce osteogenic differentiation of 10T1/2 cells without adding exogenous biochemical factors. The bioactivity of the inorganic phase and the dual drug release from homogenous, biodegradable, biocompatible, osteoinductive, and intrinsically fluorescent microparticles may offer a unique platform for bone regeneration and therapy.