Microfluidic Synthesis and Angiogenic Activity of Ginsenoside Rg-Loaded PPF Microspheres.

Next generation drug-loaded polymer scaffolds for hard tissue engineering require unique structures to enhance release kinetics while enabling bone cell growth (osteogenesis). This study examined the encapsulation of the pro-angiogenic mediator, ginsenoside Rg, into biodegradable poly(propylene fumarate) (PPF) microspheres to facilitate osteogenesis, while examining the release mechanism using advanced X-ray absorption near edge structure spectroscopy (XANES). Ginsenoside Rg-loaded PPF microspheres were prepared using both an emulsion method and a microfluidic device, with the microfluidic technique providing tunable unimodal PPF spheres ranging in size from 3 to 52 μm by varying the flow rates. The morphology and composition of the Rg-loaded PPF microspheres were characterized using FTIR, XRD, and XANES to examine the distribution of ginsenoside Rg throughout the polymer matrix. Encapsulation efficiency and release profiles were studied and quantified by UV-Vis spectrophotometry, showing high encapsulation efficiencies of 95.4 ± 0.8% from the microfluidic approach. Kinetic analysis showed that Rg release from the more monodisperse PPF microspheres was slower with a significantly smaller burst effect than from the polydisperse spheres, with the release following Fickian diffusion. The released Rg maintained its angiogenic effect , showing that the PPF microspheres are promising to serve as vehicles for long-term controlled drug delivery leading to therapeutic angiogenesis in bone tissue engineering strategies.