Oxygen-releasing polycaprolactone/calcium peroxide composite microspheres

Oxygen-releasing polycaprolactone/calcium peroxide (PCL/CaO₂ ) composite microspheres were fabricated via homogenization, electrospray with a single nozzle, and electrospray with a co-axial nozzle, resulting in homogenized, single-walled, and double-walled microspheres, respectively. Scanning electron microscopy revealed that homogenized microspheres had pores, while electrosprayed microspheres did not. Alizarin Red S staining showed a core-shell structure for double-walled microspheres. In a hypoxia incubator, single-walled, double-walled, and homogenized microspheres could maintain oxygen tension in PBS at or above 10% for approximately 5, 4, and 3 days, respectively. All the PCL/CaO₂ microspheres could support viability of pancreatic β-cell line MIN6 cells in 2D cultures in a hypoxia incubator for 1 week, with the cells supported by double-walled and homogenized microspheres exhibiting the highest and the lowest metabolic activity, respectively. For 3D MIN6 cell cultures in a hypoxia incubator, single-walled and homogenized PCL/CaO₂ microspheres led to the highest and the lowest live cell densities, respectively. Double-walled and single-walled microspheres provided the best support for 2D and 3D cultures, respectively, suggesting that they are suitable for different applications.