Polymer microsphere for water-soluble drug delivery via carbon dot-stabilizing W/O emulsion

Emulsions, usually oil-in-water emulsions, have been widely applied to the preparation of hydrophobic drug carriers. However, the synthesis of safe, biocompatible and high-performance carriers for water-soluble drugs remains a challenge. So polyacrylamide (PAM) microspheres stabilized by carbon dots (CDs) were fabricated via a water-in-oil Pickering emulsion without the use of any surfactant. The PAM/CD microspheres were spherical with an even distribution of the CDs on their surfaces. The size of the microspheres can be controlled by changing the amount of CDs, which also influenced the drug loading properties. The hydrophilic chemotherapy drug, 5-fluorouracil (5-FU), was successfully loaded into the PAM/CD microspheres through incubation. The encapsulation efficiencies ranged from 68 to 82% with a maximum drug loading of 48%. The 5-FU release profiles depended on the concentration of the drug incubation solution, the concentration of the CD solution and the pH of the drug release environment. The release of 5-FU was relatively steady for the first 12 h and followed non-Fickian diffusion kinetics. This synthetic approach could be extrapolated to loading of other water-soluble drugs into hydrophilic polymers.