Preparation and properties of vancomycin-loaded PLA-PEG-PLA microspheres by electrostatic spray technology

Vancomycin in sustained release still needs to be investigated. Polylactic acid (PLA) was widely used in the biomedical field for its good biocompatibility, especially in the field of controlled drug release. In this study, polyethylene glycol (PEG) was used to modify PLA to improve the hydrophilicity of the material. The synthesis of the block copolymers was proven by infrared and nuclear magnetic characterization and the hydrophilicity was tested. Vancomycin was immobilized by coaxial electrospray, and PLA-PEG6000-PLA was used as the shell layer. The parameters of coaxial electrospray under this material were explored, and the effects of concentration, voltage and temperature on the formation of microspheres were systematically studied. The optimum parameters were determined as follows: concentration 20 wt%, temperature 35 °C and voltage 14 kV. The maximum encapsulation rate and drug loading were calculated to be 89.54 ± 1.22 % and 15.33 ± 0.97 %, respectively, and the cumulative release of drug-loaded microspheres was less than 45 % in 24 h with a slow releasing time of more than one month. The drug loaded microspheres showed good sustained release and good control of burst release.