Polymeric drug delivery systems are designed to encapsulate therapeutic agents and provide their release in a predesigned manner.The main purpose for controlling the drug delivery process is to achieve more effective therapies.We focus on biodegradable double-walled microspheres fabricated by coaxial electrohydrodynamic atomization (CEHDA) technique and tailor them with well-controlled release rates and profiles.New techniques to form double-walled microspheres may offer several advantages in drug delivery,including:i) low initial burst release,ii) improved drug stability,iii) tunable drug release by the variation of the shell/core material(s) or thickness,and iv) enhanced drug efficacy by releasing multiple drugs in core/shell phases in various stages.