High-voltage, electric field-driven micro/nanofabrication for polymeric drug delivery systems

One of the major challenges in drug delivery is to provide an appropriate dosage of therapeutic agents at the right time to the right location. The therapeutic agents include small molecules, macromolecules, nanoparticles, and cells, whose sizes range from less than 0.5 nm to 20 mum. Major noninvasive routes of administration include oral, pulmonary, and transdermal drug delivery. Transport barriers associated with these drug delivery routes prevent the delivery of appropriate dosage of therapeutic agents to the right location. Size is one of the determining factors for drug delivery systems. Polymeric microstructured or nanostructured systems show a great potential to stabilize therapeutic agents and overcome transport barriers by controlling the size and surface properties. A high-voltage electric field can be imposed on a polymer liquid to form microcapsules, to produce nanoparticles through electrospray or electrostatic assembly and to fabricate nanofibers through electrospinning. The addition of an electric field results in charging the components of the system and the resulting electrostatic interactions. Because electrostatic forces become meaningful at the nanoscale, electrostatic technologies attractmuch attention in microfabrication or nanofabrication [1]. There are several recent review articles available for microencapsulation [2], [3], electrospray [4], and electrospinning [5]-[9]. However, very few have investigated connections among all these processes. The major objectives of this article are to discuss mechanisms behind these electrostatic processes and explore connections among these techniques that can lead to the design and fabrication of specific drug delivery systems using an electrostatic generator.