Electrospun nanofibers for customized drug-delivery systems

Nanofiber-based drug-delivery systems are widely applicable for specific drug release, according to the target location and timing, to achieve the desired therapeutic effects. A nanofiber formulation is usually developed for a specific drug, and a change of drug can drastically affect the release kinetics from the same delivery system. Here, we review the various types of nanofibers from the latest available literature, based on their composition and drug-release properties. Nanofibers are characterized according to their mode of drug release, and according to their structure and composition. Nanofibers designed for immediate drug release have generally simple structures. A suitable polymer, large surface-to-volume ratio, and high porosity of the nanofiber mesh are exploited to achieve immediate drug release. Nanofibers for modified drug release are classified here according to their drug-release characteristics, as prolonged, stimulus-activated, and biphasic. In general, swellable or degradable polymers are used to modify the drug release. As well as the selection of the polymer, the process and environmental conditions can significantly influence the release properties of nanofibers. The formulation of nanofibers is very complex and depends on many variables, although at the same time, the design of the formulation offers many opportunities to achieve the desired nanofiber drug-release properties.