Encapsulation of active species is an important technical issue to be applied to a variety of practical areas such as drug delivery, nutraceuticals carrier, pesticide delivery, prolonged computed tomography (CT) contrasting agent, corrosion inhibition, and energy storage. For instance, in drug delivery, the active species in a drug are often decomposed before reaching to a desired zone in a body. Therefore, a new drug delivery system based on encapsulation may minimize degradation of active drug species, prevent harmful side effects, and increase drug bioavailability. Various encapsulating materials such as polymers, liposomes, dendrimers, and carbon nanotubes (CNTs) have been investigated.