A robust and refillable magnetic sponge capsule for remotely triggered drug release

Numerous different delivery systems have been developed for local administration of drugs. However, their service lives generally depend on the payload depletion time and most of them are designed for one time use due to lack of drug replenishment abilities. To address this issue, a refillable magnetic porous polydimethylsiloxane (PDMS) capsule is proposed for remotely controlled drug delivery applications. An inner cavity is built in the sponge scaffold to provide space for drug storage and the refilling is accomplished by injecting drugs with a syringe. The rapid and reversible deformation of the magnetic porous structure under a magnetic field offers a controlled pumping force to push drugs out of the capsule. In this work, low molecular weight (methylene blue, MB, 320 g mol^-1) and high molecular weight (bovine serum albumin, BSA, 67 000 g mol^-1) molecules were used as model compounds to test and verify the operational principle. This proof-of-concept study has demonstrated the capability of the refillable porous capsule in controlled drug delivery under external magnetic stimuli.