A Soft Capsule for Magnetically Driven Drug Delivery Based on a Hard-Magnetic Elastomer Foam

Drug delivery systems based on porous soft biomaterialshave beenwidely reported because of stimuli-responsive drug release and theirinherent reservoirs for drug storage. Especially, magnetic-responsiveporous soft biomaterials achieve rapid and real-time control of drugrelease due to the magnetic field-triggered large deformation. However,the drug release profiles of these materials are difficult to predictand repeat, which restrict them from releasing drugs in the requireddosage. Here, we report a soft capsule based on a flexible hard-magneticelastomer foam (HEF) for magnetically controlled on-demand drug delivery.The HEF capsule contains an inner HEF and an outer elastomer shell.The HEF exhibits low elastic modulus (10 kPa) and highly interconnectedpores (81% interconnected pores). Benefitting from the novel precompressedmagnetization, the compressive deformation of HEF reaches 66%. Thus,an adjustable drug release rate ranging from 0.02 to 1.7 mL/min inthe HEF capsule is achieved. The deformation-triggered drug releaseprofiles of the HEF capsule under the magnetic field are accuratelypredicted, allowing 85% accuracy in drug dosage regulation and morethan 90% maximum cumulative drug release. Especially, the HEF capsuleis proven capable of acting as a soft robot to perform magneticallydriven drug delivery in a human stomach model. HEF can potentiallyserve as a soft robot for biomedical applications in the human body.