Degradable silk-based soft actuators with magnetic responsiveness

This study reports the fabrication of degradable, protein-based soft actuators composed of regenerated silk fibroin, glycerol plasticizer, and magnetic Fe₃O₄ nanoparticles. The resulting magnetic silk films exhibited high stretchability (>200% strain under wet conditions), tissue-matching stiffness (~5 MPa), enzymatic degradability, and excellent biocompatibility in vivo. Through thermal forming and welding, the films were converted into three-dimensional soft actuators capable of controlled locomotion under external magnetic fields. The authors further demonstrated X-ray visibility, subcutaneous biocompatibility, and magnetically guided retention and localized drug delivery in gastrointestinal model systems, highlighting the potential of silk-based magnetic actuators for minimally invasive biomedical applications.