Self-folded microrobot for active drug delivery and rapid ultrasound-triggered drug release

Abstract The concept of an active drug delivery and controlled drug release using microrobot system has attracted attention over the past decade. However, developing these microrobot system is hindered by the low drug release rate upon external stimuli, such as an alternating magnetic field or light, with a long stimulation period (>40% release upon 10 min stimulation). This study evaluated using self-rolled helical microrobots to provide a controlled drug delivery system that uses magnetic manipulation and provides for highly efficient drug release. The rapid and simple fabrication of helical microrobots that change shape upon exposure to protic/aprotic stimuli was demonstrated using a single-layer self-folding technique. The self-folded helical microrobots navigated in the desired direction using a rotating magnetic field produced by an electromagnetic actuator. After arrival at the target location, non-covalently bonded anti-cancer drugs were released during a short period of ultrasound stimulation. The results demonstrate that, with 1 min of ultrasound stimulation, more than 90% of drug release was achieved. This efficient drug release system could enable the practical application of a microrobot-based drug delivery system.