Development of a magnetically driven microrobot covered with a time-dependent film for colon drug delivery

Oral administration is an ideal method for drug delivery, but achieving targeted drug delivery to the colon remains a challenge. In this study, a magnetic microrobot incorporating a colon-specific method was developed, featuring both time-dependent and magnetically driven functions. With the help of commercially available enteric-coated capsules, this microrobot functioned like a pH- and time-dependent sequential trigger system in an in vitro gastrointestinal (GI) simulation environment, a common approach for colon-targeted drug delivery. This design also endowed the microrobot with the ability to achieve in vitro targeted drug delivery without the need for external control. However, in some cases, the complexity and variability of the GI tract may lead to ineffectiveness in colon-specific methods. With internally sealed neodymium-iron-boron (NdFeB) N52 magnets, the microrobot tumbled on the intestinal surface in vitro, demonstrating good controllability and speed. This means that the microrobot can be controlled by a rotating magnetic field when the colon-specific method fails, offering the possibility of in vitro intervention. The in vitro results indicated that this magnetic microrobot, which incorporates a colon-specific method, holds promise as a drug-delivery platform with reduced control costs and enhanced targeting capabilities.