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 <i>in vitro</i> gastrointestinal (GI) simulation environment, a common approach for colon-targeted drug delivery. This design also endowed the microrobot with the ability to achieve <i>in vitro</i> 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 <i>in vitro</i>, 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 <i>in vitro</i> intervention. The <i>in vitro</i> 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.