A Soft Biodegradable Chitosan-Based Medical Microrobot with Optimized Structural Design and X-Ray Visibility for Targeted Vessel Chemoembolization

Although many medical microrobots have been developed for treating diseases, their designs have not been optimized for disease environments and their functionality and capabilities have been primarily demonstrated in vitro. In addition, the imaging of microrobots within blood vessels in deep tissues remains a challenge. Herein, a chitosan-based biodegradable microrobot with optimized structural design and X-ray imaging for targeted vessel chemoembolization is reported. The design of the microrobot takes into account its magnetizability and stackability in blood vessels. The microrobot is prepared through laser micromachining of a porous chitosan sheet, attachment of nanoparticles, and filling the pores with gelatin. The optimized microrobot is biocompatible, biodegradable, thrombogenic, magnetically targetable, and drug-loadable, as demonstrated both in vitro and in a blood vessel phantom. X-ray imaging of the gold nanoparticle-attached microrobots compares well with using commercial iodinated contrast materials, thereby demonstrating their real-time long-term X-ray imaging capability. The in vivo real-time imaging and targeted vessel embolization of the microrobot are demonstrated in rat liver. The proposed microrobot overcomes the limitations of embolic microbeads currently used in targeted vessel chemoembolization (i.e., targeted vessel blocking and X-ray visibility) and expands the capability of microrobots in advanced platforms for treating human diseases.