Soft Magnetic Microrobots for Photoactive Pollutant Removal.

"Soft" robotics based on hydrogels appears as an alternative to the traditional technology of "hard" robotics. Soft microrobots are employed for drug delivery and cell manipulation. This work develops magnetic hydrogel-based microrobots using chitosan (CHI) as the body of the micromotor and Fe 3 O 4 nanoparticles to allow for its magnetic actuation. In addition, ZnO nanoparticles are incorporated inside the CHI body of the microrobot to act as an active component for pollutants photodegradation. CHI@Fe 3 O 4 -ZnO microrobots are used for the efficient photodegradation of persistent organic pollutants (POPs). The high absorption of CHI hydrogel enhances the POP photodegradation, degrading it 75% in just 30 min. The adsorption-degradation and magnetic properties of CHI@Fe 3 O 4 -ZnO microrobots are used in five cycles while maintaining up to 60% photodegradation efficiency. The proof-of-concept present in this work represents a simple way to obtain soft microrobots with magnetic actuation and photodegradation functionalities for several water purification applications.