Bifunctional biohybrid magnetically propelled microswimmer

Inspired by the intrinsic helical structures of vessels in banana leaves, a novel bifunctional biohybrid magnetic microswimmer with both environment remediation and biomedical application was synthesized by a simple chemical method. Here, spiral vessels isolated from banana leaves were used as biological templates, where nickel layers with magnetic properties and Fe 3+ -TA (tannic acid, TA) films with pH-dependent degradation capabilities were modified on their surfaces by simple chemical reactions in solution at room temperature. The obtained magnetic helical (Helix/Ni/Fe 3+ -TA) microswimmers can be efficiently propelled in either pollutant solution (rhodamine B, RhB) or biofluid solution (DMEM culture medium and fetal bovine serum) in the presence of a magnetic field. The developed Helix/Ni/Fe 3+ -TA microswimmers can be used to efficiently degrade organic pollutant RhB due to the Fe 3+ -TA films which can produce reactive oxygen species under the action of hydrogen peroxide (H 2 O 2 ). Moreover, due to the specific chemical interaction between the microswimmers and the surface of cancer cells, the microswimmers can precisely capture cancer cells and then produce heat under light irradiation to kill those cells. These novel helical microswimmers with simple and economic fabrication, efficient magnetic propulsion and diverse functionality show great potential in future environmental and biological applications.