Microparticles Use Only Magnetic Fields for Navigation, Release of Therapeutics

Tiny therapeutic particles already exist that can be externally guided toward their destination and that can be triggered to release their cargo precisely where needed. Yet, they’ve all required two different energy sources to be used, often magnetism for navigation and near-infrared to open up the cargo doors. Now researchers at ETH Zurich in Switzerland have reported in journal Materials Horizons on new microparticles that use an external magnetic field for propulsion and guidance while being able to generate a local electric field from changes in the external magnetic field. This electric field is then used to release a drug, imaging agent, or some other compound stored within the particle’s interior.

The SiO₂ microspheres have a cobalt ferrite-barium titanate composite coating them. The magnetic field pulls on the iron and can drag the particle along. But, if  a specific pulse of the magnetic field is delivered over the particle, the bilayer warps and changes its volume, creating stress within the piezoelectric layer of the coating. This generates a tiny bit of electricity that is effectively a different kind of energy source that can be used to power the release of cargo or some other process within the microscopic device.

From the study abstract:

Here, we demonstrate this concept employing magnetoelectric Janus particle-based micromachines, which are fabricated by coating SiO₂ microspheres with a CoFe₂O₄–BaTiO₃bilayer composite. While the inner magnetic CoFe₂O₄ layer enables the micromachines to be maneuvered using low magnitude rotating magnetic fields, the magnetoelectric bilayer composite provides the ability to remotely generate electric charges upon the application of a time-varying magnetic field. To demonstrate the capabilities of these micromachines, noble metals such as Au, Ag and Pt are magnetoelectrochemically reduced from their corresponding precursor salts and form nanoparticles on the surface of the micromachines. Magnetoelectric micromachines are promising devices for their use as metal scavengers, cell stimulators and electric field-assisted drug delivery agents.

Study in Materials Horizons: Magnetoelectric micromachines with wirelessly controlled navigation and functionality…

Via: ETH…