Drugs and cells can be delivered on demand by a porous material engineered to compress in response to an applied magnetic field.
David Mooney at Harvard University in Cambridge, Massachusetts, and his team prepared an alginate-based gel with micrometre-sized pores, and paramagnetic iron nanoparticles embedded throughout. On exposure to a magnetic field, the nanoparticles put the squeeze on the ferrogel. The authors used this to release a drug payload in in vitro experiments and, by implanting the gel into mice, for localized release of dye-stained stem cells.
With a reversible volume reduction of more than 70% (pictured), such ferrogels may also find applications as actuators and sensors in biomedical applications.
NATL ACAD. SCI.