A UK collaboration between the University of Liverpool and the University of Nottingham has resulted in the development of polymer-coated magnetic nanoparticles that change solubility properties in response to heat. 

The team, led by Nguyen Thanh at the University of Liverpool, used thermo-responsive polymers to synthesise Co and gamma-Fe2O3 magnetic nanoparticles. These polymers are hydrophobic at high temperature and so can be used to synthesise nanoparticles in organic solvents at high temperature. Upon cooling, the polymers change their shape and become hydrophilic, therefore allowing the nanoparticles to dissolve in water. 'This approach provides the means to harness many different nanomaterials for biology and medicine,' says Thanh. 

Such magnetic nanoparticles may have potential therapeutic application by binding agents such as anionic DNA or hydrophobic anti-cancer drugs to the polymer. The magnetic nanoparticles could then be directed to a specific site by using a magnetic field. Subsequent induction of a change in temperature and/or pH would allow the controlled release of the therapeutic agent at the site of action. 'The sensitivity of the polymer to acidity and temperature provides further means to exploit magnetic nanomaterials in sensing, tracking stem cells and magnetic resonance imaging,' says Thanh. 

Kathleen Too