Magnetic field and pH synergy controls therapeutic burst

Australian researchers have shown how alternating magnetic fields could be used to localise the release of cancer-fighting drugs to cancer cells, limiting side effects in the rest of the body.

May Lim at the University of New South Wales, and colleagues, have devised a system where a magnetite (Fe3O4) nanoparticle is bound to a temperature-responsive polymer onto which drug molecules can be attached via Schiff base bonds.

Two simultaneous stimuli are necessary for rapid drug deployment – acidic conditions to break the chemical bonds between the polymer and the drug, and an alternating magnetic field to provide sufficient thermal energy to accelerate contraction of the polymer and trigger a therapeutic ‘burst’. As cancer cells are typically more acidic than healthy tissue, this innovative approach could enable drug release precisely when and where it is required, minimising damage to healthy cells.

A magnetic field combined with the acidic environment of cancer tissue results in rapid hydrolysis of the Schiff base bond

‘We envisage the nanoparticle–polymer composite will be injected into the affected tissue; this is how magnetic nanoparticle-based therapy is currently being administered,’ Lim tells Chemistry World.

‘Nanomedicine could be the key to deal with cancer as it is focused on targeted, personalised treatment,’ says to Cordelia Selomulya, a functional materials expert at Monash University in Australia. But could materials like this work in the body? ‘Here, the main component is magnetite which is FDA [the US Food and Drug Administration]-approved. If the composites can be shown to be non-toxic to healthy cells in vivo, then they could be adopted for medical applications. Of course the translation into medicinal applications, especially in humans, has strict requirements’.

Although the research is still at the proof-of-concept stage, the team are hopeful. Polymers similar to the one employed by the group have been shown to be safe and non-toxic, and are currently undergoing clinical trials. The group’s next task will be to decrease the size of the nanoparticles, whilst remaining responsive to magnetic field strengths and frequencies that are clinically relevant.


This paper is free to access until 2 May 2014. Download it here:

A Dunn et al, Polym. Chem., 2014, DOI: 10.1039/c4py00150h

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