Small 6, 1388–1392 (2010)

Removing toxins or other disease-causing substances from the blood is an attractive alternative to using drugs. One example is haemodialysis, which is the removal of waste products such as urea and creatinine from the blood of patients with kidney failure using semipermeable membranes. Dialysis is useful for filtering out compounds with low molecular weight but not other large and harmful biomolecules. Now, Wendelin Stark and co-workers at various institutes in Switzerland show that magnetic nanoparticles injected into blood can remove compounds with both low and high molecular weight.

Stark and colleagues synthesized carbon-coated iron carbide magnets (mean diameter ∼30 nm) and functionalized them with either chelators that can remove metals, or antibodies that recognize specific proteins and inflammatory substances in the blood. Fresh human blood was spiked with different substances to model different intoxication or disease scenarios before adding the nanomagnets for about five minutes. After removing the magnets, blood was analysed for remaining toxins or substances. The method effectively removed lead ions, digoxin (a cardiac drug) and an anti-inflammatory substance (interleukin-6) that plays a role in the development of arthritis. Blood integrity remained intact; no clotting occurred and clinically relevant levels of ions and other substances remained in the normal range.

Although the method is promising for treating intoxications, several parameters, including the quantity of magnets required, need to be optimized in an in vivo model.