ACS Nano http://doi.org/9c3 (2015)

Engineered nanoparticles are of potential use in biomedical applications such as magnetic resonance imaging and drug delivery, but typically offer limited haemocompatibility. This means that, when intravenously injected, the nanoparticles are recognized by the immune system and mechanisms are put in place to reduce or completely eliminate their presence. Dmitri Simberg and colleagues at the University of Colorado, Jilin University, and the University of Copenhagen have now used magnetic nanoparticles to explore immune recognition mechanisms and identify ways to mitigate their effects.

The researchers examined the interaction between blood leukocytes, which are cells known to be involved in intercepting pathogens, and superparamagnetic iron oxide nanoparticles that had a worm-like shape and were coated with dextran chains (referred to as 'nanoworms'). Uptake of these nanoworms by leukocytes in both mice and human blood was found to be dependent on the complement system of proteins. Haemocompatibility of the nanoworms could, therefore, be improved by using inhibitors of the complement system. Simberg and colleagues also found that haemocompatibility could be improved through crosslinking and hydrogelation of the dextran on the surface of the nanoworms.