A physiological defence mechanism called the blood–brain barrier prevents toxins from entering the brain, but it also blocks molecules such as drugs and fluorescent dyes. Tara Spires-Jones at the Massachusetts General Hospital in Charlestown and her colleagues circumvented this problem by coating molecules with carbohydrate nanoparticles.
The researchers show that the nanoparticles allow imaging dyes, contrast agents and antibodies that normally cannot cross the blood–brain barrier to be rapidly delivered into the mouse brain. By injecting a nanoparticle-coated dye that binds to the protein plaques found in the brains of people with Alzheimer's disease, the authors visualized the plaques in a mouse model of the disease (pictured right, with arrow). This was not possible when using the dye alone (left).
The nanoparticles bind to a protein in the bloodstream called apolipoprotein E, which allows them to penetrate the blood–brain barrier without disrupting it.
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Getting past a brain block. Nature 479, 271 (2011). https://doi.org/10.1038/479271b
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DOI: https://doi.org/10.1038/479271b
