The brain presents a host of delivery issues, not least that drug-embedded nanoparticles often stick to their surroundings therefore blocking the therapy from spreading out in the organ.
Challenges have been particularly problematic for oncology treatments issued after brain tumour surgery, because it is difficult to administer enough chemotherapy to penetrate the tissue but not so much that it poses a health threat.
But now using a drug-loaded nanoparticle coated with “non-stick” polyethylene glycol (PEG) the researchers believes the particles will interact less with their environment, and will hence travel deep into the brain.
In previous studies, the PEG coating has also been found to protect nanoparticles from the body's defense mechanisms, providing a sustained release of up to three times as long as those without PEG.
Furthermore the study, published in Science of Translational Medicine journal, found that the coating allowed delivery of bigger nanoparticle structures than ever thought possible in the brain – some almost twice the size of the previously-thought maximum.
“Nanoparticles as large as 114 nm in diameter [around 1000th the diameter of a human hair] diffused within the human and rat brain, but only if they were densely coated with PEG,” said the research team, led by Justin Hanes, director of the Johns Hopkins Center for Nanomedicine.
“Using these minimally adhesive PEG-coated particles, we estimated that human brain tissue ECS has some pores larger than 200nm and that more than one-quarter of all pores are around 100nm.”
The additional finding means the particles could carry up to five times more therapy than their smaller counterparts.
"It's really exciting that we now have particles that can carry five times more drug, release it for three times as long and penetrate farther into the brain than before," added Elizabeth Nance, a graduate student working on the project.
The tech has so far only been applied to rodent and human tissue, however the team now plans to move the studies in vivo.
Hopkins neurosurgeon Graeme Woodworth said they "also wants to optimize the particles and pair them with drugs to treat other brain diseases, like multiple sclerosis, stroke, traumatic brain injury, Alzheimer's and Parkinson's."