Nanoparticles cross blood-brain barrier for 'brain tumour painting'

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Washington, Aug 4 (ANI): In a new research, scientists have succeeded in illuminating brain tumours by injecting fluorescent nanoparticles into the bloodstream that safely cross the blood-brain barrier-an almost impenetrable barrier that protects the brain from infection.

The study by University of Washington researchers revealed that the nanoparticles remained in mouse tumours for up to five days, and did not show any evidence of damaging the blood-brain barrier.

The results showed that the nanoparticles improved the contrast in both MRI and optical imaging, which is used during surgery.

"Brain cancers are very invasive, different from the other cancers. They will invade the surrounding tissue and there is no clear boundary between the tumour tissue and the normal brain tissue," said lead author Miqin Zhang, a UW professor of materials science and engineering.

Being unable to distinguish a boundary complicates the surgery, while severe cognitive problems are a common side effect.

"If we can inject these nanoparticles with infrared dye, they will increase the contrast between the tumour tissue and the normal tissue. So during the surgery, the surgeons can see the boundary more precisely. We call it 'brain tumour illumination or brain tumour painting'. The tumour will light up," said Zhang.

Further, she said that nano-imaging could also help with early cancer detection.

Current imaging techniques have a maximum resolution of 1 millimetre, and nanoparticles could improve the resolution by a factor of 10 or more, allowing detection of smaller tumours and earlier treatment.

To date, no nanoparticle used for imaging has been able to cross the blood-brain barrier and specifically bind to brain-tumour cells.

With current techniques doctors inject dyes into the body, and use drugs to temporarily open the blood-brain barrier, risking infection of the brain.

The researchers overcame the challenge by building a nanoparticle that remains small in wet conditions-the particle was about 33 nanometers in diameter when wet, about a third the size of similar particles used in other parts of the body.

Crossing the blood-brain barrier depends on the size of the particle, its lipid, or fat, content, and the electric charge on the particle.

Zhang and colleagues built a particle that can pass through the barrier and reach tumours.

To specifically target tumour cells they used chlorotoxin, a small peptide isolated from scorpion venom that scientists are exploring for its tumour-targeting abilities.

On the nanoparticle's surface Zhang placed a small fluorescent molecule for optical imaging, and binding sites that could be used for attaching other molecules.

Zhang said that future research would evaluate this nanoparticle's potential for treating tumours,

Her team has already showed that chlorotoxin combined with nanoparticles dramatically slows tumours' spread.

And they will see whether that ability could extend to brain cancer, the most common solid tumour to affect children.

The study has been published in the journal Cancer Research. (ANI)

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