Nanoparticles triggered by convertible NIR light show promise for targeted drug delivery

Newly developed nanoparticles that release a drug when exposed to NIR light allow medicine to go only where needed.

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A team of researchers at McGill University (Montreal, QC, Canada) has developed nanoparticles that only release a drug when exposed to near-infrared light, which doctors could beam onto a specific site within, for example, a cancerous tumor. The approach allows medicine to go only where needed and without harm to healthy cells.

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Scientists have long been striving to develop localized treatments to reduce side effects of therapeutic drugs. They have designed drug delivery systems that respond to light, temperature, ultrasound, and pH changes. One promising approach involved drug-carrying materials that are sensitive to ultraviolet (UV) light, as shining a beam in this part of the light spectrum causes the materials to release their therapeutic cargo at a designated location. But UV light has major limitations, as it cannot penetrate body tissues and is carcinogenic. Near-infrared (NIR) light can go through 1–2 cm of tissue and would be a safer alternative, but photosensitive drug carriers don't react to it. So McGill University engineering professor Marta Cerruti and colleagues sought a way to bring the two kinds of light together in one possible solution.

The researchers started with nanoparticles that convert NIR light into UV light and coated them in a UV-sensitive hydrogel shell infused with a fluorescent protein, a stand-in for drug molecules. When exposed to NIR light, the nanoparticles instantaneously converted it to UV, which induced the shell to release the protein payload. The researchers note that their on-demand delivery system could not only supply drug molecules, but also agents for imaging and diagnostics.

Full details of the work appear in the Journal of the American Chemical Society; for more information, please visit http://dx.doi.org/10.1021/jacs.5b12357.

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