For years, scientists have been striving to develop localized treatments to reduce side effects of therapeutic drugs. Unwanted symptoms are often the result of medicine going where it's not needed and harming healthy cells.
Scientists 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. 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. It can't penetrate body tissues, and it is carcinogenic.
Near-infrared (NIR) light can go through one to two centimeters of tissue and would be a safer alternative, but photosensitive drug-carriers don't react to it. 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.