Photocleavable Hydrogel-Coated Upconverting Nanoparticles: A Multifunctional Theranostic Platform for NIR Imaging and On-Demand Macromolecular Delivery. Lanthanide-doped upconverting nanoparticles (UCNPs) have emerged as excellent nanotransducers for converting longer wavelength near-infrared (NIR) light to shorter wavelengths spanning the UV to visible (Vis) regions of the spectrum via a multiphoton absorption process, known as upconversion. Here, we report the development of NIR to UV–Vis–NIR UCNPs consisting of LiYF4:Yb3+/Tm3+@SiO2 individually coated with a 10 ± 2 nm layer of chitosan (CH) hydrogel cross-linked with a photocleavable cross-linker (PhL).
Some drug regimens, eg those designed to eliminate tumors, are notorious for nasty side effects. Unwanted symptoms are often the result of medicine going where it’s not needed and harming healthy cells. To minimize this risk, researchers in Quebec have developed nanoparticles that only release a drug when exposed to near-infrared light, which doctors could beam onto a specific site.
For years, scientists have 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 UV. 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 1 to 2 centimeters of tissue and would be a safer alternative, but photosensitive drug-carriers don’t react to it. McGill University Professor Marta Cerruti and colleagues sought a way to bring the 2 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. http://www.alphagalileo.org/ViewItem.aspx?ItemId=160213&CultureCode=en
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