Posted by: Hourglass PJ16 APR 2014
Controlled drug delivery systems such as nanoparticles have some advantages compared with traditional formulations. A drug is transported to the site of action using, for example, nanoparticles as carriers, with the result that the required dose may be lower. The potential for side effects from the drug is also minimised because of the facility to target the therapy, although challenges remain with regard to potential toxicity from the nanoparticles themselves since they may be delivered into the cell along with the drug molecule.
Researchers are looking for ways to deliver drugs to cells without the accompanying nanoparticles and one of the newest methods, reported in the journal ACS Nano, describes the use of near-infrared (NIR) light to activate drug-delivering nanoparticles inside the body and release the drug where needed. NIR-triggered release is not brand new but methods developed to date have not been widely applied because, among other things, they depend on the use of special polymers, encapsulating materials whose safety is uncertain and expensive, high-powered lasers.
This latest technology, which has been developed by researchers from the Skaggs School of Pharmacy in California in collaboration with others, uses a low-powered laser to deliver NIR light at a wavelength of 980nm to heat pockets of water trapped within hydrated polymer particles. The water pockets absorb the light energy as heat, which softens the polymer and allows the drug to be released into the surrounding tissue.
The researchers say that this technique potentially resolves many of the problems associated with previous attempts to use NIR light to deliver drugs contained in nanoparticles to target tissues. This technique allows controlled release of drugs into tissues and aqueous environments without significantly heating the surrounding aqueous environment.
The selective heating can be compared to putting a glass of water inside a bath of water and heating the water inside the glass. The water inside the glass is heated much more rapidly because of its smaller volume.