Researchers have designed a capsule shell polymer to liberate drugs from within the polymer in the presence of near-infrared (NIR) light.
This study has been done by a chemist, Adah Almutairi and collaborators, from University of California, San Diego and published September 30 issue of the journal Macromolecules.
Researchers have developed a polymer that degrades after absorption of NIR light. This study is based on the commercially available NIR-absorbing group called o-nitrobenzyl (ONB). ONB groups fall off the polymer upon absorbing the light but it is only an NIR absorber and can be toxic to cells after detaching from polymer.
Researchers strung together a long chain of small ring-containing compounds called cresol groups in polymer. They used the highly unstable property of cresol in its polymeric form although it contains reactive components. After polymerization of the cresols, the reactive components were capped with light absorbing compound called as Bhc. Upon absorption of NIR light, the reactive groups are revealed and break the long polymer into two short chains. More light causes more breakdown leading to the release of drugs in the polymer.
In the study, researchers found that Bhc can absorb NIR 10 times better than ONB and is nontoxic to cells.
This research has its importance as NIR light passes through the tissues in large amount. On the other hand, ultraviolet (UV) or visible light can liberate the drugs from tissues only near the skin.
Nadezda Fomina, Cathryn L. McFearin, Marleen Sermsakdi, José M. Morachis, and Adah Almutairi, (2011). Low Power, Biologically Benign NIR Light Triggers Polymer Disassembly. Macromolecules, DOI: 10.1021/ma201850q