Near-infrared light heats water molecules inside polymer particles, triggering the tiny capsules to deliver payload

To deliver drugs at a certain time and place inside the body, scientists have been developing tiny particles that release their cargo when triggered by infrared light. Capable of penetrating human tissue, this light heats metals or activates designer photosensitive polymers at a particle’s core to set off delivery. Looking for a release mechanism that’s less reliant on a particle’s composition, a research team at the University of California, San Diego, has for the first time released cargo from particles by using hot water (ACS Nano 2014, DOI: 10.1021/nn500702g). The scientists, led by Adah Almutairi, focused 980-nm laser light onto hydrated particles made of a commercially available biodegradable polymer called poly(lactic-co-glycolic acid) (PLGA). Because that laser wavelength excites vibrations in water absorbed inside the particles, the spheres heat up, soften, and discharge molecules embedded within. The team demonstrated that this strategy works when the particles are in a water-based solution and when they are inside cells. According to Christopher Bettinger, a materials scientist at Carnegie Mellon University, this is a clever technique, and because it uses simple materials, “it has the potential to make a large impact on the controlled release of therapeutics.”