Drug Delivery System Hits Gold

MIT researchers are reporting on a new multi-drug delivery system based on an interesting type of gold nanoparticles. Drugs attached to their surface are released when the gold nanoparticles dissolve after exposure to a specific frequency of infrared light. The infrared frequency is related to the nanoparticle shape and allows for the targeted release of drugs.
From the press release:

Delivery devices already exist that can release two drugs, but the timing of the release must be built into the device — it cannot be controlled from outside the body. The new system is controlled externally and theoretically could deliver up to three or four drugs.
The new technique takes advantage of the fact that when gold nanoparticles are exposed to infrared light, they melt and release drug payloads attached to their surfaces.
Nanoparticles of different shapes respond to different infrared wavelengths, so “just by controlling the infrared wavelength, we can choose the release time” for each drug, said Andy Wijaya, graduate student in chemical engineering and lead author of the paper.
The team built two different shapes of nanoparticles, which they call “nanobones” and “nanocapsules.” Nanobones melt at light wavelengths of 1,100 nanometers, and nanocapsules at 800 nanometers.
In the ACS Nano study, the researchers tested the particles with a payload of DNA. Each nanoparticle can carry hundreds of strands of DNA, and could also be engineered to transport other types of drugs.
In theory, up to four different-shaped particles could be developed, each releasing its payload at different wavelengths.

MIT press release: Gold particles deliver more than just glitter
Dr. Kimberly Hamad-Schifferli’s MIT Lab Website…
Image: The top image shows a mixture of gold nanoparticles. The longer particles are called nanobones, and the smaller are nanocapsules. Bottom left: After the nanoparticles are hit with 800 nanometer wavelength infrared light, the nanocapsules melt and release their payload. Nanobones remain intact. Right: After the nanoparticles are hit with 1100 nanometer wavelength infrared light, the nanobones melt and release their payload. Nanocapsules remain intact.