Controlling the independent release of multiple drugs with nanotechnology

Nanotech could make possible the controlled release within the patient of up to four different drugs by irradiation with different wavelengths of near-infrared radiation. Near-IR light passes through human flesh to release drugs within the body. In a proof-of-concept experiment, two different DNA oligonucleotides were loaded on gold nanorods of two different shapes. Because the two different shaped-nanorods have different surface plasmon resonance peaks, radiation of an IR laser of 800-nm wavelength melted one type of nanorod and released one type of DNA oligonucleotide, while irradiation with a 1100-nm laser melted the other type and released the other DNA nucleotide. The released oligonucleotides were still functional. From MIT News Office, written by Anne Trafton “Gold particles deliver more than just glitter, Nanoparticles could carry drugs to treat cancer, other diseases

Using tiny gold particles and infrared light, MIT researchers have developed a drug-delivery system that allows multiple drugs to be released in a controlled fashion.

Such a system could one day be used to provide more control when battling diseases commonly treated with more than one drug, according to the researchers.

“With a lot of diseases, especially cancer and AIDS, you get a synergistic effect with more than one drug,” said Kimberly Hamad-Schifferli, assistant professor of biological and mechanical engineering and senior author of a paper on the work that recently appeared in the journal ACS Nano [abstract].

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.

The bag of tricks that ingenious experimenters have engineered into a wide range of nanoparticle drug delivery systems is becoming increasingly impressive. We eagerly await clinical trials to sort out which combinations of nanoparticles, control strategies, and associated targeting, imaging, and therapeutic molecules prove to be most useful for which diseases. (Credit:

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