Scientists at UCSB have developed a nanoparticle-based drug delivery system that uses non-harmful lasers to send chemicals directly into cells, which may lead to improved drug efficacy and fewer side effects.

The method, which was published in the American Chemical Society’s journal ACS Nano, uses a pulse laser to deliver infrared light to the biological system, activating the nanoparticles and causing them to release their payload. According to Gary Braun, first author and a chemistry & biochemistry graduate student, the laser penetrates the skin but does not damage the body, because the pulse only affects the nanoparticles.

“By using a pulse laser, we have packets [of energy] absorbed by the nanoparticles. Almost all of the energy is injected into the particle,” Braun said. “The particle rises in temperature rapidly with minimal loss of energy to its surroundings. The inside material gets hot enough to disrupt the bonds in the particle, [resulting in the drug release].”

The particle consists of a gold nanoshell with a peptide-lipid coating, which can contain various drugs and targeting mechanisms. According to Braun, gold is used due to its stability and its reaction to pulses of infrared light.

The researchers tested the delivery of silencing ribonucleic acid (siRNA), a molecule that deactivates targeted genes by introducing the nanoparticles into a culture of cancer cells. When the area was exposed to the infrared laser, the particles released their payload into the cells.

Norbert Reich, a professor of chemistry & biochemistry and the senior author of the paper, said the laser trigger can greatly improve genetic research by allowing scientists to have more control over which genes are expressed in cells.

“This entirely novel tool will allow biologists to investigate how genes function by providing them with temporal and spatial control over when a gene is turned on or off,” Reich said in a press release. “In a nutshell, what we describe is the ability to control genes in cells — and we are working on doing this in animals — simply by briefly exposing them to a non-harmful laser.”

While infrared light is given off by many objects, such as the sun or hot objects, the threshold for activating the nanoparticles is high enough to protect the subject from unwanted activation of the mechanism, Braun said.

“The sun and incandescent bulbs, as well as anything hot, can give off infrared light,” Braun said. “But it’s not enough [to activate the nanoparticles.] … The nanoparticles require a pulse laser [to be triggered.]”

In the future, Braun said the researchers will look into attaching different peptides to the nanoshell, allowing them to control what type of cells the nanoparticles can enter as well as the drug payload that will be released once the laser is activated. The researchers also hope to test the delivery method in larger biological systems.

The paper received contributions from second author Alessia Pallaoro and collaborating authors Guohui Wu, Joseph A. Zasadzinski, Dimitris Missirlis and Matthew Tirrell.