The Golden Touch: CEAS Professor Uses Gold Nanoparticles to Control Drug Release

By:    Brandon Pytel
Date: March 22, 2018

A new study by UC chemical engineering professor Yoonjee Park, PhD, finds that nanodroplets coated in gold can lead to more effective drug release. 

Yoonjee Park headshot

Park studies new drug delivery systems.

Pills are becoming an outdated way to deliver medicine to patients. Patients prescribed pills have to remember to take them every day and get prescriptions refilled every week. Sometimes pills are even ineffective, unnecessarily attacking healthy cells.

Fortunately, with new drug delivery systems, doctors have several ways of delivering and activating drugs in patients. Recent research out of the University of Cincinnati (UC) studies the effect of a new drug delivery system using gold nanoparticles.

Rather than a person taking a pill every couple of hours, or even going to the hospital every month to activate a drug, this new modulated drug delivery system can deliver a drug into a body—through one single injection, for example—and then activate the drug on the spot using light.

“We can turn on and off the releases of the drug,” says Yoonjee Park, PhD, assistant professor of chemical and environmental engineering and corresponding author of the study. “We can save the drug when not needed, and we can release drug when it is needed.”

Using lasers, doctors and medical professionals can send near infrared light through a patient’s body and trigger the drug release. “Many doctors are familiar with lasers and if used safely, all people can use it,” says Park.

Gold nanoparticles make this instantaneous release possible. “Gold is highly responsive to light,” says Park. Gold nanorods coat an encapsulated liquid drug, called a nanodroplet. When the light from the lasers hits the nanodroplet, the gold nanorods absorb the light and heat up. The liquid within the droplet then turns into gas, releasing the drug.

“It’s like boiling water,” says Park. “If you boil water, the water turns to vapor. Gold generates lots of heat, which vaporizes liquid into gas.”

In the study, Park and her students tested the delivery system and the imaging agents in pig’s eyes. Injecting the nanodroplets in the eyes, she then used different lasers in a near-infrared region to release the drug and ultrasound imaging to measure that release.

before and after diagram of drug showing how light activates the drug.

Park's study uses light to heat gold nanorods, which leads to the drug release.

This delivery system is more effective than a traditional pill in several ways. With this technology, doctors and medical professionals can control the exact moment they release the drug, activating the drug when they need to with a laser.

This drug delivery system can also reduce negative side effects of drug therapy. With a controlled release of the drug, medical professionals can target the diseased area and reduce the effects the drug has on healthy tissues.

Just as importantly, doctors can now closely monitor the drug’s release using ultrasound imaging.

“The good thing about gas is that it dissolves fast,” says Park. “Gas is also an ultrasound contrast imaging agent: you can see the drug’s release noninvasively using ultra sound imaging modality. You know when and where the drug is releasing.”

Park continues, “Currently there is no technique that will tell you exact dosage of the drug in the body, so you have to draw blood out. With ultra sound imaging, we can analyze in real time how much of the drug is released.”

Park’s background is in both drug delivery systems and imaging contrast agents. This project allowed her to combine the two specialties.

This research is currently limited to animal trials. Though Park studied this drug delivery system in relation to posterior eye disease, she sees this new delivery system being applied to other types of diseases like cancer. Whatever the case may be, this new technology is an exciting step forward in the ever-expanding field of medical treatments.

To view the full study, visit the American Chemical Society Applied Materials & Interfaces online journal.