Dr. Hyo-Jick Choi

Bioengineering sustainable ways to fight pandemics

“I want to give back to our society, our community, our country,” says Dr. Hyo-Jick Choi, “And I think that this is the way. This is what I’m good at. I want to help better the world, and I think that I can contribute.”

Choi, an assistant professor in the Department of Chemical and Materials Engineering at the University of Alberta in Edmonton, isn’t “giving back” to Canada alone. His groundbreaking research into sustainable bioengineered technologies promises to change the world’s response to pandemics.

His research combines biology and engineering into effective solutions to prepare humanity to fight deadly pathogens that strike in pandemic proportions.

Turning surgical masks into pandemic fighters

Choi has invented a way to turn common surgical masks into virus killers. And, he is working to develop edible solid oral vaccines that could immunize populations quickly and efficiently during viral outbreaks.

When pandemics occur, due to current technical limitations, scientists cannot immediately identify an attacking viral strain. They must kill the pathogen and analyse its structure after the outbreak – a time-consuming process.

It takes several months to develop a vaccine and to deliver it, says Choi. Yet, an airborne pathogen – for example, influenza, SARS, or MERS – can spread throughout a country within a few weeks.

“That’s why personal protective measures are really important,” says Choi. “To prepare us for that non-vaccine period.” 

It’s the reason that The World Health Organization (WHO) and other national health protection agencies have recommended the use of non-pharmacological weapons to deter the rapid spread of unidentified pathogens.

During outbreaks, many people wear common surgical masks or N95 respirators as protection, but in truth, these masks do not kill viruses and they are only effective for a single use.

Choi has found an elegantly simple way to functionalize surgical masks by using a coating of sodium chloride – common salt crystals – to trap and kill viruses.

Small water droplets of less than 5 µm carry the airborne pathogens, he explains. When a virus-laden water nodule lands on a salt-coated filter membrane, it dissolves the salt. When the water vaporizes, the salt crystals reform. The recrystallization process destroys the virus.

“We can re-use the mask,” says Choi, “and there are no cross-contamination issues, which have been a major technical challenge in developing personal protective measures against airborne pathogens.”

During post-doctoral research at the Georgia Institute of Technology (Georgia Tech), Choi began to study how to develop an effective solid microneedle vaccine. Sugar is a major component of solid formulations.

“We added vaccine to the sugar and other components in the formulation, and then we dried it. The biggest technical challenge during the drying process was the sugars.”

The sugar formed crystals, which destroyed the viral components of the vaccine, rendering it ineffective. That’s one reason why it’s so hard to develop solid vaccines, Choi adds.

“So, I thought about using that idea to kill live airborne viruses. I simply coated masks with some formulations (of table salt), and it actually worked! It happened so quickly.”

The next challenges for Choi and Ilaria Rubino, a graduate student in Choi’s group working on mask technology, are to fine-tune the masks to weather humidity conditions in different countries and evenly coat different-sized filters.

Dynamic duo: science and engineering

Choi has built his career on a foundation of biomechanical and chemical engineering and bioscience. Early on, he realized that applying engineering concepts to medical science had the potential to lead to great advances in health care.

“I want to bridge the gap between engineering and medical science,” he says. There’s still a huge gap between the two disciplines, and “engineers can do so many things to make it better.”

Before joining the University of Alberta, Choi was a research assistant professor at the University of Cincinnati, where he was the principal investigator on an oral vaccine delivery project. He holds degrees in ceramic engineering from Yonsei University in Korea and, for his PhD, studied biomedical engineering at UCLA and the University of Cincinnati. He worked in the private sector before pursuing post-doctoral research at Georgia Tech.

Pursuing research in solid oral vaccines

To prepare for pandemics, such as influenza outbreaks, countries need to produce large quantities of vaccine. However, Choi points out, current influenza vaccines are liquids that require storage at 4 °C and only last 6 or 12 months depending on vaccine type.

“Because they are unstable, it is not technically feasible to stockpile (liquid) vaccines. So, the idea is to develop solid vaccines – to embed vaccine particles in a solid matrix, like a candy. They’re stable and edible, and we don't need needles to deliver them.”

Choi foresees a day when people will buy solid vaccines at their local pharmacy and take them at home. Solid vaccines have no needle-related safety problems and no storage issues. He predicts that they will remain stable for longer than 2 years at ambient conditions.  

So far, Choi has developed the structure of a solid vaccine delivery system. He is in the midst of laboratory testing and expects to complete studies showing that a solid vaccine can retain its efficacy in a gastric environment in about one year. His next challenge will be to test the stability of the solid formulation under different environmental conditions.

The dual challenge will determine the solid vaccine’s ability to survive both internal and external environments. For these experiments, he is using a solid vaccine formulated to immunize against the H1N1 and H5N1 strains of influenza.

Choi decided to pursue solid vaccine research in Edmonton because of “good infrastructure and great scientists with specialities in vaccines and immunology. It’s a really good environment in which to find collaborators. Research-wise, it’s just a great environment.”