Core-Shell Particle Technology Gains Attention During the Pandemic

Core-Shell Particle Technology Gains Attention During the Pandemic

The pandemic over the past few years has disrupted many lives but has also brought some previously underestimated coating technologies to the forefront.

Professor Pei Li from the Department of Applied Biology and Chemical Technology at The Hong Kong Polytechnic University (PolyU) has been passionately researching “Core-Shell Particle Technology” for over 20 years. Her work focuses on combining two inherently incompatible substances into water dispersible particles that feature a hydrophobic core and a functional hydrophilic outer layer. By altering the structure, composition, and size of the particles, she creates new nanomaterials with a wide range of applications.

The outbreak of the pandemic has highlighted the importance of preventive measures, and the scientific community has recognized that Professor Li's core-shell particle technology can transform natural disinfectants into coatings.

“Many people have likely heard of photocatalysts, which were introduced as a new product during the pandemic,” said Professor Li. Photocatalysts, such as titanium dioxide (TiO₂), require exposure to a light source to become activated to form reactive oxygen species (ROS).

However, titanium dioxide in photocatalysts and the generation of potent oxidizing agents ROS may pose health risks to humans. “This concern led us to explore the use of natural materials as alternatives to the chemical components in photocatalysts for disinfection.”

Natural, Safe and Long-lasting – “Biobased Core-Shell Particle Technology”

Chitosan, a natural substance derived from the shells of marine crustaceans, has antimicrobial and antiviral properties.

However, chitosan is in powder form and insoluble in water, presenting a challenge in converting it into a sprayable form that can form a quick-drying coating upon application.

“The purpose of the coating is to maintain the antimicrobial effect on the surface of objects; otherwise, it would evaporate quickly like alcohol,” she continued. “By using core-shell particle technology, we modified the material's structure, incorporating a hydrophilic chitosan outer layer with a hydrophobic polymer core for film forming.”

This technology not only allows chitosan to be sprayed in a water-based form but also forms a coating around 15 minutes, achieving long-lasting antimicrobial effects. “Without the hydrophobic polymer core, the coating might take all day to dry,” Professor Li further explained.

Currently, this biobased coating is widely used on the PolyU campus. “During the pandemic, we tested the spray's effectiveness in 10 classrooms, and the data showed excellent antimicrobial results on various surfaces,” Professor Li explained. A year later, PolyU incorporated the natural antimicrobial spray into its anti-pandemic measures. The spray only needs to be applied twice a year, drying quickly each time, thus reducing labor and time costs. “The pandemic has once again proven that our technology can provide innovative application methods, developing new coating materials that offer the public with natural, environmentally friendly, safe and long-lasting anti-pandemic products,” she added.

Award-winning Core-Shell Particle Technology Brings Endless Commercial Potential

Professor Li's research on core-shell particles and other technologies had already won numerous awards and holds over ten patents during the last two decades. Among them is the Nano “Anti-Erasing (ATE) Inks” which can print indelible information on plastic surfaces, effectively preventing counterfeit goods, expired foods and resold items, allowing consumers to identify altered expiration dates or barcodes. This technology includes three Chinese and international patents and has been widely adopted by the renowned Chinese enterprise Mengniu Dairy Company Limited to its dairy product packaging.

Additionally, Professor Li has developed nano-carriers that can deliver genes, enhancing the effectiveness of gene therapy in treating various diseases. Core-shell particles can also be used to adsorb and filter stubborn organic and inorganic pollutants in landfill and industrial wastewater.

“After the pandemic, the market has realized the broad application potential of our core-shell particle technology,” said Professor Li. “As a scientist, I certainly hope the applications of core-shell particle technology can be more prevalent, benefiting more people.”