Breakthrough technologies developed by a materials engineer and his team at City University of Hong Kong (CityU) hold great promise for effective cancer treatment and energy saving.

Both applications were developed based on the study of photoluminescence and light scattering mechanisms, as well as the plasmonic properties of micro-nanostructures.

Such is the importance of this research that the findings have earned the team, comprising researchers from CityU and Nanjing University in mainland China, the highly prestigious First Class Award (Natural Science) in the 2017 Higher Education Outstanding Scientific Research Output Awards (Science and Technology) of the Ministry of Education, China.

CityU’s research team was led by Professor Paul Chu Kim-ho, Chair Professor in the Department of Physics and the Department of Materials Science and Engineering.

One of the applications that Professor Chu has developed involves using intense heat triggered by a photothermal process to kill cancer cells, and the results are encouraging.

Professor Chu said that photothermal therapy, an emerging cancer treatment, involved the targeted delivery of photothermal agents to tumours, and subsequent light irradiation to produce a high local temperature to kill tumour cells.

He described the strategy as a “Trojan horse” carrying “bombs”.

“When the ‘bombs’ interact with near-infrared light, the temperature rapidly increases, killing the tumours,” said Professor Chu.

His team has discovered two effective types of carriers with photothermal agents: Bi₂Se₃-laden-macrophages and Nile blue dye with black phosphorus.

In trials, the tumours in mice were completely destroyed and removed, and there was no recurrence until the end of the experiment.

“Both types of carriers with photothermal agents possess good biocompatibility, and most of the materials can be excreted from the body within 25 days to eliminate potential cytotoxicity,” Professor Chu added.

He concluded that photothermal therapy was minimally invasive and fast-acting, and could easily be combined with other therapeutic approaches.

The other application is thermochromic smart coating, which can control the transmission of solar radiation dynamically and automatically in accordance with the ambient temperature and illumination intensity.

The smart coating blocks heat under strong illumination at 28 degrees Celsius, but is heat transparent in weak irradiation conditions or at a temperature of 20 degrees Celsius or lower.

That is, the smart coating works basically as a transparent blind to control heat transmission and minimise the need for air conditioning or heating.

“We have combined the properties of TiN [titanium nitride] nanoparticles and VO₂ [vanadium dioxide]. TiN nanoparticles can absorb light quickly and increase the local temperature, while VO₂ changes its phases depending on different temperatures in order to block heat or allow heat to pass through. Therefore, the coating is suitable to be applied to windows in buildings or vehicles to save energy,” said Professor Chu.

“The fundamental knowledge gained from the collaborative research has enabled us to develop new materials and technology to combat cancer and save energy effectively,” he added.

In addition to receiving the First Class Award in natural sciences from mainland China's Ministry of Education, Professor Chu was selected for the list of Highly Cited Researchers in the category of Materials Science for the second year in 2017, according to an announcement by Clarivate Analytics.