Optical activity of molecules is amplified in more than 10 folds, by structure-specific adsorption of the molecules on chiral nanoparticles.

Nanotech key for purer and safer drugs

30 May 2019

Physicists and chemists have developed a new method that could potentially produce pure, higher-quality medicinal drugs with a faster drug discovery process and reduced risks of side effects.

The method developed by a team jointly led by Dr Ken Leung Cham-fai (Croucher Fellowship 2003), of the Department of Chemistry, Hong Kong Baptist University, and Dr Jeffery Huang, of the Department of Physics, involves detecting target molecules in pharmaceuticals and pesticides in just five minutes through a specific nanomaterial layer.

The invention can be applied to the drug discovery process, and the production and quality control stages of pharmaceutical manufacturing. It can also be used in environmental monitoring of pesticides. The findings have been published in Advanced Functional Materials.

Medicinal drugs and pesticides are composed of organic molecules. Normally each molecule has two “chiral” versions that are mirror images of each other in their absolute configuration. While otherwise identical, these “right-handed” and “left-handed” molecules can have totally different effects. For example, with a particular type of chirality, anti-inflammatory drug naproxen can treat arthritic pain while its mirror image can result in liver poisoning.

However, it is not cost-effective for the pharmaceutical industry to produce the pure drug due to the challenges in sensitively monitoring small molecules and the time involved. Thus, current medicinal drugs are often made up of equal amounts of left and right-handed chiral molecules in what is known as a racemic mixture. This approach reduces production costs but also results in less efficacy and, in some cases, can lead to toxic side effects.

The team has designed and synthesised a specific nanomaterial composed of silver chiral nanoparticles that can “amplify” the signal of the desired chiral molecules and improve detection sensitivity by more than 10-fold, making the location process faster, more accurate, and less expensive.

With few nanomaterial fabrication techniques currently on offer, Leung believes this work paves the way for material scientists to apply such metallic chiral nanoparticles to drug production processes.

He explained that in the current multi-step drug synthesis process, the crucial controlling factors for producing extra-pure synthetic drug molecules involve both product and chiroptical purities – the latter referring to the use of optical techniques for investigating chiral substances.

“The nanomaterial developed by the team will provide a new platform for efficiently and effectively detecting the chiroptical purity of synthesised compounds, and will help to produce drugs without side effects,” he said.

Dr Ken Leung Cham-fai is an Associate Professor in the Department of Chemistry at Hong Kong Baptist University. He concurrently holds an Honorary Associate Professor position in the Faculty of Dentistry at the University of Hong Kong. His research interests encompass supramolecular chemistry, nanoscience, and nanomedicine. He gained his BSc and PhD in chemistry from Chinese University of Hong Kong in 1999 and 2003 respectively. From 2003 to 2006, he conducted postdoctoral research in the laboratory of Professor Sir J. Fraser Stoddart (Nobel Laureate in Chemistry 2016) at the California NanoSystems Institute and Department of Chemistry and Biochemistry at the University of California, Los Angeles. He received a Croucher Fellowship in 2003.

To view Dr Leung’s Croucher profile please click here