In brief

The complex supramolecule called Gua-POSS features an inorganic core, flexible linkers of different lengths and peripheral guanidinium groups which help to destroy disease-causing microbes and disrupt biofilms.

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Super surface sanitisers to the rescue

19 Jul 2023

Safe for human cells but toxic to bacteria, fungi and viruses, a new strategy for sanitising surfaces could give us the advantage in the fight against pathogens.

Even the cleanest-looking everyday surfaces such as phone screens and door handles can harbour a host of potentially disease-causing pathogens. Recent waves of global infectious disease outbreaks and increasing reports of antibiotic-resistant bacteria have proven the need to not just clean, but also effectively sanitise surfaces to stop the spread of disease.

Traditional chemical-based sanitisers don’t work universally against bacteria, viruses and fungi, and are particularly ineffective against sticky colonies of bacteria called biofilms. Yi Yan Yang, Institute Scientist at A*STAR’s Bioprocessing Technology Institute (BTI) and former covering Executive Director at A*STAR’s Institute of Bioengineering and Bioimaging (IBB), said a new class of molecules with unique properties may offer a new solution.

“Supramolecules are multi-component systems that can display multi-faceted disruptive interactions against target pathogens like bacteria and viruses,” said Yang. The function of these synthetic materials is dictated by their molecular components, the arrangement of their individual chemical modules and the linkages that hold the entire system together.

Together with collaborators from A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE2) and Fuzhou University in China, Yang and her team generated a novel class of antimicrobial supramolecules called guanidinium-perfunctionalised polyhedral oligomeric silsesquioxane (Gua-POSS). Gua-POSS features an inorganic core, flexible linkers and peripheral guanidinium groups (positively charged sections of molecules that disrupt cell membranes of pathogens).

“As Gua-POSS supramolecules act as a single species, their molecular structures are well-defined and characterised by a variety of techniques,” said Ning Li, co-corresponding author and a Senior Research Fellow at the A*STAR Infectious Diseases Labs (ID Labs). “This allows for further opportunity to precisely modify the structure and elevate the antimicrobial potency to the next level.”

The researchers found that even at low concentrations, Gua-POSS effectively destroyed various bacterial species, including Staphylococcus aureus and Escherichia coli, which commonly cause skin infections, pneumonia and urinary tract infections. It also showed strong antiviral and membrane-disrupting effects against BSL-2 murine hepatitis coronavirus, a virus similar to SARS-CoV-2. However, Gua-POSS is non-toxic to mammalian cells at effective concentrations.

Strikingly, Yang and colleagues also reported that Gua-POSS broke down and inhibited biofilms. These bacterial networks are highly resistant to antibiotics and can form on a variety of surfaces, including medical implants, catheters and surgical instruments, causing difficult-to-treat infections.

The team envisions the use of Gua-POSS and other next-generation supramolecules as potent sanitisers to keep surfaces pathogen-free and help stymie the spread of infectious diseases in the community.

Speaking about their next steps, Li said: “We are now building a library of guanidinium-perfunctionalised supramolecules with different geometric configurations, aiming to reveal the key design principles to achieve higher potencies.”

The A*STAR-affiliated researchers contributing to this research are from the A*STAR’s Institute of Bioengineering and Bioimaging (IBB) and the Institute of Sustainability for Chemicals, Energy and Environment (ISCE2).

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Li, N., Luo, H.-K., Chen, A.X., Tan, J.P.K., Yang, C., et al. Guanidinium-perfunctionalized polyhedral oligomeric silsesquioxanes as highly potent antimicrobials against planktonic microbes, biofilms, and coronavirus. ACS Applied Materials & Interfaces 15 (1), 354−363 (2023). | article

About the Researchers

Yi Yan Yang is an Institute Scientist at the Bioprocessing Technology Institute and an Adjunct Professor (Research) at the Department of Orthopaedic Surgery, National University of Singapore. She has over 280 publications in peer-reviewed journals and 70 patents granted, with three patents licensed to two spinoff companies. Her work on antimicrobial polymers was named Scientific American’s 'Top 10 World Changing Ideas' in 2011. In January 2016, she was elected to the American Institute for Medical and Biological Engineering (AIMBE) College of Fellows. In July 2021, she was elected as a Fellow of the Academy of Engineering Singapore. In 2022, she was recognised as a highly cited researcher by Clarivate™.
Ning Li obtained his bachelor's degree from the National University of Singapore in 2013 and PhD from the University of Cambridge in 2018. During his PhD degree, he studied atomically precise titanium-oxo clusters for multifunctional coating application. For his postdoctoral training, Ning worked with Huaqiang Zeng at the NanoBio Lab (NBL) on synthetic ion transporters and artificial water channels (2018-2020), and then with Yi Yan Yang at the Institute of Bioengineering and Bioimaging (IBB) on antimicrobial research (2020-2023). In 2021, he received the AME Young Individual Research Grant for developing novel antimicrobial compounds and surface coatings. Currently, he is a Senior Research Fellow with Yue Wang’s team at the A*STAR Infectious Diseases Labs (ID Labs) working on antifungal designs and strategies.

This article was made for A*STAR Research by Wildtype Media Group