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).