Swansea scientists' sugar-coated nanoparticle blocks 98.6% of Covid-19 infection

What is the background?

Covid-19 still circulates worldwide, and scientists keep searching for new ways to stop the virus infecting human cells. Vaccines train the immune system to respond, but they do not physically block the virus from attaching to a cell in the first place. At Swansea University, chemist Dr Sumati Bhatia builds synthetic “glycomaterials” that copy natural sugars found on human cell surfaces, aiming to intercept viruses before infection starts.

What happened?

Bhatia and international collaborators created a synthetic sugar-coated nanoparticle, called a glycosystem, that blocked SARS-CoV-2 from infecting human lung cells by up to 98.6% in laboratory tests. The particle also bound to the virus roughly 500 times more strongly than a similar compound built with sulfates instead of sugars. The peer-reviewed findings appeared in the journal Small on 16 July 2025, and Swansea University’s press office announced them publicly on 11 August 2025.

How did it happen?

The nanoparticle, a polysialylated dendritic polyglycerol given the lab code dPG500SA0.55, is coated with polysialosides. These are repeating chains of sialic acid sugar that copy structures naturally found on human cell surfaces. SARS-CoV-2 targets these same sugars to begin infection, so the synthetic particle acts as a decoy. It latches onto the virus’s spike protein and stops the protein reaching real lung cells.

Researchers at Swansea University worked with teams at Freie Universität Berlin and Charité – Universitätsmedizin Berlin to test the compound. They used a technique called microscale thermophoresis to measure how tightly the particle bound to the virus. They then tested antiviral activity on Calu-3 human lung cells infected with the original SARS-CoV-2 strain and the D614G variant, checking viral replication 48 hours later. Molecular dynamics simulations and computer docking studies helped explain why the sugar coating outperformed the sulfate-based version.

Why does it matter?

Dr Bhatia said the research “opens a new direction for using glycosystems as a therapeutic strategy against SARS-CoV-2 and could lay the foundation for a new class of antiviral therapies to protect those most at risk.” Because the particle works as a physical shield rather than an immune trigger, researchers say it could eventually support treatments for people who respond poorly to vaccines, including some elderly or immunocompromised patients.

What were the key results?

• 98.6% reduction in SARS-CoV-2 infection of human lung cells (Calu-3) at a concentration of 0.5 micromolar
• Dissociation constant of 4.78 nanomolar, versus 2.46 micromolar for a sulfate-only compound — about 500 times stronger binding
• Effective against both the original SARS-CoV-2 strain (B.1) and the D614G variant in cell-based infection tests
• Peer-reviewed and published in the journal Small (Wiley) on 16 July 2025, announced by Swansea University on 11 August 2025
• Built through collaboration between Swansea University, Freie Universität Berlin, and Charité – Universitätsmedizin Berlin
• Funded in part by the Berlin University Alliance, Deutsche Forschungsgemeinschaft, the Royal Society of Chemistry, and the Novo Nordisk Foundation

What happens next?

The team is preparing further tests in high-containment laboratories to check how the glycosystem performs against other SARS-CoV-2 variants. Earlier binding assays already covered the Delta and Omicron lineages. Researchers say potential future products could include antiviral nasal sprays or surface disinfectants, though these would need further development and clinical testing before reaching the public.

Dr Bhatia’s group continues related glycomaterials research at Swansea University, including a separate 2024–2027 grant from the Novo Nordisk Foundation to develop antiviral candidates against influenza. That ongoing work suggests the sugar-decoy approach could extend beyond Covid-19 to other respiratory viruses in future studies.