Spray Coating Fights Viruses and Bacteria

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Researchers at the University of Sydney in Australia engineered a new spray coating for surfaces that provides long-term protection against bacterial and viral contamination. The material is intended as a long-term alternative to disinfectant sprays and combines hydrophobic properties with antimicrobial nanoparticles to reduce microbial contamination.

The hydrophobicity of the coating prevents liquid droplets from spreading over the surface, helping to prevent biofilm formation and microbial colonization. If the coating becomes damaged, reducing its hydrophobic properties, a second line of defense in the form of nanoparticles containing bactericidal zinc ions helps to kill any microbes that wish to call the surface home. The researchers hope that the material can help to reduce outbreaks of illness, including COVID-19 outbreaks, in care homes and healthcare facilities.

During the early days of the COVID-19 pandemic, handwashing and awareness of surface contamination was the mantra for reducing transmission. While it turns out that the risk of surface transmission of COVID-19 was largely overblown compared with aerial transmission, contaminated surfaces definitely play a role. Moreover, surface transmission is a huge driving force behind many other illnesses, including bacterial infections and viruses that cause colds and gastrointestinal illnesses.

This is a particular issue in healthcare facilities and care homes filled with vulnerable people, with frequently touched surfaces, from hand-rails to lift buttons, providing the perfect vectors for microbes to jump between people. “Without a barrier, viruses such as coronaviruses can stay on surfaces and remain infectious for up to a week,” said Antonio Tricoli, a researcher involved in the study. “Other viruses such as reoviruses, which can cause colds or diarrhoea, for instance, can remain on surfaces for several weeks, causing large outbreaks in health and aged care facilities.”

These researchers have designed an antimicrobial coating that is intended to be a long-term solution compared to disinfectant sprays which require frequent reapplication. The spray coating contains a polyurethane and polymethyl methacrylate polymer network that contains superhydrophobic nanoparticles. This hydrophobic layer causes liquid droplets that land on the surface to bead up. Any microbes in the droplets don’t get the chance to spread over the surface and establish themselves, rendering them less effective.

As a second line of defense, the coating also contains nanoparticles containing bactericidal zinc ions which help to kill any microbes that do make it through the hydrophobic surface. “Like a lotus leaf, the surface spray creates a coating that repels water,” said Tricoli. “Because the pathogens like to be in water, they remain trapped in the droplets and the surface is protected from contamination. If this mechanism fails, a secondary burst of ions is triggered by carefully designed nanomaterials dispersed in the coating.”

Study in journal Advanced Science: Shielding Surfaces from Viruses and Bacteria with a Multiscale Coating

Via: University of Sydney

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