In outbreaks of lethal pathogens like the Ebola virus or food-borne bacteria, health care workers and lab staff alike need the most effective antimicrobial clothing they can get. But there is a problem with today鈥檚 bug-busting suits, face masks and gloves: the active ingredient, or biocide, impregnated into their fabrics is consumed in the process of destroying the virus or bacterium 鈥� so they get less and less effective over time.
Not for much longer, perhaps. Polymer chemists led by and at the University of California in Davis have engineered a biocidal material where the active ingredient is constantly recharged by a widely available, free resource: broad daylight.
The team say this fibrous membrane can be inserted into the fabric of protective clothing. It was formed in a process called electrospinning, in which polymers are melted and then drawn into threads that can be criss-crossed to make a mat-like membrane that has pores that trap viruses and bacteria.
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Sun and Si used electrospinning to create a membrane from two substances: a plant extract called chlorogenic acid which is then grafted onto benzophenone, an additive from sunscreen, soap and perfume.
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Both substances have the useful property that, in daylight and in the presence of oxygen, they produce pathogen-killing hydroxl radicals and superoxides 鈥� collectively known as reactive oxygen species, or ROS. The oxygen comes from air, while the hydrogen is produced by the nanomaterial.
鈥淩OS rapidly damages DNA and RNA in bacteria, and also leads to virus inactivation by damaging the protein shell,鈥� says Si. But crucially, the active ingredients are not used up. In the presence of daylight, 鈥渋t continuously generates the active ROS while not being consumed itself,鈥� Si says.
In tests, the team鈥檚 Rechargeable Nanofibrous Membrane (RNM) destroyed Escherichia coli and Listeria innocua bacteria in just over half an hour, and a T7 phage, a virus that infects bacteria, in five minutes. The team is now working with what Si describes as 鈥減rotective equipment companies, a military research agency and a medical school鈥� on product development with their RNMs.
Jean-Yves Maillard at Cardiff University in the UK, says the daylight-replenished technology sounds like it has great potential. 鈥淭his is welcome and exciting. It will help in controlling infection if the microbicidal efficacy demonstrated experimentally is retained in practice,鈥� he says.
Science Advances
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