An account of the Fugates from 1982 says their skin was nearly purple.ĭespite having the disorder, most of the Fugates lived into their 80s and 90s with no significant health problems. From there, the family members married each other, and the genes were passed down from one inbred generation to the next, making the blue family locally famous. ‘If we’ve evolved alongside them, then that suggests they may not be so dangerous.Four of their seven children had blue skin. ‘If we’re living in a world awash with nanoparticles formed by natural processes, then it does change the way we think about engineered particles,’ he says. ‘You don’t want to put the public off good products, but neither do you want to get them hooked on something that isn’t going to do them any good,’ he says.Īrgyria aside though, Hurt thinks his work may suggest a new way of thinking about Ag-NPs. But he emphasises that this result should be approached with real caution. Lansdown agrees that Ag + is likely to be the bioavailable form of silver. All this points to Ag + as the major bioavailable silver species and indicates the argyrial deposits are not the nanoparticles that were ingested in the first place. The pure silver can then be sulfidated and sulfur or selenium exchange reactions produce the very mixture of Ag 2 S and Ag 2 Se that is observed in argyrial deposits. The model skin converted complexed Ag + to elemental silver, which spontaneously formed Ag-NPs. The reaction is a lot like the one used to develop the first photographs. When model silver-thiol complexes in a skin-simulating collagen matrix were irradiated with UV light, a photo-oxidation took place.
Previous studies have shown this complex can enhance the transport rate of Ag + across biological membranes, so Hurt reasons this could act as a transport mechanism. His group showed that silver salts like silver chloride can form soluble complexes with thiols like glutathione, an endogenous antioxidant. Hurt thought that the silver ions could then hitch a ride around the body complexed to proteins. It is already known that silver salts produced by oxidative dissolution can enter the bloodstream via ion pumps. Perhaps unsurprisingly, they found the amount of leached Ag + depends on pH and residence time. First, they looked at how Ag-NPs oxidatively dissolve in simulated gastric juices. The team tried to understand argyria by studying the individual chemical transformations that Ag-NPs undergo in the body. ‘We thought: “Hey! The body is an environment too, so let’s see how the particles behave in there”,’ he says. That made his team start to ask what happens to silver in environments with a low pH – like the stomach. One day he made the innocuous discovery that they dissolve very quickly in acidic solutions. In most cases these argyrial deposits are very unpleasant, but not actually toxic to humans, according to Alan Lansdown, an expert on silver in healthcare at Imperial College London, UK.īecause of the broader worries about Ag-NPs, Hurt studies what happens to them in the environment. Biopsies of people with argyria have shown that the blue skin colour is caused by ‘argyrial deposits’: mixtures of silver sulfide (Ag 2 S) and silver selenide (Ag 2 Se).
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