Two materials chemistry stories stood out in the New Year newsfeeds that hit my desk after the festive break. The first one was about scientists looking for molecular diversity in the most unusual of places - roadkill! Now, in more than a quarter of a century of writing about science, I've covered research into natural products from some quite diverse environments, obscure moulds, Easter Island soil, Caribbean marine sponges, rare tree bark, and the like, but I think this is the first time I have seen an investigation into possible pharmaceutical candidates that might be excised from an unfortunate animal run over by a moving vehicle.
According to Chemistry World magazine, and I have no reason to doubt their assertion, Robert Cichewicz of the University of Oklahoma, USA and colleague Bradley Stevenson have been patrolling a thirty-mile stretch of their local state highway sampling and swabbing the splattered remains of deer, skunk and any other inadvertent sacrifices to the infernal combustion engine they find. Their reasoning follows a not unreasonable road from living creature, via the creature that has ceased to be, to the colonization of said carcass by microbial life with its diverse array of enzymes and digestive aids. Any one of the consequent metabolic processes might convert the creature's previously vital molecules into novel molecular structures for subsequent assay against disease targets, one can assume.
The magazine goes on to report that Cichewicz and colleagues have discovered cyclic lipodepsipeptides manufactured by two bacteria isolated from the ear canal of a dead opossum. These compounds were, it seems, active in stymieing the formation of fungal biofilms commonly seen in yeast infections. The headline fun any sub-editor worth their salt might have with that slice of research is almost limitless. However, while the science and its ultimate outcome, a possible new treatment for thrush, are intrinsically of interest, it was the mention of the location of the rot that led to the cyclic compounds...the dead animal's ear canal...which caught my attention. This was so, because the next odd news story that popped up was about the technological potential of earwax.
Earwax is perhaps one of the most unappealing of biological substances, but not, according to the news story, for Alexis Noel, a doctoral student in the research group of David Hu at the Georgia Institute of Technology. Noel, in this post-Christmas news, has recognized the material's potential as a high-tech filter for use in robotics and other applications. While the marine sponge science I mentioned earlier involved a lot of diving in balmy waters by the research team of George Pettit looking for anticancer compounds, Noel's more mundane diving inspiration came when her boyfriend got water trapped in his ear canal and she realized it was his earwax that was doing the trapping. "A couple years later I was reminiscing [about earwax!] and thought: why would it block the water like that? And it just started this snowball effect of me and David just asking questions about earwax and how it works," says Noel.
Earwax, which also goes by the name cerumen (from the Latin cera for "wax" and modeled on the word albumen, or else from the Greek keroumenos "formed of wax") is a yellowish, brown waxy secretion produced by humans and other mammals. This biosubstance protects the lining of the ear canal, assists in cleaning and lubrication, and also provides some protection against bacteria, fungi, insects and water ingress. It is not a single substance but rather comprises long chain fatty acids (both saturated and unsaturated) from the ceruminous and sebaceous glands of the outer ear canal, alcohol molecules, squalene, and cholesterol, and of course sloughed dead skin cells and hairs. A complex matrix to study and in the event of finding an application, mimic.
Noel and undergraduate researcher Zac Zachow collected earwax samples from pigs, sheep, rabbits and dogs and found that the composition in all these animals is very similar despite the obviously very different ear sizes and canal shapes in these species. The thickness, the way it flows, and even the appearance are very similar, the team reports, leading to the conclusion that nature has evolved a fairly consistent solution to a universal problem in mammals. Of course, biomaterials are rarely simple and further investigation reveals earwax to be a non-Newtonian, shear-thinning fluid. Untouched it is very thick and viscous, like molasses, but apply a shear force and it will flow. This phenomenon means that the repeated movement and pressure of chewing usually allows the ear to expel earwax so that it does not accumulate to problematic levels that might impinge on hearing.
Earwax can however filter air, the team found forming a web of waxy hairs within the ear. If it accumulates dust it becomes crumbly as occurs when there is too much flour in a dough mix. All properties that help earwax do its job and that the researchers have a hunch might be useful in various non-aural applications, such as robotic ventilation systems. "Obviously you're not going to have earwax sitting on a Mars rover to protect it from dust," laughs Noel. "We are still trying to understand what is earwax and how does it work the way it works. And once we really understand that we can start applying it [to new technology]."
Either way at least one of these projects is almost certainly going to be picking up one of those alternative science awards that run parallel to the Nobels and are anything but ignominious despite their name. And, I say to that: 'ear, ear!
As a kind of postscript to this article, there was another news story that was even more bizarre than these two about ears and that was how British students had worked out that should a zombie apocalypse arise it would take just 100 days to reduce the human race to a mere 300 or so living, breathing Homo sapiens. The "research" was an exercise in analysis and science communication, I believe. Either way, I don't think earwax would be enough to protect any of us from that and becoming roadkill would almost certainly be a better end...
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".