It is a familiar thought that the flap of a butterfly's wing
can change the course of history. In the latest in our series of
Cambridge innovation articles, I wanted to consider how the wing of
the butterfly might – at the very least! – have
inspired one start-up to pioneer the future of man-made
colour.
But first, it's worth making a quick visit to a ghost of
Cambridge past.
Charles Darwin is most celebrated for his work On the Origin
of Species, a seminal articulation of evolution by natural
selection, influenced by his famous voyage on HMS Beagle.
While this publication came later in his life, his passion for
ecology was in early evidence during his undergraduate years in
Cambridge.
As a student at Christ's College, Darwin was a prolific
collector of local beetle species. His collection survives today
and is on display at the University's Museum of Zoology.
If you pay a visit, some of the beetles might catch your eye more
than others. Members of a small subset of the species seem to
shimmer with a vibrant metallic hue, a natural beauty untouched by
time.
Image credit: Wikipedia
Silvia Vignolini, a professor in Cambridge's Yusuf Hamied
Department of Chemistry, noticed a similar appearance in a museum
specimen of Pollia condensate – the marble berry
–, whose fruit has a similarly rich iridescence.
Image credit: Wikipedia
This effect comes from a phenomenon called structural
colouration¹. It derives from the interaction of light with
highly-ordered biomolecular micro- or nano-structures at
light-exposed surfaces. The interaction transforms the properties
of the light to produce the brilliant, iridescent colour observed
by the human eye. The same mechanism is responsible for the
intensely striking colours in certain other animals and
plants², including in the peacock and – you guessed it
– butterflies such as Morpho.
Professor Vignolini's insight would form the basis of
technology developed by Sparxell, a company spun-out of her
research group. Sparxell aims to replicate the beauty of
nature's structural colour for diverse applications such as
cosmetics, textiles, and coatings.
They do so by harnessing cellulose, the particular biomolecule
responsible for the colour of the marble berry, and which can be
sustainably obtained from abundant plant-based sources.
Sparxell's particular innovation appears to lie in their method
for driving the self-assembly of cellulose crystals into the
ordered structures which are needed to engender colour.
Having formed the crucial structures, vividly coloured products
such as films, liquids, powders, and glitters can be formed. There
appears to be some capacity to tailor the final appearance by
tuning the interactions between the cellulose crystals.
What I find most compelling about the Sparxell story is the
drawing of inspiration from the natural world - butterfly, berry,
and beetle! – and a desire to mimic an effect Darwin might
have noticed in his Cambridge collection centuries ago.
Perhaps inevitably, learning the lessons from nature, rather than
trying to beat it at its own game, reduces the negative impact on
that same natural world. Traditional dyes and pigments are often
derived from high emissions processes, and frequently contain toxic
ingredients. In contrast, Sparxell's use of renewable
plant-derived cellulose makes for a biodegradable product with a
more circular life cycle.
It seems that Sparxell have tapped into a wider trend towards
sustainable colour. Norwich-based Colorifix has taken inspiration
from nature's colour palette to devise a biological process for
producing textile dyes. The methodology here is completely
different to that used by Sparxell, but again has improved
environmental impact.
Spraxell's innovation has not gone unnoticed, with the recent
completion of a $3.2 million funding round, which included
investment from cosmetics giant L'Oréal. This is in
addition to a series of high-profile awards over the company's
history, including the Biomimicry Institute's Ray of Hope
Prize, and the Cambridge-based Trinity Bradfield and 21toWatch
prizes.
With some neat links to Cambridge past, and some exciting
innovations in the present, we are sure that Sparxell will have a
glittering future. We look forward to seeing how their work
develops.
Footnotes
1 A subject of interest to another Cambridge figure,
Isaac Newton.
2 Many of which are also on display at the University of Cambridge Museum of Zoology!
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