Unlike the famous plant that lures insects into its mouth to catch and consume them, new Venus flytrap-like biosensors developed by scientists at Trinity College Dublin (TCD) are designed to trap something very different.

In a paper published to Angewandte Chemie – and featured on its front page – the scientists said these sensors are designed to detect and grab specific molecules from mid-air. In particular, it can be used to trap pollutants, which could have major environmental, medical and security applications.

Key to the breakthrough were porphyrins, a unique class of intensely coloured pigments, also referred to as the ‘pigments of life’. In living organisms, porphyrins play an important role in metabolism.
Some of the most prominent examples include heme – responsible for the colour of red blood cells – and chlorophyll, which is responsible for the green colour in plants and is a main driver of photosynthesis.

Dazzling molecules
While containing a variety of metals in their core in nature, the TCD scientists explored metal-free versions of porphyrins by turning them inside out and creating a saddle shape that has been inaccessible until now.

By introducing functional groups near the active centre, they were able to catch small molecules – such as agricultural pollutants – and hold them in a receptor-like cavity. Because of their intense colour, once porphyrins capture a pollutant molecule they change colour drastically.

“These sensors are like Venus flytraps,” said Karolis NorvaiĊĦa, first author of the study.
“If you bend the molecules out of shape, they resemble the opening leaves of a Venus flytrap and, if you look inside, there are short, stiff hairs that act as triggers. When anything interacts with these hairs, the two lobes of the leaves snap shut.

“The peripheral groups of the porphyrin then selectively hold suitable target molecules in place within its core, creating a functional and selective binding pocket, in exactly the same way as the finger-like projections of Venus flytraps keep unfortunate target insects inside.”

Colm Gorey
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