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Science’s latest mash-ups: pollen-powered muscles, batteries built with salmon sperm, and a golden tongue

by Alex Scott
June 11, 2020 | A version of this story appeared in Volume 98, Issue 23


Pollen muscles

Gold paper made from pollen is folded into a flower.
Credit: NTU Singapore
Inspired by nature: Pollen paper could one day be used to make implantable electronics.

Ah, pollen, the bane of seasonal allergy sufferers everywhere. But now scientists at Nanyang Technological University think they may have a practical use for the pesky allergen. They’ve created a form of paper from pollen that they say could be used to make soft robots or artificial muscles (Proc. Natl. Acad. Sci. U.S.A. 2020, DOI: 10.1073/pnas.1922560117).

The researchers made the paper by converting tough pollen grains from sunflowers into a pliable gel. To make the gel, they removed sticky, oil-based pollen cement from the flowers and incubated the pollen in an alkaline solution for hours in a process reminiscent of soap making.

Cast into a mold, the gel forms a paper featuring alternating layers, with a top layer that appears to have a frosted surface that is significantly rougher than the mirror-like surface of the bottom layer. The structural difference within the layers leads the pollen particles to swell more on one side in the presence of water vapor, causing the paper to bend.

Folded into a flower, the scientists demonstrated how, in the presence of water vapor, their pollen paper could be opened. In this way, a pollen-paper muscle could be made to contract and relax using cycles of exposure to water vapor followed by a drying phase.

The approach is not to be sneezed at; the production process removes the pollen’s allergenic properties.


Salmon batteries

Illustrations show DNA winding around nanotubes, which are incorporated in battery components.
Credit: Korea Institute of Science and Technology
Salmon power: This illustration shows how salmon DNA and carbon nanotubes are combined in a lithium-ion battery.

While natural phenomena have long provided inspiration for chemists, a team of scientists in South Korea have taken things a step further by selecting a natural material—salmon sperm DNA—and using it in the distinctly nonbiological setting of a lithium-ion battery. They combined the DNA with carbon nanotubes to stabilize the surface of over-lithiated layered oxides present in a next-generation lithium-ion battery cathode (Adv. Energy Mater. 2020, DOI: 10.1002/aenm.201903658).

Their eureka moment wasn’t the result of a clumsy hand dropping a salmon sandwich into a beaker. Rather, the researchers knew salmon DNA was already being used in medical products and cosmetics as a stabilizer. So they thought they would try it out in a battery.

The researchers are certainly swimming against the current on this one. “Unlike preexisting attempts, this study uses DNA, the basic unit of life, suggesting a new direction for the development of high-performance battery materials,” says Kyung Yoon Chung, head of the Center for Energy Storage Research at the Korea Institute of Science and Technology, which participated in the study.


Gold tongues

While metals may one day be replaced with DNA for making batteries, DNA can now be replaced by a metal to make an artificial tongue. Researchers at the University of Montreal have created what they’re calling a “tongue” from gold nanoparticles to differentiate between good- and bad-tasting batches of Quebec’s maple syrup, known locally as liquid gold.

Small plastic tubes contain red liquid.
Credit: Amélie Philibert
Sweet: If the gold-containing reagent stays red after a drop of maple syrup, then the syrup is good.

The approach involves adding a few drops of syrup to a gold nanoparticle reagent. If the reagent is still red after about 10 seconds, the syrup is pancake-ready. If the reagent turns blue, the syrup may have a defect due to sulfur and amine-containing amino acids that produce off-flavor organic compounds, the pancake misses out, and the syrup may end up in animal feed (Anal. Methods 2020, DOI: 10.1039/C9AY01942A). The research team likens the golden tongue to a pH test for a swimming pool (ooooh, this analogy almost put the Newscripts gang off its pancakes).

Jean-François Masson, who led the study, assures Newscripts that the gold tongue is not about to end the sweet, sweet life of professional maple syrup tasters. “Human tasters remain highly relevant,” he says.The technology could be adapted to testing honey or wine, Masson says. But that favorite otherworld job for the Newscripts gang—wine tasting—also appears to be safe. Masson suggests here that the gold tongue’s best uses could be in identifying grape ripeness or detecting the level of tannins, a source of wine’s bitterness. Phew.

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