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Study uncovers technologically appealing trick used by microalgae to manipulate light

Skoltech researchers and their colleagues have uncovered an intricate light manipulation mechanism likely used by microscopic algae to boost photosynthesis.

By studying the interaction of light with the elaborately patterned silicon dioxide shells enclosing the single-celled algae, the team hopes to reveal principles that could eventually be leveraged in light detectors, bio- and chemical sensors, protective coatings against ultraviolet rays, solar cells, and other nature-inspired technology, right up to artificial photosynthesis systems using CO₂ and water to make fuel.

The study was in the journal Optica.

Diatom algae are extremely widespread and well-adapted microorganisms. They comprise a large part of phytoplankton, making up nearly half of the organic material found in the oceans and generating a quarter of the planet's oxygen.

The distinctive feature of diatoms is a rigid cell wall made of a glassy substance and perforated with intricate hole patterns, which the algae use for protection, waste removal, nutrient uptake, and—as has been strongly suspected—manipulating light to make the most of the solar energy that reaches the ocean depths inhabited by the algae.

"By investigating the optical properties of diatoms of the species Coscinodiscus oculus-iridis, we have shown that these algae's frustules, or outer shells, with their intricate pattern of pores, exhibit what's known as the Talbot effect," said the lead author of the study, Associate Professor Sergey Dyakov from Skoltech Â鶹ÒùÔºics.

"Light undergoes diffraction on the hole pattern and is focused in numerous hotspots within the shell. While we don't think this is specifically what the diatoms evolved their sieve-like shells for, they certainly seem to exploit them to boost the efficiency of photosynthesis, possibly by strategically positioning their light-harvesting chloroplasts."

The team confirmed the occurrence of the Talbot effect with calculations and is planning to support the findings with an experiment with a scaled-up artificial structure mimicking the hole pattern of the frustule.

Senior Research Scientist Julijana Cvjetinovic from Skoltech Photonics, a co-author of the study, commented on the kinds of biomimetic technology that could benefit from a better understanding of diatoms, saying, "As we gain more insights into the properties of diatom frustules, eventually some of the uncovered mechanisms could make their way into photonic devices, biosensors, self-adjusting light-sensitive coatings, and photovoltaics, maybe even artificial photosynthesis systems, which would tap into light energy and store it in the form of chemical fuel rather than electricity."

The grant project's principal investigator, Professor Dmitry Gorin from Skoltech Photonics, shared his opinion on diatoms as an object of research: "Diatoms are a striking example of another masterpiece of nature, which over millions of years of evolution has managed to create a perfect object in terms of combining optical and mechanical properties.

"I am sure that we will find many more interesting things in the process of further studying the physical and biochemical properties of diatoms."