A new study reveals how the glassy shells of diatoms help these microscopic organisms photosynthesize in dim conditions. A better understanding of how these phytoplankton harvest and interact with light could improve solar cells, sensing devices and optical components.
“The computational model and toolkit we developed could pave the way for large-scale fabrication, sustainable optical devices and more efficient diatom frustule-based light harvesting tools,” said research team member Santiago Bernal from McGill University in Canada. Say. “This could be used in bioinspired devices for sensing, new telecommunications technologies or affordable ways to make clean energy.”
Diatoms are single-celled organisms found in most bodies of water. Their shells are riddled with holes that respond to light differently depending on their size, spacing and configuration.in the magazine Optical Materials Express, researchers led by David V. Plant and Mark Andrews of McGill University report the first optical study of an entire diatom frustule. They analyzed how different parts of the shell, or frustule, respond to sunlight and how this response relates to photosynthesis.
“Based on our findings, we estimate that frustule can boost photosynthesis by 9.83%, especially during the transition from high to low insolation,” said Yannick D’Mello, lead author of the paper. “Our model is the first to explain the optical behavior of the frustule as a whole. It therefore contributes to the hypothesis that the frustule enhances photosynthesis in diatoms.”
Combining Microscopy and Simulation
Diatoms have evolved over millions of years to survive in any aquatic environment. This includes their shells, which are made up of many regions that work together to capture sunlight. To study the optical response of diatom frustules, the researchers combined computer optical simulations with several microscopy techniques.
The researchers first imaged the structure of the diatom frustule using four high-resolution microscopy techniques: scanning near-field optical microscopy, atomic force microscopy, scanning electron microscopy, and dark-field microscopy. They then used these images to inform a series of models the researchers built that analyzed each part of the frustule through 3D simulations.
Using these simulations, the researchers examined how different colors of sunlight interacted with the structure and identified three main solar energy harvesting mechanisms: capture, redistribution, and retention. This approach allowed them to combine different optical aspects of the frustule and show how they work together to aid in photosynthesis.
“We used different simulations and microscopy techniques to examine each component individually,” D’Mello said. “We then use this data to study how light interacts with the structure, from the moment it is captured, to where it is distributed afterwards, how long it remains, until the moment it may be absorbed by the cell”
Promote photosynthesis
The study shows that the shell interacts at wavelengths that coincide with those absorbed during photosynthesis, suggesting it may have evolved to help capture sunlight. The researchers also found that different regions of the frustule can redistribute light to be absorbed throughout the cell. This suggests that the shell evolved to maximize exposure of the cell to ambient light. Their findings also suggest that during the transition from high to low illumination, light circulates within the diatom frustule long enough to aid photosynthesis.
The new frustule model enables the cultivation of diatom species that harvest different wavelengths of light, allowing them to be tailored for specific applications. “These light-harvesting mechanisms of diatoms could be used to improve solar panel absorption by allowing sunlight to be collected at more angles, thereby partially eliminating the dependence of the panels on facing the sun directly,” Bernal said.
The researchers are now working to improve their model and plan to apply their new toolkit to study other species of diatoms. Afterwards, they plan to extend the model beyond light interactions within a single frustule to examine behavior among multiple frustules.
This production is in memory of Dan Petrescu, who passed away last year. This research would not have been possible without his insight, help and dedication.
