A new study has revealed how the glass-like shells of diatoms help these tiny microbes carry out photosynthesis in dim conditions. A better understanding of how these harvest phytoplankton and interact with light could lead to improvements in solar cells, sensors and optical materials.
“The integrated model and tools we developed could pave the way to mass-produced, sustainable and functional light-harvesting devices based on diatom shells,” said research team member Santiago Bernal from McGill University in Canada. “This could be used for biomimetic hearing devices, new communication technologies or affordable ways to generate clean energy.”
Diatoms are single-celled organisms found in most waters. Their shells are covered in holes that respond to light differently depending on their size, spacing and configuration. In a journal Visual material Express, researchers, led by McGill University’s David V. Plant and Mark Andrews, report the first optical study of a diatom shell. They analyzed how different parts of the shell, or frustule, responded to sunlight and how this response was linked to photosynthesis.
Based on our results, we estimate that the frustule can contribute to a 9.83 percent increase in photosynthesis, especially during the transition from high to low sunlight,” said Yannick D’Mello, first author of the paper. “Our model is the first to explain the optical behavior of the entire frustule. So, it contributes to the hypothesis that the frustule increases photosynthesis in diatoms.”
Combining microscopy and measurement
Diatoms have evolved over millions of years to survive in any aquatic environment. This includes their shell, which is made up of many areas that work together to harvest sunlight. To study the light response of diatom frustules, the researchers combined computer vision simulations with multiple microscopy techniques.
The researchers began by imaging the structure of the frustule using four high-resolution microscopy techniques: scanning optical near-field 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 to analyze each part of the frustule through 3D simulations.
Using this simulation, researchers evaluate how different colors of sunlight interact with buildings and identify three main methods of harvesting sunlight: capture, redistribution and storage. This method allowed them to combine the different optical aspects of the frustule and show how they work together to aid photosynthesis.
“We used different imaging and microscopy techniques to look at each component separately,” D’Mello said. “We used that data to build a study of how light interacts with the structure, from the moment it is captured, to where it is then distributed, how long it is stored, and until the moment it is likely to be absorbed by the cell. .”
The study revealed that the wavelengths that the shell interacts with are those that are absorbed during photosynthesis, suggesting that it could not have evolved to help capture sunlight. Researchers have discovered that different regions of the frustule can transmit light to enter the cell. This suggests that the shell evolved to increase the exposure of the cell to ambient light. Their results also showed that light circulates inside the frustule long enough to aid photosynthesis during the transition from high to low light.
The new frustule model could make it easier to cultivate diatom species that harvest light at different wavelengths, allowing them to be tailored for specific applications. “These light-harvesting methods of diatoms can be used to improve the absorption of solar panels by allowing sunlight to be collected at more angles, thus partially removing the dependence of the panel to look directly at the sun,” said Bernal.
The researchers are now working to refine their model and plan to use their new tool to study other diatom species. Next, they plan to extend the model beyond the interaction of light within a single frustule to examine behavior between multiple frustules.
This work commemorates Dan Petrescu, who died last year. The research would not have been possible without his insight, help and dedication.
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