Understanding complex biomaterials by in-situ electron microscopy
Mohammad Soleimani developed a toolbox that may pave the way for materials scientists to characterize and improve the properties of glass-based coatings for industrial applications.
Many biomaterials are well-known due to their sophisticated morphologies and remarkable mechanical properties that have been produced by combining relatively simple ingredients. Researcher Mohammad Soleimani developed a versatile toolbox to determine the mechanical properties of biogenic silica of an algae known as diatom and to monitor the effects of environmental variations on these properties by a combination of cutting-edge electron microscopy techniques with micromanipulators and ion beam nanomachining.
Through the evolutionary process for millions of years, many living organisms have discovered a way of creating hierarchical biogenic materials. The development of characterization techniques that lead to discovering the various properties of such biomaterials can provide unique opportunities not only to advance our understanding of the properties and behavior of these biomaterials but also to utilize the obtained knowledge in the fabrication of man-made materials with improved properties.
These biogenic materials can even be produced from basic ingredients such as silica (“sand”) which is found in the diatom “glass house” exoskeleton. As humans, we may not be able to copy exactly what nature is so cleverly doing but we can learn from her to overcome the limitations of our current state-of-the-art man-made materials.
In his research, Soleimani aimed to understand how diatoms form their exoskeleton structure, and what changes happens in their properties while Al ions are present, or salt levels vary in the growth medium. To do so, he designed a new toolbox to precisely cut and isolate different parts of the diatom exoskeleton inside an electron microscope.
Then, the mechanical properties of the cut parts of the diatom exoskeletons were individually determined at micrometer length scales. Soleimani discovered that not only different parts of the diatom body can have different mechanical properties but also, they behave differently upon the presence of Al ions in the growth medium or changes in the amount of fed salt.
He showed that even a small amount of Al ions in the medium of diatoms can alter the chemical, morphological, and mechanical properties of their exoskeletons. His findings and the developed toolbox may pave the way for materials scientists to characterize and improve the properties of glass-based coatings for industrial applications.
Mohammed Soleimani defends his PhD thesis entitled Exploring the Morphology, Chemistry, and Mechanics of Biogenic Silica in Diatoms on April 21th. He was supervised by prof.dr. Rolf van Benthem and dr. Heiner Friedrich.