In the quest to develop advanced biomaterials and functional materials, researchers have turned to an unlikely source: the humble sea urchin. A recent study published in the journal PeerJ Materials Science (PeerJ 物質科学), led by Pathitta Suteecharuwat of the Kitami Institute of Technology in Hokkaido, Japan, has uncovered fascinating insights into the structural and mechanical differences between the spines of the sea urchin species Strongylocentrotus nudus. The findings could have significant implications for the energy sector and beyond.
Sea urchin spines have long been of interest to materials scientists due to their remarkable mechanical properties. However, until now, no study has examined the structural distinctions between the spines in the ambulacral and interambulacral areas—regions that play different roles in the sea urchin’s locomotion and defense. Suteecharuwat and her team set out to address this gap, using a combination of cantilever bending tests, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to analyze the composition, elasticity, and microstructure of the spines.
The results were striking. The bending modulus of elasticity was significantly higher in the ambulacral area (52.067 GPa) compared to the interambulacral area (10.133 GPa), indicating that the spines in these regions have different mechanical properties. “This suggests that the sea urchin modulates the magnesium concentration in its calcite to achieve functional specialization of its spines,” Suteecharuwat explained.
Further analysis revealed that the ambulacral shaft had a slightly higher concentration of magnesium (0.9844 wt%) compared to the interambulacral shaft (0.9804 wt%), while the calcium concentration was lower in the ambulacral shaft (39.6578 wt%) compared to the interambulacral shaft (42.1076 wt%). Additionally, a variation in magnesium concentration was observed between the base and shaft parts of the spine. XRD showed a narrower (104) lattice spacing in the ambulacral spine (3.0264 Å) compared to the interambulacral spine (3.0275 Å), correlating with the higher magnesium concentration.
These findings suggest that the sea urchin S. nudus fine-tunes the magnesium content in its calcite to tailor the mechanical properties of its spines for specific functions, such as locomotion and defense. This bio-inspired approach to materials design could have significant implications for the development of novel functional materials, particularly in the energy sector.
For instance, the ability to control the mechanical properties of materials by modulating their elemental composition could lead to the development of more durable and efficient materials for use in energy generation, storage, and transmission. Additionally, the insights gained from this study could inform the design of new biomaterials that mimic the sea urchin’s ability to adapt its structure to different functional demands.
As Suteecharuwat noted, “Understanding the structural and mechanical differences in sea urchin spines could open up new avenues for the development of advanced materials that are inspired by nature.” With the energy sector increasingly looking to nature for inspiration, this research could pave the way for the development of innovative materials that are both high-performing and sustainable.
In the meantime, the study published in PeerJ Materials Science (PeerJ 物質科学) serves as a reminder of the incredible diversity of natural structures and the potential they hold for advancing materials science. As we continue to explore the natural world, we may yet uncover even more inspiring examples of bio-inspired design that could shape the future of the energy sector and beyond.