Artificial Materials Inspired by a Sea Mollusk Shell and Eyes


Credit: Wyss Institute at Harvard.

Scientists from the Wyss Institute for Biologically Inspired Engineering at Harvard have discovered how a biomineral can generate two mollusk structures as different as the protective shell and the eyes. The study, published in Science, will help to create multifunctional materials.

Material scientists have long been trying to obtain artificial materials with multiple functions, but they don’t understand the theoretical basis of the phenomenon. Dr. Joanna Aizenberg, based on her studies of the brittlestar mineral skeleton and visual organs, hypothesized that she could deduct those principles from multifunctional biomaterials. With that intention, a multidisciplinary team was formed to study the chiton Acanthopleura granulata. This animal has hundreds of eyes made from a not organic material, aragonite, the same material that makes up its shell. The eyes allow the sea mollusk to detect predators through changes in light.

Biomimetic materials developed following nature´s cues

Performing microscopy and high-resolution X-ray microtomography experiments, the research team unraveled the 3D structure of the chiton´s eye.  It has a cornea, a lens and photoreceptive cells. Aragonite crystals, bigger than the ones in the shell, form the lens, and are aligned to concentrate light in a retina-like point. The researchers discovered that the eyes appeared later than the shell, with a necessary trade off among material properties. Because of the different properties favored, the eyes are more vulnerable than the shell, so evolution dictated their small size and relatively protected localization.

These materials are a valuable source of information on how to design materials with different functions, an advance for the development of biomimetic materials. For example, a house could be built from a robust material that could also generate lenses to regulate light and temperature inside.

The study paves the way for the design of synthetic materials that can bring new solutions for industrial and medical applications.

Source: Wyss Institute

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