Protein Assists Self-assembly of Materials

Biological Strategy

Orange puffball sponge

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Chemically Assemble Polymers

We might think that complex polymers are the result of human industrial ingenuity, but nature cornered the market on polymers billions of years earlier. Examples of biopolymers are proteins, carbohydrates, and genetic material. In contrast to human industrial processes, within a cell, ribosomes covalently bond amino acids together to form proteins.

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Chemically Assemble Inorganic Compounds

The vast majority of biochemical assembly and break down processes––even by the most complex organisms––occur within cells. In fact, cells are able to perform hundreds, even thousands, of chemical transformations at the same time under life-friendly conditions (ambient temperature and pressure in an aqueous environment). For example, coral polyps transform dissolved calcium and carbonate ions into crystalized calcium carbonate within the calicoblastic cells.

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Sponges

Phylum Porifera (“pore-bearing”): Sponges

Sponges may seem simple, but there’s more to them than meets the eye. True, they don’t have nerves, muscles, or organs. But they do have unique, specialized cells that help them survive. Collar cells have long tails or flagella that line the inner sponge cavity and funnel water through the body. Sponges are filter feeders, taking in large amounts of water and trapping tiny particles to eat. They also have small spiky spicules made of silica or calcium carbonate that help them keep their structure. There are at least 5,000 known species of sponges living in aquatic systems, with 98% of them in the ocean.

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Silica structures of sponges self-assemble with the help of silicatein (a protein).

“The growing demand for benign materials synthesis methods has spawned research on self-assembly in living organisms. In sponges, silica structures are formed at ambient conditions with the help of silicatein, a that hydrolyzes and condenses the precursor molecule tetraethoxysilane. Researchers at the University of California, Santa Barbara synthesized cysteine-lysine block copolypeptides mimicking the properties of silicatein. The copolypeptides self-assembled into structured aggregates that hydrolyzed tetraethoxysilane while simultaneously directing the formation of ordered silica structures. Different types of silica structures could be produced by differentially oxidizing the cysteine sulphydryl groups. Species studied was Tethya aurantia.” (Courtesy of the Guild)

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