Spider silk is well known to naturalists and engineers for its exceptional resistance. At equal diameter, these fibers can be up to five times stronger than steel !
Obviously, these properties are of interest greatly researchers; in materials science, spider silk is an inexhaustible source of inspiration. Science has already made some great discoveries by trying to replicate its structure. This is how in 2018, Professor Fuzhong Zhang and his team at Washington University in St. Louis succeeded in making a bacterium produce recombinant spider silk, inx performance similar to real material. This gave the researcher an idea: by pushing the same structural recipe further, would it be possible to create a material that performs better than spider silk?
According to the latest work published by him and his team in ACS Nano , it would seem that the answer is a big “yes”. They have an “ amyloid polymeric ” fiber that is stronger than kevlar, and even stronger than some natural bristles.
© Li et. al.
The well-kept secrets of eight-legged engineers
To achieve this result, the researchers had to overcome a large number of obstacles. In particular, the most difficult was to solve the problem of the β nanocrystals. These structures are the one of the main components of spider silk; despite their small size, these crystals are directly responsible for the resistance of the thread. However, the cooking recipe of a spider's web is extremely precise; if the fiber contains too little from these crystals, it loses its properties and disintegrates.
The problem is that if our eight-legged friends obviously master the manufacturing process, thishumans do not. “Spiders know how to weave fibers with a precise amount of nanocrystals”, explains Zhang . “But when humans weave it artificially, the amount of nanocrystals is often too low ”.
To solve this problem, the researchers had an idea: they produced the fiber to genetically modified bacteria. To do this, they isolated the part of the spider genome corresponding to the formation of silk, which they transferred to a bacterium. They introduced a sequence capable of generating a rather particular structure, called sequence amyloid . There are several types, but what they have in common is that they allow certain proteins to fold and stick together ; in this case