Silk originates from this strange structure; to truly understand what it is, one must start here. The image was produced using an electron microscope and highlights the structure of a natural silk thread exactly as it is produced by the silkworm. The thread was brought to its maximum level of hydration and the fractures were obtained using an ultrasonic probe. It took countless attempts to achieve what can be seen.
Natural silk fiber is composed of two proteins: fibroin, which forms the two inner filaments, and sericin, which holds them together. Both proteins are produced in two glands in the form of a dense solution, but as soon as the caterpillar extrudes them, they separate, generating this kind of two-component cable. This process has been studied for more than a century, but only today has the mechanism that generates this strange and incredible natural polymer been fully understood.
Its properties are countless and never cease to amaze. In the collective imagination, silk is associated with textiles, but the caterpillars that produce it have never thought about ties. Today silk is produced for the textile industry, but future applications include biomedicine, cosmetics and many other advanced fields. Yet one question remains: why do caterpillars go to such lengths to produce such a complex structure, with two filaments, an outer coating and two chemically opposite proteins?
