The spider being studied is the American brown recluse spider (Loxosceles reclusa). This spider produces necrotic venom, and the bite, like various other recluse bites, sometimes requires medical attention. The spiders range in color from whitish to dark brown or blackish gray and they have markings on the dorsal side of their cephalothorax (the head and the thorax fused together), with a black line coming from it that looks like a violin.
It is not the venom that is of interest to materials scientists but rather how the spider manages to produce silk that is very strong, even relative to other spiders. The basis of the research, carried out at Oxford University’s Department of Zoology, is to see if the principles behind the silk can be used to create tougher and stronger materials. The development of very strong materials is required for space travel, among other applications, particularly NASA’s plans to send humans to Mars on deep-space travel expeditions.
The new material would be synthetic. Observations to date show that unlike other types of spiders, which produce round ribbons of thread, the recluse spider’s silk is thin and flat. This is an important structural difference and it gives the basis to the thread’s strength. The silk is not only very strong, it also maintains flexibility. The flexibility prevents the silk from breaking.
According to the lead researcher, Professor Hannes Schniepp: “Observation of the recluse spider provided the breakthrough solution; unlike all spiders its silk is not round, but a thin, nano-scale flat ribbon. The ribbon shape adds the flexibility needed to prevent premature failure, so that all the microloops can provide additional strength to the strand.”
The new understanding of the spider and the silk was provided through computer imaging and computer simulations; the simulations were used to design synthetic fibres. This showed that adding even a single loop to the structure significantly enhanced the strength of the material.
The insights into the structure of spider silk will provide the basis for new fibre technology. For example carbon filaments could be looped to make them less brittle. The research is published in the journal Materials Horizons under the heading “Toughness-enhancing metastructure in the recluse spider’s looped ribbon silk.”
