Natural dragline silk can withstand extreme environmental conditions, such as tem­perature and pressure. MA silks submerged in liquid nitrogen, which at atmospheric pressure corresponds to -196°C, have exhibited increased breaking stress.28 Under these conditions, spider silk has been reported to have 64% higher tensile strength after cryogenic treatment.28 Also, cooling the fibers from room temperature to -60°C has been reported to produce increases in breaking stress and strain, leading to fibers that are tougher.27b Natural dragline silk is also thermally stable to approximately 230°C.29 Other factors that have been shown to influence the mechanical proper­ties of spider silk include humidity, acidity, alcohol treatment (methanol, ethanol and butanol), and special chaotrophic solvents.273-30 In general, treatment of dragline silks with solvents that have increased polarity, the Young’s modulus and breaking strength of dragline silk has been reported to decrease gradually.27a Humidity or incubation of the fibers in water or 8 M urea has been shown to result in shrinking or supercontraction of the fibers. For example, exposure to water can cause some dragline silk threads to shrink by 50% of their original length.31 For the medical in­dustry there are also benefits, for example, spider silk films have been shown to be biocompatible, elicit poor immune responses and have shown benefits in the wound healing process and promoter of coagulation.32 Natural dragline silk has also been demonstrated to provide a suitable matrix for 3-dimensional skin cell culturing.33