 Spider silk has not been used in tissue engineering until now because of the predatory nature of spiders and the low yield of silk from individual spiders.It has been discovered that the species Nephila clavipes produces silk that is less immunogenic than silkworm silk; it has a tensile strength of 4 x 109 N/m, which is six times the breaking strength of steel.Because spider silk is proteolytically degraded, there is not a shift in pH from the physiological pH during degradation.