A new bonding agent may soon be used as a substitute for present-day commercial and biomedical adhesives and may even be used to repair torn tendons or fix broken bones, thanks to a team of scientists who got their inspiration straight from nature's silk-weaving masters - spiders.
Scientists at the University of Akron in Ohio came up with artificial duplicates of the spiders' organs for spinning their ultra-sticky silk called "attachment discs," which are used when these arachnids undergo a remarkable weaving process of pinning down threads of silk with the use of additional strands for stitching or stapling, usually for locomotion and for catching prey. Dubbed as a "staple-pin," this neat geometry spun by attachment discs illustrated that a strong binding force is possible even by only using little material.
Realizing this unique method, the researchers hoped to apply this spider-like procedure in hastening the healing process of any human injury. The Akron team then came up with "electrospinning" technique, duplicating that of the spiders' attachment discs through pinning down nylon threads with fibers made from the new method. The fibers that would act as the "staple-pin" are produced by electrical charges that draw finely woven fibers from polyurethane, a flexible and durable polymer mainly used as substitute for cotton, rubber, metal or wood.
"This adhesive architecture holds promise for potential applications in the area of adhesion science, particularly in the field of biomedicine where the cost of the materials is a significant constraint," wrote the authors of the study that was published in Journal of Polymer Physics.
"Instead of using big globs of glue, for example, we can use this unique and efficient design of threads pinning down a fiber," said lead author Ali Dhinojwala, who is also a H.A. Morton professor and department chair of polymer science at Akron. "The inspiration was right in front of us, in nature."
Four years ago, Dhinojwala conducted a study about the adhesiveness of the silk spun by spiders. Together with Vasav Sahni and biology professor Todd Blackledge, Dhinojwala, who has long been intrigued with how nature produces its own adhesives, tried to find out what makes up the microscopic substance that makes the spiders' web sticky. In an experiment, the webs spun by spider were put in a glass plate, to which the researchers tried to pull it to measure the silk's strength and elasticity.
"The material is called spiral silk and its purpose is to catch insects, so it is sticky," Dhinojwala said in a previous interview. "If you look at spiral silk under a microscope, you will see these little drops -- the glue." The glue Dhinojwala was referring to was produced by a gland that all spiders possess in fours, the aggregate gland.
