In one of our earlier posts, we introduced you to the work of Fiorenzo Omenetto and a TED Talk he gave about the potential applications of silk in the medical industry and how silk can be used to fabricate better medical implants. Now, Omenetto and his team of researchers at Tufts University have created an silk optical implant.
A microscopic image of a silk optical implant embedded with gold nanoparticles
The optical implants are made of a purified silk protein and arranged in microprism array by pouring the solution of silk protein into molds of multiple micro-sized prism reflectors. After the cast solution dries, a silk sheet is formed that looks very similar to reflective tape. The benefit of fabricating silk sheets in the MPAs is that when the silk films are implanted into the body, reflect back photons that are ordinarily lost with reflection-based imaging technologies, which allows for enhanced imaging even in deep tissue. These silk optical implants, which are an improvement to current tissue imaging techniques, can do much more than simple providing imaging for doctors. The devices can be engineered to also administer therapeutic treatments to patients. The researchers are able to embed both gold nanoparticles and the cancer drug doxorubicin into the silk sheets to treat targeted parts of the body were the silk sheets can be implanted. The benefit of this is that it allows for the precise delivery of drugs while also providing a mechanism with which to monitor the body with. When silk sheet is no longer needed, it dissolved into the body, doing no harm because it is biocompatible. For more information visit Fiorenzo Omenetto's website.
Previously on our blog, we mentioned the wonders of silk - a natural material that exhibits properties found in nanomaterials. Scientists that are trying to make tougher nanomaterials are now looking at the structures of animals for inspiration. A finding over the summer has shown that due to its nanoscale structure, the mantis shrimp, otherwise known as Gonodactylus smithii, can strike prey with speeds, "matching that of a 5.56mm rifle."
A feature on USA Today even claims that club of a mantis shrimp can shatter a hole into aquamarine glass. Science Daily reports that Assistant Professor Ali Miserez lead a team that found that the unique structure of the mantis's claw makes it stronger than most ceramics out in the implant market now. Check out the original article over here. The following video illustrates the sheer strength of the shrimp's claw - the reasons behind this will be discussed a little later.
A video illustrating the awesome strength of the mantis shrimp.
Chitosan - an extremely long carbohydrate
This is an extremely important discovery, as it leads to many implications in the science of implants. Currently, a combination of titanium and polyethylene (aka plastic) is used in hip and other implants. This presents two problems. The first problem is that this combination of materials is, while not weak, not particularly strong. Also, since these implants are made of foreign materials, the body is more likely to reject them. Prof. Miserez's finding mollifies both these problems. The claw of the mantis shrimp is composed of hydroxylapatite, a strong calcium compound, and chitosan, a naturally occuring carbohydrate molecule, according to a Discovery News article. The hydroxylapatite allows for initial toughness, while the chitosan allows for more impact to be absorbed. The chitosan was found to be arranged like stacks of paper, thus effectively dissipating most of the impact incurred after the blow dealt by the mantis shrimp. The study of the shrimp's structure can lead to new and interesting innovations in the art of making ceramics.
