Strength, biodegradability and biocompatibility are all features of spider silk that make it an appealing option for biomedical applications. However, spider silk is hard to mass produce in potential spider farms due to the territorial and cannibalistic nature of spiders. To overcome this issue, scientists have been able to create recombinant spider silk from other sources such as E.coli. Now, an interdisciplinary team from the University of Nottingham has gone one step further to produce a recombinant spider silk that can be modified and applied to drug delivery, regenerative medicine and wound healing.
The new approach functionalizes recombinant spider silk with the ability to bind and release a wide range of small molecules. By adding in an amino acid containing an azide group to the silk proteins, the team was able to use ‘click chemistry’ to add on other small molecules such as antibiotics once the proteins are made.
Click chemistry is a common protocol for the modification of molecules. It uses a copper catalyst to initiate a reaction only between an already specified azide group and an alkyne group and does not interfere with other organic groups within the system. The groups are introduced into DNA and proteins so can be inserted at the optimal location chosen by the creator. In this case, the click chemistry reaction helps develop a site-specific chemical conjugation of various organic molecules.
Using E. coli as the machines to create the special silk, the group is able to click the molecule of choice into its place before or after the fibers are built. This allows more control of the process and of the types of molecules that can be incorporated into the silk.
Once the silk is made, there is a wide range of potential applications. In wound healing, the silk can dually act as a scaffold on which new cells can grow and as a protectant that slowly releases antibiotics over time to prevent infection. And with the low reactivity rates with the immune system, synthetic spider silk is easily introduced to immunocompromised patients.
Professor Neil Thomas, lead author and Professor of Medicinal and Biological Chemistry, said: "There is the possibility of using the silk in advanced dressings for the treatment of slow-healing wounds such as diabetic ulcers. Using our technique infection could be prevented over weeks or months by the controlled release of antibiotics. At the same time tissue regeneration is accelerated by silk fibers functioning as a temporary scaffold before being biodegraded."
The collaborative group is working on application of the process. The study, published in Advanced Materials, also introduces the potential of synthetic spider silk in a variety of different disciplines.
"Our technique allows the rapid generation of biocompatible, mono or multi-functionalized silk structures for use in a wide range of applications. These will be particularly useful in the fields of tissue engineering and biomedicine."