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 Synthetic spider silk and spider, below, which has been produced at the Centre of Biomolecular Sciences by a team headed by professor Neil Thomas, bottom left, of which Dr David Harvey, bottom right, was the first to join


An interdisciplinary teamof scientists at the University of Nottinghamhas developed a technique to produce “chemically functionalised” spider silk that can be tailored to applications used in drug delivery, regenerativemedicine andwound healing. The Nottinghamresearch teamhas shown

for the first time how“click-chemistry” can be used to attachmolecules, such as antibiotics or fluorescent dyes, to artificially produced spider silk synthesised by E.coli bacteria. Spider silk is strong, biocompatible and

biodegradable. Yet themedicinal properties of spider silk have been recognised for centuries, though not clearly understood. It is a protein-basedmaterial that does not appear to cause a strong immune, allergic or inflammatory reaction.With the recent development of recombinant spider silk, the race has been on to findways of harnessing its remarkable qualities. The chosenmolecules can be “clicked”

into place in soluble silk protein before it has been turned into fibres, or after the fibres have been formed. Thismeans that the process can be easily controlled and more than one type ofmolecule can be used to “decorate” individual silk strands. In a laboratory at the Centre of

Biomolecular Sciences, professor Neil Thomas fromthe School of Chemistry in collaborationwith Dr Sara Goodacre from the School of Life Sciences, has led a team of BBSRC DTP-funded PhD students – startingwith David Harveywhowas then joined by Victor Tudorica, Leah Ashley and TomCoekin. They have developed and diversified this newapproach to functionalising “recombinant” — artificial —

spider silkwith awide range of small molecules. When these “silk” fibres are “decorated”

with the antibiotic levofloxacin, it is slowly released fromthe silk, retaining its anti- bacterial activity for at least five days. Thomas, a professor ofmedicinal and

biological chemistry, said: “Our technique allows the rapid generation of biocompatible,mono- ormulti- functionalised silk structures for use in a wide range of applications. Thesewill be particularly useful in the fields of tissue engineering and biomedicine.” The biodegradablemesh produced

can do two jobs at once: it can replace the extra cellularmatrix that our own cells generate, to accelerate growth of the newtissue. It can also be

used for the slowrelease of antibiotics. “There is the possibility of using the silk in

advanced dressings for the treatment of slow-healingwounds such as diabetic ulcers. Using our technique, infection could be prevented overweeks ormonths by the controlled release of antibiotics,” added Thomas. “At the same time, tissue regeneration is accelerated by silk fibres functioning as a temporary scaffold before being biodegraded.” The approach requires the production of

the silk proteins in a bacteriumwhere an amino acid not normally found in proteins is included. This amino acid contains an azide groupwhich iswidely used in “click” reactions that only occur at that position in the protein. No-one had used this approach beforewith spider silk.

February 2017 /// Environmental Engineering /// 7

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