Almost exactly one year ago, we interviewed Professor Anna Rising on her and her team’s breakthrough to start the industrial production of artificial spider silk. Today, the researchers at Karolinska Institutet in Sweden and the Swedish University of Agricultural Sciences unveil the next step.
The team have discovered that spider silk proteins can be fused to biologically active proteins and be converted into a gel at body temperature. The mentioned injectable protein solution that they now hope to develop forms a gel inside the body, which could be used in tissue engineering and for drug release, but also make gels that can streamline chemical processes where enzymes, a form of proteins, are used to speed up various chemical processes.
— We have developed a completely new method for creating a three-dimensional gel from spider silk that can be designed to deliver different functional proteins, says Anna Rising. The proteins in the gel are very close together and the method is so mild that it can be used even for sensitive proteins.
— In the slightly longer term, I think injectable gels can become very useful in regenerative medicine. We have a long way to go, but the fact that the protein solution quickly forms a gel at body temperature and that the spider silk has been shown to be well tolerated by the body is promising, says Tina Arndt, PhD student in Rising’s research group at Karolinska Institutet.
The ability of spiders to spin incredibly strong fibres from a silk protein solution in fractions of a second has sparked an interest in the underlying molecular mechanisms. The researchers have been particularly interested in the spiders’ ability to keep proteins soluble so that they do not clump together before the spinning of the spider silk.
— We have previously shown that a specific part of the spider silk protein called the N-terminal domain is produced in large quantities and can keep other proteins soluble, and we can exploit this for medical applications. We have let bacteria produce this part of the protein linked to functional proteins, including various drugs and enzymes, says Anna Rising.
The new study, published in Nature Communications, shows that the N-terminal domain also has the ability to change shape and transition to small fibrils (structural biological materials) that cause the protein solution to be converted into a gel if incubated at 37 °C. In addition, it can be fused to functional proteins that preserve their function in the gel.