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Forschungsarbeit


Biofabrication of biomineralized 3D protein gradient scaffolds

von Vanessa Jutta Wicklein

Modern medicine faces great challenges, and among them is the regeneration of human tissues in context of the shortage of available donor organs and tissues. One promising approach is the tailor-made design and manufacturing of tissue scaffolds for personalized regenerative medical approaches on demand, the so-called tissue engineering.

In this context, the production of complex (non-) living and hierarchically structured materials based on cells (eventually from the patient), biopolymers, biominerals and functional peptides, can overcome this problem. Therefore, functional materials, inspired by the natural blueprint, are tailored for distinct biomedical applications and medical cases. However, there are several requirements for tissue-engineered scaffolds to be fulfilled such as biocompatibility, biodegradability during the natural tissue regeneration process and appropriate mechanical properties to guarantee an optimal environment for cell adhesion, proliferation and function. [1,2]

Spider silk is a suitable candidate for biomaterial applications as it shows no immunogenicity, good biocompatibility and biodegradability. In ancient times, people already used its properties e.g. as wound cover devices. [3] Recently, the workgroup of Prof. Dr. Thomas Scheibel developed engineered recombinant spider silk proteins, based on the genetic information of A. diadematus dragline silk. These proteins are biotechnologically produced in continuously high quality and can be processed into various morphologies. For instance, highly elastic and tough fibers, which excel even the toughest man-made fibers as Kevlar and Nylon, were produced from recombinant spider silk proteins. [4] Further, particles, films, capsules and non-woven meshes could be prepared via different processing methods for a variety of applications. [3] Moreover, hydrogel preparation was examined in detail to develop so-called "bioinks" for 3D printing (Fig. 1A, B). Bioinks are cell-encapsulating biomaterials that can be directly processed into scaffolds for biomedical applications (Fig. 1C). [5,6]

At the Department of Biomaterials, one subgroup focuses on gradient biomaterials. Gradient formation serves the linear transmission of external loads from one to the other side of the material to avoid crack propagation and material failure at material interfaces. Functional gradient materials can be inspired by the transition of soft to hard biogenic materials, e.g. are found in the anchoring of mussels to stone by byssus threads.

My focus of research lies in the biofabrication of biomineralized 3D protein gradient scaffolds for biomedical applications. In a first step, new spider silk variants are designed and produced recombinantly in E. coli bacteria. With the purified protein, different morphologies can be achieved with a focus on hydrogel formation for an application as bioink. During 3D printing, scaffolds with distinct design criteria and different composition are processed.

 

References

[1] Langer, R.; Vacanti, J., Science 1993, 260 (5110), 920-926.
[2] Mironov, V.; Trusk, T.; Kasyanov, V.; Little, S.; Swaja, R.; Markwald, R., Biofabrication 2009, 1 (2).
[3] Leal-Egana, A.; Scheibel, T., Biotechnol. Appl. Biochem. 2010, 55, 155-167.
[4] Doblhofer, E.; Heidebrecht, A.; Scheibel, T., Applied Microbiology and Biotechnology 2015, 99 (22), 9361-9380.
[5] DeSimone, E.; Schacht, K.; Pellert, A.; Scheibel, T., Biofabrication 2017.
[6] Schacht, K.; Juengst, T.; Schweinlin, M.; Ewald, A.; Groll, J.; Scheibel, T., Angew. Chem.-Int. Edit. 2015, 54 (9), 2816-2820.
[7] Schacht, K.; Scheibel, T., Biomacromolecules 2011, 12 (7), 2488-2495.
[8] Schacht, K.; Juengst, T.; Zehnder, T.; Boccaccini, A. R.; Groll, J.; Scheibel, T., Nachrichten aus der Chemie 2016, 64, 13-16.

Fig. 1: A) The properties of recombinant spider silk hydrogels can be modified during processing.[7] B) Recombinant spider silk “bioinks” can be used for 3D printing. [8] C) A modified silk variant with an RGD-cell binding motif enhances cell adhesion (green) in spider silk scaffolds. [6]

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