» Former research projects
3D cultivation of tumor cells as in vitro model for cancer research (A. Döbl)
So far, preclinical tumor research for identification of possible drugs is based on 2D cell culture methods and xenograft mice. 3D tumor cell cultivation techniques will expand the tools of in vitro cancer models, providing additional insights into cancerous tissue analysis. Hydrogels made of recombinant spider silk proteins are a well-suited material for 3D cell culture due to their suitable mechanical and biochemical properties, and they can be used as bioink to create cell-laden constructs using 3D-printing technologies. The project objective is to develop a 3D in vitro tumor model.
Development and analysis of gradient scaffolds for Achilles tendon replacement (K. Koeck)
Tissue engineering of fibrous tissues of the musculoskeletal system, such as tendon, presents a major challenge for biomedical research due to its complex architecture and mechanical behavior. Natural healing of tendon is limited due to a low number of cells and its avascularity. In healing, a hierarchically organized structure is replaced by a disorganized fibrous scar tissue with inferior mechanical properties. To address this problem, fabric-like braided polymer ropes are used as partial tendon replacements, however, these tend to be inferior due to a lack of biological function as well as lack of material/mechanical gradients. This projects aims to create a total tendon replacement based on a gradient fiber-reinforced composite by combining a textile approach with abio-inspired materials approach. The tendon-like replacement tissue will be evaluated based on the mechanical stability and biocompatibility.
Investigation of structural formation and phase separation behavior of (ultra-)thin spider silk proteins (S. Lentz)
Spider silk proteins can be considered as block-copolymers of repetitive amino acid sequence modules. The availability of various recombinantly produced short spider silk peptides with different properties, and their processing in (ultra-)thin films enables the investigation of structural formation and phase separation properties under controlled 2D and 3D conditions. The aim of this project is to analyze the influence of composition and sequence of the silk peptide modules in order to generate coatings with defined molecular and morphological surface properties for a controlled interaction with biopolymers, cells, drugs and biominerals
Development and engineering of skeletal muscle tissue (C. Müller)
Despite the self-regenerative abilities of skeletal muscle tissue, in case of great volumetric muscle loss suitable biomaterials and tissue engineering approaches are required to restore the functionality of the tissue. Muscle tissue has a highly unidirectional oriented and hierarchical structure, which is essential for the function of the muscle. This unique structure should be considered when growing muscle cells in-vitro. In this research, in collaboration with the Friedrich-Alexander University of Erlangen-Nuremberg (Institute of Biomaterials) and the University of Würzburg (Department Tissue Engineering and Regenerative Medicine) and in framework of SFB-TRR225, we focus on developing composite inks for biofabrication of anisotropic skeletal muscle tissue within printed bioreactors.
See also: http://trr225biofab.de/
Co-expression, purification and self-assembly of recombinant spider silk proteins (M. Saric)
Spider dragline silk consists of two spider protein classes (spidroin classes), i.e. major ampullate spidroin 1 and 2 (MaSp1 and MaSp2), which differ by their proline content, and enable outstanding mechanical properties like high tensile strength, as well as high extensibility and toughness.
Project 1
The dragline silk of Araneus diadematus contains two MaSp2 proteins, namely ADF3 and ADF4, differing from other orb-weaver spiders. ADF3 and ADF4 exhibit remarkable different characteristics regarding solubility and assembly, but research on their interaction during fiber assembly and within the fiber of these spidroins is sparse. To date, either ADF3 or ADF4 engineered protein mimics have been used for fiber processing. The project aims to produce heterodimers of the engineered silk protein variants eADF3 and eADF4 in order to study their interaction during fiber assembly.
Project 2
Spidroins are composed of a highly repetitive core domain flanked by a carboxy- and amino-terminal domain. Both terminal domains play an important role for controlling spidroin storage in the lumen as well as for fiber formation within the spinning duct. In this project the assembly behavior and the influence of terminal domains thereon are studied.
Development and Production of bioinspired “glues“ (A. Winkler)
Man-made synthetic glues are used to stick two objects together. Natural adhesive systems, however, are multifunctional and used for different processes, such as protection, self-defense, propagation, prey hunting and capturing. The natural “glues” are mostly proteins including typical amino acid residues or motifs in combination with posttranslational modifications. One well-researched example for under water adhesives are mussel foot proteins (mfp) from blue mussel (Mytilus edulis), which anchor themselves to various surfaces in the sea. It is known that high concentrations of lysine and DOPA (3, 4-dihydroxyphenylalanine, a posttranslational hydroxylation of tyrosine) residues are the key factors for the successful surface attachment. Additionally, serine- or threonine-rich motifs partially modified by phosphorylation or glycosylation, are used by other organisms.
Different protein-based glueing systems will be characterized in detail. Understanding of the adhesive mechanisms enables their mimicry and the development of application-specific recombinantly produced glue proteins.
Entfernung von Endotoxinen aus rekombinanten Proteinen unter Verwendung wässriger biphasischer Systeme (S. Strassburg)
Wässrige zweiphasige Systeme erfahren zunehmender Aufmerksamkeit für Anwendungen zur Proteintrennung. Viele dieser Systeme verwenden ionische Flüssigkeiten oder binäre/ternäre Mischungen von Salzen, die als „tief-eutektische Lösungsmittel“ (DES) bezeichnet werden. Dies sind einzigartige Lösungsmittel, die sich in zwei wasserreiche Phasen aufteilen. In diesem Projekt wollen wir ein Zwei-Phasen-System etablieren, um rekombinante Spinnenseide und Modell-Endotoxine (z.B. Lipoproteine, Polysaccharide, etc.) mit Hilfe des Phasenverhaltens für mehrere einfach zu produzierende DES-basierte ABS zu trennen.
Design, characterization and manufacturing of recombinant spider silk protein variants
The dragline silk produced by the European garden spider (Araneus diadematus) is a fascinating protein-based biopolymer. The underlying spider silk proteins (spidroins) of the fiber are responsible for its unique combination of strength and extensibility, resulting in a remarkably high fiber toughness. Independent of the spider species, spidroins have three characteristic domains: a relatively large core domain comprising repetitive amino acid sequences which is flanked by a non repetitive amino- and carboxyterminal domain. These terminal domains regulate the spidroin assembly process during the extrusion of a fiber and are highly conserved across different silk types, while the main mechanical properties of the spun silk thread are based on the spidroin core domain.
The two primary spidroin classes found in dragline silk are produced in the major ampullate silk gland, thus referred to MaSp1 and MaSp2 (Major Ampullate Spidroins). Their repetitive core sequences mainly differ in the proline content, i.e. MaSp2 contains a relative high amount (>10%) and MaSp1 a smaller amount (<0.4%) of prolines. In this project, artificial spidroins comprising different sequences will be produced and characterized.