Martin Humenik, Anton Molina, Tamara Preiß, Demetrio Piro and Thomas Scheibel
University Bayreuth, Faculty of Engineering Science, Department of Biomaterials, Bayreuth, Germany
We established DNA-spider silk conjugates using “click” coupling of the recombinant protein eADF4(C16) with short DNA strands to create hybrid materials. Whereas the spider silk moiety enabled self-assembly into nanofibrils controlled by phosphate ions in aqueous buffers, the DNA part enabled DNA specific fibril labeling  or DNA-hybridization based self-organization of the fibrils into hierarchically ordered nano-ribbons and microscopic rafts . In our recent work, we applied sequence specific DNA hybridization for the immobilization of DNA-spider silk conjugates on complementary modified surfaces. Addressing of the conjugates onto predestined spots was achieved using micro-contact printing. Addition of the unmodified protein and phosphate buffer triggered localized protein nucleation and fibril self-assembly on the surface resulting in nanofibril-based patterns with a submicrometer resolution . Further, we conjugated the spider silk protein with DNA-aptamers, which specifically bind to a selected enzyme. The spider silk moiety did not disturb the aptamer-enzyme binding and enabled immobilization of the aptamer via nanofibril self-assembly on surfaces. The nanostructured and aptamer-functionalized surfaces revealed high enzyme binding capacity. Moreover, a specific switch in the secondary structure of the immobilized DNAs allowed fast release of the active enzyme .
In summary, we have demonstrated that the localization of nucleation and self-assembly of spider silk cross-beta nanofibrils on surfaces is possible. This approach is compatible with soft lithography allowing complex patterns of fibrils in a submicrometer range as well as incorporation of ligand-binding aptamers for specific immobilization and release of active enzymes.
 M. Humenik & T. Scheibel, ACS Nano 8, 1342-1349 (2014)
 M. Humenik, M. Drechsler & T. Scheibel, Nano Letters 14, 3999-4004 (2014)
 M. Humenik, A. Molina & T. Scheibel, Biomacromolecules 20, 347–352 (2019)
 M. Humenik, T. Preiß, S. Gödrich, G. Papastavrou and T. Scheibel, submitted