Nucleated protein self-assembly of an azido modified spider silk protein was employed in the preparation of nanofibrillar networks with hydrogel-like properties immobilized on coatings of the same protein. Formation of the networks in a mild aqueous environment resulted in thicknesses between 2 and 60 nm, which were controlled only by the protein concentration. Incorporated azido groups in the protein were used to “click” short nucleic acid sequences onto the nanofibrils, which were accessible to specific hybridization-based modifications, as proved by fluorescently labeled DNA complements. A lipid modifier was used for efficient incorporation of DNA into the membrane of nonadherent Jurkat cells. Based on the complementarity of the nucleic acids, highly specific DNA-assisted immobilization of the cells on the nanohydrogels with tunable cell densities was possible. Addressability of the DNA cell-to-surface anchor was demonstrated with a competitive oligonucleotide probe, resulting in a rapid release of 75–95% of cells. In addition, we developed a photolithography-based patterning of arbitrarily shaped microwells, which served to spatially define the formation of the nanohydrogels. After detaching the photoresist and PEG-blocking of the surface, DNA-assisted immobilization of the Jurkat cells on the nanohydrogel microstructures was achieved with high fidelity.

Photolithography combined with surface nucleated protein self-assembly of azido-modified spider silk proteins is used to create an arbitrarily shaped, inherently cell repellent micropattern based on nanofibrillar networks. Using "click" chemistry with dibenzocyclooctin modified oligonucleotides, the microstructures are functionalized with DNA-aptamers, which selectively bind cancer cell markers protein tyrosine kinase 7 or nucleolin. The epitopespecific cell interaction on the aptamer-modified surfaces is tested using human non-adherend leukemia T cells (Jurkat), as well as adherent cervix carcinoma (HeLa) and neuroblastoma (Kelly) cells. The cells can be immobilized with high precision and cell densities on the pattern, also revealing spatially defined proliferation and spreading into distinct morphologies upon cultivation. The formation of integrin-based focal adhesions occurs in the case of the aptamer immobilized cancer cells, similarly to those anchored on RGD-modified pattern. The firm aptamer-marker anchorage allows for the formation of integrin-dependent cell adhesions. Due to the amenability of the recombinant spider silk protein towards chemical and genetical modifications, the presented micropatterned fibrous networks have great potential for further development of adjustable and biocompatible cell-specific arrays, enabling applications in circulating cancer cell isolation and cultivation, studies on the cell's pathogenesis, progression and metastasis capabilities as well as enabling development of platforms for personalized medicine.

Janus fibers are a class of composite materials comprising mechanical and chemical to biological functionality. Combining different materials and functionalities in one micro-or even nanoscale fiber enables otherwise unreachable synergistic physicochemical effects with unprecedented opportunities for technical or biomedical applications. Here, recent developments of processing technologies and applications of polymeric Janus fibers will be reviewed. Various examples in the fields of textiles, catalysis, sensors as well as medical applications, like drug delivery systems, tissue engineering and antimicrobial materials, are presented to illuminate the outstanding potential of such high-end functional materials for novel applications in the upcoming future.

well as cell-cell and cell-ligand interactions. [10,11] Due to their reduced size and compact construction, these require fewer resources for their production, reducing their costs, whilst also minimizing the amount of analyte. This enables a much higher throughput of samples and their readouts than with more conventional macroscopic methods. [10,12] Photolithography represents a commonly used approach for microstructuring, whereby substrates are covered by a photosensitive resin, onto which illumination with a specific pattern imparts spatially defined soluble/insoluble areas, thus enabling selective deprotection of the surface and subsequent modifications at microscales. [10,13] Nonetheless, such microstructuring is often limited to the usage of covalently coupled synthetic polymers, due to the relatively harsh conditions involved in the photoresist processing.Milder methods have been developed, such as polymer grafting using photocatalyzed coupling reactions, [14,15] but 3D structuring and additional functionalization of the networks require ever more complex polymers increasing associated synthesis costs. The polymerization of dopamine could also be used to generate a pattern with high fidelity, which can be further modified, [16,17] but the spectrum of reactions that can be employed, is limited to the dopamine moiety, requiring elaborate chemistry if desiring to spatiotemporally implement several different functions.An approach to multilayering different functional substrates is presented by self-assembling protein films, which adhere to the prior layer using non-covalent interactions. [18] Such approaches are more versatile in the functionality and modification alternatives, but the introduction of specific functions on different spots of the substrate is often problematic. The non-covalent bonding, which predominates among the film layers, must also be resilient to breaking, limiting the variety of available interactions dependent on the application conditions, and impeding the development of a generally applicable system.A strong non-covalent bonding interaction is found in silks, where the intrinsically random coil domains self-assemble into β-sheet-rich formations, whereby they are stabilized in a network of the same proteins. [19] The difference in solubility and the inducible nature of the conversion could be used for micropatterning. [20][21][22][23][24] Yet, a method, which provides the duality of being able to introduce high fidelity, high-resolution micropattern with a plethora of possible functionalization Self-assembly of a recombinant spider silk protein into nanofibrillar networks in combination with photolithography is used to produce diversely functionalized micropattern. Amino-modified substrates coated with a positive tone photoresist are processed into 1 µm deep arbitrarily shaped microwells, at the bottom of which spider silk proteins are covalently coupled to the deprotected aminated surface. The protein layer serves to seed the self-assembly of nanofibrils from the same protein in the ...