Nanostructured biomaterials are of high interest to study and control cell-material interactions on the nanoscale since they can mimic the nanotopography of the natural extracellular matrix (ECM). Our aim is to develop novel nanofibrous biomaterials from different proteins and polysaccharides, which resemble the nanostructure and molecular composition of the native ECM.
We developed a novel extrusion approach through anodic alumina nanopores to prepare nanofibres from various proteins and polysaccharides in aqueous buffers. Nanofibre assembly was achieved for a wide range of ECM proteins including collagen, fibronectin and elastin. We were also able to extrude nanofibres from polysaccharides like hyaluronan and chitosan.1 Using scanning electron microscopy we found that extruded nanofibres either assembled into aligned fibre bundles up to millimetre length or into randomly oriented fibre meshes. Moreoever, our extrusion approach facilitated the first-time preparation of nanofibrous composites from collagen and fibronectin. Immunofluorescence staining of these scaffolds confirmed that both proteins were present in the extruded nanofibres. Adjusting the protein concentration and the diameter of the alumina nanopores enabled us to reproducibly control the diameter of single nanofibres. Further on, Förster resonance energy transfer measurements in a confocal fluorescence microscope revealed lasting conformational changes in extruded fibronectin nanofibres. By tailoring the fibronectin concentration and nanopore diameter we could reproducibly control the degree of fibronectin unfolding in extruded fibre bundles.2
In summary, we established a new approach to prepare nanofibrous biopolymer scaffolds via extrusion. This method holds great potential to promote the design of novel nanofibrous biomaterials and tissue engineering scaffolds for controlled interaction with cells.
1. Raoufi, M. et al. Template-Assisted Extrusion of Biopolymer Nanofibers under Physiological Conditions. Integrative Biology 8, 1059–1066 (2016).
2. Raoufi, M. et al. Nanopore Diameters Tune Strain in Extruded Fibronectin Fibers. Nano Lett 15, 6357–6364 (2015).