Periodic Reporting for period 2 - BioCombs4Nanofibers (Antiadhesive Bionic Combs for Handling of Nanofibers)
Okres sprawozdawczy: 2020-10-01 do 2022-09-30
Nanofibers are of great technical interest due to their superior surface-to-used-material-ratio for many applications, e.g. for respiratory face masks as those used in the Covid-19 crisis. However, technical nanofiber processing is often inhibited by their attraction to any surface by van der Waals forces.
The overall objective of the BioCombs4Nanofibers project is to enable that future tools for nanofiber handling are antiadhesive towards nanofibers which will facilitate considerably the processing of nanofibers and widen their application spectrum. Similar nanostructures can hinder the adhesion of nanofibrous protrusions of cells or microorganisms, which may enable cell-repellent or antiseptic areas on medical devices and implants.
The overall objective of the BioCombs4Nanofibers project is to enable that future tools for nanofiber handling are antiadhesive towards nanofibers which will facilitate considerably the processing of nanofibers and widen their application spectrum. Similar nanostructures can hinder the adhesion of nanofibrous protrusions of cells or microorganisms, which may enable cell-repellent or antiseptic areas on medical devices and implants.
There is a biological example to show how to tackle this problem: cribellate spiders bear a specialized comb, the calamistrum, to handle and process nanofibers, which are assembled to their capture threads.
In one of our first publications (A.-C. Joel et al., ACS Applied Nano Materials 3, 3395 (2020), [1]), we were able to prove that these fibers do not stick to the calamistrum because of a special fingerprint-like nanostructure on the comb. This structure prevents the nanofibers from smoothly adapting to the surface of the comb, thus minimizing contact and reducing the adhesive van der Waals forces between the nanofibers and surface. This leads to the spiders’ ability of nonsticky processing of nanofibers for their capture threads. The successful transfer of these structures to a technical surface proved that this biological model can be adapted to optimize future tools in technical areas in which antiadhesive handling of nanofibrous materials is required, including tissue engineering applications in medicine.
Mimicking the principle of nanostructures on the calamistrum of cribellate spiders, we were able to define an upscaled surface nanostructure with reduced adhesion force towards technical electro spun fibers (S. Lifka et al., Beilstein Arch. 2022, 202223 (2022), [2]). The biomimetic surface can be produced on metals by means of ultrashort pulse laser processing of self-organized laser-induced periodic surface structures, so-called laser-induced periodic surface structure (LIPSS). For the technically relevant materials steel and titanium-alloy, the presence of LIPSS reduced the peel-off forces by approximately 50% in both cases. Even more importantly, in contrast to the polished reference surface no nanofibers remained at the LIPSS-covered surfaces.
Inspired by anti-adhesive properties of nanostructures on the calamistrum of cribellate spiders, we could also demonstrate a strategy for bacteria repellent surface with promising potential applications in medicine and biotechnology (A. Richter et al., Nanomaterials 11, 3000 (2021), [3]). Many bacteria are equipped with nanofiber-like appendages (e.g. pili and flagella) that mediate the first contact with a surface and act as strong adhesins. However, the outstanding role of cell appendages in surface adhesion has so far not sufficiently been taken into account when bacteria repellent surfaces are in focus. Using laser processing as a tool for surface nano-structuring, adhesion of bacterial cells—and therefore the initial steps of biofilm formation—was strongly impeded. Systematic analysis of a broad range of nanostructures clearly demonstrates the dependence of bacterial adhesion on spatial periods. In addition, our results point out that the efficiency of bacteria-repellent surfaces can be significantly improved when surface structures impair nanofiber-mediated adhesion.
In one of our first publications (A.-C. Joel et al., ACS Applied Nano Materials 3, 3395 (2020), [1]), we were able to prove that these fibers do not stick to the calamistrum because of a special fingerprint-like nanostructure on the comb. This structure prevents the nanofibers from smoothly adapting to the surface of the comb, thus minimizing contact and reducing the adhesive van der Waals forces between the nanofibers and surface. This leads to the spiders’ ability of nonsticky processing of nanofibers for their capture threads. The successful transfer of these structures to a technical surface proved that this biological model can be adapted to optimize future tools in technical areas in which antiadhesive handling of nanofibrous materials is required, including tissue engineering applications in medicine.
Mimicking the principle of nanostructures on the calamistrum of cribellate spiders, we were able to define an upscaled surface nanostructure with reduced adhesion force towards technical electro spun fibers (S. Lifka et al., Beilstein Arch. 2022, 202223 (2022), [2]). The biomimetic surface can be produced on metals by means of ultrashort pulse laser processing of self-organized laser-induced periodic surface structures, so-called laser-induced periodic surface structure (LIPSS). For the technically relevant materials steel and titanium-alloy, the presence of LIPSS reduced the peel-off forces by approximately 50% in both cases. Even more importantly, in contrast to the polished reference surface no nanofibers remained at the LIPSS-covered surfaces.
Inspired by anti-adhesive properties of nanostructures on the calamistrum of cribellate spiders, we could also demonstrate a strategy for bacteria repellent surface with promising potential applications in medicine and biotechnology (A. Richter et al., Nanomaterials 11, 3000 (2021), [3]). Many bacteria are equipped with nanofiber-like appendages (e.g. pili and flagella) that mediate the first contact with a surface and act as strong adhesins. However, the outstanding role of cell appendages in surface adhesion has so far not sufficiently been taken into account when bacteria repellent surfaces are in focus. Using laser processing as a tool for surface nano-structuring, adhesion of bacterial cells—and therefore the initial steps of biofilm formation—was strongly impeded. Systematic analysis of a broad range of nanostructures clearly demonstrates the dependence of bacterial adhesion on spatial periods. In addition, our results point out that the efficiency of bacteria-repellent surfaces can be significantly improved when surface structures impair nanofiber-mediated adhesion.
Our vision is to adapt and convert the biological nanostructures into future tools and devices with controlled antiadhesive and antimicrobiotic properties, by means of laser-induced nanostructures.