Novel Processing Technologies for Recombinant Spider Silk Proteins Von der Fakultät für Ingenieurwissenschaften der Universität Bayreuth zur Erlangung der Würde eines Doktor-Ingenieur (Dr.-Ing.) genehmigte Dissertation vorgelegt von Stephan Jokisch (M. Sc.) aus Hoyerswerda Erstgutachter: Prof. Dr. rer. nat. Thomas Scheibel Zweitgutachter: Prof. Dr.-Ing. Volker Altstädt Tag der mündlichen Prüfung: 14.10.2019 Lehrstuhl Biomaterialien Universität Bayreuth 2019 „Phantasie ist wichtiger als Wissen, denn Wissen ist begrenzt.“ - Albert Einstein - Contents Contents Contents ......................................................................................................................................... iv List of Figures .............................................................................................................................. vii List of Tables ............................................................................................................................... xiv List of Abbreviations and Symbols ........................................................................................... xvi 1 Introduction ..................................................................................................................... 1 1.1 Polymers in modern production processes and the need of surface modification ........... 1 1.2 Filtration ............................................................................................................................ 3 1.3 Synthetic polymers ........................................................................................................... 4 1.3.1 Poly(ethylene terephthalate) ......................................................................................... 5 1.3.2 Poly(acrylonitrile) .......................................................................................................... 6 1.3.3 Poly(ethylene oxide) ..................................................................................................... 7 1.4 Biopolymers ...................................................................................................................... 8 1.4.1 Natural Polymers ........................................................................................................ 10 1.5 Properties of synthetic and natural polymers ................................................................. 15 1.6 Fiber production methods ............................................................................................... 18 1.6.1 Melt spinning ............................................................................................................... 20 1.6.2 Solution spinning methods .......................................................................................... 22 1.6.3 Centrifugal spinning methods ..................................................................................... 26 1.6.4 Electrospinning methods ............................................................................................ 27 1.7 Mechanical textile processing ......................................................................................... 34 1.7.1 Compacting ................................................................................................................. 34 1.7.2 Calendering ................................................................................................................. 34 1.7.3 Raising or napping ...................................................................................................... 35 1.7.4 Sueding ....................................................................................................................... 35 1.8 Coating methods ............................................................................................................. 36 1.8.1 Protective planar coatings in form of closed layers .................................................... 36 1.8.2 Special coatings in form of nonwoven meshes .......................................................... 38 1.9 Motivation and aim of the thesis ..................................................................................... 40 iv Contents 2 Materials and Methods ................................................................................................. 43 2.1 Materials and instruments ............................................................................................... 43 2.1.1 Chemicals and Consumables ..................................................................................... 43 2.1.2 Textiles and yarns ....................................................................................................... 44 2.1.3 Instruments and devices ............................................................................................. 45 2.1.4 Software ...................................................................................................................... 47 2.2 Recombinant production of ChryC1 lacewing and eADF4(C16) spider silk proteins ..... 48 2.3 Foam processing from spider silk solutions .................................................................... 48 2.4 Foam coating of fibers and fabrics .................................................................................. 49 2.5 Processing of spider silk protein and polymer solutions for production of nonwoven meshes .......................................................................................................... 50 2.5.1 Electrospinning ............................................................................................................ 50 2.5.2 Centrifuge electrospinning........................................................................................... 50 2.6 Processing of nonwoven meshes for filter production .................................................... 51 2.7 Analytical methods .......................................................................................................... 52 2.7.1 Spectroscopic methods ............................................................................................... 52 2.7.2 Microscopy .................................................................................................................. 53 2.7.3 Rheological characterization of foaming and spinning dopes ..................................... 54 2.7.4 Analysis of coating stability and efficiency .................................................................. 55 2.7.5 Mechanical analytical methods for foam coated yarns and textiles ............................ 55 2.7.6 Filtration efficiency tests .............................................................................................. 57 3 Results ........................................................................................................................... 59 3.1 Protective effects of spider silk foam coatings on furniture textiles ................................ 59 3.1.1 Textiles and yarns for coating ..................................................................................... 59 3.1.2 Rheological analysis of spider silk foaming dopes ...................................................... 60 3.1.3 Analysis of foam coating parameters .......................................................................... 62 3.1.4 Distribution of spider silk foams on furniture textiles ................................................... 63 3.1.5 Coating stability and protective effects of spider silk on single yarns ......................... 64 3.1.6 Abrasion tests of spider silk coated fabrics ................................................................. 66 3.2 Electrospun nonwoven mesh for the improvement of a filtration surface ....................... 68 3.2.1 Preliminary analyzes ................................................................................................... 68 3.2.2 Electrospun nonwoven fiber meshes for filtration purposes ....................................... 71 3.2.3 Centrifuge electrospinning parameter analysis for large scale nonwoven mesh production .................................................................................................................... 88 v Contents 3.3 Influences of E- and CE-spinning on the resulting fiber mesh quality ............................ 94 3.3.1 Comparison of resulting fiber diameter in classical and centrifuge electrospinning ............................................................................................................ 95 3.3.2 Influence of ES and CES on the secondary structure of spider silk fibers ................. 98 4 Discussion ................................................................................................................... 101 4.1 Coating of industrially produced fibers using spider silk proteins ................................. 101 4.1.1 Influence of shear forces and surfactant deployment on foam production ............... 102 4.1.2 Adhesion behavior of spider silk proteins on different yarn fiber materials .............. 105 4.1.3 Stabilizing and protective effects of spider silk protein foam coatings ..................... 106 4.2 Fiber production based on spider silk proteins ............................................................. 110 4.2.1 Differences in the dope materials and their rheological effects and concentration ranges ................................................................................................ 110 4.2.2 The field strength as guiding spinning parameter for upscaling