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  • Dependency of Cell Mechanics on Substrate Topography

    Dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science (MSc) of the Program of Advanced Materials Ulm University

    Submitted by

    Farida Yasmin 849697 farida.yasmin@uni-ulm.de Dhaka June 2016

    mailto:farida.yasmin@uni-ulm.de

  • Head of the Department

    Prof Dr. Kay E. Gottschalk

    First Supervisor:

    Prof Dr. Kay E. Gottschalk

    University Ulm

    Second Supervisor:

    Prof Dr. Rolf Brenner

    Universittsklinikum Ulm

  • Page 2 of 63

    Contents

    Abbreviations ..10

    Abstract 11

    Chapter 1. Introduction ............................................................................................................ 12

    Materials Science And Engineering ................................................................................ 12

    1.1.1 Nanomaterials ........................................................................................................ 12

    1.1.2 Biomaterials ............................................................................................................ 13

    Importance of Studying Cell Mechanics In Biomaterials ................................................ 14

    Chapter 2. Background Information......................................................................................... 15

    An Introduction To Cell ................................................................................................... 15

    Cell Surface interaction ................................................................................................ 17

    Theory of Elasticity (Hertz Contact Model) .................................................................... 18

    Chapter 3. Experimental........................................................................................................... 20

    Cleanroom Technique .................................................................................................... 20

    Spin Coating: Deposition By Spinning ............................................................................. 21

    Dip Coating: Preparation of Nanoparticles ..................................................................... 22

    H2 Plasma ........................................................................................................................ 24

    Photochemical Deposition ............................................................................................. 25

    Plasma Etching: Reactive Ion Etching (RIE) .................................................................... 26

    3.6.1 Effects of Oxygen addition ..................................................................................... 28

    3.6.2 Effects of Hydrogen addition .................................................................................. 28

    3.6.3 Effects of CHF3 and Noble gas addition .................................................................. 28

    Electron Microscope ....................................................................................................... 29

    3.7.1 Scanning Electron Microscopy (SEM) ..................................................................... 29

    3.7.2 Atomic Force Microscopy (AFM) ............................................................................ 30

    Cell Culture Preparation ................................................................................................. 34

    Chapter 4. Results and Discussion ............................................................................................ 35

    Fabrication of Nano-Pillars ............................................................................................. 35

    4.1.1 Micellar technique by using block copolymer ........................................................ 35

    4.1.2 Photochemical growth of Gold (Au) particle .......................................................... 37

    4.1.3 Reactive Ion Etching (RIE) ....................................................................................... 38

    Cell Mechanics on Nanostructure Topography .............................................................. 41

    4.2.1 Indentation depth ................................................................................................... 41

    4.2.2 Measurements........................................................................................................ 42

    Cell-Surface interaction .................................................................................................. 53

    Chapter 5. Conclusion .............................................................................................................. 57

    Chapter 6. References .............................................................................................................. 58

  • Page 3 of 63

    List of Tables

    Table 3-1 Preparation of micellar solution ..................................................................................... 23

    Table 3-2 Description of different types of filter ............................................................................ 24

    Table 3-3 Preparation of the gold solution for photochemical growth ......................................... 26

    Table 3-4: Settings of AFM ............................................................................................................. 33

    Table 4-1: Experimental data of particle diameter, etching time and average height .................. 40

    Table 4-2: Elastic modulus with different Samples and Spring Constant ....................................... 53

    List of Figures

    Figure 1-1: Correlation of nano and biotechnology [8] .................................................................. 13

    Figure 2-1: Schematic diagram of a Eukaryotic cell [18] ................................................................ 15

    Figure 2-2: Schematic diagram of Fibroblast in ECM [22] .............................................................. 16

    Figure 2-3: Schematic diagram of components of cytoskeleton, a) Microtubules b) Intermediate

    filament c) Actin filament [25] ....................................................................................................... 17

    Figure 2-4: Movement of cell by crawling over the surface [28] ................................................... 17

    Figure 2-5: Schematic representation of a cell possessing different types of forces [30] ............. 18

    Figure 2-6: Schematic diagram of Hertz contact model with a spherical tip (radius R2), loading

    force F, Cell radius R1, a is contact radius and is indentation depth [34] .................................... 19

    Figure 3-1: Classification of cleanroom [39] ................................................................................... 20

    Figure 3-2: schematic diagram of different steps of spin coating: a) dispensation of photoresist,

    b) acceleration, c) spreading of the liquid, d) evaporation [40] ..................................................... 21

    Figure 3-3: Schematic diagram of stages of dip-coating process [46] ............................................ 22

    Figure 3-4: Preparation of Au micellar solution [50] ...................................................................... 23

    Figure 3-5: Structure of PS-b-P2VP blocked copolymer, modified from [51] ................................ 23

    Figure 3-6 Photochemical growth of Au particle [54] .................................................................... 25

    Figure 3-7: Schematic diagram of optical system of mask aligner Karl SUSS MJB 3 Mask UV 400

    [58] ................................................................................................................................................. 26

    Figure 3-8: Schematic representation of the process of etching adopted from [61] .................... 27

    Figure 3-9: Schematic diagram of Scanning Electron Microscope (SEM) [66] ............................... 29

    Figure 3-10: Emission of various electrons and electromagnetic waves from the specimen [65] 30

    Figure 3-11: Schematic diagram of AFM [69] ................................................................................. 31

    Figure 3-12: Schematic diagram of scanning system in AFM, redrawn from [70] ......................... 31

    Figure 3-13: Force spectroscopy mode in AFM [71] ...................................................................... 32

  • Page 4 of 63

    Figure 3-14: Calibration of cantilever spring constant, blue line is for cantilever resonance peak

    (measured) and red is the Lorentz fit [71] ..................................................................................... 33

    Figure 4-1: Plot of average interparticle distance over withdrawal velocity from experimental

    data, from figure it is seen that for 130nm interparticle distance the withdrawal speed is

    2.8mm/min ..................................................................................................................................... 36

    Figure 4-2: Interparticle distance changes depending on the concentration of the solution [58] 36

    Figure 4-3: HRSEM image of Au nanoparticle after H2 Plasma. A) Grey scale picture and B) after

    adjusting threshold, inset hexagonal arrangement (bandpass filter). Scale is 1m, 30kV. ........... 36

    Figure 4-4: Plot of Au NPs diameter as a function of exposure time from experimental data. ..... 37

    Figure 4-5: HRSEM image