SURFACES MODIFIED WITH POLYELECTROLYTE MULTILAYERS FOR

2,47

MB

BIO-INTERFACE APPLICATIONS

217

stron

4313

ID

FLORIDA STATE UNIVERSITY

2004

rok

TABLE OF CONTENTS

List of Tables xi

List of Figures xiii

Abstract xxv

CHAPTER 1

INTRODUCTION 1

1.1 Polymers in Biomaterials 2

1.1.1 Polymers used in biomaterials 3

1.1.2 Surface modifications for biocompatibility 3

1.1.3 Polyelectrolytes in biomedical applications 5

1.2 Polyelectrolyte Multilayer Films 8

1.2.1 Method overview 8

1.2.2 Mechanism of buildup: overcompensation regime .8

1.2.3 Diversity of method 10

1.3 Polyelectrolyte Multilayers as Biofilms11

1.4 Background on Proteins at Interfaces .12

1.5 Thesis Outline .18

CHAPTER 2

EXPERIMENTAL METHODS AND INSTRUMENTATION.21

2.1 Chemicals21

2.2 Polyelectrolyte Synthesis 22

2.2.1 Synthesis of 3-[2-(acrylamido)-ethyl dimethylammonio] propane sulfonate AEDAPS .22

2.2.2 Synthesis of PAA-co-PAEDAPS copolymer.23

2.2.3 Synthesis of poly(4-vinyl- trideca-fluoro-octyl pyridinium iodide), P4VTDFOP-co-P4VP

copolymer, “PFPVP”24

2.2.4 Synthesis of quaternized poly(4(5)-vinylimidazole), QPVI .24

2.3 Polyelectrolyte Multilayers Deposition and Assembly.24

2.4 Thickness Measurements 25

2.4.1 Ellipsometry25

2.4.2 Profilometry27

2.5 Spectroscopy.27

2.5.1 UV-vis spectroscopy.27

2.5.2 FTIR and total internal reflectance spectroscopy, ATR-FTIR. 27

2.5.3 Optical waveguide lightmode spectroscopy, OWLS. .30

2.6 Atomic Force Microscopy 33

2.7 Electrochemical Techniques .33

2.8 Polyelectrolyte Multilayer Nomenclature .35

CHAPTER 3

PROTEIN ADSORPTION MODALITLITIES ON POLYELECTROLYTE MULTILAYERS:

“ELECTROSTATIC” CONTRIBUTIONS 38

3.1 Introduction.38

3.2 Experimental Setup .40

3.2.1 ATR-FTIR.40

3.2.2 Penetration depth “dp” calculations .40

3.2.3 UV-vis .41

3.2.4 Polyelectrolyte multilayer surface morphology using AFM and profilometry 44

3.3 Results and Discussion .44

3.3.1 Surface charge.44

3.3.2 Electrostatic contribution: Ionic strength study45

3.3.3 Bulk versus sorption: Thickness effect study .48

3.3.4 Surface characterization using atomic force microscopy (AFM) .50

3.3.5 Salt-induced desorption 59

3.3.6 Protein adsorption onto Pt electrodes coated with PEMUs 59

3.4 Conclusion 66

CHAPTER 4

SURFACE MODIFICATIONS WITH POLYELECTROLYTE MULTILAYERS FOR PROTEIN

ADSORPTION CONTROL .67

4.1 Introduction.67

4.2 Experimental Setup .70

4.2.1 ATR-FTIR.70

4.2.2 UV-vis .71

4.2.3 Optical waveguide lightmode spectroscopy, OWLS 71

4.3 Results and Discussion .72

4.3.1 Surface charge effect.72

4.3.2 Fluorinated hydrophobic salt ion cap77

4.3.3 Hydrophilic repelling diblock .81

4.3.4 Hydrophilic homopolyelectrolytes86

4.3.5 Zwitterionic copolymers .89

4.4 Conclusion 96

CHAPTER 5

VASCULAR SMOOTH MUSCLE CELLS CULTURED ON POLYELECTROLYTE MULTILAYERS.98

5.1 Introduction.98

5.2 Experimental Setup .100

5.2.1 PEMUs on glass cover slips100

5.2.2 Film thickness .101

5.2.3 Polymer on polymer stamping 101

5.2.4 Contact angle measurements.101

5.2.5 Cell culture and microscopy .101

5.3 Results and Discussion .102

5.3.1 Surface charge and hydrophobicity.102

5.3.2 Use of diblock copolymers with PEO groups .105

5.3.3 Use of zwitterionic copolymers as cell repellants.106

5.3.4 Cell micropatterning .109

5.4 Conclusion 112

CHAPTER 6

SURFACE CHARGE REVERSAL IN PH-TUNABLE POLYELECTROLYTE MULTILAYERS:

TOWARD ACIDIC AND BASIC PROTEIN PURIFICATION114

6.1 Introduction.114

6.2 Experimental Setup .118

6.2.1 In situ ATR-FTIR for pKa determination118

6.2.2 ATR-FTIR for protein interaction studies 118

6.2.3 Coating glass beads with PEMUs for ion exchange chromatography experiments 121

6.2.4 Calculations for amounts of lysozyme adsorbed on the column in mg m-2 .122

6.3 Results and Discussion .123

6.3.1 Charge reversal in PEMUs123

6.3.2 Loading/releasing of protein using pH-tunable multilayers .126

6.3.3 Ion “expulsion” chromatography experiment .135

6.4 Conclusion 136

CHAPTER 7

ION SELECTIVITY, ELECTRODES MODIFICATION AND DRUG PARTITIONING IN

POLYELECTROLYTE MULTILAYERS 138

7.1 Introduction.138

7.2 Results and Discussion .139

7.2.1 Ion selectivity in polyelectrolyte multilayers139

7.2.2 Rectified ion currents through ultrathin PEMUs: towards chemical transistors 145

7.2.3 Ion selective electrodes coated with PEMUs 155

7.2.5 ATR-FTIR for determination of drug partition coefficients on PDADMA/PSS .158

7.3 Conclusion 165

BIBLIOGRAPHY 166

BIOGRAPHICAL SKETCH 189