Nanoscale Surface Modification for Enhanced Biosensing (eBook)

Preface 8
Acknowledgments 10
Contents 12
Acronyms 16
1 A Brief Overview of Biosensors 17
1.1 What is Biosensor 17
1.2 Basic Requirements for Biosensors 18
1.3 Various Surface Sensitive Elements 19
1.4 Various Transduction Methods 20
1.4.1 Mechanical Transduction 20
1.4.2 Optical and Electromagnetic Transduction 21
1.4.3 Electrical Transduction 22
1.4.4 Electrochemical Transduction 23
1.5 The Surface of Electrodes in Biosensors 24
References 25
2 Morphological Surface Modification 29
2.1 Increasing Surface Area with Nanopillars 29
2.2 Fabricating Aqua-Robust Nanopillar Structures 31
2.2.1 Making PAA Templates 31
2.2.2 Quantifying the Pore Dimensions and Their Relationships with Anodization Potential 33
2.2.3 Fabricating Nanopillar Structures 35
2.2.4 Confirmation for Surface Area Enhancement 37
2.3 Fabricating Nanopillar Structures on-a-Chip 39
2.3.1 Depositing Al/Au/Ti layers on a Glass Slide 39
2.3.2 Anodizing the Al Layer and Removing the Barrier Layer 40
2.3.3 Electrodepositing Nanopillars and Removing PAA 41
2.3.4 A Film of Standing Nanopillars on-a-Chip and Its Further Processing into Micropatterns 42
References 43
3 Biochemical Surface Modification 45
3.1 The Need for Surface Functionalization 45
3.2 Surface Functionalization Using Conducting Polymers 46
3.2.1 Experimental Procedure 47
3.2.2 Some Basics on Amperometry 48
3.2.3 Effect of Varying Surface Roughness Factor 49
3.2.4 Effect of Varying Deposition Current Density 50
3.2.5 Effect of Varying Total Charge Passed for Deposition 52
3.2.6 Calibration for Detection Sensitivity 53
3.3 Surface Functionalization Using Self-Assembled Monolayers 54
3.3.1 Experimental Procedure 55
3.3.2 Some Basics on CV and EIS Experiments 56
3.3.3 Characterization of SAM Formation 58
3.3.4 Calibration for Detection Sensitivity 62
3.4 SAM Based Surface Modification for Affinity-Type Biosensors 64
3.4.1 Surface Adsorption of MUA, Avidin and Biotin 65
3.4.2 Coupling of Avidin and Biotin at Various Concentrations 67
3.4.3 Calibration for Detection Sensitivity for Avidin–Biotin Interaction 69
References 71
4 Adding Nanoparticles in Chemical Modification 73
4.1 The Possibility of Using Nanoparticles to Improve Enzyme Stability 73
4.2 Experimental Procedures 74
4.2.1 Reagents and Solutions 74
4.2.2 GNPs Synthesis 74
4.2.3 Electrode Functionalization with Enzyme and GNPs 75
4.3 TEM Views of GNPs 76
4.4 Electrochemical Characterization of GNP AssistedFunctionalization 77
4.5 Zeta Potential 78
4.6 UV–Vis Absorbance Spectroscopy 79
4.7 UV–Vis Fluorescence Spectroscopy 80
4.8 Glucose Detection and Sensitivity Calibration 80
References 83
5 Surface Modified Electrodes in a Microfluidic Biosensor 84
5.1 Fluidic Biosensors 84
5.2 Development of a Fluidic Sensor Device 85
5.3 Electrode Functionalization 86
5.4 Glucose Detection 87
5.5 Effect of Flow Rate, Channel Height and Width 90
5.6 Effect of Adding GNPs 93
References 93
6 Concluding Remarks 95
6.1 What Have We Learned? 95
6.2 What is Ahead? 96
A Detailed Processing Steps Used for the Experiments Discussed 98
A.1 RCA Cleaning 98
A.2 PVD of Multi-Layer Metal Films on Glass Slides 99
A.2.1 Cleaning of Glass Slides 99
A.2.2 Film Deposition Using E-Beam Evaporator 99
Depositing the First Ti Layer 100
Depositing the Second Au Layer 100
Depositing the Third Al Layer 101
A.2.3 Leaving the E-Beam in Stand-by 101
A.2.4 Getting the Samples Out of the E-Beam Evaporator 101
A.3 PAA Templates Formation by Anodization 102
A.3.1 One-Step Anodization of the E-Beam Formed Film 102
A.3.2 Two-Step Anodization of the E-Beam Formed Film 102
A.3.3 Two-Step Anodization of a High Purity Al Sheet 103
A.4 Nanopillar Development Through Electrodeposition 103
A.4.1 Gold Nanopillars 104
A.4.2 Silver Nanopillars 104
A.5 Micro-Patterning 104
A.6 Fabricating Integrated Micro-Nano Electrodes 105
Index 107