OPTICAL TECHNIQUES FOR BIOMOLECULAR SENSING
by
MOHINI GUPTA
Centre for Applied Research in Electronics
submitted
in fulfilment of the requirements of the degree of
Doctor of Philosophy
to the
Indian Institute of Technology Delhi New Delhi - 110 016, India
Dedicated to my family
Certificate
This is to certify that the thesis entitled,“Optical Techniques for Biomolecular Sensing,”being submitted byMs. Mohini Gupta, to the Indian Institute of Technology Delhi, New Delhi, for the award of degree ofDoctor of Philosophyin Centre for Applied Research in Electronics is a record of bonafide research work carried out by her under my supervision and guidance. She has fulfilled the requirements for submission of the thesis, which to the best of my knowledge has reached the requisite standard.
The material contained in the thesis has not been submitted in part or full to any other Uni- versity or Institute for the award of any degree or diploma.
B. S. Panwar (Professor)
Centre for Applied Research in Electronics Indian Institute of Technology Delhi New Delhi -110016
India
November 2013
Acknowledgement
First of all, I would like to express my sincere thanks to my supervisors prof. B. S. Panwar and Dr. Manish Sharma, Centre for Applied Research in Electronics, New Delhi. Dr. Manish Sharma has guided me through the amazing world of optical techniques and Biological sensing. He has imparted his valuable research insights to me through useful discussions and motivated to acquire better understanding of subject. He has also instructed me several things apart from research work, which has extensively modulated my personality.
I express my sincere thanks to Dr. G. Vijya Prakash, Dept. of Physics, IIT Delhi, for his constant support and suggestions throughout my Ph.D career. I express my special thanks to Prof.
Suneet Tuli (former Head of the Centre) and Prof. Arun Kumar (present Head of the Centre), Centre of Applied Research in Electronics, IIT Delhi, for their invaluable inspiration, motivation and all needful support throughout my Ph.D.
I express my sincere thanks to Dr. Krishnendu Chatterjee for all the helps and discussions during my Ph.D work. His suggestions were of great importance for my research work.
I really felt immense pleasure while working with Nanomag, Nanophotonics and Nanostech groups and thanks to all members for their cordial help and support throughout my Ph.D. My spe- cial thanks to members of Nanomag, Mrs. Vanchna Singh, Mrs. Neetu Garg, Mr. Sachin Pathak, Mrs. Monika Sharma, Mr. Lalat Indu Giri, Ms. Anima Johri, and members of Nanophotonics lab, Mr. Gautam Singh, Mr. Vindesh Kumar Dwiedi, Mr. Nageshwara Rao Kotla, Ms. Suman and members of Nanostech lab Mr. Sarab Preet Singh, Dr. Sangeeta Handuja, Mr. Ravi Bomali.
I specially acknowledge to Dr. Pradeesh K for his help throughout my Ph.D, especially, while doing SERS experiments at the initial stage of my research work. I extend my sincere thanks to Mr. Manoj Singh for his suggestions and comments throughout my research career. I am thankful to all my friends, especially Mrs. Usha Rani Sahoo, Ms. Aradhana Nyal, Mrs. Aruna patel, Mrs.
Priyam Soni, Mr. Harish Chandra Soni, Mr. Amit Soni, Mrs. Shweta Soni, Mrs. Mamta Chadar, and Mrs. Senjuti Chatterjee for their continuous moral support and encouragement throughout my Ph.D career. I am thankful to members of Micro-Electronics lab, Mr. Atul Singh, Ruchi Tiwari, Mr. Govind Ram (Lab Assistant), Mr. Chana and Mr. Govind Prasad for all the helps during my
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Ph.D work.
I especially acknowledge the Council of Scientific and Industrial Research (CSIR), New Delhi, India, for providing me financial assistance through prestigious Junior Research Fellowship (JRF) to complete my Ph.D.
I am grateful to my father Mr. Shiv kumar, mother Mrs. Saroj, elder brother Mr. Manish and younger sister Sohini for their patience, moral support, encouragement, and for everything throughout my Ph.D.
From the core of my heart, I specially thank to my spouse Mr. Pradeep Gupta and my cute pie Master Aditya Gupta, for their moral support, encouragement and for everything throughout my Ph.D. During my Ph.D, Whenever I disappointed from my research work due to the lack of good results, my spouse gave me strength and moral support and motivated me to do hard work.
A big smile on the face of my cute pie, always realize me that smile is best thing to forget your pains. I cant explain my happiness with my spouse and my child in few words, simply these are the best moments which we had together and will have in future. I extend my sincere thanks to all my family members and relatives for their support and encouragement throughout my Ph.D.
Finally, I would like to express my deepest gratitude to my supervisor prof. B. S. Panwar, Centre of Applied Research in Electronics, IIT Delhi, who has introduced me about the emerging research field Biological sensing using optical techniques in a very comprehensive and lucrative way. I greatly acknowledge to his kind support in the form of essential suggestions, criticism, support, motivation, care and an integral view on the research, which laid a solid foundation of my research career.
Mohini Gupta
Abstract
This thesis is devoted to the assembling and designing of custom built real time measurement techniques, and synthesis, properties of nanomaterials and their long term stability. It deals with structural, morphological, magnetic and photonic studies of magnetic nanoparticles to explore their basic and applied aspects. This study is further extended to functionalization with biological coat- ings over the surface of magnetic nanoparticles to obtain stable and soluble magnetic nanoparticle (MNP) suspensions for using biological applications especially biosensing.
After a detailed survey of prior work in nanoparticles and their biomedical uses in Chapter 1, procedures for their synthesis and characterization are discussed in Chapter 2. Chapters 3- 6 form the main work done in this thesis. After describing the synthesis of monodisperse iron oxide nanoparticles and their functionalization (Chapter 3), we give details of the magneto-optical system (Chapter 4) that was custom-built for the purpose of measurements on the nanoparticle suspensions. This system is capable of measuring nanoparticle sizes in dispersion and also help in performing time-dependent long-term stability studies. Studies done on small-sized nanoparticle suspensions in Chapter 5, where we fit our measurements with an aggregation and fragmentation model over a length of time. The long term stability of materials in biological suspensions can be then studied using scaling models based on modified Smoluchowski rate equations. In Chapter 6 are presented measurements done for uncoated and coated medium sized magnetic nanoparticles suspended in water by means of dynamic light scattering. For all the MNP suspensions, power law behaviour is observed at moderate time scales. Conclusions of the work done and possible directions to pursue in the future are given in Chapter 7.
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Table of Contents
Certificate i
Acknowledgement iii
Abstract v
Table of contents vi
1 Introduction 1
1.1 Motivation and Objective of present work . . . 1
1.2 Nanomaterials and properties . . . 4
1.3 Special features of magnetic nanoparticles . . . 4
1.3.1 Finite Size effects . . . 5
1.3.2 Surface effects . . . 8
1.3.3 Size dependent Coercivity . . . 9
1.4 Ferrites . . . 10
1.4.1 Iron oxides . . . 10
1.4.2 Magnetism of ferrites . . . 12
1.5 Magnetic nanoparticles suspension (MNPs) . . . 12
1.5.1 Relaxation phenomena . . . 13
1.5.2 Interaction energies and Stability criteria . . . 14
1.6 Biomedical Applications . . . 19
1.6.1 Hyperthermia . . . 19
1.6.2 Targeted drug delivery . . . 20
1.6.3 Magnetic Resonance Imaging (MRI) . . . 21
1.7 A brief survey of literature . . . 21
2 Synthetic Procedures and Experimental Techniques 29 2.1 Nanoparticles Synthesis Procedures . . . 29
2.1.1 Co-precipitation Method . . . 30
2.1.2 Thermal Decomposition . . . 30
2.1.3 Microemulsion . . . 32
2.1.4 Hydrothermal synthesis . . . 33
2.1.5 Nanoparticles Functionalization (Stabilization/Protection against aggrega- tion) . . . 34
2.2 Structural and morphological analysis . . . 36
2.2.1 X-ray Diffractometer (XRD) . . . 36
2.2.2 Transmission Electron Microscopy (TEM) . . . 38
2.2.3 Scanning Electron Microscopy (SEM) . . . 41
2.3 Magnetic Characterization . . . 42
2.3.1 SQUID Magnetometer . . . 43
2.3.2 Sample Preparation and Data analysis . . . 45
2.4 Photonic studies . . . 46 vii
2.4.1 UV-Visible spectroscopy . . . 46
2.4.2 Fourier Transform Infrared Spectroscopy (FTIR) . . . 47
2.5 Conclusion . . . 48
3 Materials and Characterization 50 3.1 Introduction . . . 50
3.2 Synthesis of silver nanoparticles . . . 51
3.2.1 Borohydride Method . . . 52
3.2.2 Citrate Method . . . 52
3.2.3 Characterization . . . 52
3.3 Magnetic alloy nanoparticles . . . 54
3.3.1 Synthesis . . . 54
3.3.2 Characterization . . . 56
3.4 Iron oxide Nanoparticles . . . 60
3.4.1 Synthesis of smaller size magnetic nanoparticles . . . 60
3.4.2 Characterization . . . 61
3.5 Synthesis of Medium size iron oxide MNPs . . . 64
3.5.1 Medium size MNPs Prepared in first batch . . . 64
3.5.2 Characterization . . . 68
3.5.3 Medium size MNPs prepared in second batch . . . 72
3.5.4 Characterization . . . 72
3.6 Conclusion . . . 76
4 Instrumentation 78 4.1 Introduction . . . 78
4.2 Custom-built magneto optical relaxation of ferrofluids (MORFF) setup . . . 79
4.2.1 System design and assembling . . . 79
4.2.2 Measurements and data analysis . . . 85
4.3 Custom-built photon correlation spectroscopy (PCS) system . . . 86
4.3.1 System design and assembling . . . 86
4.3.2 Working principle and data analysis . . . 88
4.4 conclusion . . . 90
5 Clustering and Dynamics of Smaller Size Magnetic Nanoparticles Suspension 93 5.1 Introduction . . . 93
5.2 Experiment Details . . . 95
5.2.1 Regularization Method . . . 97
5.3 Diffusion dominated aggregation model . . . 99
5.4 Results and discussions . . . 101
5.5 Conclusion . . . 107
6 Stability of Medium size MNPs in Different Suspension Media 109 6.1 Introduction . . . 109
6.2 Experimental details . . . 111
6.3 Results and discussions . . . 113
6.4 Conclusion . . . 123
7 Conclusions and Future Scope of Work 126 7.1 Conclusions . . . 126
7.2 Future Scope of Work . . . 129
Bibliography 132
A Surface Enhanced Raman Scattering 172
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A.1 Introduction . . . 172
A.2 Theory of Surface Enhanced Raman Scattering . . . 174
A.2.1 Electromagnetic Enhancement Mechanism . . . 174
A.2.2 Chemical Effect . . . 175
A.3 SERS System Design and assembling . . . 176
A.4 Results and discussion . . . 177
A.5 Conclusion . . . 182
A.6 Helmholtz Coils Construction . . . 182
A.7 Preamplifier . . . 183
List of Publicataions 186
Author’s Biography 188
