First and foremost, I would like to thank my ex-supervisor, Prof. Zheng Lianxi, for giving me an opportunity to embark on this journey of PhD in the area of nanotechnology. These four years have undoubtedly been the toughest phase of my life as I kept encountering several hurdles both personally and academically. Nevertheless, every time I look up to Prof. Zheng, he has given me priceless suggestions, constant encouragement, and timely guidance, which have largely been the source of my strength during these strenuous phases. Prof. Zheng has been a true role model for me for his simple attitude towards work and life. I am deeply indebted to him, and without his guidance, I would not have been able to improve in various aspects of research and life. I also sincerely thank my current supervisor Prof. Wong Chee How, who has been instrumental in my thesis submission process following Prof. Zheng's departure from NTU. He has been kind and I am extremely grateful to him for lending a helping hand in my troubled times.