Fluorescent nanodiamond (FND) is a carbon‐based nanomaterial with exceptional physicochemical properties and extraordinary functional capacities. Invented in 2005, FND evolved from the studies of nanometer‐sized diamond particles and color centers in bulk diamonds. The invention was followed by an ever‐growing list of applications in diverse areas of science and engineering, which has led to fast increasing interests among researchers worldwide. While all is going well and fine, it brings us to the question:

Why this book now?

There are two versions of answers to this question: a comprehensive answer obviously requires reading the entire book and the brief one (perhaps, also closer to our initial thoughts) is shared here.

As illustrated multiple times in the book, the FND’s superior biocompatibility coupled with its long emission lifetimes makes it a unique drug carrier with an added benefit that its movement in living organisms can be tracked in three dimensions and of real time. Using FND as a platform for drug delivery falls in the hardcore of the much‐anticipated development in nanomedicine, which actively looks for new solution in target‐selective and site‐specific therapeutic treatments at the molecular level. This is the medicine of the twenty‐first century and, when fully developed, FND will have a great role to play in the field. The foreseeable impact on human physiology and health is so profound that it may change the way the therapeutic treatment is delivered for future generations.

It has become a trend that new science grows from a sector in the overlapping areas of knowledge subdomains, complimentary and/or collectively benefited and strengthened by all participating disciplines. This is certainly the case for the FND studies, originally rooted in basic sciences such as physics, chemistry, and materials science; it also covers (to a lesser extent) bioengineering, electrical engineering, and optoelectronics. Accordingly, FND can be adapted in just about any areas in science and applied to a wide range of research and industry. With a further and in‐depth understanding of FND, it is expected that the use of this nanomaterial will inspire more new thinking in physics, chemistry, and biology as well as innovative designs for more potential applications.

So far, to the best of our knowledge, there is no single book that has provided a coherent presentation of all the subject materials necessary for a consistent understanding of FND. This book takes a systematic approach, beginning with the basic principles, to cover the status of current FND research and future outlook. Also included in the book is a collection of application examples in some specific areas, intended to inspire our readers to devise new applications for their own needs. We find creative use of FND every day. As we all know, creativity grows out of imagination; and when it comes to imagination, sky is the limit.

Like any other cutting‐edge sciences, FND is still relatively young in the scientific community. Much more can be achieved if there are more people to know about it (and, hence, be benefited by it). Throughout the years, we have enjoyed working with FND in a variety of aspects, been rewarded with many exciting discoveries, and learned a great deal of what FND is capable of doing for us humans and for our environment as well. It has been (and still is) such a fascinating adventure for us. With passion, we put together in this book the materials that we have learned from working with FND, which, we hope, will bring the same (or, more) excitement to our readers, ultimately, inviting more contributions to the growth of this field. Who knows what wonders FND may bring to us tomorrow?

This book intends to be a comprehensive treatment of the subjects with FND up to date (2018), with only a brief review of nanodiamonds in Chapter 2. Further discussions on nanodiamonds can be found elsewhere. Categorically, the content materials are grouped into two parts, namely, basics (Part I, Chapters 1–5) and specific topics (Part II, Chapters 6–14). A list of the titles of all 14 chapters in the book is given here as a quick view of the content in the book:

• Chapter 1: Introduction to Nanotechnology
• Chapter 2: Nanodiamonds
• Chapter 3: Color Centers in Diamond
• Chapter 4: Surface Chemistry of Nanodiamonds
• Chapter 5: Biocompatibility of Nanodiamonds
• Chapter 6: Producing Fluorescent Nanodiamonds
• Chapter 7: Single Particle Detection and Tracking
• Chapter 8: Cell Labeling and Fluorescence Imaging
• Chapter 9: Cell Tracking and Deep Tissue Imaging
• Chapter 10: Nanoscopic Imaging
• Chapter 11: Nanoscale Quantum Sensing
• Chapter 12: Hybrid Fluorescent Nanodiamonds
• Chapter 13: Nanodiamond‐Enabled Medicine
• Chapter 14: Diamonds in the Sky

These topic‐oriented chapters, not necessarily independent, explore multiple aspects of FND, comprising structural configurations, fundamental optical and magnetic properties, various fabrication techniques, and specific applications involving the state‐of‐the‐art instrumentation, with ample illustrations, case studies, practical examples, and historical perspectives. Putting it all together in a book provides our readers a full landscape of what is out there in this field today and plenty of opportunities for future growth.

It is our goal that the book will serve a broad audience, including beginners such as upper division (junior or senior level) undergraduate students majoring in science and engineering, and graduate students of related majors. This book can be adopted as a textbook or a reference for a one‐semester‐long special topic course in biology, chemistry, physics, materials science, and other engineering areas. The exhausted list of citations at the end of each chapter should provide our readers sufficient resources either to patch up their background or for their further study of some specific subjects. The book’s bottom‐up approach, emphasizing the understanding of the basics first, is equally suited for experienced researchers or industry professionals who have needs to work with nanomaterials or related biotechnology. While they may find the book helpful in refreshing and enhancing the necessary backgrounds, we expect these readers will be particularly interested in the current progress on cell tracking, nanoscale sensing, drug delivery, and/or any of the contemporary techniques still under development. The book supplies plenty of materials extracted from the primary literature concerning the specific areas of interest, which we believe will adequately prepare our readers before they launch into their own research.

Therefore, a recommended use of the book is to begin with Part I for a fundamental understanding of the working principles, followed by a thorough reading throughout the chapters in Part II, including the subjects of cell tracking, nanoscale imaging, and quantum sensing, which are arguably the most important use of FND at the moment. Experienced researchers in the nanocarbon areas may wish to skip the chapters in Part I and choose only topics from Part II that seem to appeal to them as they extend their interests further into new directions of the FND development. Of course, there are several other ways to use the book, all tailored to fit the individual’s special needs, and our readers will be the ones to make that ultimate judgment, deciding for themselves.

Finally, we fully understand that a book like this represents mainly a working progress, while much advancement is being made each and every day. By no means should we claim that the book has covered all areas of the field in FND. In fact, we are confident that the book probably has missed to include some exciting or even important work that may be of particular interest to some of our readers. However, we made a strategic decision in an early stage of the writing to include materials that we are familiar with and those that can clearly be presented in a cohesive and coherent context. We believe a well‐thought‐out presentation will be the best way to help our readers learn, hopefully, more effectively. If you, the reader, find it otherwise, please send us your comments and advices how we may improve to achieve this goal. We will appreciate your input.

Welcome to the world of FND and enjoy your reading of the book.