10-10-2012, 04:58 PM
biophotonics
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INTRODUCTION
The author intends that this book serve both as a textbook for education
and training as well as a reference book aiding research and development. An
aim of the book is to stimulate the interest of researchers and to foster collaboration
through multidisciplinary programs. This can lead to the creation
of a common language among researchers of widely varying background. The
inability to communicate effectively is a major hurdle in establishing any interdisciplinary
program.
OPPORTUNITIES FOR BOTH BASIC RESEARCH AND
BIOTECHNOLOGY DEVELOPMENT
Biophotonics offers tremendous opportunities for both biotechnology
development and fundamental research. From a technological perspective,
biophotonics, as described above, integrates four major technologies:
lasers, photonics, nanotechnology, and biotechnology. These technologies have
already established themselves in the global marketplace, collectively generating
hundreds of billions of dollars per year. Biophotonics also impacts a wide
range of industries including biotechnology companies, health care organizations
(hospitals, clinics, and medical diagnostic laboratories), medical instrument
suppliers, and pharmaceutical manufacturers, as well as those dealing
with information technology and optical telecommunication. In the future,
biophotonics will have a major impact both in generating new technologies
and in offering huge commercial rewards worldwide.
Biophotonics offers challenging opportunities for researchers. A fundamental
understanding of the light activation of biomolecules and bioassemblies,
and the subsequent photoinduced processes, is a fundamental
requirement in designing new probes and drug delivery systems. Also, an
understanding of multiphoton processes utilizing ultrashort laser pulses is a
necessity both for developing new probes and creating new modalities of
light-activated therapy. Some of the opportunities, categorized by discipline,
are listed below:
Chemists
• Development of new fluorescent tags
• Chemical probes for analyte detection and biosensing
• Nanoclinics for targeted therapy
• Nanochemistries for materials probes and nanodevices
• New structures for optical activation
Physicists
• Photoprocesses in biomolecules and bioassemblies
• New physical principles for imaging and biosensing
4 INTRODUCTION
• Single-molecule biophysics
• Nonlinear optical processes for diagnostics and therapy
Engineers
• Efficient and compact integration of new generation lasers, delivery
systems, detectors
• Device miniaturization, automation, and robotic control
• New approaches to noninvasive or minimally invasive light activation
• Optical engineering for in vivo imaging and optical biopsies
• Nanotechnologies for targeted detection and activation
• Optical BioMEMS (micro-electro-mechanical systems) and their
nanoscale analogues.
Biomedical Researchers
• Bioimaging to probe molecular, cellular, and tissue functions
• Optical signature for early detection of infectious diseases and cancers
• Dynamic imaging for physiological response to therapy and drug
delivery
• Cellular mechanisms of drug action
• Toxicity of photoactivatable materials
• Biocompatibility of implants and probes
Clinicians
• In vivo imaging studies using human subjects
• Development of optical in vivo probes for infections and cancers
• In vivo optical biopsy and optical mammography
• Tissue welding, contouring, and regeneration
• Real-time monitoring of drug delivery and action
• Long-term clinical studies of side effects
The opportunities for future research and development in a specific biophotonics
area are provided in the respective chapter covering that area.
SCOPE OF THIS BOOK
This book is intended as an introduction to biophotonics, not as an in-depth
and exhaustive treatise of this field. The objective is to provide a basic knowledge
of a broad range of topics so that even a newcomer can rapidly acquire
the minimal necessary background for research and development.
SCOPE OF THIS BOOK 5
Although several books and journals exist that cover selective aspects of
biophotonics, there is a clear need for a monograph that provides a unified
synthesis of this subject. The need for such a book as this became apparent
while teaching this topic as an interdisciplinary course available to students in
many departments at the University at Buffalo.While offering tutorial courses
at several professional society conferences such as BIOS of SPIE, the need
became even more apparent. The makeup of the registrants for these tutorial
courses has been multidisciplinary. Over the years, participants in these
courses have constantly emphasized the need for a comprehensive and multidisciplinary
text in this field.
The book is written with the following readership in mind:
•’ Researchers working in the area; it will provide useful information for
them in areas outside their expertise and serve as a reference source.
• Newcomers or researchers interested in exploring opportunities in this
field; it will provide for them an appreciation and working knowledge of
this field in a relatively short time.
• Educators who provide training and tutorial courses at universities as
well as at various professional society meetings; it will serve them as a
textbook that elucidates basic principles of existing knowledge and
multidisciplinary approaches.
This book encompasses the fundamentals and various applications of biophotonics.
Chapters 1 through 6 cover the fundamentals intended to provide
the reader with background, which may be helpful in understanding biophotonics
applications covered in subsequent chapters. Chapters 7 through 11
illustrate the use of light for optical diagnostics. Chapters 12 and 13 provide
examples of light-based therapy and treatment. Chapters 14 and 15 present
specialized topics dealing with micromanipulation of biological objects by light
and the infusion of nanotechnology into biophotonics. Chapter 16 discusses
the other aspect of biophotonics—that is, the use of biomaterials for photonics
technology (see Figure 1.1).
Each chapter begins with an introduction describing what a reader will find
in that chapter. In the case of Chapters 1–6, the introductory section also provides
a guide to which parts may be skipped by a reader familiar with the
content or less inclined to go through details. Each chapter ends with highlights
of the material covered in it. The highlights are basically the take home
message from the chapter and may serve as a review of the materials presented
in the chapter. For an instructor, the highlights may be useful in the preparation
of lecture notes or power point presentations. For researchers who may
want to get a cursory glimpse, the highlights will provide a summary of what
the chapter has covered.
In each of the chapters dealing with applications (Chapters 7–16), a description
of future directions of research and development is also provided, along
with a brief discussion of current status and the identification of some areas
INTRODUCTION
of future opportunities. Each of these application chapters also lists commercial
sources of instrumentation and suppliers relevant to the content
of the chapter. This list may be useful to a researcher new to this area and
interested in acquiring the necessary equipment and supplies or to a
researcher interested in upgrading an existing facility.
The book is organized to be adapted for various levels of teaching.
Chapters 2–6 can be covered partly or completely, depending on the depth
and length of the course and its intended audience. Chapters 7–13 are the
various applications of photonics to life sciences and are somewhat interrelated.
Chapters 14–16 can be optional, because they deal with specialized
topics and do not necessarily require the detailed contents of preceding chapters.
Chapters 8–16 are, to a great degree, independent of each other, which
allows considerable freedom in the choice of areas to be covered in a course.
Chapter 2 begins with a discussion of the fundamentals of light and matter
at a basic level, emphasizing concepts and avoiding mathematical details. For
those readers with little exposure to the subject, the materials of this chapter
will assist them in grasping the concepts. For those readers already familiar
with the subject, the chapter will serve as a condensed review. The dual nature
of light as electromagnetic waves and photon particles is described, along with
manifestations derived from them. The section on matter introduces a simplified
quantum description of atoms, molecules, and the nature of chemical
bonding. The description of P-bonding and the effect of conjugation are provided.
The geometric effect derived from the shapes of molecules, along with
intermolecular effects, is also covered.
Chapter 3 focuses on building a molecular understanding of biological
structures and their relation to biological functions. It provides the basics of
biology and introduces the necessary terminology and concepts of biology
used in this book. The chapter is written primarily for those unfamiliar with
biological concepts, or those wishing to refresh their background in this
subject. The chapter describes the chemical makeup of a biological cell and
the different organelles. The various cellular functions are also discussed.
Then, assembling of cells to form a tissue structure is described, along with the
nature of extracellular components in a tissue. The chapter ends with a brief
description of tumors and cancers.
Various aspects of light and matter, which form the fundamental basis for
biophotonics, are addressed in Chapter 4. This chapter, written for a multidisciplinary
readership with varied backgrounds, provides knowledge of the
necessary tools of optical interactions utilized in biophotonics applications.
These are covered in Chapters 7–16.The emphasis again is on introducing concepts
and terminologies, avoiding complex theoretical details.Various spectroscopic
techniques useful for biology are covered.
Chapter 5 describes the principle of laser action, relying on simple diagrammatic
descriptions. The various steps involved and components used
in laser operation are briefly explained. The present status of the laser
technology, useful for biophotonics, is described. The chapter also introduces
SCOPE OF THIS BOOK 7
the concepts of nonlinear optical interactions that take place under the action
of an intense laser beam. These nonlinear optical interactions are increasingly
recognized as useful for biophotonics. The chapter also provides a brief
discussion of laser safety.
Chapter 6 discusses photobiology—that is, the interactions of various
molecular, cellular, and tissue components with light. Light-induced radiative
and nonradiative processes are described, along with a discussion of the
photochemical processes at both the cellular and tissue levels. As important
examples of biophotonics in Nature, the processes of vision and photosynthesis
are presented. A fascinating topic in photobiology is in vivo photoexcitation
in live specimens, which has opened up the new area of optical biopsy. Another
exciting new area is the use of optical techniques to probe interactions and
dynamics at the single-cell/single-biomolecule level.