Optical Tweezers

A comprehensive guide to the theory, practice and applications of optical tweezers, combining state-of-the-art research with a strong pedagogic approach.

The aim of this volume is to provide a comprehensive overview of optical tweezers setups, both in practical and theoretical terms, to help biophysicists, biochemists, and cell biologists to build and calibrate their own instruments and to perform force measurements on mechanoenzymes both in isolation in vitro and in living cells. Chapters have been divided in three parts focusing on theory and practical design of optical tweezers, detailed protocols for performing force measurements on single DNA- and microtubule/actin-associated mechanoenzymes in isolation, and describing recent advances that have opened up quantitative force measurements in living cells. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and cutting-edge, Optical Tweezers: Methods and Protocols aims help to further expand the accessibility and use of optical traps by scientists of diverse disciplines.

The technical development of optical tweezers, along with their application in the biological and physical sciences, has progressed significantly since the demonstration of an optical trap for micron-sized particles based on a single, tightly focused laser beam was first reported more than twenty years ago. Bringing together many landmark papers on

This detailed volume explores a wide variety of techniques involving optical tweezers, a technology that has become increasingly more accessible to a broad range of researchers. Beginning with recent technical advances, the book continues by covering the application of optical tweezers to study DNA-protein interactions and DNA motors, protocols to perform protein (un)folding experiments, the application of optical tweezers to study actin- and microtubule-associated motor proteins, and well as protocols for investigating the function and mechanical properties of microtubules and intermediate filaments, and more. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Optical Tweezers: Methods and Protocols, Second Edition serves as an ideal resource for expanding the accessibility and use of optical traps by scientists of diverse disciplines.

Thanks to the pioneering works of Ashkin and coworkers, optical tweezers (OTs) have become an invaluable tool for myriad studies throughout the natural sciences. Their success relies on the fact that they can be considered as exceptionally sensitive transducers that are able to resolve pN forces and nm displacements, with high temporal resolution, down to μs. Hence their application to study a wide range of biological phenomena such as measuring the compliance of bacterial tails, the forces exerted by a single motor protein, and the mechanical properties of human red blood cells and of individual biological molecules. The number of articles related to them totals to a whopping 58,000 (source Google Scholar)! Microrheology is a branch of rheology, but it works at micrometer length scales and with microliter sample volumes. Therefore, microrheology techniques have been revealed to be very useful tools for all those rheological/mechanical studies where rare or precious materials are employed, such as in biological and biomedical studies. The aim of this book is to provide a pedagogical introduction to the physics principles governing both the optical tweezers and their application in the field of microrheology of complex materials. This is achieved by following a linear path that starts from a narrative introduction of the "nature of light," followed by a rigorous description of the fundamental equations governing the propagation of light through matter. Moreover, some of the many possible instrumental configurations are presented, especially those that better adapt to perform microrheology measurements. In order to better appreciate the microrheological methods with optical tweezers explored in this book, informative introductions to the basic concepts of linear rheology, statistical mechanics, and the most popular microrheology techniques are also given. Furthermore, an enlightening prologue to the general applications of optical tweezers different from rheological purposes is provided at the end of the book.

The authors of this book provide the first review of haptic optical tweezers, a new technique which brings together force feedback teleoperation and optical tweezers. This technique allows users to explore the microworld by sensing and exerting piconewton-scale forces with trapped microspheres. The design of optical tweezers for high-quality haptic feedback is challenging, given the requirements for very high sensitivity and dynamic stability. The concept, design process and specification of optical tweezers reviewed throughout this book focus on those intended for haptic teleoperation. The authors provide two new specific designs as well as the current state of the art. Furthermore, the remaining important issues are identified for further developments. Haptic optical tweezers will soon become an invaluable tool for force feedback micromanipulation of biological samples and nano- and micro-assembly parts.