MEASURING THE MECHANICAL PROPERTIES OF PRIMARY CILIA WITH AN
OPTICAL TRAP
TARA DIBA
Bachelor of Science in Physics
Azad University, Central Tehran
December, 2011
Submitted in partial fulfillment of requirements for the degree
MASTER OF SCIENCE IN BIOMEDICAL ENGINEERING at the
CLEVELAND STATE UNIVERSITY
December, 2015
©COPYRIGHT BY TARA DIBA 2015
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We hereby approve this thesis for
(Tara Diba)
Candidate for the Master of Science in Biomedical Engineering degree for the
Department of Chemical and Biomedical Engineering
and the CLEVELAND STATE UNIVERSITY
College of Graduate Studies
______Thesis Chairperson, (Dr. Andrew Resnick) Physics, Cleveland State University/Dec.4.2015 Department & Date
______Thesis Committee Member, (Dr. Chandra Kothapalli) Chemical and Biomedical Engineering, Cleveland State University/ Dec.4.2015 Department & Date
______Thesis Committee Member (Dr. Christopher L. Wirth) Chemical and Biomedical Engineering, Cleveland State University/ Dec.4.2015 Department & Date
______Thesis Committee Member (Dr. Moo Yeal Lee) Chemical and Biomedical Engineering, Cleveland State University/ Dec.4.2015 Department & Date
Student’s Date of Defense: (Dec.4.2015) iii
ACKNOWLEDGEMENTS
I would like to first and foremost express my appreciation and sincere gratitude to Dr.
Andrew Resnick for providing me this wonderful opportunity to conduct research under his astute guidance. His boundless energy, wonderful analytical skills, cool and calm composure, and motivational power has made this experience a truly memorable one. I am sure this will stand me in good stead in my future research and professional career as well. I sincerely thank him for introducing me to the research of biomedical optics.
Because of him, I was able to work on many intriguing projects and learn more than I ever dreamed possible. I must also acknowledge the seemingly infinite support and kind advice from Dr. Chandra Kothapalli and Dr. Moo Yeal Lee as well. I also would like to thank Dr. Joanne Belovich for playing a pivotal role in my thesis. I owe my deepest thanks to my parents who have always stood by me with patience and satisfaction, they guided me through life and I wouldn’t have been able to finish my degree without them.
Moreover, I offer my regards and blessing to all of the people, especially Rebecca Laird and Darlene Montgomery, who did not hesitate to help me in my entire life in the US.
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MEASURING THE MECHANICAL PROPERTIES OF A PRIMARY CILIA WITH AN
OPTICAL TRAP
TARA DIBA
ABSTRACT
Nonmotile primary cilia are slender subcellular structures that extend from the mother centrosome, are typically several microns long, and are used by eukaryotic cells to sense fluid flow. Cilia perform various roles to maintain tissue homeostasis through multiple signaling pathways, and their sensing ability is not restricted to physical stimuli but also biochemical stimuli from the extracellular environment. Cilia play a mechanosensory role in numerous tissues including kidney, liver and bone; where mechanical deflection of cilia due to mechanical loading leads to a cellular response. However, the relationship between cilia mechanical responses and downstream regulatory processes that are ciliary- initiated is still unknown. Optical tweezers provide a unique method to mechanically stimulate a primary cilium because of the noncontact nature of the method. We present a method to measure the mechanical properties of a primary cilium by exciting a resonant oscillation of the cilium. This is done by by applying an optical force directly to the cilium. We will show that the resonant frequency of cilia can be used to extract mechanical properties of the cilium base.
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TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS ...... IV
ABSTRACT ...... V
NOMENCLATURE ...... IX
LIST OF TABLES ...... XI
LIST OF FIGURES ...... XII
CHAPTER I ...... 1
INTRODUCTION AND OBJECTIVE OF THE THESIS ...... 1
1.1 INTRODUCTION ...... 1
1.2 MOTIVATION ...... 2
1.3 OBJECTIVE ...... 3
CHAPTER II ...... 4
HISTORY AND ADVANCEMENT OF OPTICAL TWEEZERS ...... 4
2.1 INITIAL DEVELOPMENT OF OPTICAL TWEEZERS ...... 4
2.2 BASIC OPTICS ...... 6
CHAPTER III ...... 11
THEORY AND APPLIED FORCE ...... 11
3.1 THEORY OF OPTICAL TWEEZERS ...... 11
3.2 OPTICAL FORCES ...... 14
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3.2.1 RAYLEIGHT SCATTERING ...... 17
3.2.2 RAY OPTICS APPROXIMATION ...... 22
3.2.3 GENERALIZED LORENTZ MIE THEORY (r~λ) ...... 24
3.3 FORCE CALIBRATION ...... 25
3.4 QPD POSITION DETECTION ...... 27
CHAPTER IV ...... 29
MOTILE AND NONMOTILE CILIA ...... 29
4.1 CILIA ...... 29
4.2 PRIMARY CILIA ...... 32
4.3 CILIOPATHY ...... 35
CHAPTER V ...... 38
DEVELOPED MODEL OF THE PRIMARY CILIUM ...... 38
5.1 CILIARY MECHANICS AND MODELS ...... 38
CHAPTER VI ...... 41
METHODS AND MATERIALS ...... 41
6.1 METHODS ...... 41
6.2 CELL CULTURE ...... 42
6.3 IMMUNOCYTOCHEMISTRY ...... 43
6.4 OPTICAL TWEEZERS APPARATUS ...... 44
6.4.1 Major Components Description ...... 47
CHAPTER VII ...... 50
PRIMARY CILIUM TRAPPING ...... 50
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7.1 TRAPPING PROTOCOLE ...... 50
CHAPTER VIII ...... 52
RESULTS ...... 52
8.1 ANALYSIS AND RESULT ...... 52
8.2 TWEEZERS CALIBRATION ...... 64
CHAPTER IX ...... 69
CONCLUSION ...... 69
9.1 CONCLUSION AND FUTURE WORK ...... 69
REFERENCES ...... 70
APPENDIX A ...... 87
APPENDIX B ...... 94
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NOMENCLATURE
PCP: planar cell polarity
HH: Hedgehog
CICR: Calcium-induced Calcium release
Intraflagellar Transport: IFT
Bardet-Biedl Syndrome: BBS
Electromagnetic: EM
Continuous wave: CW
Infrared: IR
Pre-implantation Genetic Diagnosis: PGD
Holographic Optical Tweezers: HOT
Atomic Force Microscopy: AFM
Numerical Aperture: NA
Quadrant Photo Diode: QPD
Microtubules: MT
Polycystin-1 and Polycysin-2: PC1 and PC2
Sonic hedgehog: Shh
Platelet-Derived Growth Factor: PDGFR
Polycystic kidney disease: PKD
Autosomal Dominant Polycystic Kidney ADPKD Disease:
Autosomal Recessive PKD: ARPKD
Polycystic Kidney and Hepatic Disease1 and 2: Pkhd1 and 2
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Nephronophthisis: NPHP
Madin-Darby canine Kidney: MDCK
Mouse Mortical Collecting Duct: mCCD
Epithelial Growth Factor: EGF
Fetal Bovine Serum: FBS
Bovine Serum Albumin: BSA
Virtual Instrument: VI
Standard Deviation: STD
The Mean Square Displacement: MSD
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LIST OF TABLES
Table Page
TABLE 1 - DATA OF THE 5 RUNS FOR 2M BEADS AT TRAP FOLLOWING THE STD, AVERAGE AND FORCE ..68
TABLE 2- BOUNDARY CONDITIONS OF THE BEAM ...... 90
TABLE 3- RAW QPD ACQUIRED DATA ...... 101
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LIST OF FIGURES
Figure Page
FIGURE 1- EVOLUTION OF OPTICAL TWEEZERS ...... 6
FIGURE 2- 2ΜM MICROSPHERE IN AN OPTICAL TRAP ...... 10
FIGURE 3- CHANGING IN THE MOMENTUM OF THE BEAM PARTICLE ...... 14
FIGURE 4- OPTICAL FORCES ON A DIELECTRIC SPHERE IN RAY REGIME...... 22
FIGURE 5- QS, QG AND QT MAGNITUDE ...... 24
FIGURE 6- QPD DIAGRAM THAT USED IN OUR EXPERIMENTS ...... 27
FIGURE 7- MOTILE CILIA SCHEMATIC ...... 32
FIGURE 8-CILIA SCHEMATIC ...... 34
FIGURE 9- HEALTHY KIDNEY VERSUS KIDNEY WITH PKD. LEFT IS THE SCHEMATIC OF THE ...... 36
FIGURE 10- EN FACE IMAGES OF THE STAINED MCD CELLS ...... 44
FIGURE 11- HARDWARE CONFIGURATION OF THE LASER TWEEZERCOMPUTER ...... 46
FIGURE 12- LEICA CTR 6000 FRONT SIDE POWER SUPPLY ...... 47
FIGURE 13- Z CONTROLLER ...... 48
FIGURE 14- PRIOR PRESCAN II AT THE RIGHT AND ERGONOMIC JOYSTICK IS AT THE LEFT SIDE ...... 48
FIGURE 15- CRYSTALASER LASER SHUTTER AND POWER SOURCE ...... 49
FIGURE 16- QPD POSITION AND SCHEMATIC...... 49
FIGURE 17- CILIUM AT THE TRAP ...... 51
FIGURE 18- NATIONAL INSTRUMENT LABVIEW DATA ACQUISITION SOFTWARE FRONT VIEW ...... 53
FIGURE 19- RESULTS VS. MSD PLOT...... 54
FIGURE 20- A SAMPLE OF RAW QPD OUTPUT A) X-DIRECTION DATA B) Y-DIRECTION DATA ...... 56
FIGURE 21- RAW ACQUIRED DATA FROM THE QPD ...... 56
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FIGURE 22- DECOMPOSED SIGNAL...... 58
FIGURE 23- X VERSUS Y DIRECTION THAT SHOWS THE PATH OF THE TRAPPED PARTICLE ...... 59
FIGURE 24- CILIA IN A TRAP ANIMATION ...... 59
FIGURE 25- HISTOGRAM OF THE DATA WITH A GAUSSIAN MODELED FIT ...... 61
FIGURE 26- FOURIER TRANSFORM OF THE DATA ...... 62
FIGURE 27- POWER SPECTRUM ...... 63
FIGURE 34- PRIMARY CILIUM MODELED AS A CLASSICAL CANTILEVERED ...... 92
FIGURE 35- PRIMARY CILIUM MODELED AS A CANTILEVERED BEAM WITH ROTATORY SPRING ...... 93
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CHAPTER I
INTRODUCTION AND OBJECTIVE OF THE THESIS
1.1 INTRODUCTION
Cilia are antenna-like organelles that emanate from the surface of the either growth- arrested or differentiated eukaryotic cells [1]. Cilia originate from the mother centriole of the mother-daughter pair of centrioles in the centrosome of the cell [2], consist of 9 microtubule doublets arranged in a ring, and are encased in the cell membrane. Cilia are generally characterized as either motile or non-motile. Motile cilia are distinguished from non-motile cilia (primary cilia or sensory cilia) by the presence of an extra microtubule doublet in the center of the axoneme. Primary cilia are hypothesized to be a mechanotransduction structure. Primary cilia can bend as a result of applied fluid flow, and ciliary bending initiates a variety of signaling cascades [4] such as; non-canonical
Wnt/planar cell polarity (PCP) pathway, Hedgehog (HH) pathway, and Polycystin
1
pathway. Typically, initiation of a mechanotransduction pathway is accompanied by an increase of intracellular Calcium, through Calcium-induced Calcium release (CICR) [5].
Measuring the essential mechanical properties of the cilia can support the mechanosensation hypothesis, and provide improved understanding of its signaling role in the cell. In contrast to application of fluid flow, manipulating individual cilia via optical trapping allows us to better define the connection between mechanical stimulation and initiation of mechanosensation pathways. Optical trapping is a non-contact method that can cause cilia to bend. Cilium deflection occurs along the axoneme land rotating. around the hinge located at the basal body. Thus, quantitative stimulation of a single cilium, coupled with careful measurements of the mechanical response, can provide a significant amount of new information regarding the mechanical properties of the cells’ mechanical sensor. In this study, the force was applied to the tip of the cilia directly by the laser tweezers. In previous studies, microspheres were attached to the cilium, and the microspheres were trapped and used to dislocate the tip of the cilia.
1.2 MOTIVATION
The primary cilium exists in the majority of the human body cells. Because the cilium contains no ribosomes, all proteins present in cilia must be trafficked into and out of the cilia via intraflagellar transport (IFT) particles. The length of the primary cilium is controlled by an unknown regulatory mechanism. Since cilium originate from the centrioles, any mutation that changes either function or structure of the centrosome can potentially have an effect on the function of the cilia [6], which associated, with a broad spectrum of complex human diseases known as ciliopathies. Cilia have various roles in
2
sensory transduction of many eukaryotic cells. They can probe the extracellular environment with transmembrane proteins and ciliary associated proteins have been shown to participate in chemosensing, osmosing and mechanosensing processes. [7].
Mutations that cause a disruption in the structure of the cilia can be responsible for shortened or absent primary cilia, and this has been shown to lead to disease phenotypes, most notably in the ORPK mouse model. Conclusive evidence has shown that, cilia dysfunction in either motile or non-motile cilia can affect multiple organ systems, generally causing devastating, pathologies.
Many ciliopathies are associated with a common set of symptoms including polydactyly, hydrocephalus, cysts, and infertility. A few ciliopathies include: situs inverses (defects of left-right patterning), obesity, [6] Bardet-Biedl syndrome (BBS), blindness, deafness, chronic respiratory infections, diabetes, Retinal degeneration, rod-cone dystrophy and retinitis pigmentosa, cystic liver disease and skeletal abnormality. We generally focus on polycystic kidney disease, and specifically autosomal dominant polycystic disease.
1.3 OBJECTIVE
The structure and mechanical properties of the cilium and the way that these features contribute to the function of the cilia are still not completely known. In this study, the mechanical properties of the cilium present on kidney epithelial cells (Principal
Cortical Collecting Duct cells from the Immortomouse and Madin–Darby canine kidney) were measured. The purpose was to apply an well controlled and repeatable mechanicl stimulus to a single cilium.
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CHAPTER II
HISTORY AND ADVANCEMENT OF OPTICAL TWEEZERS
2.1 INITIAL DEVELOPMENT OF OPTICAL TWEEZERS
At the early 17th century the German astronomer Johannes Kepler suggested that the reason a comet’s tail points away from the sun is because the sun’s radiation exerted a pressure. Later, in 1873, James Clerk Maxwell probed the consequences of electromagnetic (EM) radiation and deduced the radiation pressure of light [8]; he showed that light itself could exert force or pressure. This theory was not verified until the turn of the century. The primary experimental difficulty was because of the weakness of radiation pressure. Milliwatts of power impinging on an object produce piconewtons of force (l pN = 10-12 N) [9]. Pico-newton forces was measured in 1901 by Lebedev [10] and Nicolas and Hull [11]. That discovery was not useful in the real world applications until 1960’s after the discovery of the laser [12]. Laser light consists of highly coherent light that can focus down to a volume about the size of a single wavelength. The use of
4
lasers to create optical traps enables the stable, three-dimensional optical trapping of dielectric particles [14]. In 1987, Ashkin and his coworkers showed another use of optical tweezers. By choosing an appropriate wavelength it can be used to manipulate living cells, while minimizing any optical damage. In 1993, Ashkin and his colleague Dziedzic were awarded the 1993 Rank Prize in Optoelectronics for their groundbreaking work
[15]. The first commercial optical tweezers, known as “Laser Tweezers”, was brought to market by Cell Robotics, Inc., of Albuquerque, New Mexico in 1992 [16]. Ashkin successfully captured viruses, yeasts, bacteria and protozoa by utilizing the continuous wave (CW) near infrared (IR) laser (Nd: YAG) with the wavelength of 1064nm [17-18].
After the first observation of the accelerating and trapping particles by an optical trap in
1970 by Ashkin and Colleagues [19], optical trapping has developed from two- dimensions (2D) to three-dimensions (3D), and [13] from single to dual trap [20] or even multi optical trap [21-23]. In addition, the laser beam itself that forms the optical trap has been changed, while many traps are formed by TEM00 mode Gaussian laser beams, hollow beam [24], Laguerre-Gaussian beams [25], and vector beam [26], have all been sued to create stable optical traps. All of these advancements give optical traps some new design characteristics, such as; orbital angular momentum, variable trap stiffness, and trap depth. Optical tweezer instruments have also advanced from simple to sophisticated devices under the feedback control by the computer for the measurement and control of forces and displacement with resolutions approaching single nanometer and piconewton.
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Figure 1- Evolution of optical tweezers
2.2 BASIC OPTICS
Once an optical beam is incident on an interface, the beam is deflected because of reflection and refraction. The beam carries momentum and this momentum changes due to deflection of the beam, and these changes in the momentum is the origin of optical forces applied to the trapped object. The optical forces can be along the same direction or opposite to the propagation direction of the incident photons. These optical forces are typically classified into either scattering and gradient [13] that will be expanded in later chapters. The scattering force results from reflection, scattering, and absorption of incident photons, and this scattering force is always along the direction of the optical beam propagation. The gradient force is along to the intensity gradient of the optical field and causes the object to move toward the position of the highest intensity. Basically, an optical trap is an optical field that can apply optical forces on the particles that located with in the field and hence, confine the position of the particles, as if the particles are
“trapped” by the optical field. 3D optical traps have an equilibrium position therefore,
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any displacement from this position will cause a restoring force analogous to a spring but in all three dimensions. To create a stable 3D optical trap, the beam needs to be tightly focused in order to achieve a large optical field gradient, and the particle must have a refractive index higher than the solvent fluid. Additionally, the size of the trapped object should be small enough to mostly fit within the focal volume
2.4 OPTICAL TWEEZERS APPLICATION
The history and development of the optical tweezers gives it unique characteristic in a broad range of fields such as physics, biology, medicine, nanotechnology, micro- hydrodynamics and so forth. Since 1986, Dr. Arthur Ashkin is one of the foremost researchers in this field who has trapped a particles ranging from polystyrene beads to bacteria to different proteins [18]. It can be used to measure the elasticity, force, torsion, position, surface structure and particle interaction [27]. One of the reasons that it has such broad application is due to the unique, non-contact and non-invasive nature of the applied force. Optical tweezers are used widely in the area of biology and medicine, immunology and molecular genetics [28] too.
Some common applications of optical tweezers in life science are immune assay development, single molecule binding, trapping cells and bacteria, micelle and liposome analysis and in nanoparticles. Additionally, optical trapping has applications in material science, synthesis and analysis of the nanoparticles, nano-assembly of hybrid nanostructures, and the analysis of the optical interaction [29]. In 2005 by collaboratin of the by John Joannopolous's group at MIT and Federico Capasso's group at Harvard they conclude that it is possible to use gradient force on a chip. The theories from the Maxwell equations used ultimately for the conclusion that the sufficient gradient force can 7
generated in the piconewtons, more than enough to get a nanometer-scale oscillator thrumbing. Based on the calculation of the researchers on a device involving two parallel waveguides, which are light-conducting channels engineered to confine waves of a given frequency in a beam so that it can travel through the guide with very little loss. Even though the two waveguides kept their beams separate, the bonding of the optical fields between the beams was surprisingly strong. In the single-waveguide case, the optical field around the waveguide must be asymmetrical, in order to create the inequality which required to exert a total force.
Technologies such as optical tweezers and correlate with electrical, magnetic and acoustic systems, with a focus on obtaining synergies among different modalities and on novel bio-applications. Optical trapping also covers applications in emerging fields of optofluidics, lab-on-a-chip, nanophotonics, plasmonics, fiber-based manipulation, aerosol analysis and holographic techniques.
2.4.1 BIOPHYSICAL APPLICATION
Optical tweezers used as an effective micromanipulator in the field of biology, biophysics, and medicine for a two main reasons. First is the advantage of the capturing and trapping objects without any true mechanical contact, which can cause even contaminations or damage to the sample. Second, is the ability of the optical tweezers in the exertion of the forces in the range of pN and can be related to the microscopic organisms. Consequently, this technology has all sorts of use in biophysics, begging from the study of the exerted forces by the molecules that can cause particles move around in
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the cells. Ashkin and his co-workers first used optical tweezers on the large enough particles and materials to manipulate directly by using optical tweezers. They used it to capture bacteria and a small number of tobacco mosaic viruses [1] and after this the single cell manipulation and cell organelles had been done. Eventually, the force of cell organelle in the living cell measured [2]. The first calibrated measurement of the compliance of bacterial flagella by tweezers to grab and rotate the bacteria by force done at 1989, by Block et al. [3]. In most of the biological study of the tweezers instead of the direct manipulation, a latex (polystyrene) microsphere applied a force. The other early studies of the biological application of the optical tweezers can be named as; yeast cells
[4], blood cells [4], [5], plant cells [6]–[8], protozoa [1], studying DNA [9]–[11]. In 1997, a group of researchers at Rockefeller University used an optical tweezer for DNA manipulation by attaching a DNA to polystyrene beads and then by trapping the attached bead they manipulate the DNA [12]. Dr. Richard Dickinson had studied cell adhesion and migration at the University of Minnesota [13].
Single optical tweezers let the study of the mechanical properties of the biological cell membranes [14]. Recently, advancement in optical tweezers not only made it as a powerful tool in the field of biophysics, biophotonics and biomedical but also used as in a tool for clinical studies and neuroscience and surgery too. Neuroscience takes an advantage from these evolutions to record, modulate and manipulate the physiological activity of neurons. Optical tweezers can be count as one of the non-contact tools for the optical surgery. It can be used for axonal manipulation that enables researchers to pull the filopodium and influence the transport of intra-axonal organelles by use of microparticles as a handle [15]. Another advancement of Tweezers is, in the cell surgery, that has a high
9
potential in the microinjection [16], [17], micropositioning [18], micro gripping
[19]extraction and modification, and pre-implantation genetic diagnosis (PGD). Advance cell surgery research had been done at the University of Hong Kong by utilizing two optical traps. Optical traps were generated by robotically controlled holographic optical tweezers (HOT) to the rotation the cell [20]. Difato and his colleagues at the Italian
Institute Technology developed the system for combining optical tweezers and a laser dissector with electrophysiological tools. In this system, optical tweezers apply mechano- chemical stimuli to the cells and laser dissector can change the neuronal connection [21].
Besides all of these progress, researchers make this technology more advanced and decrease the applications day by day.
Figure 2- 2µm Microsphere in an optical Trap
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CHAPTER III
THEORY AND APPLIED FORCE
3.1 THEORY OF OPTICAL TWEEZERS
The non-invasive and non-contact characteristics of the optical tweezers enable for an accurate positioning, measurement, and control of the trapped microscopic objects.
On the objects that have the same wavelength as light pN force can be applied with sub- pN resolution. There are various methods of force spectroscopy techniques to investigate the biological system such as atomic force microscopy (AFM), optical, magnetic [22] and microneedle manipulation including the other techniques of spatiotemporal resolution to manipulate objects. Among all these methods, optical tweezers have shown better accuracy and performance. The spatial-temporal sensitivity of the AFM to the motion of the tethered object is less than tweezers; However, the excreted force is much larger.
Consequently, optical tweezers have the most flexibility due to the adequate control throughout a comprehensive range of applied forces as well as the ability of 3D
11
measurement of motion in the vast range of small molecules to the whole living cells.
Years after the discovery of the laser, Ashkin stated that laser has the energy to accelerate the particles in the scale of microscopic for about times because of the gravity, and the force can be measured with these small particles. Ashkin did the experiment on the transparent particles because they do not absorb the light. Hence, they can avoid thermal effects and deflect the light as they have a higher index of refraction comparing with the surrounding fluid. Ashkin experiment showed that the particles were stretched into the beam axis, and they accelerate in the same direction as light, which is an indication of two mechanisms of pulling and pushing the particle into the trap and upwards. Therefore, the analysis is based on the reflection of the beam at the surface of the object. This reflection produces a force that is a radiation pressure. When a beam is focusing on a certain point, gradient force should be considered, and it is mandatory for understanding the trapping procedure [23]. Optical tweezers use tightly focused laser beams to trap and move particles [24] that are originally known as ‘’gradient force optical trap’’. The main feature of the optical trapping is focusing of the beam that enables us to use the intrinsic characteristic of the light to pull a high refractive index objects into high- intensity regions.
Light can transfer momentum to objects based on the electromagnetic theory of
Maxwell. The force is depending on the velocity in the medium and can be calculated for a single ray of the power (P) as:
� ∝ �/� (3.1) Where, υ = , nm is the medium index of refractive and C is the velocity of light in the vacuum. The magnitude of exerted force by light can be found by the assumption of an 12
incident light beam on a plane mirror perpendicularly.
Every photon has a momentum of ℏ�, where � is the light wave vector and ℏ is