Plasmonic और Photonic क्रिस्टल nanostructures की बढ़ी माइक्रो Nanoparticle और हेरफेर के लिए उपयोगिता
Summary
Plasmonic चिमटी और photonic क्रिस्टल nanostructures के ऑप्टिकली माइक्रो और नैनो कणों को फँसाने की दक्षता और ओरिएंटेशन नियंत्रण में उपयोगी संवर्द्धन का उत्पादन करने के लिए दिखाए जाते हैं.
Abstract
A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET’s have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP’s generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.
Protocol
Discussion
फँसाने के इन तरीकों का महत्व यह है कि वे 10 μW / 2 सुक्ष्ममापी के आदेश पर 10 3 μW / 2 सुक्ष्ममापी कहीं के आदेश पर ऑप्टिकल कहीं से निरंतर फँसाने के लिए आवश्यक तीव्रता में कमी 10,11 इन तकनीकों पर सीमाओं….
Declarações
The authors have nothing to disclose.
Acknowledgements
हम भी Xiaoyu Miao और बेन विल्सन में वर्णित विधियों की सबसे अधिक विकसित करने के लिए धन्यवाद देना चाहूंगा. यह काम राष्ट्रीय विज्ञान फाउंडेशन (0,454,324 DBI) और राष्ट्रीय स्वास्थ्य संस्थान (EB005183 R21) द्वारा और Eck के लिए NIGMS से T32 एनआरएसए GM07270 PHS द्वारा वित्त पोषित किया गया था.
Materials
| Material Name | Tipo | Company | Catalog Number | Comment |
| Axio Imager Microscope | D1M | Zeiss | D1M | Zeiss Axio Imager.D1M |
| Microscope Objective | 50x/0.55 | Zeiss | LD EC Epiplan – NEOFLUAR 50x/0.55 HD DIC | |
| Zeiss Microscope Camera | AxioCam MRc | Zeiss | ||
| Helium Neon Laser | 35 mW | Research Electro-Optics | ||
| Variable Attenuator | Continuously Variable ND | ThorLabs | NDC-100C-4M | For adjusting microscope intensity |
| Zeiss Filter Set | Filter Set #17 | Zeiss | 488017-9901-000 | Filter Set #17 |
| Microscope Slides | 0.5 mm thickness | VWR | ||
| 3T3 mouse cell nuclei | Fred Hutchinson Cancer Research Center | Store as cold as possible | ||
| Acridine Orange dye | Fred Hutchinson Cancer Research Center | |||
| Bovine Serum Albumin | 1 to 10 ration in PBS | Fred Hutchinson Cancer Research Center | ||
| 454 nm polystyrene latex spheres | Polysciences, Inc. | |||
| carbodiimide hydrochloride (EDC) | 1-ethyl-3-(3-dimethylaminopropyl) | G-Biosciences | BC25-1 | |
| gold (for deposition) | ||||
| Reflective ruled diffraction grating | Edmund Optics | |||
| Phosphate Buffered Saline (PBS) | Dulbecco’s Phosphate-Buffered Saline (D-PBS) (1X) | Invitrogen | 14190-144 | |
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