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PLASMON ENHANCED NEAR-FIELD INTERACTIONS IN SURFACE COUPLED NANOPARTICLE ARRAYS FOR INTEGRATED NANOPHOTONIC DEVICES
Title
PLASMON ENHANCED NEAR-FIELD INTERACTIONS IN SURFACE COUPLED NANOPARTICLE ARRAYS FOR INTEGRATED NANOPHOTONIC DEVICES.
Creator
Ghoshal, Amitabh, Kik, Pieter, University of Central Florida
Abstract / Description
The current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at...
Show moreThe current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at optical and infrared frequencies. Numerous plasmon based integrated optical devices such as waveguides, splitters, resonators and multimode interference devices have been developed, however no standard integrated device for coupling light into nanoscale optical circuits exists. In this thesis we experimentally and theoretically investigate the excitation of propagating surface plasmons via resonant metal nanoparticle arrays placed in close proximity to a metal surface. It is shown that this approach can lead to compact plasmon excitation devices. Full-field electromagnetic simulations of the optical illumination of metal nanoparticle arrays near a metal film reveal the presence of individual nanoparticle resonances and collective grating-like resonances related to propagating surface plasmons within the periodic array structure. Strong near-field coupling between the nanoparticle and grating resonances is observed, and is successfully described by a coupled oscillator model. Numerical simulations of the effect of nanoparticle size and shape on the excitation and dissipation of surface plasmons reveal that the optimum particle volume for efficient surface plasmon excitation depends sensitively on the particle shape. This observation is quantitatively explained in terms of the shape-dependent optical cross-section of the nanoparticles. Reflection measurements on nanoparticle arrays fabricated using electron-beam lithography confirm the predicted particle-grating interaction. An unexpected polarization-dependent splitting of the film-mediated collective resonance is successfully attributed to the existence of out-of plane polarization modes of the metal nanoparticles. In order to distinguish between the excitation of propagating surface plasmons and localized nanoparticle plasmons, spectrally resolved leakage radiation measurements are presented. Based on these measurements, a universally applicable method for measuring the wavelength dependent efficiency of coupling free-space radiation into guided surface plasmon modes on thin films is developed. Finally, it is shown that the resonantly enhanced near-field coupling the nanoparticles and the propagating surface plasmons can lead to optimized coupler device dimensions well below 10 microns.
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Date Issued
2010
Identifier
CFE0003091, ucf:48322
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003091
The cytopathic activity of cholera toxin requires a threshold quantity of cytosolic toxin.
Title
The cytopathic activity of cholera toxin requires a threshold quantity of cytosolic toxin.
Creator
Bader, Carly, Teter, Kenneth, Zervos, Antonis, Jewett, Travis, Tatulian, Suren, University of Central Florida
Abstract / Description
Cholera toxin (CT), secreted from Vibrio cholerae, causes a massive fluid and electrolyte efflux in the small intestine that results in life-threatening diarrhea and dehydration which impacts 3-5 million people per year. CT is secreted into the intestinal lumen but acts within the cytosol of intestinal epithelial cells. CT is an AB5 toxin that has a catalytic A1 subunit and a cell binding B subunit. CT moves from the cell surface to the endoplasmic reticulum (ER) by retrograde transport. Much...
Show moreCholera toxin (CT), secreted from Vibrio cholerae, causes a massive fluid and electrolyte efflux in the small intestine that results in life-threatening diarrhea and dehydration which impacts 3-5 million people per year. CT is secreted into the intestinal lumen but acts within the cytosol of intestinal epithelial cells. CT is an AB5 toxin that has a catalytic A1 subunit and a cell binding B subunit. CT moves from the cell surface to the endoplasmic reticulum (ER) by retrograde transport. Much of the toxin is transported to the lysosomes for degradation, but a secondary pool of toxin is diverted to the Golgi apparatus and then to the ER. Here the A1 subunit detaches from the rest of the toxin and enters the cytosol. The disordered conformation of free CTA1 facilitates toxin export to the cytosol by activating a quality control mechanism known as ER-associated degradation. The return to a folded structure in the cytosol allows CTA1 to attain an active conformation for modification of its Gs? target through ADP-ribosylation. This modification locks the protein in an active state which stimulates adenylate cyclase and leads to elevated levels of cAMP. A chloride channel located in the apical enterocyte membrane opens in response to signaling events induced by these elevated cAMP levels. The osmotic movement of water into the intestinal lumen that results from the chloride efflux produces the characteristic profuse watery diarrhea that is seen in intoxicated individuals.The current model of intoxication proposes only one molecule of cytosolic toxin is required to affect host cells, making therapeutic treatment nearly impossible. However, based on emerging evidence, we hypothesize a threshold quantity of toxin must be present within the cytosol of the target cell in order to elicit a cytopathic effect. Using the method of surface plasmon resonance along with toxicity assays, I have, for the first time, directly measured the efficiency of toxin delivery to the cytosol and correlated the levels of cytosolic toxin to toxin activity. I have shown CTA1 delivery from the cell surface to the cytosol is an inefficient process with only 2.3 % of the surface bound CTA1 appearing in the cytosol after 2 hours of intoxication. I have also determined and a cytosolic quantity of more than approximately .05ng of cytosolic CTA1 must be reached in order to elicit a cytopathic effect. Furthermore, CTA1 must be continually delivered from the cell surface to the cytosol in order to overcome the constant proteasome-mediated clearance of cytosolic toxin. When toxin delivery to the cytosol was blocked, this allowed the host cell to de-activate Gs?, lower cAMP levels, and recover from intoxication. Our work thus indicates it is possible to treat cholera even after the onset of disease. These findings challenge the idea of irreversible cellular toxicity and open the possibility of post-intoxication treatment options.
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Date Issued
2013
Identifier
CFE0004810, ucf:49759
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004810
INTEGRATED OPTICAL SPR (SURFACE PLASMON RESONANCE) SENSOR BASED ON OPTOELECTRONIC PLATFORM
Title
INTEGRATED OPTICAL SPR (SURFACE PLASMON RESONANCE) SENSOR BASED ON OPTOELECTRONIC PLATFORM.
Creator
Bang, Hyungseok, LiKamWa, Patrick, University of Central Florida
Abstract / Description
Current major demands in SPR sensor development are system miniaturization and throughput improvement. Structuring an array of integrated optical SPR sensor heads on a semiconductor based optoelectronic platform could be a promising solution for those issues, since integrated optical waveguides have highly miniaturized dimension and the optoelectronic platform enables on-chip optical-to-electrical signal conversion. Utilizing a semiconductor based platform to achieve optoelectronic...
Show moreCurrent major demands in SPR sensor development are system miniaturization and throughput improvement. Structuring an array of integrated optical SPR sensor heads on a semiconductor based optoelectronic platform could be a promising solution for those issues, since integrated optical waveguides have highly miniaturized dimension and the optoelectronic platform enables on-chip optical-to-electrical signal conversion. Utilizing a semiconductor based platform to achieve optoelectronic functionality poses requirements to the senor head; the sensor head needs to have reasonably small size while it should have reasonable sensitivity and fabrication tolerance. This research proposes a novel type of SPR sensor head and demonstrates a fabricated device with an array of integrated optical SPR sensor heads endowed with optoelectronic functionality. The novel integrated optical SPR sensor head relies on mode conversion efficiency for its operational principle. The beauty of this type of sensor head is it can produce clear contrast in SPR spectrum with a highly miniaturized and simple structure, in contrast to several-millimeter-scale conventional absorption type or interferometer type sensor heads. The integrated optical SPR sensor with optoelectronic functionality has been realized by structuring a dielectric waveguide based SPR sensor head on a photodetector-integrated semiconductor substrate. A large number of unit sensors have been fabricated on a substrate with a batch fabrication process, which promises a high throughput SPR sensor system or low-priced disposable sensors.
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Date Issued
2008
Identifier
CFE0002312, ucf:47841
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002312
Synthesis, Characterization And Antibacterial Activity Of Silver Embedded Silica Nanoparticle/Nanogel Formulation
Title
Synthesis, Characterization And Antibacterial Activity Of Silver Embedded Silica Nanoparticle/Nanogel Formulation.
Creator
Menezes, Roseline, Santra, Swadeshmukul, Naser, Saleh, Self, William, University of Central Florida
Abstract / Description
The antibacterial property of silver (Ag) has been known since ancient time. It is reported in the literature that silver nanoparticles (AgNPs) exhibit improved antibacterial properties in comparison to silver ions of equivalent metallic Ag concentration. Such improvement in antibacterial activities is due to the high surface area to volume ratio of AgNPs (which facilitates interaction with the bacterial cells), increased release of silver ions and direct intra-cellular uptake of AgNPs...
Show moreThe antibacterial property of silver (Ag) has been known since ancient time. It is reported in the literature that silver nanoparticles (AgNPs) exhibit improved antibacterial properties in comparison to silver ions of equivalent metallic Ag concentration. Such improvement in antibacterial activities is due to the high surface area to volume ratio of AgNPs (which facilitates interaction with the bacterial cells), increased release of silver ions and direct intra-cellular uptake of AgNPs leading to localized release of Ag ions. To date, over 300 consumer products containing AgNPs are available in the market and the inventory is rapidly expanding. The antibacterial efficacy is related to the loading of AgNPs (which controls availability of active Ag ions). It is perhaps challenging to increase AgNPs loading in consumer products without compromising its aesthetic appearance. AgNPs exhibit yellow-brown color due to strong Surface Plasmon Resonance (SPR) absorption; and therefore, it is expected that an increase in loading would change the color of AgNP-containing materials. For applications, such as creating a fast-acting touch-safe surface, higher loading of AgNPs is desirable. It is also desirable to obtain a non-color forming surface. To meet the demands of desirable higher loading of AgNPs and non-color forming surface, the objective of this study is to minimize SPR by engineering Ag containing nanomaterials for potential fast-acting spray-based applications. Within this thesis several reports have been made including synthesis, characterization and antibacterial properties of Ag-loaded silica nanoparticle/nanogel (AgSiNP/NG) material containing nanoformulations. The effects of nanoformulation pH and metallic Ag content on the SPR absorption and antibacterial properties have been studied. The AgSiNP/NG materials were synthesized using silica sol-gel technique at room temperature in water. The color formation of the AgSiNP/NG material was found to be dependent on silver ion loading (15.4 wt% and 42.3 wt %) as well as on the pH (pH 4.0 and pH 7.0). A number of material characterization techniques such as HRTEM, SEM and AFM were used to characterize particle size, crystalline and surface morphology in dry state. Dynamic light scattering (DLS) technique was used to characterize particle size and size distribution in solution. UV-VIS spectroscopy technique was applied to characterize Ag ions and AgNPs in the AgSiNP/NG material. Antibacterial studies were conducted against gram negative E.coli and gram positive B.subtilis and S.aureus. A number of qualitative (well diffusion, BacLightTM live-dead(&)#174; viability) and quantitative (turbidity, resazurin viability) assays were used for antibacterial studies. It was observed that lower pH and low Ag loading minimized SPR absorption, resulting in no yellow-brown color formation. The HRTEM confirmed the formation of ~5-25 nm size highly crystalline AgNPs which were coated with dielectric silica layer (silica gel). AFM, SEM and DLS studies confirmed formation of AgSiNPs in the range between 100 nm (-) 200 nm. The AgSiNP/NG material was effective against both gram-negative and gram-positive bacteria. Based on this research it is suggested that by coating AgNPs with a dielectric material (such as silica); it is possible to suppress SPR absorption.
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Date Issued
2011
Identifier
CFE0004483, ucf:49308
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004483
Thermally annealled plasmonic nanostructures
Title
Thermally annealled plasmonic nanostructures.
Creator
Wang, Chaoming, Su, Ming, Coffey, Kevin, Chai, Xinqing, Schelling, Patrick, University of Central Florida
Abstract / Description
Localized surface plasmon resonance (LSPR) is induced in metal nanoparticles by resonance between incident photons and conduction electrons in nanoparticles. For noble metal nanoparticles, LSPR can lead to strong absorbance of ultraviolet-violet light. Although it is well known that LSPR depends on the size and shape of nanoparticles, the inter-particle spacing, the dielectric properties of metal and the surrounding medium, the temperature dependence of LSPR is not well understood. By...
Show moreLocalized surface plasmon resonance (LSPR) is induced in metal nanoparticles by resonance between incident photons and conduction electrons in nanoparticles. For noble metal nanoparticles, LSPR can lead to strong absorbance of ultraviolet-violet light. Although it is well known that LSPR depends on the size and shape of nanoparticles, the inter-particle spacing, the dielectric properties of metal and the surrounding medium, the temperature dependence of LSPR is not well understood. By thermally annealing gold nanoparticle arrays formed by nanosphere lithography, a shift of LSPR peak upon heating has been shown. The thermal characteristics of the plasmonic nanoparticles have been further used to detect chemicals such as explosive and mercury vapors, which allow direct visual observation of the presence of mercury vapor, as well as thermal desorption measurements.
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Date Issued
2012
Identifier
CFE0004454, ucf:49322
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004454
Light-Matter Interactions of Plasmonic Nanostructures
Title
Light-Matter Interactions of Plasmonic Nanostructures.
Creator
Reed, Jennifer, Zou, Shengli, Belfield, Kevin, Zhai, Lei, Hernandez, Eloy, Vanstryland, Eric, University of Central Florida
Abstract / Description
Light interaction with matter has long been an area of interest throughout history, spanning many fields of study. In recent decades, the investigation of light-matter interactions with nanostructures has become an intense area of research in the field of photonics. Metallic nanostructures, in particular, are of interest due to the interesting properties that arise when interacting with light. The properties are a result of the excitation of surface plasmons which are the collective...
Show moreLight interaction with matter has long been an area of interest throughout history, spanning many fields of study. In recent decades, the investigation of light-matter interactions with nanostructures has become an intense area of research in the field of photonics. Metallic nanostructures, in particular, are of interest due to the interesting properties that arise when interacting with light. The properties are a result of the excitation of surface plasmons which are the collective oscillation of the conduction electrons in the metal. Since the conduction electrons can be thought of as harmonic oscillators, they are quantized in a similar fashion. Just as a photon is a quantum of oscillations of an electromagnetic field, the plasmon is a quantum of electron oscillations of a metal. There are three types of plasmons:1. Bulk plasmons, also called volume plasmons, are longitudinal density fluctuations which propagate through a bulk metal with an eigenfrequency of ?_p called the plasma frequency.2. Localized surface plasmons are non-propagating excitations of the conduction electrons of a metallic nanoparticle coupled to an electromagnetic field. 3. Surface plasmon polaritons are evanescent, dispersive propagating electromagnetic waves formed by a coupled state between a photon and the excitation of the surface plasmons. They propagate along the surface of a metal-dielectric interface with a broad spectrum of eigenfrequencies from ?=0 to ?= ?_p??2. Plasmonics is a subfield of photonics which focuses on the study of surface plasmons and the optical properties that result from light interacting with metal films and nanostructures on the deep subwavelength scale. In this thesis, plasmonic nanostructures are investigated for optical waveguides and other nanophotonic applications through computational simulations primarily base on electrodynamic theory. The theory was formulated by several key figures and established by James Clerk Maxwell after he published a set of relations which describe all classical electromagnetic phenomena, known as Maxwell's equations. Using methods based on Maxwell's equations, the optical properties of metallic nanostructures utilizing surface plasmons is explored. In Chapter 3, light propagation of bright and dark modes of a partially and fully illuminated silver nanorod is investigated for waveguide applications. Then, the origin of the Fano resonance line shape in the scattering spectra of a silver nanorod is investigated. Next, in Chapter 4, the reflection and transmission of a multilayer silver film is simulated to observe the effects of varying the dielectric media between the layers on light propagation. Building on the multilayer film work, metal-insulator-metal waveguides are explored by perforating holes in the bottom layer of a two layer a silver film to investigate the limits of subwavelength light trapping, confinement, and propagation. Lastly, in Chapter 5, the effect of surface plasmons on the propagation direction of electromagnetic wave around a spherical silver nanoparticle which shows an effective negative index of refraction is examined. In addition, light manipulation using a film of silver prisms with an effective negative index of refraction is also investigated. The silver prisms demonstrate polarization selective propagation for waveguide and optical filter applications. These studies provide insight into plasmonic mechanisms utilized to overcome the diffraction limit of light. Through better understanding of how to manipulating light with plasmonic nanostructures, further advancements in nanophotonic technologies for applications such as extremely subwavelength waveguides, sensitive optical detection, optical filters, polarizers, beam splitters, optical data storage devices, high speed data transmission, and integrated subwavelength photonic circuits can be achieved.
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Date Issued
2013
Identifier
CFE0005049, ucf:49964
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005049
Development of a nano-sensing approach and a portable prototype for real-time detection and quantification of free mercury in stream-flow: combining science and engineering in pro of the environment
Title
Development of a nano-sensing approach and a portable prototype for real-time detection and quantification of free mercury in stream-flow: combining science and engineering in pro of the environment.
Creator
Chemnasiri, Warinya, Hernandez, Florencio, Kuebler, Stephen, Zou, Shengli, Uribe Romo, Fernando, Huo, Qun, University of Central Florida
Abstract / Description
Mercury (Hg) is a well-known hazardous environmental contaminant existing in several forms, but all are toxic to human in one way or the others. Since Hg usually settles into water polluting the environment and accumulating in living organisms, it is crucial to monitor Hg levels in the aquatic ecosystem. Although there are many well established techniques currently used to detect Hg, most of them require elaborate and time-consuming sample preparation and pre-concentration procedures, as well...
Show moreMercury (Hg) is a well-known hazardous environmental contaminant existing in several forms, but all are toxic to human in one way or the others. Since Hg usually settles into water polluting the environment and accumulating in living organisms, it is crucial to monitor Hg levels in the aquatic ecosystem. Although there are many well established techniques currently used to detect Hg, most of them require elaborate and time-consuming sample preparation and pre-concentration procedures, as well as costly and bulky equipment that limit their practical application in the field. In order to overcome the existent limitations in Hg determination methods, Hernandez and co-workers proposed the first surface Plasmon resonance (SPR) (-) based Hg sensor using gold nanorods (AuNRs) that offers high sensitivity and selectivity, attributed to the strong affinity between Au and Hg. In this dissertation, I first present my contribution to the understanding of the effect of size and aspect ratio of AuNRs on the limit of detection (LOD) and the dynamic range (DR) of the SPR-based Hg sensor using the qualitative model. In this part I demonstrate how both sensitivity and DR can be improved simultaneously via a modified wet chemistry procedure. Then, I show our approach towards the immobilization of AuNRs silane coated glass slides to expand the application of the SPR-based Hg sensor to stream-flow. Finally, I present the design and fabrication of the first real prototype of the SPR-based Hg sensor, and its application in stream-flow detection and speciation of mercury in the environment. The outcomes of my research have resulted in an innovative real-time portable Hg sensor apparatus with the desired high sensitivity, selectivity and DR to be used in stream-flow applications in Oak Ridge National Labs sites.
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Date Issued
2015
Identifier
CFE0006283, ucf:51589
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006283
THEORETICAL TAILORING OF PERFORATED THIN SILVER FILMS FOR AFFINITY SURFACE PLASMON RESONANCE BIOSENSOR APPLICATIONS
Title
THEORETICAL TAILORING OF PERFORATED THIN SILVER FILMS FOR AFFINITY SURFACE PLASMON RESONANCE BIOSENSOR APPLICATIONS.
Creator
Gongora Jr., Renan, Zou, Shengli, University of Central Florida
Abstract / Description
Metallic films, in conjunction with biochemical-targeted probes, are expected to provide early diagnosis, targeted therapy and non-invasive monitoring for epidemiology applications. The resonance wavelength peaks, both plasmonic and Wood-Rayleigh Anomalies (WRAs), in the scattering spectra are affected by the metallic architecture. As of today, much research has been devoted to extinction efficiency in the plasmonic region. However, Wood Rayleigh Anomalies (WRAs) typically occur at...
Show moreMetallic films, in conjunction with biochemical-targeted probes, are expected to provide early diagnosis, targeted therapy and non-invasive monitoring for epidemiology applications. The resonance wavelength peaks, both plasmonic and Wood-Rayleigh Anomalies (WRAs), in the scattering spectra are affected by the metallic architecture. As of today, much research has been devoted to extinction efficiency in the plasmonic region. However, Wood Rayleigh Anomalies (WRAs) typically occur at wavelengths associated with the periodic distance of the structures. A significant number of papers have already focused on the plasmonic region of the visible spectrum, but a less explored area of research was presented here; the desired resonance wavelength region was 400-500nm, corresponding to the WRA for the silver film with perforated hole with a periodic distance of 400nm. Simulations obtained from the discrete dipole approximation (DDA) method, show sharp spectral bands (either high or low scattering efficiencies) in both wavelength regions of the visible spectrum simulated from Ag film with cylindrical hole arrays In addition, surprising results were obtained in the parallel scattering spectra,where the electric field is contained in the XY plane, when the angle between the metallic surface and the incident light was adjusted to 14 degrees; a bathochromic shift was observed for the WRA peak suggesting a hybrid resonance mode. Metallic films have the potential to be used in instrumental techniques for use as sensors, i.e. surface plasmon resonance affinity biosensors, but are not limited to such instrumental techniques. Although the research here was aimed towards affinity biosensors, other sensory designs can benefit from the optimized Ag film motifs. The intent of the study was to elucidate metal film motifs, when incorporated into instrumental analysis, allowing the quantification of genetic material in the visible region. Any research group that routinely benefits from quantification of various analytes in solution matrices will also benefit from this study, as there are a bewildering number of instrumental sensory methods and setups available.
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Date Issued
2014
Identifier
CFH0004538, ucf:45155
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004538