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1
Ishihara, M., S. Okawa, R. Sato, T. Hirasawa, and T. Teranishi. "Photoacoustic Signal Enhancement by Localized Surface Plasmon of Gold Nanoparticles." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35430.
Full textAbstract:
Photoacoustic imaging has been widely studied as a deep biological tissue imaging modality combining
optical absorption and ultrasonic detection. It enables multi-scale high resolution imaging of optical absorbing
intrinsic molecules as well as exogenous molecules. Gold nanoparticles have the primary advantages
of large absorption cross section and bioconjugation capability for the imaging contrast agents. In
order to design the photoacoustic imaging agents for enhancing the contrast with high specificity to targeted
molecules and / or cell, we measured and analyzed time-of-flight photoacoustic signals of aqueous solutions
of various shapes and sizes of gold nanoparticles. The signal intensities were sensitive to the shapes
and sizes of the gold nanoparticles. We found a strong photoacoustic signal of the polyhedral gold nanoparticle
due to the localized surface plasmon resonance. The experimental results derive the strategy of designing
the optimum photoacoustic contrast agents.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35430
2
Para, Prashanthi. "FABRICATION OF NANOSTRUCTURES FOR IMPROVED PERFORMANCE OF ELECTROCHEMICAL SENSORS AND FOR REFERENCE COMPENSATION IN LOCALIZED SURFACE PLASMON RESONANCE SENSORS." UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_theses/130.
Full textAbstract:
L‐glutamate is associated with several neurological disorders; thus, monitoring fast dynamics of L‐glutamate is of great importance in the field of neuroscience. Electrode miniaturization demanded by many applications leads to reduced surface area and decreased amounts of immobilized enzymes on coated electrodes. As a result, lower signal‐to‐noise ratios are observed for oxidase‐enzyme based sensors. To increase the signal‐to‐noise ratio we have developed a process to fabricate micro‐ and nano‐ structures on the microelectrode surface.
Localized surface‐plasmon resonances (SPR) has been extensively used to design label‐free biosensors that can monitor receptor‐ligand interactions. A major challenge with localized SPR sensors is that they remain highly susceptible to interference because they respond to both solution refractive index changes and surface binding of the target analyte. The key concept introduced in the present work is the exploitation of transverse and longitudinal resonance modes of nanorod arrays to differentiate between bulk refractive index changes and surface interactions. The transverse bulk sensitivity of the localized SPR sensor (107 nm/RIU) remains competitive with typical single mode gold nanosphere SPR sensors. The figure of merit for the device’s cross‐sensitivity (1.99) is comparable to that of typical wavelength‐interrogated propagating SPR sensors with self referencing.
3
Segervald, Jonas. "Fabrication and Optimization of a Nanoplasmonic Chip for Diagnostics." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-163998.
Full textAbstract:
To increase the survival rate from infectious- and noncommunicable diseases, reliable diagnostic during the preliminary stages of a disease onset is of vital importance. This is not trivial to achieve, a highly sensitive and selective detection system is needed for measuring the low concentrations of biomarkers available. One possible route to achieve this is through biosensing based on plasmonic nanostructures, which during the last decade have demonstrated impressive diagnostic capabilities. These nanoplasmonic surfaces have the ability to significantly enhance fluorescence- and Raman signals through localized hotspots, where a stronger then normal electric field is present. By further utilizing a periodic sub-wavelength nanohole array the extraordinary optical transmission phenomena is supported, which open up new ways for miniaturization. In this study a nanoplasmonic chip (NPC) composed of a nanohole array —with lateral size on the order of hundreds of nanometer— covered in a thin layer of gold is created. The nanohole array is fabricated using soft nanoimprint lithography on two resists, hydroxypropyl cellulose (HPC) and polymethyl methacrylate (PMMA). An in depth analysis of the effect of thickness is done, where the transmittance and Raman scattering (using rhodamine 6G) are measured for varying gold layers from 5 to 21 nm. The thickness was proved to be of great importance for optimizing the Raman enhancement, where a maximum was found at 13 nm. The nanohole array were also in general found beneficial for additionally enhancing the Raman signal. A transmittance minima and maxima were found in the region 200-1000 nm for the NPCs, where the minima redshifted as the thickness increased. The extraordinary transmission phenomena was however not observed at these thin gold layers. Oxygen plasma treatment further proved an effective treatment method to reduce the hydrophobic properties of the NPCs. Care needs be taken when using thin layers of gold with a PMMA base, as the PMMA structure could get severely damaged by the plasma. HPC also proved inadequate for this projects purpose, as water-based fluids easily damaged the surface despite a deposited gold layer on top.
4
Nehru, Neha. "Reference Compensation for Localized Surface-Plasmon Resonance Sensors." UKnowledge, 2014. http://uknowledge.uky.edu/ece_etds/41.
Full textAbstract:
Noble metal nanoparticles supporting localized surface plasmon resonances (LSPR) have been extensively investigated for label free detection of various biological and chemical interactions. When compared to other optical sensing techniques, LSPR sensors offer label-free detection of biomolecular interactions in localized sensing volume solutions. However, these sensors also suffer from a major disadvantage – LSPR sensors remain highly susceptible to interference because they respond to both solution refractive index change and non-specific binding as well as specific binding of the target analyte. These interactions can severely compromise the measurement of the target analyte in a complex unknown media and hence limit the applicability and impact of the sensor. In spite of the extensive amount of work done in this field, there has been a clear absence of efforts to make LSPR sensors immune to interfering effects. The work presented in this document investigates, both experimentally and numerically, dual- and tri-mode LSPR sensors that utilize the multiple surface plasmon modes of gold nanostructures to distinguish target analyte from interfering bulk and non-specific binding effects. Finally, a series of biosensing experiments are performed to examine various regeneration assays for LSPR sensors built on indium tin oxide coated glass substrate.
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Rapisarda, Antonino. "Localized Surface Plasmon Resonance: Nanoscale Sensing for Processes at Interfaces." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/4022.
Full textAbstract:
This PhD thesis reports the use the emerging surface-sensitive optical technique of localized surface plasmon resonance (LSPR) to characterize the interaction of relevant classes of biomolecules, e.g. peptides, proteins, lipids and DNA strands, at solid-liquid interfaces, with an emphasis on deciphering kinetics and pathways of dynamic adsorption processes.
LSPR-based biosensor exploits the high sensitivity of the plasmon frequency to refractive index changes confined to 5-30 nanometers around the metal nanoparticles deposited on the sensor surface to monitor in situ and in real time the interaction of unlabeled biological molecules skipping the misleading contribution from the bulk of solution affecting conventional optical technique, e.g. SPR and OWLS.
In the present dissertation the advantages of applying this powerful technique are thoroughly demonstrated by investigating four case studies concerning relevant aspects for the biointerfaces science. The case of study 1 will involve the adsorption kinetics of single and binary solution of proteins onto model hydrophilic and hydrophobic surfaces. The analysis of the adsorption kinetics reveals that competitive adsorption occurs, at physiological pH 7.4 and relatively high ionic strength (NaCl 0.1 M), favoring the heavier protein (fibronectin, in our case), which is shown to adsorb faster and in larger amount than the lighter one (human serum albumin, in our case). The case of study 2 will discuss the DNA hybridization process for binary solutions of respectively perfectly matching (PM) and single base mismatching (MM) 93-mer ssDNA from KRAS codon 12, with a surface tethered probe complementary to the PM sequence. Sensitivity down to obtaining down to 10 nM and 13 nM, respectively for PM and MM were obtained, showing that the hybridization process occurs at a lower rate for MM with respect to PM target. The competitive hybridization was accounted for by an inhibition model, where the non-complementary sequences kinetically hinder the hybridization of the perfect matching sequences, owing to their above mentioned affinity constant differences for the same probe. The case of study 3 will cover the kinetics of phospholipid vesicle adsorption on silicon oxide surfaces as function of pH. Two different regimes have been observed for acidic and basic conditions. At low pH, vesicles adsorption showed one-step exponential kinetics. Moreover, no significantly variation of the adsorption rate was observed over the investigated pH range 3-6, suggesting the process is controlled by Van der Waals interactions and steric forces. At high pH, vesicles adsorb showing two-step kinetic. Furthermore, it was observed that the rate of the first step slows down linearly with the increasing of pH, suggesting that the process is primarily driven by vesicle-surface electrostatic repulsion. The case of study 4 will report preliminary results from the study of pH stimuli-responsive smart surfaces, formed by gold nanodisks array of an LSPR sensor chip decorated with Trichogin GA IV and two of its positively-charged analogs, i.e. Lipo-Lys and L20, in which four and eight Lysines positive charged residues have been introduced respectively. The surface-bound peptides exhibit reversible and rapid switching between conformations and can withstand several cycles of swelling and collapsing with no significant loss from the surfaces.
Overall, the results here reported demonstrated the great potential of LSPR technique as a unique tool to monitor specific and non-specific biomolecular interactions at interfaces in application fields ranging from biosensing to materials science.
6
CANTALE, Vera. "Towards label-free biosensors based on localized surface plasmon resonance." Doctoral thesis, Università degli studi di Ferrara, 2011. http://hdl.handle.net/11392/2388765.
Full textAbstract:
Medical diagnostics is in constant search of new tools and devices able to provide in short
time, accurate and versatile tests performed on patients. Nanotechnology has contributed
largely in developing biosensors of smaller size at a lower cost by using a minimal amount of
sample. Biosensors aim to monitor and diagnosticate “in situ” the patient status and the
diseases caused by alteration of the body metabolism by, for example, the detection of gene
mutations, alteration of gene expression or alteration of proteins.
The aim of this work is the development of biosensors that satisfy the requirements which are
critical for applications. A biosensor must be i) easy to use, ii) economically convenient, and
therefore preferentially label free, iii) highly sensitive, iv) reversible, v) and suitable for Point
of Care Testing, that is to be used ”in situ” on the patient.
We have focused on biosensors based on the optical properties of nanostructured metals as Au
or Ag, in particular by using on Localized Surface Plasmon Resonance (LSPR) spectroscopy.
Nanostructured metals under irradiation of electromagnetic wave (as light) exhibit intense
absorption bands as results of the localized electronic charges of the metal surface coming into
resonance with the incident energy. According to the Mie’s theory, the LSPR absorption band
feature changes when the refractive index of the media surrounding the metal nanostructures is
varied.
Of particular interest for our purpose are the possible changes of the LSPR band features taking
place under molecular interactions occurring at the nanostructures surfaces: the shift of LSPR
bands is the “transducer” of molecular interactions. These changes can be easily detected by
conventional UV-Vis spectroscopy, in transmittance mode.
While a large number of studies have been carried out on monodisperse nanoparticles
suspended in solution, gold nanoparticles (NPs) deposited on a transparent surface open the
possibility to fabricate biosensor based on multiplex array platforms. Nonetheless, one of the
major problems in using these plasmonic materials for biosensing purpose is related to the
stability of the metal NPs in different solvents and in particular in aqueous solutions.
In this study we demonstrate i) the possibility to achieve highly stable NPs by simple thermal
evaporation of Au on a substrate commercially available, the Fluorine Tin Oxide (FTO) (Chapter 2); ii) a reproducible variation of the LSPR bands under formation of organic selfassembled
monolayers (SAMs), iii) reversible changes in the features of the LSPR bands,
(Chapter 3), iv) a specific and reproducible LSPR band changes under molecular interactions
occurring at NPs surfaces, as DNA hybridization (Chapter 4).
This work demonstrates that the plasmonic material based on Au NPs deposited on FTO
surfaces represents a convenient platform for biosensors because of i) inexpensive fabrication,
ii) stability of this material in various solvent, including water, of, iii) the easy way to detect
the molecular interaction, and iv) the good sensitivity to molecular interactions.
7
Acomovic, Srdjan S. "Localized surface plasmon resonance for biosensing lab-on-a-chip applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/113676.
Full textAbstract:
In recent times, metallic nanoparticle plasmonics coupled with applications towards biosensing has gathered momentum to the point where commercial R&D are investing large resources in developing the so-called localized surface plasmon resonance (LSPR) biosensors.
Conceptually, the main motivation for the research presented within this thesis is achievement of fully-operational LSPR biosensor interfaced with the state-of-the-art microfluidics, allowing for very precise control of sample manipulation and stable read-out. LSPR sensors are specifficaly engineered by electron beam lithography nanofabrication technique, where nanoparticle interactions are optimized to exhibit increased sensitivity and higher signal-to-noise ratio. However, the overall performance of LSPR lab-on-a-chip device depends critically on the biorecognition layer preparation in combination with surface passivation.
As an introduction, the principles of plasmonic biosensing are identified encompassing both Surface Plasmon Resonance (SPR) and Localized SPR. Being successfully implemented into commercial product, the governing physics of SPR is compared to LSPR in chapter 1, together with advantages and disadvantages of both.
Chapter 2 describes methods necessary for LSPR biosensor development, beginning with nano-fabrication methods, the modelling tool (COMSOL Multiphisics), while the basics of micro-fabrication in microfluidics conclude this chapter, where passive and active microfluidics networks are discerned.
Particularly attractive optical properties are exhibited by closely-coupled nanoparticles (dimers), with the dielectric gap of below tens of nm, which were theoretically predicted to be very suitable as LSPR biosensing substrates. Chapter 3 is subjected to optical characterization (dependence on the size of the dielectric gap) of nanofabricated dimer arrays. The acquired data demonstrate the advantages of the nanofabrication methods presented in chapter 2 and the technique for fast and reliable determination of nanoparticle characteristic parameters.
The initial biosensing-like experiments presented in chapter 4 (no integration with microfluidics) proved for the first time, the theoretical predictions of higher sensitivity, yielding additionally the specific response as function of analyte size and dielectric gap between nanoparticles. The overall response of different dimer arrays (various gaps) provides information about adopted conformation of analyte protein once immobilized.
Broad resonances of dimers feature higher noise when employing them for the real-time LSPR biosensing. As a way to circumvent such problem, the feasibility of employing far-field interaction within the nanoparticle array to spectrally narrow resonance is investigated in chapter 5 by optimizing the array periodicity and introducing thin waveguiding layers.
Finally, the concluding chapter 6 is dedicated to a full assembly of a Lab-on-a-chip (LOC) LSPR biosensor, starting with interfacing plasmonic substrates with compatible active microfluidic networks, allowing the precise sample delivery and multiplexing. The prototype device consisting of 8 individual sensors is presented with typical modes of operation. The bulk refractive index determination of various samples demonstrates the working principle of such device. Finally, various strategies of biorecognition layer formation are discussed within the on-going research.
8
Cao, Jie. "Creation of novel gold-nanorod-based localized surface plasmon resonance biosensors." Thesis, City University London, 2013. http://openaccess.city.ac.uk/2990/.
Full textAbstract:
Starting with a comprehensive review of both surface plasmon resonance (SPR) based and localized surface plasmon resonance (LSPR) based sensors, this thesis reports the studies on the development of a novel sensitive gold nanorod (GNR) based label-free LSPR optical fibre biosensor, and the development of a novel robust method for effectively modifying the surface of cetyl-trimethyl ammonium bromide (CTAB) capped GNRs and their LSPR biosensing applications. A novel GNR-based LSPR optical fibre sensor was fabricated and evaluated in this work. The sensor probe was prepared by covalently immobilizing GNRs, synthesized using a seed-mediated growth method, on the decladed surface of a piece of multimode optical fibre. In order to operate the LSPR sensor as a reflective sensor, a silver mirror was also coated at one distal end of the sensor probe by a dip coating method. In the refractive index sensitivity test, it was found that the longitudinal plasmon band (LPB) of GNRs is highly sensitive to the refractive index change close to the GNRs surface, and the sensitivity of the LSPR optical fibre sensor increases with the increase of the aspect ratio of GNRs. The results showed that the GNR-based LSPR optical fibre sensors prepared in this work have linear and high refract index sensitivities. For sensors based on GNRs with aspect ratios of 2.6, 3.1, 3.7 and 4.3, their refractive index sensitivities were found to be 269, 401, 506 and 766 nm/RIU (RIU = refractive index unit), respectively, in the refractive index range from 1.34 to 1.41. In order to evaluate the biosensing performance, the GNR-based LSPR optical fibre sensor with aspect ratio of 4.1 and a 2 cm sensing length was further functionalized with human IgG to detect the specific target — anti-human IgG, and a detection limit of 1.6 nM was observed using a wavelength-based interrogation approach. In another study, in order to overcome the drawbacks of the CTAB-capped GNRs found in biosensing and biomedical applications, a simple yet robust pH-mediated method for effectively modifying the surface of CTAB-capped GNRs synthesized by the seed-mediated growth method was developed. This method allows the complete replacement of the CTAB molecules attached on the GNRs surface with the 11-mercaptoundecaonic acid (MUA) molecules to take place in a total aqueous environment by controlling the pH of the MUA aqueous solution, thus avoiding the irreversible aggregation of GNRs during the complex surface modification process observed in the previous reported methods. The success of the complete replacement of CTAB with MUA was confirmed by the surface elemental analysis using an X-ray photoelectron spectroscopy (XPS), and the MUA-modified GNRs created in this work demonstrated a high stability up to 4 months at least when stored in a buffer solution at pH 9 at 4°C. The MUA-modified GNRs with an aspect ratio of 3.9 were furthered developed as a solution-phase-based label-free LSPR biosensor by functionalizing the GNRs with human IgG. A detection limit as low as 0.4 nM for detecting anti-human IgG was achieved by this sensor. The achievements of this work are concluded and the directions of future work are also pointed out.
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Matcheswala, Akil Mannan. "GOLD NANOSPHERES AND GOLD NANORODS AS LOCALIZED SURFACE PLASMON RESONANCE SENSORS." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/60.
Full textAbstract:
A novel localized surface plasmon resonance (LSPR) sensor that differentiates between background refractive index changes and surface-binding of a target analyte (e.g. a target molecule, protein, or bacterium) is presented. Standard, single channel LSPR sensors cannot differentiate these two effects as their design allows only one mode to be coupled. This novel technique uses two surface plasmon modes to simultaneously measure surface binding and solution refractive index changes. This increases the sensitivity of the sensor.
Different channels or modes can be created in sensors with the introduction of gold nanospheres or gold nanorods that act as receptor mechanisms. Once immobilization was achieved on gold nanospheres, the technique was optimized to achieve the same immobilization for gold nanorods to get the expected dual mode spectrum. Intricate fabrication methods are illustrated with using chemically terminated self assembled monolayers. Then the fabrication process advances from chemically silanized nanoparticles, on to specific and systematic patterns generated with the use of Electron Beam Lithography.
Comparisons are made within the different methods used, and guidelines are set to create possible room for improvement. Some methods implemented failed, but there was a lot to learn from these unsuccessful outcomes. Finally, the applications of the dual mode sensor are introduced, and current venues where the sensors can be used in chemical and biological settings are discussed.
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Liu, Chang. "Localized Surface Plasmon Resonance Biosensors for Real-Time Biomolecular Binding Study." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/837.
Full textAbstract:
Surface Plasmon Resonance (SPR) and localized surface plasmon resonance (LSPR) biosensors have brought a revolutionary change to in vitro study of biological and biochemical processes due to its ability to measure extremely small changes in surface refractive index (RI), binding equilibrium and kinetics. Strategies based on LSPR have been employed to enhance the sensitivity for a variety of applications, such as diagnosis of diseases, environmental analysis, food safety, and chemical threat detection. In LSPR spectroscopy, absorption and scattering of light are greatly enhanced at frequencies that excite the LSPR, resulting in a characteristic extinction spectrum that depends on the RI of the surrounding medium. Compositional and conformational change within the surrounding medium near the sensing surface could therefore be detected as shifts in the extinction spectrum.
This dissertation specifically focuses on the development and evaluation of highly sensitive LSPR biosensors for in situ study of biomolecular binding process by incorporating nanotechnology. Compared to traditional methods for biomolecular binding studies, LSPR-based biosensors offer real-time, label free detection. First, we modified the gold sensing surface of LSPR-based biosensors using nanomaterials such as gold nanoparticles (AuNPs) and polymer to enhance surface absorption and sensitivity. The performance of this type of biosensors was evaluated on the application of small heavy metal molecule binding affinity study. This biosensor exhibited ~7 fold sensitivity enhancement and binding kinetics measurement capability comparing to traditional biosensors. Second, a miniaturized cell culture system was integrated into the LSPR-based biosensor system for the purpose of real-time biomarker signaling pathway studies and drug efficacy studies with living cells. To the best of our knowledge, this is the first LSPR-based sensing platform with the capability of living cell studies. We demonstrated the living cell measurement ability by studying the VEGF signaling pathway in living SKOV-3 cells. Results have shown that the VEGF secretion level from SKOV-3 cells is 0.0137 ± 0.0012 pg per cell. Moreover, we have demonstrated bevacizumab drug regulation to the VEGF signaling pathway using this biosensor. This sensing platform could potentially help studying biomolecular binding kinetics which elucidates the underlying mechanisms of biotransportation and drug delivery.
11
Wolf, Andreas [Verfasser]. "Tuning the localized surface plasmon resonance in copper chalcogenide nanoparticles / Andreas Wolf." Hannover : Technische Informationsbibliothek (TIB), 2016. http://d-nb.info/1127548689/34.
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Scheffler, Christopher M. "Localized Photoemission in Triangular Gold Antennas." Thesis, Portland State University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13808008.
Full textAbstract:
With the development of ultra-fast laser technology, several new imaging techniques have pushed optical resolution past the diffraction limit for traditional light-based optics. Advancements in lithography have enabled the straightforward creation of micron- and nanometer-sized optical devices. Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Varying the materials or geometry of the structures, the plasmonic response can be tailored for a wide range of applications.
Photoemission electron microscopy (PEEM) has been used to image excitations in micron-sized plasmonic devices. With PEEM, optical responses can be characterized in detail, aiding in the development of new types of plasmonic structures and their applications. We show here that in thin, triangular gold platelets SPPs can be excited and concentrated within specific regions of the material (thickness ~50 nm); resulting in localized photoemission in areas of high electric field intensity. In this regard, the platelets behave as receiver antennas by converting the incident light into localized excitations in specific regions of the gold platelets. The excited areas can be significantly smaller than the wavelength of the incident light (λ ≤ 1 µm). By varying the wavelength of the light, the brightness of the excited spots can be changed and by varying the polarization of the light, the brightness and position can be changed, effectively switching the photoemission on or off for a specific region within the triangular gold structure.
In this work, the spatial distribution of surface plasmons and the imaging results from photoemission electron microscopy are reproduced in simulation using finite element analysis (FEA). In addition, we show that electromagnetic theory and simulation enable a detailed and quantitative analysis of the excited SPP modes, an explanation of the overall optical responses seen in PEEM images, and prediction of new results.
13
Chegel, V. I., A. M. Lopatynskyi, V. K. Lytvyn, V. I. Nazarenko, J. L. Guo, and B. D. Lucas. "Preparation of Au Nanostructure Arrays for Fluorometry and Biosensors Applications." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34962.
Full textAbstract:
The paper describes the fabrication of random and ordered gold nanostructure arrays (NSA) of different
morphology using island film thermal annealing and nanoimprint lithography techniques. Structural
parameters of obtained NSA were investigated using atomic force microscopy method. Spectral characteristics
of obtained NSA were studied in air atmosphere, and NSA light extinction spectra exhibited an expressed
plasmon peak. Spectral position of localized surface plasmon resonance can be tuned depending on
geometrical parameters of nanostructures, which is an important factor for resonant investigation methods
of various types of molecular structures. Proposed technological approaches can be used to implement the
resonance fluorometry in electromagnetic field of nanostructures (surface-enhanced fluorescence) method
and in chemical and biosensors based on localized surface plasmon resonance.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34962
14
Humphrey, Alastair Dalziell. "Exploration of how light interacts with arrays of plasmonic, metallic nanoparticles." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/19365.
Full textAbstract:
The content of this thesis is based upon the interaction of light with metallic nanoparticles arranged in different array geometries. An incident electric field (light) can force the conduction electrons of a metallic nanoparticle to oscillate. At particular frequencies, in the optical regime for gold and silver particles, absorption and scattering of the light by the particle is enhanced, corresponding to the particle plasmon resonance. The spectral position and width of the particle plasmon resonance of an isolated single particle may be tuned by adjusting its size and shape, thus changing the surface charge distribution. Periodic arrays of particles offer additional control over the frequency and width of the resonance attributed to the re-radiating (scattering) property of plasmonic particles. By fabricating arrays with a pitch comparable to the wavelength of an isolated single particle plasmon resonance, a coherent interaction between particles may be produced, known as surface lattice resonances (SLRs). The electromagnetic coupling between in-plane particle plasmon modes for different particle array geometries is explored through experiment and theory. Firstly, SLRs in square, hexagonal and honeycomb arrays are investigated by normal-incidence extinction measurements and compared to a simple-coupled dipole model. Secondly, to verify the nature of the coupling between the scattered electric field associated with particle resonances, the incident electric field polarization-dependence of the extinction of rectangular arrays and chains is studied. Thirdly, the optical response of square arrays with a symmetric two-particle basis is investigated, particularly the retardation of the scattered electric field between particles in a pair. Fourthly, square arrays with an asymmetric two-particle basis are fabricated to explore the symmetric (dipole moments of both particles are parallel) and anti-symmetric (dipole moment of both particles anti-parallel) SLRs, excited by normal-incidence light.
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Unser, Sarah A. "Improving the Sensitivity and Selectivity of Localized Surface Plasmon Resonance Biosensors Toward Novel Point-of-Care Diagnostics." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1561997005551383.
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Chen, Chao. "Visible light photocatalysts for synthesis of fine organic chemicals on supported nanostructures." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/66437/1/Chao_Chen_Thesis.pdf.
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This thesis is focus on developing new photocatalysts for synthesis of fine organic chemicals on supported nanostructures. These photocatalysts can facilitate reactions by using visible light, moderate temperature and atmospheric pressure which is suitable for a sustainable, green and eco-friendly modern chemical industry. Both Semiconductor Photocatalyst and Noble Metal Photocatalysts are designed to facilitate the homocouplings reaction of imine generation by amines.
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Yeshchenko, O. A., I. S. Bondarchuk, S. Z. Malynych, G. Chumanov, and I. Luzinov. "Laser-Induced Light Absorption in 2D Silver Nanoparticle Array." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42550.
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Nanocomposite comprising planar array of silver nanoparticles in polymer matrix was submitted to Ar laser irradiation at the wavelength of 488 nm. The extinction spectra of the array were measured as a function of the irradiation power density. Two collective surface plasmon modes, namely T and P, associated with particle dipoles parallel and perpendicular to the plane of the layer were identified. The extinction bands of T and P modes exhibit blue spectral shift with the increase of radiation power. P mode band
broadens when laser power increases. The observed effects are explained by heating of the nanocomposite by the intense laser radiation.
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Samaimongkol, Panupon. "Surface plasmon resonance study of the purple gold (AuAl2) intermetallic, pH-responsive fluorescence gold nanoparticles, and gold nanosphere assembly." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96549.
Full textAbstract:
In this dissertation, I have verified that the striking purple color of the intermetallic compound
AuAl2, also known as purple gold, originates from surface plasmons (SPs). This contrasts to a
previous assumption that this color is due to an interband absorption transition. The existence of
SPs was demonstrated by launching them in thin AuAl2 films in the Kretschmann configuration,
which enables us to measure the SP dispersion relation. I observed that the SP energy in thin films of purple gold is around 2.1 eV, comparable to previous work on the dielectric function of this
material. Furthermore, SP sensing using AuAl2 also shows the ability to measure the change in the refractive index of standard sucrose solution. AuAl2 in nanoparticle form is also discussed in terms of plasmonic applications, where Mie scattering theory predicts that the particle bears nearly
uniform absorption over the entire visible spectrum with an order magnitude higher than a lightabsorbing carbonaceous particle. The second topic of this dissertation focuses on plasmon enhanced fluorescence in gold nanoparticles (Au NPs). Here, I investigated the distance-dependent fluorescence emission of rhodamine green 110 fluorophores from Au NPs with tunable spacers. These spacers consist of polyelectrolyte multilayers (PEMs) consisting of poly(allylamine
hydrochloride) and poly(styrene sulfonate) assembled at pH 8.4. The distance between Au NPs and fluorophores was varied by changing the ambient pH from 3 to 10 and back, which causes the
swelling and deswelling of PEM spacer. Maximum fluorescence intensity with 4.0-fold enhancement was observed with 7-layer coated Au NPs at ambient pH 10 referenced to pH 3. The last topic of this dissertation examines a novel approach to assemble nanoparticles, in particular, dimers of gold nanospheres (NSs). 16 nm and 60 nm diameter NSs were connected using
photocleavable molecules as linkers. I showed that the orientation of the dimers can be controlled
with the polarization of UV illumination that cleaves the linkers, making dipolar patches. This type
of assembly provides a simple method with potential applications in multiple contexts, such as
biomedicine and nanorobotics.PHD
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Hajebifard, Akram. "Plasmonic Nano-Resonators and Fano Resonances for Sensing Applications." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41616.
Full textAbstract:
Different types of plasmonic nanostructures are proposed and examined experimentally and theoretically, with a view towards sensing applications. First, a self-assembly approach was developed to create arrays of well-ordered glass-supported gold nanoparticles (AuNPs) with controllable particle size and inter-particle spacing. Then, a periodic array of gold nano-disks (AuNDs) supported by a Bragg reflector was proposed and examined in a search for Fano resonances in its optical response. Arrays of heptamer-arranged nanoholes (HNH) in a thin gold film were also proposed and explored theoretically and experimentally, revealing a very rich spectrum of resonances, several exhibiting a Fano lineshape.
A commercial implementation of the vectorial finite element method (FEM) was used to model our plasmonic structures. Taking advantage of the periodic nature of the structures, a unit cell containing a single element was modelled. The transmittance, reflectance or absorbance spectra were computed, and the associated electromagnetic fields were obtained by solving the vector wave equations for the electromagnetic field vectors throughout the structures, subject to the applicable boundary conditions, and the applied source fields. The sensing performance of the structures, based on the bulk sensitivity, surface sensitivity and figure of merit (FOM) was calculated.
First, a novel bottom-up fabrication approach was applied (by our collaborators) to form a periodic array of AuNPs with controllable size over large areas on SiO2 substrates. In this method, self-assembly of block copolymer micelles loaded with metal precursors was combined with a seeding growth route to create ordered AuNPs of desired size. It was shown that this new fabrication method offers a new approach to tune the AuNP size and edge-to-edge inter-particle spacing while preserving the AuNP ordering. The optical characteristics of the AuNP arrays, such as their size, interparticle spacing, localized surface plasmon resonance (LSPR) wavelength, and bulk sensitivity, were examined, numerically and experimentally. This proposed novel fabrication method is applicable for low-cost mass-production of large-area arrays of high-quality AuNPs on a substrate for sensing applications.
Then, we proposed and examined the formation of Fano resonances in a plasmonic-dielectric system consisting of uncoupled gold nano-disk (AuND) arrays on a quarter-wave dielectric stack. The mechanism behind the creation of Fano resonances was explained based on the coherent interference between the reflection of the Bragg stack and the LSPPs of the AuNDs. Fano parameters were obtained by fitting the computational data to the Fano formula. The bulk sensitivities and figure of merit of the Fano resonances were calculated. This plasmonic structure supports Fano resonances with a linewidth around 9 nm which is much narrower than the individual AuND LSPP bandwidth ( 80 nm) and the Bragg stack bandwidth ( 100 nm). Supporting Fano resonances with such a narrow linewidth, the structure has a great potential to be used for sensing applications. Also, this metallic-dielectric nanostructure requires no near-field coupling between AuNDs to generate the Fano resonances. So, the AuNDs can be located far enough from each other to simplify the potential fabrication process.
The optical properties of HNH arrays on an SiO2 substrate were investigated, numerically and experimentally. Helium focused ion beam (HeFIB) milling was applied (by Dr. Choloong Hahn) to fabricate well-ordered and well-defined arrays of HNHs. Transmittance spectra of the structures were obtained as the optical response, which exhibits several Fano resonances. Then, the mechanism behind the formation of the Fano resonances was explained, and the sensing performance of the structure was inspected by measuring the bulk sensitivities. This array of nanohole cluster is exciting because it supports propagating SPPs and LSPPs, and also Wood’s anomaly waves, which makes the optical response very rich in excitations and spectral features. Also, as a periodic array of sub-wavelength metallic nanoholes, the system produces extraordinary optical transmission - highly enhanced transmission through (otherwise) opaque metallic films at specific wavelengths, facilitating measurement acquisition in transmission.
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Liu, Zhe. "New supported metal photocatalysts for synthesis of fine organic chemicals driven by visible light." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/95889/1/Zhe%20Liu%20Thesis.pdf.
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This project is to develop a series of new photocatalyst for fine organic synthesis in irradiation of visible light under mild conditions. To achieve this goal, the detailed study of photocatalytic properties of plasmonic metal nanoparticles supported on zirconium dioxide was carried out, including the catalyst synthesis, characterization and application in redox reactions with high activity. The discovery of these new plasmonic metal nanoparticle photocatalyst may inspire further studies on other efficient photocatalysts and enhance the potential to utilize sunlight via a controlled and environmentally friendly process.
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Marchesini, Matteo. "Plasmon decay dynamics in hybrid metal/doped-semiconductor nanostructures." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23223/.
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The study of interactions between plasmonic nanomaterials and dielectrics is a thriving field of research, which in recent years proved that such nanostructures can be applied in a wide range of applications, from sensing to catalysts. These are all based on the nanoscale surface interactions happening between the nanomaterials and their surrounding environment. In this thesis, the possible interaction between plasmonic nanoparticles and the V doping states in the Anatase (TiO_2) bandgap, rather than in their undoped counterpart, is studied. The aim is to better understand the dynamics of these phenomena, and obtaining insights on the V states position in the TiO_2 bandgap. The work done encompasses all the steps needed to achieve the experimental results: from the preparation and characterisation of the samples, to the simulations of the phenomena involved, until the actual measurements of their optical properties and the discussion of the results. The findings achieved are not decisive in explaining the dynamics involved, but preliminary interpretations could be formulated. Moreover, the specific investigations displayed in this thesis have never been done before in literature, and the work performed might be used in the future as a starting point for more thorough and deep studies of these phenomena.
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Sheremet, E., A. G. Milekhin, R. D. Rodriguez, T. Weiss, M. Nesterov, E. E. Rodyakina, O. D. Gordan, et al. "Surface- and tip-enhanced resonant Raman scattering from CdSe nanocrystals." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-161500.
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Surface- and tip-enhanced resonant Raman scattering (resonant SERS and TERS) by optical phonons in a monolayer of CdSe quantum dots (QDs) is demonstrated. The SERS enhancement was achieved by employing plasmonically active substrates consisting of gold arrays with varying nanocluster diameters prepared by electron-beam lithography. The magnitude of the SERS enhancement depends on the localized surface plasmon resonance (LSPR) energy, which is determined by the structural parameters. The LSPR positions as a function of nanocluster diameter were experimentally determined from spectroscopic micro-ellipsometry, and compared to numerical simulations showing good qualitative agreement. The monolayer of CdSe QDs was deposited by the Langmuir–Blodgett-based technique on the SERS substrates. By tuning the excitation energy close to the band gap of the CdSe QDs and to the LSPR energy, resonant SERS by longitudinal optical (LO) phonons of CdSe QDs was realized. A SERS enhancement factor of 2 × 103 was achieved. This allowed the detection of higher order LO modes of CdSe QDs, evidencing the high crystalline quality of QDs. The dependence of LO phonon mode intensity on the size of Au nanoclusters reveals a resonant character, suggesting that the electromagnetic mechanism of the SERS enhancement is dominant. Finally, the resonant TERS spectrum from CdSe QDs was obtained using electrochemically etched gold tips providing an enhancement on the order of 104. This is an important step towards the detection of the phonon spectrum from a single QDDieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Mann, Daniel [Verfasser], Martin [Akademischer Betreuer] Möller, and Regina [Akademischer Betreuer] Palkovits. "Design, synthesis and characterization of Au and Ag nanoshells and Au semishells with tunable localized surface plasmon resonance / Daniel Mann ; Martin Möller, Regina Palkovits." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1181193184/34.
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Mann, Daniel Verfasser], Martin [Akademischer Betreuer] [Möller, and Regina [Akademischer Betreuer] Palkovits. "Design, synthesis and characterization of Au and Ag nanoshells and Au semishells with tunable localized surface plasmon resonance / Daniel Mann ; Martin Möller, Regina Palkovits." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1181193184/34.
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Chen, Lihui. "Synthesis and Plasmonic Properties of Copper-based Nanocrystals." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/217134.
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Dorney, Kevin Michael. "A Chemical Free Approach for Increasing the Biochemical Surface-Enhanced Raman Spectroscopy (SERS)-Based Sensing Capabilities of Colloidal Silver Nanoparticles." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401206511.
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Huda, Gazi Mostafa. "EFFECT OF A SILICON TIP ON ABSORPTION CROSS SECTION, FIELD ENHANCEMENT, AND LOCALIZED SURFACE PLASMON RESONANCE OF DIFFERENT SIZED GOLD NANOPARTICLES UNDER EVANESCENT WAVE ILLUMINATION." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/114.
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We have numerically investigated the influence of a nanoscale silicon tip in proximity to an illuminated gold nanoparticle. We describe how the position of the high-permittivity tip and the size of a nanoparticle impact the absorption, peak electric field and surface plasmon resonance wavelength under different illumination conditions. We detail the finite element method (FEM) approach we have used for this, whereby we specify a volume excitation field analytically and calculate the difference between this source field and the total field (i.e., scattered-field formulation). We show that a nanoscale tip can locally enhance the absorption of the particle as well as the peak electric field at length scales far smaller than the wavelength of the incident light.
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Chen, Kai. "Self-organization on Nanoparticle Surfaces for Plasmonic and Nonlinear Optical Applications." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/30111.
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This dissertation is about fabrication and functionalization of metal nanoparticles for use in plasmonic and nonlinear optical (NLO) applications. In the first two chapters, I describe a series of experiments, where I combined silver nanoparticles fabricated by nanosphere lithography with ionic self-assembled multilayer (ISAM) films, tuning the geometry of the particles to make their plasmonic resonances overlap with the frequency of optical excitation. The designed hybrid metallic/organic nanostructures exhibited large enhancements of the efficiency of second harmonic generation (SHG) compared to conventional ISAM films, causing a modified film with just 3 bilayers to be optically equivalent to a conventional 700-1000 bilayer film.
SHG responses from Ag nanoparticle-decorated hybrid-covalent ISAM (HCISAM) films were investigated as the next logical step towards high-Ï ²⁺ ISAM films. I found that the plasmonic enhancement primarily stems from interface SHG. Interface effects were characterized by direct comparison of SHG signals from PAH/PCBS ISAM films and PAH/PB HCISAM films. Though interface &chi²⁺ is substantially smaller in PAH/PCBS than in PAH/PB, plasmonically enhanced PAH/PCBS films exhibit stronger NLO response. I propose that the structure of PAH/PB film makes its interface more susceptible to disruptions in the nanoparticle deposition process, which explains our observations.
During the fabrication of monolayer crystals for nanosphere lithography, I developed a variation of the technique of convective self-assembly, where the drying meniscus is restricted by a straight-edge located approximately 100 μM above the substrate adjacent to the drying zone. This technique can yield colloidal crystals at roughly twice the growth rate compared to the standard technique. I attribute this to different evaporation rates in the thin wet films in the two cases. I also found that the crystal growth rate depends strongly on the ambient relative humidity.
Finally, dithiocarbamate (DTC)-grafted polymers were synthesized and employed to functionalize surfaces of Au nanopartciles. PAH-DTC shows greater stability in different environments than PEI-DTC. I also investigated the stability of PAH-DTC coated particles in suspensions with UV-Vis spectroscopy and autotitration. The covalently bonded PAH-DTC enhances the colloidal stability of the Au nanoparticles and enables subsequent ISAM film deposition onto the particles.Ph. D.
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Schenström, Karl. "Biofunctionalization of a Fiber Optics-Based LSPR Sensor." Thesis, Linköpings universitet, Molekylär fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-125726.
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When exposed to light, metal nanoparticles exhibit a phenomenon known as LSPR, Localized Surface Plasmon Resonance. The wavelengths at which LSPR occurs is very dependent on the refractive index of the surrounding medium. Binding of biomolecules to the surface of gold nanoparticles result in a change in the refractive index that can be detected spectrophotometrically by monitoring the LSPR peak shift. When functionalized with the corresponding ligand(s), gold nanoparticles can be utilized in biosensors to detect the presence and concentration of a predetermined analyte. However, the system must exhibit high specificity and give rise to a detectable shift for analytes in the desired concentration range to be of commercial interest. The aim of the diploma project was to investigate and optimize the biofunctionalization and performance of a fiber optics based LSPR biosensor. Three ligand systems were investigated for detection of antibodies (IgG), insulin and avidin. Binding of the analyte to the ligand caused a shift of a few nanometers when using spherical gold nanoparticles. The shifts were significantly larger when using gold nanorods. When using the IgG and insulin ligands, only minor unspecific binding was observed. The setup thus shows great potential for use in a wide range of sensing applications.
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Wang, Fan. "Visible light photocatalysis with supported metal nanoparticles for organic synthesis." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/103567/1/Fan_Wang_Thesis.pdf.
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This project was a step forward in developing new effective photocatalysts for fine organic synthesis under visible light irradiation. These kind of new photocatalysts are able to facilitate reaction rates by using visible light under moderate reaction conditions through a green, economical and environmentally friendly pathway. This thesis investigated the catalyst synthesis, characterization and the application in organic reactions with high activity and selectivity. The discovery of these new metal nanoparticle photocatalysts may inspire further studies on other efficient photocatalysts and enhance the potential to utilize sunlight via a controlled and environmentally friendly process.
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Zhao, Jian. "Supported gold nanoparticles as photocatalysts utilising the full solar spectrum for organic synthesis." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63703/2/Jian_Zhao_Thesis.pdf.
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This thesis is an innovative study for organic synthesis using supported gold nanoparticles as photocatalysts under visible light irradiation. It especially examines a novel green process for efficient hydroamination of alkynes with amines. The investigation of other traditional reduction and oxidation reactions also adds significantly to the knowledge of gold nanoparticles and titania nanofibres as photocatalysts for organic synthesis.
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Geng, Xi. "Bioenabled Synthesis of Anisotropic Gold and Silver Nanoparticles." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/86274.
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Anisotropic plasmonic noble metallic nanoparticles (APMNs) have received enormous attention due to their distinct geometric features and fascinating physicochemical properties. Owing in large part to their tailored localized surface plasmon resonance (LSPR) and the intensive electromagnetic field at the sharp corners and edges, APMNs are exceptionally well suited for biomedical applications such as biosensing, bioimaging, diagnostics and therapeutics. Although a rich variety of surfactant-assisted colloidal routes have been developed to prepare well-defined APMNs, biomedical applications necessitate tedious and rigorous purification processes for the complete removal of toxic surfactants. In this dissertation, we aim to develop generic bioenabled green synthetic methodologies towards APMNs. By applying a series of thermodynamic, kinetic and seed quality control, a series of APMNs with varied morphologies such as branched nanostars and triangular nanoprisms have been successfully prepared.
We first presented the preparation of gold nanostars (Au NSTs) through a two-step approach utilizing a common Good's buffer, HEPES, as a weak reducing agent. Single crystalline Au NSTs with tunable branches up to 30 nm in length were produced and the halide ions rather than the ionic strength played a significant roles on the length of the branches of Au NSTs. Then consensus sequence tetratricopetide repeat (CTPR) proteins with increasing number of repeats were used as model proteins to probe the effects of concentration as well as the protein shape on the morphology and resulting physicochemical properties of plasmonic gold nanoparticles.
Since the underlying growth mechanism for the biomimetic synthesis of APMNs remains elusive and controversial, the other objective is to elucidate the molecular interactions between inorganic species and biopolymers during the course of NP evolution. Fluorescent quenching and 2D NMR experiments have confirmed the moderate binding affinity of CTPR to the Au(0) and Au(III). We observed that the initial complexation step between gold ions and CTPR3 is ionic strength dependent. Furthermore, we also found that NPs preferentially interact with the negatively charged face of CTPR3 as observed in 2D NMR. Knowledge of binding behavior between biospecies and metal ions/NPs will facilitate rational deign of proteins for biomimetic synthesis of metallic NPs.
A modified seed-mediated synthetic strategy was also developed for the growth of silver nanoprisms with low shape polydispersity, narrow size distribution and tailored plasmonic absorbance. During the seed nucleation step, CTPR proteins are utilized as potent stabilizers to facilitate the formation of planar-twinned Ag seeds. Ag nanoprisms were produced in high yield in a growth solution containing ascorbic acid and CTPR-stabilized Ag seeds. From the time-course UV-Vis and transmission electron microscopy (TEM) studies, we postulate that the growth mechanism is the combination of facet selective lateral growth and thermodynamically driven Ostwald ripening.
By incorporation of seeded growth and biomimetic synthesis, gold nanotriangles (Au NTs) with tunable edge length were synthesized via a green chemical route in the presence of the designed CTPR protein, halide anions (Br⁻) and CTPR-stabilized Ag seeds. The well-defined morphologies, tailored plasmonic absorbance from visible-light to the near infrared (NIR) region, colloidal stability and biocompatibility are attributed to the synergistic action of CTPR, halide ions, and CTPR-stabilized Ag seeds.
We also ascertained that a vast array of biosustainable materials including negatively charged lignin and cellulose derivatives can serve as both a potent stabilizers and an efficient nanocrystal modifiers to regulate the growth of well-defined Ag nanoprisms using a one-pot or seeded growth strategy. The influential effects of reactants and additives including the concentration of sodium lignosulfonate, H2O2 and NaBH4 were studied in great detail. It implies that appropriate physicochemical properties rather than the specific binding sequence of biomaterials are critical for the shaped-controlled growth of Ag NTs and new synthetic paradigms could be proposed based on these findings.
Last but not the least, we have demonstrated the resulting APMNs, particularly, Au NSTs and Ag NTs exhibit remarkable colloidal stability, enhanced SERS performance, making them promising materials for biosensing and photothermal therapy. Since the Ag nanoprisms are susceptible to morphological deformation in the presence of strong oxidant, they also hold great potential for the colorimetric sensing of oxidative metal cation species such as Fe3+, Cr3+, etc.Ph. D.
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Geist, Brian Lee. "Properties of Nanoscale Biomaterials for Cancer Detection and Other Applications." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/27630.
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The first thermal cycling experiments of ionic self-assembled multilayer (ISAM) films have been reported examining their survivability through repeated thermal cycles from -20° C to 120° C in ambient atmospheric conditions. The films were constructed from alternating layers of Nile Blue A and gold nanoparticles which provided a strong absorbance in the optical wavelength range. No degradation of the optical characteristics of the ISAM films was observed [1]. Techniques for measuring the capacitance and resistivity of various ISAM films have also been developed allowing for a more complete electrical characterization of ISAM films. Capacitance measurements enabled a calculation of the dielectric function and breakdown field strength of the ISAM films. The capacitance measurement technique was verified by measuring the dielectric function of a spin-coated thin film PMMA, which has a well characterized dielectric function [2]. Surface-enhanced Raman spectroscopy (SERS) has been studied as a possible detection method for malignant melanoma revealing spectral differences in blood sera from healthy horses and horses with malignant melanoma. A SERS microscope system was constructed with the capability of resolving the Raman signal from biologically important molecules such as beta-carotene and blood sera. The resulting Raman signals from sera collected from horses with malignant melanoma were found to have additional peaks not found in the Raman signals obtained from sera collected from healthy horses. A systematic analysis of the combination of absorbance and fluorescence signals of blood sera collected from populations of healthy dogs and dogs with cancer has resulted in a rapid and cost-effective method for monitoring protein concentrations that could possibly be used as part of a cancer screening process. This method was developed using the absorbance and fluorescence signals from known serum proteins, the combinations of which were used to match the absorbance and fluorescence signals of blood sera allowing for an accurate determination of protein concentrations in blood sera [3]. Finally, a novel method for measuring the melting point of DNA in solution using capacitance measurements is presented. This method allows for the determination of the melting temperature as well as the melting entropy and melting enthalpy of DNA strands. Two different short strands of DNA, 5'-CAAAATAGACGCTTACGCAACGAAAAC-3' along with its complement and 5'-GGAAGAGACGGAGGA-3' along with its complement were used to validate the technique as the characteristics of these strands could be modeled using theoretical methods. This experimental technique allows for the precise determination of the melting characteristics of DNA strands and can be used to evaluate the usefulness of theoretical models in calculating the melting point for particular strands of DNA. Additionally, a micro-fluidic device has been proposed that will allow for a rapid and cost-effective determination of the melting characteristics of DNA [4].Ph. D.
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Riboni, F. "PHOTOCATALYTIC REACTIONS FOR ENERGY CONVERSION." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/244319.
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General upward trends in fossil fuel consumption and CO2 emissions, along with the accepted belief that global chemistry substantially influences climate, require that scientific research provides efficient remedies and/or alternatives to the present scenario. Photocatalysis is often proposed as one of the most promising technique to achieve these purposes.
This PhD thesis is mainly focused on the investigation of TiO2-based systems for the photocatalytic oxidation of formic acid in aqueous suspension, as well as for H2 production by methanol photo steam reforming in the gas phase. Two different approaches were adopted to minimize the drawbacks usually characterizing TiO2 photocatalysts: i) TiO2-WO3 mixed oxide photocatalysts were prepared with the aim of reducing the recombination rate of photopromoted electron/hole pairs. The superior photocatalytic performance of the mixed oxide system was mainly attributed to the positive effect induced by W in efficiently trapping the photopromoted electron from the conduction band of TiO2, ensuring extended charge carriers separation. Even better results were obtained upon the surface modification with Pt nanoparticles which, by virtue of the metal high work function, further enhanced e-/h+ separation. ii) surface modification of TiO2 with Au nanoparticles, possessing a Localized Surface Plasmon Resonance (LSPR) at λ = 530 nm was proved to be an efficient way to promote TiO2 photoactivity under visible light irradiation. By selecting three titania samples (i.e., a stoichiometric, nearly non defective TiO2, a N-doped TiO2 and a oxygen vacancy-rich TiO2), evidence of two different plasmonic photoactivity mechanisms was provided, with the so-called hot electron transfer promoting plasmonic photoactivity in the stoichiometric TiO2 and Plasmon Resonance Energy Transfer accounting for the observed plasmonic visible light photoactivity of doped samples.
Being the abatement of CO2 through (photo)electrochemical reduction very challenging (E0(CO2/CO2-* = -2.14 V)), an alternative way has been studied: pyridinyl radicals (1-PyH*), photogenerated by irradiating a pyridine (Py) solution, were found to efficiently react with CO2 yielding a carbamic species (HPy-1-COOH), triggered by a stepwise mechanism where electron transfer from 1-PyH* precedes proton transfer. Formate (HCOO-) was also obtained, demonstrating that photoexcited pyridine does catalyze the 2e—reduction of CO2.
Finally, Fenton oxidation of gaseous isoprene on the surface of aqueous Fe2+ droplets, yielding carboxylic acids, polyols and carbonyl compounds, detected in situ through ElectroSpray Ionization Mass Spectrometry, accounted for alternative routes for the conversion of organic gases into secondary organic aerosol, occurring under tropospheric conditions, and may be incorporated into present atmospheric chemistry models.
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Danilov, Artem. "Design, characterisation and biosensing applications of nanoperiodic plasmonic metamaterials." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0110/document.
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Cette thèse considère de nouvelles architectures prometteuses des métamatériaux plasmoniques pour biosensing, comprenant: (I) des réseaux périodiques 2D de nanoparticules d'Au, qui peuvent supporter des résonances des réseaux de surface couplées de manière diffractive; (II) Reseaux 3D à base de cristaux plasmoniques du type d'assemblage de bois. Une étude systématique des conditions d'excitation plasmonique, des propriétés et de la sensibilité à l'environnement local dans ces géométries métamatérielles est présentée. On montre que de tels réseaux peuvent combiner une très haute sensibilité spectrale (400 nm / RIU et 2600 nm / RIU, ensemble respectivement) et une sensibilité de phase exceptionnellement élevée (> 105 deg./RIU) et peuvent être utilisés pour améliorer l'état actuel de la technologie de biosensing the-art. Enfin, on propose une méthode de sondage du champ électrique excité par des nanostructures plasmoniques (nanoparticules uniques, dimères). On suppose que cette méthode aidera à concevoir des structures pour SERS (La spectroscopie du type Raman à surface renforcée), qui peut être utilisée comme une chaîne d'information supplémentaire à un biocapteur de transduction optiqueThis thesis consideres novel promissing architechtures of plasmonic metamaterial for biosensing, including: (I) 2D periodic arrays of Au nanoparticles, which can support diffractively coupled surface lattice resonances; (II) 3D periodic arrays based on woodpile-assembly plasmonic crystals, which can support novel delocalized plasmonic modes over 3D structure. A systematic study of conditions of plasmon excitation, properties and sensitivity to local environment is presented. It is shown that such arrays can combine very high spectral sensitivity (400nm/RIU and 2600 nm/RIU, respectively) and exceptionally high phase sensitivity (> 105 deg./RIU) and can be used for the improvement of current state-of-the-art biosensing technology. Finally, a method for probing electric field excited by plasmonic nanostructures (single nanoparticles, dimers) is proposed. It is implied that this method will help to design structures for SERS, which will later be used as an additional informational channel for biosensing
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Chamtouri, Maha. "Etude exhaustive de la sensibilité des Biopuces plasmoniques structurées intégrant un réseau rectangulaire 1D : effet de la transition des plasmons localisés vers les plasmons propagatifs." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112060/document.
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Malgré leurs contribution dans plusieurs domaines, les biopuces à lecture plasmonique conventionnelles basées sur l'utilisation d’un film métallique plan d'or, sont limitées en terme de sensibilité surtout quand il s'agit de détecter des molécules de faible masse molaire à l’état de trace.Dans ce cadre, nous étudions numériquement et expérimentalement le potentiel de détection d’interactions biomoléculaires d’une nouvelle génération de biopuces à lecture plasmonique intégrant un film métallique micro-nano-structurée en réseau rectangulaire 1D. L’étude numérique développée met en œuvre une méthode hybride, basée sur la combinaison de deux méthodes classiques : la méthode des éléments finis et la méthode modale de Fourier. Grâce à ce nouvel outil numérique, nous présentons une cartographie exhaustive du potentiel de détection d’une couche biologique, en variant les paramètres de la structuration liés aux dimensions du réseau. La réponse de la biopuce à l’accrochage de biomolécules est ensuite interprétée théoriquement par les différents phénomènes plasmoniques notamment les «points chauds» et les bandes plasmoniques interdites. Nos calculs soulignent l'importance de l’exploitation du confinement de la lumière à travers la structuration sub-longueur d’onde des surfaces plasmoniques. Ceci permet non seulement d’optimiser les paramètres géométriques afin d’améliorer la sensibilité vis-à-vis de la réponse d’une biopuce conventionnelle, mais aussi de mettre en évidence la transition entre le régime où les plasmons propagatifs dominent et le régime où les plasmons localisés dominent. De nouvelles figures de mérite sont introduites pour évaluer les performances des biopuces structurées.Cette étude montre également que de nouvelles opportunités pour améliorer davantage la bio-sensibilité sont offertes, si la localisation de biomolécules peut être effectuée dans les régions où le champ électrique est amplifié et confinéSurface plasmons resonance imaging with continuous thin metallic films have become a central tool for the study of biomolecular interactions. However, in order to extend the field of applications of surface plasmons resonance systems to the trace detection of biomolecules having low molecular weight, a change in the plasmonic sensing methodology is needed. In this study, we investigate theoretically and experimentally the sensing potential of 2D nano- and micro- ribbon grating structuration on the surface of Kretschmann-based surface plasmon resonance biosensors when they are used for detection of biomolecular binding events. Numerical simulations were carried out by employing a fast and novel model based on the hybridization of two classical methods, the Fourier Modal Method and the Finite Element Method. Our calculations confirm the importance of light manipulation by means of structuration of the plasmonic thin film surfaces on the nano- and micro- scales. Not only does it highlight the geometric parameters that allow the sensitivity enhancement, and associated figures of merit, compared with the response of the conventional surface plasmon resonance biosensor based on a flat surface, but it also describes the transition from the regime where the propagating surface plasmon mode dominates to the regime where the localized surface plasmon mode dominates. An exhaustive mapping of the biosensing potential of the nano- and micro- structured biosensors surface is presented, varying the structural parameters related to the ribbon grating dimensions. New figures of merit are introduced to evaluate the performance of the structured biosensors. The structuration also leads to the creation of regions on biosensor chips that are characterized by strongly enhanced electromagnetic fields. New opportunities for further improving the bio-sensitivity are offered if localization of biomolecules can be carried out in these regions of high electromagnetic fields enhancement and confined
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Lee, Ming-Tao. "Plasmonic Enhanced Fluorescence using Gold Nanorods." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57680.
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The aims of this study are to first immobilize positively charged gold nanorods to negatively charged cell culture surfaces. Second, to use polyelectrolytes for controlling the distance between gold nanorods and fluorophores. This is used to optimally determine the distance, of which maximum fluorescence enhancement is achieved, between gold nanorods and fluorophores. In order to approach these aims, we use UV/VIS absorption spectroscopy, fluorescence spectroscopy, atomic force microscopy, and ellipsometry. The results show that we could control the immobilization of gold nanorods on plastic microwell plates and create reproducible polyelectrolyte layers, in order to control the distance between the gold nanorods and fluorophores. In addition, the localized surface plasmon resonance wavelength red shifted as the PELs increased. In conclusion, we found that the maximum fluorescence enhancement of the fluorophores (Cy7) is about 2.3 times at a fluorophores-nanoparticles separation of approximately 9-12 nm. This work contributes some research information towards the design of optical biochip platforms based on plasmon-enhanced fluorescence.
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Wang, Chaoming. "Thermally annealled plasmonic nanostructures." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5556.
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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 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.ID: 031001538; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Ming Su.; Title from PDF title page (viewed August 21, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 95-108).
Ph.D.
Doctorate
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering
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Chou, He-Chun. "Enhancement of Raman signals : coherent Raman scattering and surface enhanced Raman spectroscopy." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5476.
Full textAbstract:
Raman spectroscopy is a promising technique because it contains abundant vibrational chemical information. However, Raman spectroscopy is restricted by its small scattering cross section, and many techniques have been developed to amplify Raman scattering intensity. In this dissertation, I study two of these techniques, coherent Raman scattering and surface enhanced Raman scattering and discuss their properties. In the first part of my dissertation, I investigate two coherent Raman processes, coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS). In CARS project, I mainly focus on the molecular resonance effect on detection sensitivity, and I find the detection sensitivity can be pushed into 10 [micromolar] with the assistance of molecular resonance. Also, I am able to retrieve background-free Raman spectra from nonresonant signals. For SRS, we develop a new SRS system by applying spectral focusing mechanism technique. We examine the feasibility and sensitivity of our SRS system. The SRS spectra of standards obtained from our system is consistent with literature, and the sensitivity of our system can achieve 10 times above shot-noise limit. In second part of this dissertation, I study surface enhanced Raman scattering (SERS) and related plasmonic effects. I synthesize different shapes of nanoparticles, including nanorod, nanodimer structure with gap and pyramids by template method, and study how electric field enhancement effects correlate to SERS by two photon luminescence (TPL). Also, I build an optical system to study optical image, spectra and particle morphology together. I find that SERS intensity distribution is inhomogeneous and closely related to nanoparticle shape and polarization direction. However, TPL and SERS are not completely correlated, and I believe different relaxation pathways of TPL and SERS and coupling of LSPR and local fields at different frequencies cause unclear correlation between them.text
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"Illuminating biomolecular interactions with localized surface plasmon resonance." Thesis, 2010. http://hdl.handle.net/1911/62203.
Full textAbstract:
Noble metal nanoparticles exhibit localized surface plasmon resonance (LSPR), in which incident light causes a collective oscillation of a nanoparticle's free electrons. This phenomenon results in unique optical properties, including enhanced electric fields near the particle surface and an extinction peak at the resonant wavelength. The LSPR extinction peak's location is sensitive to the refractive index of the surrounding medium, especially in the volume closest to the particle surface. This makes plasmonic nanoparticles ideal for biosensing: their refractive index sensitivity can be used to transduce molecular binding signals. A method has been developed to use the optical extinction of films of gold nanorods to track antibody-antigen interactions in real time, resulting in a label-free kinetic immunoassay based on LSPR. Also, this method has been adapted to scattering spectra of single gold bipyramids. The single-particle approach has allowed the label-free detection of single biomolecules with kinetics information. These methods have future applications to both molecular biology and clinical assays.
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Wu, Sheng-Hung, and 吳昇紘. "Development of Disposable Localized Surface Plasmon Resonance Biosensors." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/51545500391791637000.
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Chiu, Wei-I., and 邱瑋懿. "Surface Modification on Nanoparticles for Enhancing Localized Surface Plasmon Resonance Sensors." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/42057801542750620527.
Full textAbstract:
碩士國立臺灣師範大學
化學系
103
In this research, we developed three kind of LSPR(Localized surface plasmon resonance) sensor by modify nano Au or coating others compounds. First of all, we use MPTMS modify Carbon nanotube that it can adsorb on nano Au. Repeat absorb carbon nanotube and nano Au Staggered. We got mutilayer gold/carbon nanotube LSPR sensor. It not only improve the sensitivity of VOCs also reduce the pieces of sensor.Second, we use ionic solution coating on nano particles.Ionic solution has low volatility, low inflammability,and stable at many physical properties. We take adventage of ionic solution can catch more VOCs that sensor can responses bigger signal. Finally, we use absorbent polymer mix salts to developed humidity sensor. Different kinds of salts has varied absorbing properties. We mix several kinds of salts in polymer make a humidity sensor wide sensing range.
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Kaur, Kanwarjeet. "Optical Biosensing Using Localized Surface Plasmon Resonance of Gold Nanoparticles." Thesis, 2011. http://hdl.handle.net/10012/5983.
Full textAbstract:
This thesis describes some experiments developed to probe the fundamental aspects of the interfacial behaviour of proteins. The contents of this thesis can be broadly divided into two parts.
In the first part, we studied how the size of the nanoparticles and other variables such as pH and bulk protein concentration affect the structure of the adsorbed protein layers. We also probed how these factors can influence the binding activity of adsorbed proteins. Study on the adsorption of IgG, Protein A and streptavidin on gold nanoparticles reveals that not all proteins are similarly affected by the size of the adsorbing surface. We found that though the optical properties of all the proteins vary with the size of the nanoparticle, their functionalities are not similarly affected by nanoparticle curvature. Protein A and streptavidin retain their binding capacity to IgG and biotin, respectively, irrespective of the size of the gold nanoparticle that they are attached to. On the other hand, a reduction/ loss in binding of adsorbed IgG to Protein A molecules is observed. The reduction in biological activity further depends on the radius of curvature of the adsorbing surface.
The second part of the thesis describes how nanoparticles can used as a probe to study the complex interfacial behaviour of proteins. We have utilized the extreme sensitivity of localized surface plasmon resonance (LSPR) of gold nanoparticles to local refractive index to determine the optical properties of BSA adsorbed on various polymer surfaces. The dielectric properties of the adsorbed protein depend on the nature of the substrate. Further, we have developed a model to determine the refractive index profile of adsorbed protein as a function of the distance from the substrate.
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Tak-WangChong and 鍾德泓. "Cell growth detection using a localized surface plasmon resonance sensor." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/u6a7w3.
Full textAbstract:
碩士國立成功大學
光電科學與工程學系
104
Cell culture technology has found wide application in the field of biotechnology. Depending on their origin, animal cells grow either as an adherent monolayer or in suspension. Most cells derived from solid tissues are adherent. Adherent cells are anchorage-dependent and propagate as a monolayer attached to the cell culture vessel. This attachment is essential for proliferation. When cells reach confluence, they must be subcultured or passaged. Failure to subculture confluent cells results in reduced mitotic index and eventually cell death. By contrast, passaging cells too early will result in a longer lag time. Traditionally, cultures should be 75% to 100% confluent when selected for subculture. However, the definition of confluence is difficult to be quantified and varies from the observer. Cells in culture will undergo changes in growth, morphology, and genetic characteristics over time. Such changes can adversely affect reproducibility of laboratory results. Therefore, to develop a real-time biosensor to monitor the suitable time-point for subculture is necessary. An optical sensor based on localized surface plasmon resonance (LSPR) has low-cost, rapid, real-time, high sensitivity and label-free of advantages. The sensing principle relies on the LSPR spectral shifts caused by the surrounding dielectric environmental change in a binding event In conclusion, cell growth monitoring was successfully achieved by using a LSPR sensor. The cell growth condition can be detected instantly from a spectral extinction measurement. This optical sensing approach, which is non-destructive, rapid, label-free, and real-time, can be a powerful method for in-situ monitoring the cell condition.
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Vokac, Elizabeth Anne. "Localized surface plasmon resonance spectroscopy of gold and silver nanoparticles and plasmon enhanced fluorescence." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4511.
Full textAbstract:
This thesis presents spectroscopic studies of metallic nanoparticle localized surface plasmons and plasmon enhanced fluorescence. We investigated the dielectric sensitivity of silver nanoprisms to an external electric field and gold nanorods to the formation of a self-assembled surface monolayer. Dark field microscopy was used to image plasmonic scattering from single nanoparticles, and a liquid crystal tunable filter was used to construct corresponding spectra. The plasmon resonances of silver nanoprisms displayed both reversible red shifts and irreversible blue shifts along with drastic intensity changes upon exposure to an applied bias. The plasmon resonances of gold nanorods showed sensitivity to the presence of alkanethiol molecules adhered to the particle surface by a moderate red shift. An increase in the effective external dielectric caused a shift toward longer wavelengths. We imaged plasmon enhanced fluorescence in order to optimize experimental parameters for a developing project that can characterize nanoparticle structure on sub-wavelength dimensions. Preliminary controls were performed to account for the effect of O₂ plasma treatment, solvent and alkanethiol monolayer formation on surface plasmon resonances. We found that O₂ plasma treatment for different time intervals did not result in a plasmon shift compared to untreated nanoparticles exposed to N₂; however when exposed to solvent the surface plasmons of the treated particles shifted five times as far toward the red. Interestingly, the solvent effect only resulted in a plasmon shift when the particles were N₂ dried after solvent incubation. Gold nanorods incubated in ethanol showed no wavelength maximum shift in pure solvent over time, but shifted moderately to the red after incubation in a solution of alkanethiol molecules. Conditions for the plasmon enhanced fluorescence study were optimized using a dye conjugate of the same alkanethiol molecule used previously by formation from solution in a monolayer on the gold nanorod surface. The appropriate synthesis for dye functionalization, molecular concentrations, solvents and optical settings were determined.text
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"Localized surface plasmon resonances of gold nanocrystals: refractive index sensitivity, plasmon coupling and photothermal conversion." Thesis, 2010. http://library.cuhk.edu.hk/record=b6074917.
Full textAbstract:
Assembly of noble metal nanocrystals gives rise to extraordinary plasmonic properties that are distinct from those of isolated ones. We have prepared clusters that are composed of two-dimensionally-ordered gold nanocubes on flat substrates and investigated their plasmonic properties. It is found that the plasmon resonances of the nanocube clusters are highly dependent on both the number and ordering of the nanocubes in the clusters. FDTD calculations reveal that the rich plasmon modes in the clusters originate from the interparticle couplings in the cluster and the couplings between the entire clusters and the substrate.I believe that my research work has provided an in-depth fundamental understanding of the localized surface plasmon resonances of gold nanocrystals and will have a number of implications for the applications of metallic nanostructures in optics, optoelectronics, and biotechnology.
Noble metal nanocrystals have attracted much interest due to their rich optical properties, which arise from the localized surface plasmon resonances, the collective oscillations of free electrons confined on the nanoscale. Under resonant excitation by light, noble metal nanocrystals exhibit extremely large light scattering and absorption, as well as large near-field enhancements. These fascinating properties bring about a variety of applications, including plasmonic sensing, plasmonic waveguiding, surface-enhanced Raman scattering, plasmon-enhanced fluorescence, photothermal cancer therapy, and plasmonic-enhanced energy harvesting. Among various noble metal nanocrystals, gold nanocrystals exhibit high chemical stability and large biological compatibility. Moreover, their plasmon resonance wavelengths can be synthetically tuned from the visible to near infrared spectral regions. In this thesis, a systematic study on the localized surface plasmon resonances of gold nanocrystals is presented, both experimentally and theoretically.
Photothermal conversion of gold nanocrystals can be applied in the areas of photothermal polymerization, photothermal imaging, drug release from capsules, and photothermal therapy. We have investigated the photothermal conversion properties of different gold nanocrystals and their composites. The studies show that the plasmon wavelength, particle volume, shell coating, and assembly of gold nanocrystals all play important roles in their photothermal conversion efficiency.
The refractive index sensitivity of gold nanocrystals is a key factor in their practical sensing applications. I will first introduce the systematic studies on the dependence of the index sensitivity on the shapes and sizes of gold nanocrystals that have varying plasmon resonance wavelengths. The index sensitivity has been found to generally increase as the plasmon resonance wavelength for a fixed nanocrystal shape becomes longer and as the curvature of the nanocrystals gets larger. I have further studied the dependence of the index sensitivity on the different shapes of gold nanocrystals that have the same longitudinal plasmon resonance wavelength. The refractive index sensitivities have been found to vary with the nanocrystal shape. Finite-difference time-domain (FDTD) calculations have been performed on these nanocrystals to reveal the origin of this dependence. A linear relationship is found between the index sensitivity and the product of the electric polarizability with the curvature. On the basis of these studies, a novel plasmonic optical fiber device has further been fabricated to detect small changes in the local dielectric environment.
When fabricating plasmonic devices, such as waveguides, optical switches, plasmonic sensors, and plasmon-enhanced solar cells, one needs to attach metal nanocrystals onto different substrates. The interactions between gold nanocrystals and the substrates can strongly modify the plasmonic responses of the nanocrystals and therefore need to be taken into account when designing of various plasmonic devices. We have further investigated the coupling between gold nanocrystals and substrates with different dielectric properties, including insulating, semiconducting, and metallic ones. It is found that the substrates play an important role in both the scattering patterns and scattering spectra of the supported gold nanocrystals. Specifically, Fano-type resonances can be observed for large nanocrystals sitting on silicon substrates that have a large dielectric constant.
Chen, Huanjun.
Adviser: Jianfang Wang.
Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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李宗諺. "Optical tapered filber sensor based on localized surface plasmon resonance (LSR)." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/88680320717973303119.
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Chuang, Po-Chun, and 莊博淳. "Using disposable localized surface plasmon resonance chips to detect influenza viruses." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03781295098045779170.
Full textAbstract:
碩士國立陽明大學
生醫光電研究所
103
In this study, we utilized low-cost, disposable localized surface plasmon resonance (LSPR) chips and DNA aptamers to detect influenza viruses. Compared with the commonly used influenza diagnostic methods, including lateral flow assays and the real-time reverse transcription-polymerase chain reaction (Real time RT-PCR), the use of disposable LSPR chips have the advantages of low-cost and low sample consumption. Here we used aptamers to detect hemagglutinin of influenza virus A/California/04/2009(H1N1) and influenza virus A/Puerto/8/1934(H1N1), and our results show that the LSPR peak shifts increase with the concentration of anlyte. In addition, in another set of experiments, we used aptamer-functionalized gold nanorods to capture viruses and then used an aptamer-functionalized LSPR substrate to capture the viruse-gold nanorods conjugates. Since the gold nanorods that were very close to the substrate could cause plasmon coupling and significant changes in the refractive index, the LSPR shifts are increased by the binding of the nanorods. At the time of influenza virus A/Puerto/8/1934(H1N1) detection, we use viruses-gold nanorod conjugates to increase LSPR peak shifts. The gold nanorod can be close to the surface when viruses are captured by aptamers. The gold nanorod can cause plasmon coupling and change of refractive index. The result shows the mechanism can generate significant LSPR peak shifts. In short, we successfully used aptamer-functionalized disposable LSPR chips to detect influenza viruses and hemagglutinin of the viruses.
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Wu, Kuan-Han, and 吳冠翰. "Photoluminescence of quantum-dot nanocomposites enhanced by localized surface plasmon resonance." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/95315601804379663182.
Full textAbstract:
碩士國立雲林科技大學
化學工程與材料工程系碩士班
101
In this study, CdSe/ZnS quantum dots were synthesized by the high-temperature pyrolysis method for CdSe/ZnS quantum dots – nano-silver nanocomposites. The nanocomposites can possess special optical properties due to the nature of semiconductor quantum dot. The photoluminescence intensity of quantum dots can be enhanced by the localized surface plasmon resonance of silver nanoparticles, arising from the fact that more electrons were excited to the conduction band by the localized electrical field. On the contrary, the photoluminescence of quantum dots can be quenched by graphene to induce a photocurrent. The effect of silver nanorods/nanowires on the photocurrent was investigated. In the first part of the thesis, the enhancement of photoluminescence of quantum dot/dielectric layer/Ag nanoparticles three-layer nanocomposites caused by localized surface plasmon resonance was discussed. The silver nanoparticles fabricated by sodium citrate were coated on glass substrates first by the self-assembling method. The various thickness of SiO2 or TiO2 layer was then deposited above the silver-nanoparticle layer as a dielectric layer. Finally, the water-soluble CdSe/ZnS quantum dots were adsorbed on the surface of the dielectric layer. Effect of the dielectric layer on the photoluminescence efficiency of the nanocomposites was analyzed. The optimal thickness of the dielectric constant was found. In the second part, the photocurrent of CdSe/ZnS-graphene nanocomposites was investigate. When graphene oxide was chemically reduced to graphene, The nanocomposites showed significant optoelectronic properties and their photoluminescence was quenched. The photocurrent of the nanocomposites can be enhanced up to 80 μA by adding silver nanowires.
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Gish, Douglas. "Morphology control and localized surface plasmon resonance in glancing angle deposited films." Master's thesis, 2010. http://hdl.handle.net/10048/1264.
Full textAbstract:
This research investigates an extension of the glancing angle deposition (GLAD) technique and a biosensing application of films produced by GLAD. The extension to GLAD, called phi-sweep (PS), improves column isolation compared to films grown by traditional GLAD (TG) as well as modifies the column tilt angle, , of the slanted columns according to tan(_{PS}) = tan(_{TG}) cos(), where is the sweep angle. The biosensing application makes use of localized surface plasmon resonance in noble metal GLAD films functionalized with rabbit immunoglobulin G (rIgG) to detect binding of anti-rabbit immunoglobulin G (anti-rIgG) to the films' surface. The extinction peak red-shifts a distance dependent on the concentration of anti-rIgG solution in a manner described by the Langmuir isotherm with a saturation value, _{max}, of 29.4 0.7 nm and a surface confined thermodynamic binding constant, K, of (2.7 0.3)10 M.Microsystems and Nanodevices