Ce travail porte sur l'étude in operando des nanoparticules d'or supportées sur TiO2(110) pendant la réaction d'oxydation du CO. Il s'inscrit dans l'objectif de comprendre les propriétés catalytiques de l'or qui apparaissent à l'échelle nanométrique. Les paramètres géométriques et structuraux des nanoparticules d'or ont été mesurés en présence de 20 mbar d'oxygène ou d'argon, de 0.1-0.2 mbar de CO et en conditions réactionnelles (oxygène + CO à 473 K), par GISAXS et par GIXD en suivant simultanément la composition des gaz par spectrométrie de masse. L'exposition au mélange réactionnel déclenche une évolution instantanée des nanoparticules avec une augmentation de leur taille moyenne qui varie de la même manière que l'activité catalytique. Par contre l'oxygène et le CO ne provoquent pas de changement et seule la température a un effet. Ces évolutions démontrent l'importance des mesures in operando pour déterminer le lien qui existe entre la taille et l'activité des nanoparticules. La variation de l'activité catalytique en fonction du diamètre présente un maximum pour des particules de 2 nm de diamètre et de 1.4 nm de hauteur. Au-dessus de ce maximum, elle suit une loi de puissance du diamètre, d-2.4 ± 0,3, comme attendu pour des sites actifs situés sur les atomes de basse coordinence. La diffraction X montre que, pendant la réaction, les nanoparticules conservent la structure CFC du cristal d'or, mais la distance inter-plan se contracte quand la taille des particules décroit ce qui intervient dans la baisse d'activité au dessous de 2 nm. Cependant d'autres paramètres peuvent aussi avoir un effet négatif sur la réactivité comme la forme des particules et le fait que plus elles sont petites plus elles s'agglomèrent sur les bords de marche du substrat. La similitude des tailles obtenues par GISAXS et par GIXD et de leur comportement sous gaz réactifs indique que les particules mesurées par ces deux techniques sont les mêmes. De plus, la forte corrélation entre la variation de l'activité et les évolutions observées par GISAXS montre que ce sont les particules actives qui sont sondés par les rayons x. La comparaison des résultats avec ceux déjà publiés indique que le comportement que nous avons décrit sur la dépendance de l'activité catalytique des nanoparticules d'or sur TiO2, pour l'oxydation du CO, est représentative des propriétés de ce système. Cependant, il est nécessaire de vérifier expérimentalement comment ces résultats obtenus à 473 K peuvent être extrapolés à température ambiante. L'installation dans notre dispositif d'une nouvelle chambre de réaction doit permettre de gagner un ordre de grandeur en sensibilité et rendre envisageable une telle étude. Mots clés : Catalyse, nanoparticules d'or, GISAXS, diffraction X, in operando, oxydation du CO. / This work focuses on the in operando study of gold NPs supported on TiO2(110) during the CO oxidation reaction. Its goal is the understanding of the catalytic properties of gold appearing at the nanometer scale. The geometrical and structural parameters of gold nanoparticles were measured in the presence of 20 mbar of oxygen or argon, of 0.1-0.2 mbar of CO and reaction conditions (oxygen + CO at 473 K), by GISAXS and GIXD, by simultaneously tracking the gas composition by mass spectrometry. Exposure to the reaction mixture triggers an instantaneous evolution of nanoparticles with an increase in their average size which varies in the same way that the catalytic activity. Contrariwise, oxygen and CO don't cause any changes and only the temperature has an effect. These evolutions show the importance of in operando measures to determine the relationship between the size and activity of nanoparticles. The variation of catalytic activity depending on the diameter exhibits a maximum for particles of 2 nm in diameter and 1.4 nm in height. Above this maximum, it follows a power law of the diameter, d-2.4 ± 0.3, as expected for active sites located on the atoms of low coordination number. X-ray diffraction shows that during the reaction, the nanoparticles retain the FCC structure of the gold crystal, but the inter-plane distance contracts when the particle size decreases, which leads to the drop of the activity below 2 nm. However, other parameters may also have a negative effect on reactivity, such as the particle shape and the fact that the smaller the particles, the more they congregate on the edges of the substrate step. The similarity of the sizes obtained by GISAXS and GIXD, and their behavior under reactant gases indicates that the particles measured by both techniques are the same. In addition, the strong correlation between the activity variation and the evolutions observed by GISAXS shows that the active particles are those scanned by the X rays. The comparison of our results with those already published shows that the behavior we have described on the dependence of the catalytic activity of gold nanoparticles on TiO2, for CO oxidation reaction, is representative of the properties of this system. However, it is necessary to check experimentally how the results obtained at 473 K can be extrapolated to room temperature. The installation of a new reaction chamber in our setup has to allow us to gain an order of magnitude in sensitivity and make possible such a study. Keywords: Catalysis, gold nanoparticles, GISAXS, X-ray diffraction, in operando, oxidation of CO

Material science is an interdisciplinary area of research, which in part, designs and characterizes new materials. Research is concerned with synthesis, structure, properties, and performance of materials. Discoveries in materials science have significant impact on future technologies, especially in nano-scale applications where the physical properties of nanomaterials are significantly different than their bulk counterparts. The work presented here discusses the use of ferritin, a hollow sphere-like biomolecule, which forms metal oxo-hydride nanoparticles inside its protein shell for uses as a bio-inorganic material.Ferritin is capable of forming and sequestering 8 nm metal-oxide nanoparticles within its 2 nm thick protein shell. A variety of metal-oxide nanoparticles have been synthesized inside ferritin. The work herein focuses on three distinct areas:1) Ferritin's light harvesting properties: namely band gaps. Discrepancies in the band gap energies for ferritin's native ferrihydrite mineral and non-native minerals have been previously reported. Through the use of optical absorption spectroscopy, I resolved the types of band gaps as well as the energy of these band gaps. I show that metal oxides in ferritin are indirect band gap semiconductors which also contain a direct transition. Modifications to the ferrihydrite mineral's band gaps are measured as a result of co-depositing anions into ferritin during iron loading. I demonstrate that these band gaps can be used to photocatalytically reduce gold ions in solution with titanium oxide nanoparticles in ferritin. 2) A new method for manganese mineral synthesis inside ferritin: Comproportionation between permanganate and Mn(II) forms new manganese oxide minerals inside ferritin that are different than traditional manganese oxide mineral synthesis. This reaction creates a MnO2, Mn2O3, or Mn3O4 mineral inside ferritin, depending on the synthesis conditions. 3) Ferritin as an energetic material: Ferritin is capable of sequestering various metals and anions into its interior. Perchlorate, an energetic anion, is sequestered through a co-deposition process during iron loading and is tested with energetic binding materials. Peroxide, which can be used as an oxidant, is also shown to be sequestered within apoferritin and combined with an aluminum based fuel for solid rocket propellants.

Parmi les technologies basées sur H2 comme vecteur d’énergie, les biopiles à combustibles utilisant des enzymes comme biocatalyseurs spécifiques et efficaces au lieu des catalyseurs au platine apparaissent comme des alternatives émergentes. L’objectif de cette thèse est de comprendre les paramètres gouvernant l’immobilisation fonctionnelle sur des interfaces nanostructurées d'enzymes spécifiques de l’oxydation de H2 et de la réduction d’O2 en vue de désigner une biopile H2/O2 performante.Divers nanomatériaux sont caractérisés, nanoparticules d’or (AuNP) et nanotubes de carbone (CNT), présentant différentes tailles et chimie de surface, aptes à développer des ratios importants surface/volume, autorisant une augmentation du nombre de molécules enzymatiques incorporées et donc une augmentation des courants catalytiques. L’immobilisation des enzymes sur AuNP a permis de discriminer entre l’augmentation de surface ou un effet nano sur l’efficacité catalytique. L’étude intégrée sur CNT, avec les charges de l’interface électrochimique, les charges et moments dipolaires des enzymes considérées, a permis de démontrer que les interactions électrostatiques contrôlent le processus de transfert d’électrons. Cette étude montre que les bases moléculaires pour une immobilisation efficace des enzymes, obtenues sur monocouches est applicables aux réseaux 3D.La détermination des nanostructures optimales pour les réactions enzymatiques est étudiée pour un changement d’échelle. Ainsi des feutres de carbone sont fonctionnalisés avec les nanostructures adaptées, pour au final développer la première biopile H2/O2 capable d’alimenter un multicapteur et un système de communication sans fil. / Among the technologies based on H2 as an energy carrier, biofuel cells that use specific and effective enzymes as biocatalysts instead of platinum catalysts appear as emerging alternative. The objective of this thesis is to understand the parameters governing the functional immobilization of specific enzymes for H2 oxidation and O2 reduction reactions on nanostructured interfaces, aimed to design a performant H2 / O2 biofuel cell.Gold nanoparticles (AuNP) and carbon nanotubes (CNT) having different sizes and surface chemistry are characterized. These nanomaterials develop important ratios surface / volume ratio, allow an increment in the number of enzyme molecules immobilized and therefore an increase catalytic currents. The immobilization of enzymes on AuNP allowed the discrimination between the increase in surface area and a nanomaterial effect on catalytic efficiency. The study on CNT integrates the charge of the electrochemical interface, dipole moments and the surface charge of enzymes. It demonstrated that electrostatic interactions control the electron transfer process. This study shows that the molecular basis for effective immobilization of enzymes, obtained on monolayers is applicable to 3D networks.The determination of the best parameters for enzymatic reactions, allows the development of an optimized 3-D volumetric interface based on carbon felt. We finally design for the first time a H2/O2 biofuel cell able to generate enough electric power to feed a complete wireless communication device.

Cette thèse a exploré comment, en introduisant des interfaces nanostructurées dans des systèmes supramoléculaires pour l'électronique, il est possible de moduler, ajouter et étudier les propriétés des nano-objets. Sur ces applications de fonctionnalisation auto-assemblée des limites, le contrôle thermique sur les propriétés intrinsèques, la modulation lumineuse des structures chimiques et physiques ont été trouvés comme étant des techniques adaptées pour affecter le système supramoléculaire fonctionnalisé nano-structuré pour l'électronique organique. Des nanoparticules d'or ont été utilisées pour générer des interfaces qui ont été fonctionnalisés afin d'étudier l'effet de transport de charge dans un transistor à couche mince organique. Par conséquent, cette approche a été intensifiée en employant des molécules photochromiques et par le contrôle du piégeage de charge par irradiation de lumière. Le même principe a été utilisé pour moduler l'injection de charge dans les transistors à haute performances, par fonctionnalisation des électrodes appropriées avec des diaryléthènes. Enfin, une approche différente pour contrôler le dépôt de flocons de graphène sur surface diélectrique a été employée avec succès pour concevoir de nouveaux éléments de mémoire par ajustement de l'alignement des niveaux énergétiques du graphène après recuit thermique. / This thesis explored how, by introducing nanostructured interfaces in supramolecular system for electronics, is possible to modulate, tune, add and study properties arising from nano-objects. On these purposes self-assembled functionalization of boundaries, thermal control on intrinsic properties, light modulation of chemical and physical structures have been found as tailored techniques to affect nano-structured functionalized supramolecular system for organic electronics. Gold nanoparticles have been used to generate interfaces that have been functionalized in order to study charge transport effect in organic thin film transistor. Therefore this approach has been stepped up employing photochromic molecules and controlling charge trapping with light irradiation. The same principle has been used to modulate charge injection in high performance transistors, by functionalizing electrodes with appropriate diarylethenes. Finally, a different approach of controlling deposition of graphene flakes on dielectric surface has been successfully employed to design new memory elements by tuning energetic level alignment of graphene with thermal annealing.

Le design et l’ingénierie de nanoparticules d’or (AuNPs) polyfonctionnelles suscitent un intérêt considérable en vue d’applications en nanomédecine, reconnaissance moléculaire, dans le domaine des capteurs et en catalyse dans un environnement aqueux. Cette thèse a été dédiée à une variété de fonctionnalisations, en particulier à l’aide de la méthode “click” impliquant la catalyse par le cui vre (I) de lacycloaddition des alcynes terminaux avec les azotures avec le catalyseur [Cu(hexabenzyltren)] Br pour l’introduction de polyéthylène glycol, carborane,ferrocène, coumarine, cyclodextrine, médicaments et molécules fluorescentes sur les AuNPs. Les ligands dits “click”, c’est-à-dire des 1,2,3-triazoles fonctionnalisés en positions 1,4 et formés de cette façon ont été ici largement utilisés afin de stabiliser des AuNPs pour des applications biomédicales et catalytiques en collaboration. / The design and molecular engineering of multi-functional gold nanoparticles (AuNPs) is of considerable interest towards applications in nanomedicine, molecular recognition, sensing and catalysis in aqueous environments. This thesis has been devoted to a variety of functionnalizations, in particular with the copper(I)-catalyzed Alkyne Azide cycloaddition (CuAAC) using thecatalyst [Cu(I)(hexabenzyltren] Br for the introduction of polyethylene glycol,carborane, ferrocene, coumarin, cyclodextrin, drugs and fluorescent probes. The so called “clicked” ligands, 1,4 -bifunctional triazoles, that were formed in this way have been exensively used to stabilize AuNPs for biomedical and catalytic collaborative applications.

<p>The fascinating optical properties of metallic nanostructures, dominated by collective oscillations of free electrons known as plasmons, open new opportunities for the development of devices fabrication based on noble metal nanoparticle composite materials. This thesis demonstrates a low-cost and versatile technique to produce stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical properties. Albeit challenging, further control using thermal external stimuli to tune the local environment of gold nanoparticles embedded in VO2 host matrix would be ideal for the design of responsive functional nanocomposites. We prepared Au-VO2 nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering (ICMS) known as hollow cathode magnetron sputtering for the first time and report the reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting the external temperature stimuli. The structural, morphological, interfacial analysis and optical properties of the optimized nanostructures have been studied. ICMS has been attracting much attention for its enclosed geometry and its ability to deposit on large area, uniform coating of smart nanocomposites at high deposition rate. Before achieving the aforementioned goals, a systematic study and optimization process of VO2 host matrix has been done by studying the influence of deposition parameters on the structural, morphological and optical switching properties of VO2 thin films. A reversible thermal tunability of the optical/dielectric constants of VO2 thin films by spectroscopic ellipsometry has been intensively also studied in order to bring more insights about the shift of the plasmon of gold nanoparticles imbedded in VO2 host matrix.</p>

This research focuses on generating, isolating, and characterizing nanophase gold clusters with diameters below two nanometers. In this size regime, the metal cores exhibit electronic and optical properties very different from those of colloidal and bulk gold, arising from quantum size confinement. The unoccupied molecular orbitals of the cores are known to accept electrons, analogous to a capacitor, but with discrete electrochemical potentials. This work describes the novel production of gold clusters with structurally rigid benzenethiolate bound to the surface, rather than typically used alkanethiolates. The Aux(benzenethiolate)y clusters are anionic and charged balanced by tetraoctylammonium cations. They are enriched in ~1.5 nm diameter cores, compared to a dominance of 1.7 nm cores when alkanethiols are used during synthesis. The Aux(benzenethiolate)y clusters are more likely to form bulk crystals and possess enhanced electrochemistry relative to Aux(alkylthiolate)y clusters. They are characterized by x-ray diffraction, carbon and proton NMR, FTIR, optical spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis. The etching of clusters in the presence of hydrogen peroxide and excess benzenethiol to yield smaller 1.1 nm clusters is reported for the first time in this work. These 1.1 nm clusters have a rich optical spectrum with clear electronic transitions at room temperature and orient spontaneously when deposited from solution. This oxidative etching process was applied to alkanethiolate clusters, converting ~2.0 nm polydisperse clusters into smaller clusters. This offers the potential to produce smaller gold clusters with more available charge states and may allow increase the types of thiols that can be bound to the surface of gold monolayer protected clusters (MPCs), known also as quantum dots. The use of the bulky thiol, tert-butylmercaptan to produce 1.5 nm core gold clusters is also reported, indicating sterically hindered alkanethiols can play a role in limiting the size of Aux(alkylthiolate)y clusters. These clusters were characterized by x-ray diffraction, proton NMR, FTIR, optical spectroscopy, and mass spectrometry. The clusters are potentially useful for thiolate exchange reactions to produce new types of Aux(thiolate)y clusters.

I. Combined cloud point extraction and Tween 20-stabilized gold nanoparticles for colorimetric assay of silver nanoparticles in environmental water This study investigated a simple, sensitive and selective method for the colorimetric assay of silver nanoparticles (AgNPs) using Triton X-114-based cloud point extraction (CPE) as a preconcentration step and Tween 20-stabilized gold nanoparticles (Tween-AuNPs) as a colorimetric probe. After heating beyond the cloud point temperature of Triton X-114, a solution containing Triton X-114 micelles and AgNPs separated into a surfactant-rich phase (small volume) and a dilute aqueous phase. AgNPs partitioned into a Triton X-114-rich phase through a hydrophobic interaction between Triton X-114 micelles and AgNPs. After phase separation, the concentrated AgNPs oxidized to form Ag+ upon adding H2O2. The generated Ag+ triggered the aggregation of Tween 20-AuNPs in a high-ionic-strength solution because the reduction of Ag+ on the AuNP surface enabled Tween 20 (stabilizer) to be removed from the NP surface. The efficiency of Triton X-114-based CPE of the AgNPs was found to be iv insensitive to their size and coating type. Under optimal extraction and detection conditions, the selectivity of this method for AgNPs was considerably higher than for other nanomaterials. The minimum detectable concentrations for 7, 22, and 54 nm AgNPs were measured to be 0.1, 420, and 600 ng/mL, respectively. This method was successfully applied to the analysis of 7 nm AgNPs in drinking water, tap water and seawater. Keyword: silver nanoparticles, gold nanoparticles, cloud point extraction, Tween-20, colorimetric assay II. Functionalized silver nanoparticles as an extracting and preconcentrating agent for detection of mercury ions In this research we provided highly sensitive and selective for fluorescence assay of combined polythymine oligonucleotide (PolyT) with silver nanoparticles (AgNPs) as an extracting agent to detect mercury ion in environmental water. According to previous researches, PolyT will form a hairpin structure in the presence of Hg2+, this structure provide several 3-D grooves that the fluorescent dye can inlay with it. SYBR Green I (SG) is a staining dye for DNA, when binding with single strand DNA, it shows low fluorescence. On the contrast, SG inlay with grooves of hairpin structure, it shows v 11-fold of fluorescence signal. Hence, we used SG as a fluorescence probe for Hg2+. We modified thiol group at the 5¡¦ of PolyT DNA, because of forming silver sulfur bond, PolyT will able to modified on the surface of AgNPs. PolyT33SH-AgNPs are the extracting and concentrating agent in Hg2+ solution, by the centrifugation, we collected the PolyT33SH-AgNPs. For the purpose of releasing PolyT from AgNPs¡¦ surface, we adding H2O2 to oxidize the AgNPs into Ag+. By mixing buffer and SG into previous solution, mercury ion could be detected. In this study, we successfully detecting Hg2+ in the aqueous solution contained drinking water and tap water. The detection limit in drinking water is 20 pM, which is below Environmental Protection Agency limit for Hg2+ in drinkable water (10 nM), the linear range is from 50-600 pM. On the other hand, the detection limit in tap water is 50 pM, linear range is from 100-700 pM. Keyword: silver nanoparticles, mercury ion, PolyT, SYBR Green I, thymine

While significant progress has been made in the treatment and management of cancer, challenges remain because of the complexity and the heterogeneous nature of the disease. The improvement that has been seen in survival rates reflects advancements not only in treatment, but also in early stage detection and diagnostics for certain cancers. In particular, early stage detection and treatment of cancer before it has metastasized to other organs has resulted in a dramatic improvement in patient survival rates. One area of research that has shown considerable promise in further advancing diagnostics and early cancer detection is nanotechnology. Specifically, semiconductor and metal nanoparticles have great potential to provide advanced technology platforms for ultrasensitive and multiplexed detection of disease markers and probe disease on the molecular level. Because they are in the same size regime as biological molecules, these nanoparticles exhibit unique interactions with proteins, nucleic acids and other biomarkers of interest for detecting and diagnosing disease. However, high-quality nanoparticles are often unsuited for use in complex biological environments because of their coatings and surface chemistry. In this work, we describe the design and development of polymer-coated nanoparticle imaging agents for use in blood, cell and tissue diagnostic applications. Low-molecular weight, amphiphilic polymers capable of noncovalent interactions with nanoparticle surface ligands and the aqueous environment were synthesized and characterized for use in nanoparticle coating applications. We demonstrate that the hydrophobic and hydrophilic interactions between the nanoparticle surface, the amphiphilic polymer and the aqueous solvent were able to drive the coating and water solubilization of quantum dots. Novel nanoparticle synthetic techniques were also developed using the amphiphilic polymers in a one-pot method to make high quality semiconductor and gold nanoparticles and stabilize and encapsulate the particles for transfer into water. Using the polymer functional groups as multidentate ligands, nanoparticles were synthesized with a high degree of size control and increased stability. In addition, by performing the synthesis in a noncoordinating amphiphilic solvent such as polyethylene glycol, nanoparticles were immediately transferred to water with the excess polymer forming a water soluble coating. Next, nanoparticle surface charge and how it relates to the nonspecific binding of nanoparticles in cells, tissues and other complex biological samples was studied. We have found that highly charged (negative and positive) particles exhibit significant nonspecific binding to biomolecules and other cellular components in biological environments. By reducing the surface charge through the incorporation of hydroxyl functional groups, we have nearly eliminated the nonspecific binding of quantum dots in blood, cells and tissues. Moreover, through crosslinking and altering the surface chemistry of the polymer-coated quantum dots, we have increased the stability of the nanoparticles while maintaining a small hydrodynamic size. Finally, we have investigated the use of the low-binding, hydroxyl quantum dots in tissue staining applications, where nonspecific binding presents a considerable challenge to detection sensitivity and specificity. A number of biomolecule conjugation techniques were examined for the coupling of quantum dots to antibody targeting molecules and preliminary staining experiments were performed.

Mitochondria are an attractive target for the design of cancer therapy. One of the mechanisms by which chemotherapeutics destroy cancer cells is by inducing apoptosis through extrinsic or intrinsic apoptotic pathways. Extrinsic pathways target cell surface receptors whilst intrinsic pathways target mitochondria. Several studies have shown cancer cell destruction through the extrinsic pathways, which target cancer-specific overexpressed growth factor receptors on the cell membrane. Although the mitochondria dependent apoptotic process is well understood, its application in cancer therapy is still not well developed. Therefore, to design an effective cancer therapy targeting mitochondria, a good understanding in mitochondria dependent apoptotic process is required. Recent developments in nanotechnology have enabled live cell investigations and non-destructive methods to obtain cellular information. The availability of such information would assist to design methods of targeted apoptosis induction. In view of this, I report on studies towards development of cancer therapy where nanoparticles (NPs) were targeted to human cell mitochondria for two purposes: (a) development of cell-imaging tools to investigate the fundamental cell biological pathways inside cells and (b) induction of apoptosis by targeting nanoparticles to mitochondria. Current medical and biological fluorescent imaging methods are mainly based on dye markers, which are limited in light emission per molecule, as well as photostability. Consequently, NPs are gaining prominence for molecular imaging because of their strong and stable fluorescence. Additionally, in order to get insight of mitochondrial molecular information, I investigated the use of optical properties of gold nanoparticles (Au NPs) for surface enhanced Raman spectroscopy (SERS). In this study, two types of Au NPs - nanospheres (Au NS) and nanorods (Au NR) were investigated. Results from this study showed the enhancement effect of Au NPs in Raman spectra of mitochondria, especially in the region from 1500 to 1600 cm-1. In this region, normal Raman spectra of mitochondria showed the presence of some understated Raman peaks probably due to the excitation wavelength dependence. Au NRs showed a larger enhancement effect than Au NS with respect to the penetration depth of the plasmonic nearfield enhancement effect. Although, the details of the enhancement mechanism are beyond the current studies, Au NPs could be enhancing vibrations of aromatic residues in proteins. This study therefore showed that Au NPs could enhance Raman spectra of mitochondria and in addition the shape of the nanoparticles had a significant effect on SERS spectra. In living cells, I investigated some transfection methods and targeting of NPs to mitochondria or cytosolic actin subunits. I tested the performance of three transfection reagents to deliver nanodiamonds (NDs) into living cells. Antibody functionalized NDs were targeted to mitochondria or cytosolic actin subunits. Three transfection reagents were used: cationic liposomes PULSin™, the cell penetrating peptide protamine, and oligosaccharide modified polypropylene imine (PPI) dendrimers. Fluorescence imaging results revealed that dendrimers were the most efficient in delivering ND conjugates to targeted organelles. Protamine-mediated transfections appeared to target ND conjugates to intended organelles, although there was a tendency of unfunctionalized NDs to be directed to the nucleus. PULSin™-mediated transfection formed ND aggregates regardless of the functionalization moiety. This reflected the unsuitability of the cationic liposome to mediate ND transfections. Further, I investigated the potential use of Au NPs for cell imaging and photothermal lysis of mitochondria inside cells. Just as above, I also tested the performance of the three-transfection reagents mentioned above on transfection capacity of Au NPs into living cells. Using transmission electron microscopy (TEM), oligosaccharide modified dendrimers showed the best transfection of functionalized Au NPs. Further experiments explored the use of the nearfield enhancement effect of Au NPs in combination with low-level laser irradiation (LLLI) to induce apoptosis in living cells. Analysis of the apoptotic process using cytochrome c release showed that Au NPs induced apoptosis most probably through mechanical disruption of the outer mitochondrial membrane. However, apoptosis was significantly accelerated in cells with mitochondrially targeted Au NRs than in cells without Au NRs. This study showed successful targeting of Au NPs to mitochondria in living cells, and demonstrated the potential of using Au NPs in combination with laser irradiation to induce the mitochondria dependent apoptotic pathway. In conclusion, the potential use of Au NPs in SERS of mitochondria and the application of NDs for cell imaging of intracellular organelles were demonstrated. Lastly, Au NPs were targeted to mitochondria in living cells and could induce apoptosis due to mechanical disruption of the outer mitochondrial membrane. Consequently, application of low-level laser irradiation to Au NP transfected cells accelerated the apoptotic process.