Polymers having one of the three complementary colors (red, green, and blue) in the reduced state and high transmissivity in the oxidized state are key materials towards use in electrochromic devices and displays. Although many neutral state red and blue polymers were reported up to date, neutral state green polymeric materials appear to be limited. For potential application of electrochromic materials in display technologies, one should have to create the entire color spectrum and this can be only achieved by having materials with additive or subtractive primary colors in their neutral states. To obtain a green color there should be at least two simultaneous absorption bands. Although the neutral state color is of great importance, the transmittance in the oxidized state is crucial too. The materials having one of the three primary colors should also possess highly transmissive oxidized states in order to be used in commercial electrochromic device applications. Donor-acceptor molecules lead to lower band gap due to resonances that enable a stronger double bond character between the donor and acceptor units. The materials with low band-gaps produce cathodically coloring polymers due to the lower energy transition in the doped state. Moreover, donor-acceptor type materials commonly show two absorption maxima. Since donor-acceptor approach seems to be the key to the complex nature of producing these materials, novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail.Additionally a solution-processable donor-acceptor type polymer was realized using method of introducing alkyl side chains in the polymer structures.

Synthesis of new electroactive monomers are highly desired since these compounds can be utilized as active layers in many device applications such as ECDs, LEDs and solar cells. EDOT (3,4 ethylenedioxythiophene) and thiophene bearing polymers were also proven to be excellent candidates as electrochromic materials. Benzotriazole can be coupled to EDOT and thiophene to yield materials that can be polymerized to give donor acceptor type polymers. These materials are promising candidates as components in fast switching polymeric electrochromic devices. Donor acceptor type materials / 2-dodecyl-4-(2,3-dihydrothieno [3,4- b][1,4]dioxin-5-yl)-7- (2,3-dihydrothieno[3,4-b] [1,4] dioxin-7-yl)-2H-benzo [d][1,2,3]triazole and 2-dodecyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole were synthesized via N-alkylation, bromination, stannylation and Stille coupling reactions. Electrochemical and electrochromic properties of the polymers were examined in detail.

Polymeric electrochromic materials that has as one of the three complementary colors (red, green, and blue) in the neutral form and become transparent via oxidation (or reduction), has a crucial importance towards use of these materials in electrochromic devices and displays. To reflect red or blue color in neutral state, the materials have to absorb at only one dominant wavelength. On the contrary, to have a green color, there should exist at least two simultaneous absorption bands in the red and blue regions of the visible spectrum where these bands should be controlled with the same applied potential. The transmissivity in the oxidized state is significantly important in addition to the neutral state color of the polymer. The optical contrast between the states is the decisive point for use of these materials for many electrochromic applications, especially as smart windows and displays. Hence, the material should possess two absorption bands with definite maximum points, and upon oxidation these bands should simultaneously vanish to have a transmissive state. A donor&ndash / acceptor approach can be utilized to solve this puzzle. It has been shown that insertion of alternating donor&ndash / acceptor units on the polymer backbone leads to a significant decrease in band gap due to the increased double bond character in the structure. In this study novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail. PBDT is the first green electrochromic material which has a highly transmissive sky blue oxidized state. PDETQ was shown to be one of the few examples of neutral state green polymeric materials in literature. PDEQ has a bluish green color in the neutral state and a highly transmissive light blue oxidized state.

Cancer has become one of the leading causes of death today. The early detection of cancer may lead to desired therapeutic management of cancer and to decrease the mortality rate through effective therapeutic strategies. Advances in materials science have enabled the use of nanoparticles for added contrast in various imaging techniques. More recently there has been much interest in the use of gold nanoparticles as optical contrast agents because of their strong absorption and scattering properties at visible and near-infrared wavelengths. Highly proliferative cancer cells overexpress molecular markers such as epidermal growth factor receptor (EGFR). When specifically targeted gold nanoparticles bind to EGFR they tend to cluster thus leading to an optical red-shift of the plasmon resonances and an increase in absorption in the red region. These changes in optical properties provide the foundation for photoacoustic imaging technique to differentiate cancer cells from surrounding benign cells. In photoacoustic imaging, contrast mechanism is based on the optical absorption properties of the tissue constituents. Studies were performed on tissue phantoms, ex-vivo and in-vivo tumor models to evaluate molecular specific photoacoustic imaging technique. The results indicate that highly sensitive and selective detection of cancer cells can be achieved by utilizing the plasmon resonance coupling effect of EGFR targeted gold nanoparticles and photoacoustic imaging. In conclusion, the combined ultrasound and photoacoustic imaging technique has the ability to image molecular signature of cancer using bioconjugated gold nanoparticles. / text

Optical assays to detect cancer-associated molecular biomarkers in biological substrates are commonly performed with antibody-targeted organic dye contrast agents but the potential for precise quantification, long-term imaging, and multiplexed readouts is limited by chemical and optical instability, non-optimal spectral characteristics, and complicated synthetic chemistry of the dyes. This dissertation tested the hypothesis that a novel class of optical contrast agents termed polymer-protected Raman-encoded nanoparticle tags (PRENTs) provides practical advantages over existing optical technologies for molecular diagnostic applications. First, PRENTs were developed through a modular design utilizing gold-nanoparticle-Raman reporter complexes protected and functionalized by polyethylene glycol derivatives. PRENTs produced optical readouts through surface enhanced Raman scattering (SERS) that were brighter and more photostable than the fluorescence of semiconductor quantum dots under identical experimental conditions. Unique spectral signatures were produced with a broader class of Raman reporters than is possible with silica coated Raman tags. Spectral signatures and colloidal stability of PRENTs were unaffected by harsh chemical conditions that cause spectral changes and aggregation of dyes, quantum dots, and protein coated Raman tags. Antibody-targeted PRENTs specifically tagged cell surface cancer biomarkers on living cells at reasonable integration times. PRENTs were non-toxic to cells under conditions exceeding those required for sensitive molecular detection. Next, PRENTs were efficiently optimized for excitation with near-infrared light through inclusion of near-infrared chromophores as Raman reporters and exploitation of the size-dependent optical enhancement of gold nanoparticles. Third, the development of a slide-based Raman-linked immunosorbent assay using antibody-conjugated PRENTs enabled quantification of protein biomarkers with a dynamic range of 3 to 4 logs. In summary, this dissertation establishes PRENTs as novel optical tags with unique features useful for biomedical applications and provides insights for further assay development.

Cette thèse décrit une stratégie de synthèse de nouvelles générations des nanoparticules (NPs) pour applications biomédicales, visant à une amélioration de leurs performances pour l’imagerie, le diagnostic thérapeutique. Ces NPs présentent plusieurs fonctionnalités leur permettant de réaliser des tâches multiples. Deux types de sondes bimodales ont été développés et étudiés afin d'évaluer leur potentiel comme agents (1) de contraste en IRM et (2) luminescents. Ces objetscombinent les propriétés des complexes de lanthanide (Ln3+) et celles des NPs de silice ou de type coeur-écorce Fe2O3@SiO2 pour une imagerie bimodale. Ces NPs testées sur des cellules vivantes ont permis d’illustrer la preuve du concept aussi bien en IRM avec une augmentation d'intensité des images et un impact significatif sur les relaxivities r1, r2 et r2* qu’en photoluminescence. L’étude du système coeur-écorce a montré que l’influence du contrôle fin de l’écorce autour du noyau d'oxyde de fer a pu être modélisée. / This thesis describes a strategy of synthesis of new generations of nanoparticles (NPs) for biomedical applications, aiming at an improvement of their performances for the imaging, and the therapeutic diagnosis. These NPs present several functionalities enabling them to carry out multiple tasks. Two types of bimodal probes were developed and studied so as to evaluate their potential as contrast agents (1) in MRI and (2) and luminescence. These objects combine the properties of the lanthanide complexes (Ln3+) and those of NPs of silica or core/shell Fe2O3@SiO2 for a bimodal imaging. These NPs tested on living cells were able to illustrate the proof of the concept not only in MRI with an increase of intensity of the images and a significant impact on the relaxivities r1, r 2 and r2* but also in photoluminescence. The study of the core/shell system showed that the influence of the fine control of the shell around the iron oxide core could be modeled.

<p> In an era of advancing printed electronics, solution-processable organic semiconductors continue to make significant strides in electronic and optoelectronic applications. Electrochromic (EC) technology, which encompass reversible optical modulation under electrochemical biasing, has progressed rapidly over the past half-century and developed into niche commercial-scale devices for auto-tinting glasses as well as low-power, non-emissive displays. To utilize the advantages of organic electrochromic materials in next-generation devices, it is imperative to understand their fundamental material properties, interactions with other device components, and the underlying electrochemistry that governs the overall optical and electrochemical response of the complete electrochromic device. This dissertation presents a discussion on the synergistic role of organic electrochromes, charge-balancing layers and electrolytes in determining two key performance metrics, namely the optical contrast and operational stability, of an electrochromic device (ECD). The absorption features of colored-to-transmissive switching conjugated polymers have been investigated by exploring material design strategies in conjunction with analytical approaches to optimize and enhance the optical contrast. In parallel, transmissive redox-active radical polymer counter electrodes have been developed as compatible charge-balancing layers and integrated into devices by pairing with electrochromic polymers (ECPs) to achieve stable and high-contrast optical modulation. Electrochemical activity of both conjugated and radical polymer electrodes in different ionic and solvent environments have been further examined to understand material-electrolyte interactions governing mixed ionic-electronic conduction. Finally, a small molecular approach to realizing transparent-to-colored electrochromism is discussed, where distinct substituent-induced degradation pathways of conjugated radical cations were revealed. Overall, this research aims to assist future development of robust, ultra-high contrast organic electrochromic platforms.  </p>