Numerous semiconductive organic materials are actively being pursued for application in sensing and electronics. Chapter one introduces conjugated polymers (CPs) and their many useful properties, including electroluminescence, which has helped foster growing demand for these materials in low-power organic light emitting diodes (OLED) for solid state lighting and additionally polychromatic displays. In the second chapter of this dissertation, we develop the concept of digrignard scavengers for use in nickel catalyst transfer polymerization of diarylmagnesate monomers into conjugate polymers within a unique mixed THF/1,4-Dioxane solvent system. Our initial findings include a polymerization method which permits the formation of an electronics grade copolymer with molecular weights in excess of Mn = 50 kg/mol within 15 minutes using a scalable, room temperature method. In chapter three, we discuss the synthesis and characterization of Polysilafluorenes (PSFs), which are an important class of light-emitting conjugate polymers noted for their characteristic brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and improved thermal stability. In chapter four, we present a protocol for photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 10 μm. The resultant crosslinked material possess characteristic blue photoluminescence with solid state quantum yields > 80%. In chapter five, we present a protocol for 3-D photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 200 nm using two photon direct laser writing techniques. In chapter six, we present a unique deep blue emitting copolymer, poly(3,6-dimethoxy-9.9`-dihexylsilafluorene-co-3.6-dimethoxy-2’,3’,6’,7’-tetrahexyloxy-9,9-spiro-9-silabifluorene) (PHSSF-co-PDHSF), which exhibits brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and thermal stability. In chapter seven, we explore crosslinked conductive metallocene polymer networks that mediate chemical, electronic and mechanical signals.

Numerous semiconductive organic materials are actively being pursued for application in sensing and electronics. Chapter one introduces conjugated polymers (CPs) and their many useful properties, including electroluminescence, which has helped foster growing demand for these materials in low-power organic light emitting diodes (OLED) for solid state lighting and additionally polychromatic displays. In the second chapter of this dissertation, we develop the concept of digrignard scavengers for use in nickel catalyst transfer polymerization of diarylmagnesate monomers into conjugate polymers within a unique mixed THF/1,4-Dioxane solvent system. Our initial findings include a polymerization method which permits the formation of an electronics grade copolymer with molecular weights in excess of Mn = 50 kg/mol within 15 minutes using a scalable, room temperature method. In chapter three, we discuss the synthesis and characterization of Polysilafluorenes (PSFs), which are an important class of light-emitting conjugate polymers noted for their characteristic brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and improved thermal stability. In chapter four, we present a protocol for photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 10 μm. The resultant crosslinked material possess characteristic blue photoluminescence with solid state quantum yields > 80%. In chapter five, we present a protocol for 3-D photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 200 nm using two photon direct laser writing techniques. In chapter six, we present a unique deep blue emitting copolymer, poly(3,6-dimethoxy-9.9`-dihexylsilafluorene-co-3.6-dimethoxy-2’,3’,6’,7’-tetrahexyloxy-9,9-spiro-9-silabifluorene) (PHSSF-co-PDHSF), which exhibits brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and thermal stability. In chapter seven, we explore crosslinked conductive metallocene polymer networks that mediate chemical, electronic and mechanical signals.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Lung cancer accounted for 28% of all cancer related deaths in Hong Kong and has been the leading cause of cancer death worldwide. Non-small cell lung cancer (NSCLC) is the most common lung cancer (85%) and has been linked to poor prognosis with 5-year survival rates of only 15%. Low accumulation and lack of efficient penetration of therapeutic agents in the tumor site, and severe adverse effects are the main obstacles in efficient lung cancer chemotherapy.. Triptolide (TPL), a diterpenoid triepoxide, was first isolated from the Chinese medicinal plant Tripterygium wilfordii Hook F. It had attracted extensive attention for its anti-tumor effect. However, its therapeutic potential has been limited by the poor water solubility (0.017 mg/mL) and strong toxicity with LD50 of 0.8 mg/kg. To improve the therapeutic effects and facilitate the application of TPL in lung cancer therapy, we developed different ligands-modified TPL-loaded liposomal formulations for lung cancer specific delivery.. Antibody-decorated liposomes can facilitate the precise delivery of chemotherapeutic drugs to the lung by targeting a recognition factor present on the surface of lung tumor cells. Carbonic anhydrase IX (CA IX), an enzyme overexpressed on the surface of lung cancer cells with a restricted expression in normal lungs, is used as the target for NSCLC therapy. In the present study, anti-CA IX antibody-modified TPL-loaded liposomes was developed. CA IX-directed liposomes exhibited 1.7-fold enhancement in internalization effects and 2-fold higher cytotoxicity in CA IX-positive human non-small cell lung cancer cell line A549. In vivo, CA IX-directed liposomes confined the delivery specifically to the lung and resided up to 96 h, which further showed enhanced therapeutic efficiency in orthotopic lung tumor bearing mice.. CPP33 is a tumor lineage-homing cell-penetrating peptide reported to be highly permeable into human lung cancer cell. Here, we utilized CPP33 for translocation of TPL-liposomal formulation into lung tumor cells. In vitro, CPP33-TPL-lip significantly improved apoptotic feature on A549 cells than non-modified liposomes. CPP33-lip specifically promoted the penetration ability of liposomes on A549 rather than human lung fibroblast cells (MRC-5), showing prominent cell selectivity. Furthermore, CPP33-lip showed superior penetrating ability on 3D tumor spheroids compared to non-modified liposomes.. A dual-ligand TPL-loaded liposomes (dl-TPL-lip) via conjugation of anti-CA IX antibody (targeting module) and CPP33 (trans-membrane module) was further developed to improve the therapeutic efficacy of NSCLC. The dl-TPL-lip showed superior penetrating ability and inhibiting effect on 3D tumor spheroids and significantly enhanced TPL anti-cancer efficacy following pulmonary administration in orthotopic lung cancer nude mice. The encapsulation of TPL in liposomes reduced the exposure of TPL in systemic circulation, which is demonstrated by pharmacokinetic study in rat plasma by endotracheal administration. Further anti-cancer effect study showed that dl-TPL-lip exhibited the greatest efficacy compared to TPL solution, non-modified TPL-loaded liposomes, anti-CA IX Ab or CPP33 single ligand-modified liposomes.. In summary, the findings of this study establish promising TPL delivery systems for targeted therapy of lung cancer. Current research focusing on drug delivery systems provides an insight into targeted and safe delivery of TPL in preclinical setting.

Organic bioelectronics is the convergence of organic electronics and biology. Motivated by the unique combination of both electronic and ionic conductivity, organic semiconducting materials have been applied in OECTs for sensing applications to translate bio-logical signals into a quantitative electrical reading. Due to their carbon-based structure and flexibility, CPs can achieve improved biocompatibility compared to inorganic devices as they are intrinsically “softer”, avoiding mechanical mismatch and the need for surface compatibilizing layers. These promising materials have broad potential to be used in applications such as biosensors, drug delivery, and neural interfaces. In the second chapter, a series of lysine-functionalized DPP3T semiconducting polymers, outline their synthesis, and demonstrate that these particular polymers allow neuron cells to adhere and grow, in comparison to unfunctionalized polymers, where cells quickly die. Through covalent attachment of small lysine units, the conjugated polymer backbone and cells can directly electrically communicate, favorable for neural signals recording/stimulating. In the third chapter, NDI-based semiconducting polymers are selected for lysinefunctionalization, giving protein-like surfaces for neurons to attach, grow and form a network without the need of an intermediate PDL coating. Most importantly, this careful choice of NDI backbone allows lysinated-NDI polymers to operate in OECTs with an outstanding normalized transconductance value of 0.25 S/cm. In the fourth chapter, a new technique is presented to biofunctionalize thin film surface of polymers. Two methods including CuAAC and thiol-ene click are demonstrated to be applicable to biofunctionalize surface. In particular, both of them can achieve biocompatible surface by attaching biomolecules at high density while maintaining electrically conductive film. In the final chapter, three series of NDI-T2 are presented synthesized via Stille coupling reaction using different Pd catalysts. Following electrochemical and device characterization, the study of the influence of spacers between backbone and EG chain for performance in OFET and OECT operations is carried out. It is clearly evidenced that electron mobility increases by a factor of 10 with gradual increased spacers for all polymers in OFETs devices. For OECTs, within three series, pNDI-Cx-T2 stands out, especially pNDI-C4-T2 giving the highest reported transconductance at 0.479 S/cm and a low threshold voltage of 0.18 V.

Single-walled carbon nanotubes (SWNTs) are envisioned as one of the most promising materials for next-generation electronic devices such as field-effect transistors, photovoltaics, new power sources and bio/chemical sensors. In particular, solution processable SWNT networks are of great interest for flexible and stretchable electronics. However, most of these applications specifically require pure semiconducting (sc-) or metallic (m-) SWNTs. However, large scale synthetic methods for SWNTs always produce a mixture of semiconducting and metallic carbon nanotubes. In recent years, several biochemical separation techniques such as DNA assisted separation, density gradient ultracentrifugation, and gel chromatography techniques have been utilized to separate semiconducting and metallic SWNTs. Although these methods can be used for sorting SWNTs according to their chiralities, they are either time-consuming or not easily scalable. In addition, the supramolecular functionalization of SWNTs with conjugated polymers has received a great deal of attention due to its capability to extract sc-SWNTs via simple sonication and centrifugation steps within a few hours. Furthermore, π-conjugated polymers can be modified by suitably changing monomers and/or comonomers, and it is also easy to control molecular weight and solubility of resulting polymers in organic solvents and aqueous media. There is also the possibility for selectively extracting specific chirality (n, m) nanotubes using specifically designed macromolecular structures. Except for its application to the separation of SWNTs, the supramolecular complexes of π-conjugated polymer and SWNTs have potential applications in many research areas such as new composite materials. After a brief overview of the current work related to the investigation of the supramolecular interaction between various conjugated polymers and SWNTs (chapter 1), synthesis of a series of different types of fluorene-based conjugated copolymers and their supramolecular complex formation properties with SWNTs are described (chapter 2, 3, 4, 5 and 6). In order to understand the effect of conjugated polymer backbone and side-chain structure on formation of supramolecular complexes with SWNTs, several crucial factors were investigated by: (1) altering the polymer backbone composition; (2) introducing different solubilizing (functional) groups while the polymer backbone remains the same; (3) changing the side-chain functional groups, and (4) introducing different polymer repeat units with varying physical and chemical properties. The experimental results indicated that all of the resulting polymer-SWNTs complexes possess excellent (or moderate) solution stability in organic solvents such as tetrahydrofuran (THF), toluene, and xylene. It was also demonstrated that the interaction between the conjugated polymers and SWNTs is strongly influenced by polymer structure; even minor changes on side-chains have a significant effect on the selectivity of the polymers in dispersing specific SWNT structures. This investigation highlights the potential importance of incorporating different types of heterocyclic aromatic rings (electron rich or electron poor), and introducing side chains with varying electronic and geometric structure on selective solubilization of SWNTs. Polymer molecular weight and solvent properties also strongly influence the π-conjugated polymer assisted dispersion of specific chirality SWNTs. Although some progress has been made, the search for a conjugated polymer that selectively solubilizes specific SWNT chiralities on large scale remains a challenge. / Thesis / Doctor of Philosophy (PhD)

This comprehensive review critically evaluates whether supposed health benefits propounded upon human consumption of conjugated linoleic acids (CLAs) are clinically proven or not. With a general introduction on the chemistry of CLA, major clinical evidences pertaining to intervention strategies, body composition, cardio-vascular health, immunity, asthma, cancer and diabetes are evaluated. Supposed adverse effects such as oxidative stress, insulin resistance, irritation of intestinal tract and milk fat depression are also examined. It seems that no consistent result was observed even in similar studies conducted at different laboratories, this may be due to variations in age, gender, racial and geographical disparities, coupled with type and dose of CLA supplemented. Thus, supposed promising results reported in mechanistic and pre-clinical studies cannot be extrapolated with humans, mainly due to the lack of inconsistency in analyses, prolonged intervention studies, follow-up studies and international co-ordination of concerted studies. Briefly, clinical evidences accumulated thus far show that CLA is not eliciting significantly promising and consistent health effects so as to uphold it as neither a functional nor a medical food.

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This thesis is dedicated to the study of fluorescent conjugated polymers made of fluorene labelled with rylene moieties. Those polymers are important candidates for use in Organic Light Emitting Devices (OLEDs). The dyes present in the polymers were studied at the single-molecule level. The first part of the work is devoted to the construction and validation of an epi-fluorescent confocal/widefield/Total Internal Reflection microscope. The ensemble properties of the samples are first measured in solution. The combination of steady-state and time-resolved spectroscopies allows us to unravel the photophysics of the conjugated polyfluorene polymer containing perylenediimides in its backbone. Energy transfer is found to occur between the polyfluorene and the perylenediimide units. Beside energy transfer, a photoinduced electron transfer is also supposed to take place. Widefield microscopy is used to measure the end-to-end distance in single polymer chains. From those measurements the polymer is shown to present a quasi linear shape inside its host matrix. From the simulation of the end-to-end distance distribution, a conjugation length of 4-6 fluorene units is found. The introduction of a new subtraction method associated with defocused imaging allows us to study a more complicated polymer containing more perylenediimide units. The location and the 3D orientation of the incorporated dyes were measured at the same time by this new technique named SPIDER. Finally, the sequential two-color measurements allow us to get useful informations concerning the energy transfer occurring between polyfluorene backbone and perylenediimide units at the single molecule level.