The nature of the solvent plays an important role in the conformation and orientation of polymers in solution. A particularly interesting case is when the solvent itself possesses order, such as when dissolving the polymer in a LC. In this dissertation, the morphology and diffusion behavior of the conjugated, stiff polymer MEH-PPV, (poly[2-methoxy-5((2-ethylhexyl)oxy)-1,4-phenylenevinylene]), in liquid crystal (LC) solvents have been investigated. Using polarization sensitive fluorescence correlation spectroscopy, it was found that in a nematic LC the polymer molecules are extended and highly aligned parallel with the nematic director. The conformation and orientational order of MEH-PPV increase with chain stiffness as a result of an interplay among the conformational entropy, solvation anisotropy, and bending energy of the polymer chains. In the smectic phase, about 10% of the MEH-PPV molecules are aligned perpendicular to the director in between the smectice layers, an effect not previously observed for a polymer solute. When applying an external electric field across the LC cell, the LC director changes orientation from a planar to a homeotropic alignment. The MEH-PPV chains remain aligned parallel with the LC director with applied field in the bulk of the LC device. However, the local structure near the LC-substrate interface is more complex. Single molecule polarization distributions measured as a function of distance from the LC device interface allow us to use MEH-PPV as sensitive local probe to explore complex structures in anisotropic media. Furthermore, diffusion anisotropy of the polymer solute in a LC solvent was studied by a novel two-beam cross-correlation technique. The diffusion anisotropy was observed to be about 2. This value is comparable to the diffusion anisotropy of the solvent and suggests that, despite the high degree of alignment, the solute diffusion is governed by the solvent and not the solute.

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.

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The syntheses of new classes of conjugated polymers are presented. The synthesis of novel alkyne bridged trispyrazolylmethane ligands, their coordination behavior and their crystallographic properties are studied. A series of functionalized poly(paraphenyleneethynylene)s, PPEs, are produced by click chemistry with post and pre-polymerization. Unpredictable solid-state polymerizations of defect free conjugated polythiophenes are investigated. Finally, by click chemistry aromatic diazides and aromatic diynes are coupled to produce a library of 1,2,3-triazoles and new conjugated polymers, poly(arylenetriazoline)s.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 143-162).