Browsing by Subject "Bioimaging"
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Item Colloidal nanocrystals with near-infrared optical properties : synthesis, characterization, and applications(2011-12) Panthani, Matthew George; Korgel, Brian Allan, 1969-; Dodabalapur, Ananth; Chelikowsky, James; Mullins, C. Buddie; Manthiram, ArumugamColloidal nanocrystals with optical properties in the near-infrared (NIR) are of interest for many applications such as photovoltaic (PV) energy conversion, bioimaging, and therapeutics. For PVs and other electronic devices, challenges in using colloidal nanomaterials often deal with the surfaces. Because of the high surface-to-volume ratio of small nanocrystals, surfaces and interfaces play an enhanced role in the properties of nanocrystal films and devices. Organic ligand-capped CuInSe2 (CIS) and Cu(InXGa1-X)Se2 (CIGS) nanocrystals were synthesized and used as the absorber layer in prototype solar cells. By fabricating devices from spray-coated CuInSe nanocrystals under ambient conditions, solar-to-electric power conversion efficiencies as high as 3.1% were achieved. Many treatments of the nanocrystal films were explored. Although some treatments increased the conductivity of the nanocrystal films, the best devices were from untreated CIS films. By modifying the reaction chemistry, quantum-confined CuInSeXS2-X (CISS) nanocrystals were produced. The potential of the CISS nanocrystals for targeted bioimaging was demonstrated via oral delivery to mice and imaging of nanocrystal fluorescence. The size-dependent photoluminescence of Si nanocrystals was measured. Si nanocrystals supported on graphene were characterized by conventional transmission electron microscopy and spherical aberration (Cs)-corrected scanning transmission electron microscopy (STEM). Enhanced imaging contrast and resolution was achieved by using Cs-corrected STEM with a graphene support. In addition, clear imaging of defects and the organic-inorganic interface was enabled by utilizing this technique.Item New materials for advanced applications : electrochromism, electrocatalysis, and bioimaging(2017-05-02) Liang, Yawei; Jones, Richard A., 1954-; Que, Emily L; Rose, Michael J; Mullins, Charles Buddie; Campion, AlanElectrochromic materials have the applications in smart-windows, electrochromic mirrors, and electrochromic display devices. Three Fe(II) bis(terpyridine)-based complexes with thiophene (2.2a), bithiophene (2.2b), and 3,4-ethylenedioxythiophene (2.2c) side chains have been synthesized to provide two terminal active sites for electrochemical polymerization. The thin film of poly-2.2b has been electrodeposited on ITO/glass substrate and was characterized using electrochemistry, X-ray photoelectron spectroscopy, UV-vis spectroscopy and atomic force microscopy. The film exhibited great optical contrast with a change of transmittance of 40% upon applying voltage to it, and a coloration efficiency of 3823 cm²C⁻¹ with a switching time of 1 s. It also demonstrated commonplace stability and reversibility, with a 10% loss in peak current intensity after 200 cyclic voltammetry (CV) cycles and almost no loss in change of transmittance after 900 potential switches between 1.1 V and 0.4 V (vs Fc⁺/Fc). Lanthanide complexes have unique photophysical properties that can be utilized in areas such as bioimaging, bio-sensors, fluoroimmunoassays, and organic light emitting diodes. Our group has previously synthesized the complex-Eu(III) tris-(2-thenoyltrifluroacetonate) 2,6-bis(pyrazoly)pyridine [Eu(bppy)(tta)₃], which has a quantum yield of 60% in dichloromethane solution and 90% in solid state. Various functionalities were introduced on the original bppy ligand, such as carboxyl, hydroxyl, and amino groups to provide the active sites for bioconjugation purpose. Four Eu(III)(R-bppy)(tta)₃ complexes (3.2a-3.2d) were synthesized and their photophysical properties were fully characterized. Their quantum yields range from 20.2% to 45.4% and lifetimes range from 383.9-417.2 [mu]s. Efficiently transforming the greenhouse gas CO₂ into liquid fuels or useful synthetic precursors would have a significant impact on balancing the global carbon cycle. A series of mononuclear Re(I) complexes with dipyrido[3,2-a:2’,3’-c]phenazine (dppz) derived ligands (4.2a-4.2d) were synthesized and investigated as homogeneous electrocatalysts for CO₂ reduction. CV studies showed large enhancements of the cathodic currents under CO₂ atmosphere for the Re(I) complexes, indicating the electrocatalytic reduction of CO₂. CO was confirmed as the only gaseous phase product by gas chromatography. Compared to the Lehn catalyst, a benchmark catalyst for reducing CO₂ to CO, the Re(I) dppz complex with a larger degree of conjugation transformed CO₂ into CO at a lower overpotential.Item North American Laser Ablation Workshop 2015 : Program and Abstracts(2015-05-27) North American Laser Ablation Workshop Organizing Committee