Browsing by Subject "Micelles"
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Item Alpha(V)Beta(3)-Targeted Nanoprobes for In Vivo Imaging of Tumor Angiogenesis(2010-11-02T18:20:26Z) Kessinger, Chase William; Gao, JinmingLung cancer is the leading cause of cancer-related deaths in the US and abroad (WHO, 2010). Early detection of the disease has increased patients’ five-year survival rates from 4% to over 50% (NCI SEER, 2010). Angiogenesis plays a critical role in the carcinogenesis and cancer metastasis of solid tumors. Integrin αvβ3 is a well-established overexpressed biomarker of angiogenesis and has recently been exploited in the clinical stratification of different types of cancer. Although magnetic resonance imaging (MRI) is not a first-line clinical imaging modality for the detection and diagnosis of lung cancer, recent advances in theranostic polymeric nanoplatforms and the development of ultrasensitive contrast agents, such as superparamagnetic iron oxide (SPIO) nanoparticles, has greatly broadened the application of MRI in cancer detection and molecular imaging. The objective of this work is to develop superparamagnetic polymeric micelle (SPPM) nanoprobes that can noninvasively image tumor angiogenesis in vivo using conventional T2/T2*-weighted and off-resonance saturation (ORS) MRI methods. Therefore, we hypothesized that the inclusion of an αvβ3-specific ligand, cRGD (cyclic Arg-Gly-Asp) peptide and encapsulation of a cluster of SPIO in the SPPM nanoprobe formulation would allow the specific imaging of tumor angiogenesis. SPPM nanoprobes are small (50-70 nm), and contain a cluster of SPIO in the core while maintaining the micelle core-shell architecture. In vitro examination of αvβ3-targeted cRGD-SPPM demonstrate an increase cellular uptake in αvβ3 overexpressing cells over control SPPM formulations. Upon translation to in vivo subcutaneous lung tumor models in mice, cRGD-SPPM is able to noninvasively image and quantitate tumor angiogenesis and demonstrate in vivo colocalization with αvβ3 integrin. In parallel with SPPM characterization, the ORS imaging method was validated in vitro and was successfully applied in vivo for imaging tumor angiogenesis and demonstrated an increased sensitivity and specificity for SPPM over conventional T2*-weighted MR imaging. Application of high temporal resolution (HTR) - MRI, combined with the ultrasensitivity of the SPPM nanoprobe, allows for the kinetic analysis of cRGD-SPPM targeting to angiogenic regions in vivo. Finally, SPPM shows the ability to detect small lung cancer nodules (<700 μm - 3 mm) in tail-vein induced orthotopic lung cancer models using convention T2-weighted and ORS MRI. The results presented herein, provide the characterization and proof-of-principle experiments that point towards the diagnostic potential of SPPM nanoprobes for the early detection of lung cancer.Item Conductometry and admittance spectroscopy of micellar solutions(Texas Tech University, 1998-05) Houlne, Michael PatrickNot availableItem Cyclodextrins and micelles in separations(Texas Tech University, 1987-05) Ward, Timothy JosephNot availableItem Deposition of cationic polymer micelles on planar and patterned SiO₂ surfaces(2003-12) Hahn, Jungseok; Webber, Stephen E.Item Effect of surfactants on methane hydrate formation and dissociation(2011-05) Ramaswamy, Divya; Sharma, Mukul M.; Bryant, Steven L.Dissociation of gas hydrates has been the primary concern of the oil and gas industry for flow assurance, mainly in an offshore environment. There is also a growing interest in the rapid formation of gas hydrates for gas storage, transport of natural gas and carbon sequestration. In this thesis, we experimentally measure the kinetics of formation and dissociation of methane hydrates and the effect of various anionic and cationic surfactants such as sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB) and alpha olefin sulfonate (AOS) on the association/dissociation rate constants. The importance and necessity of micelle formation in these surfactants has been studied. The effect of foam generation on the rate of formation of these hydrates has also been measured. SDS was found to significantly decrease the induction time for hydrate formation. There was an added decrease in the induction time when a foamed mixture of water and SDS was used. On the other hand CTAB and AOS had an inhibiting effect. The contribution of micelles towards promoting hydrate formation was demonstrated with a series of experiments using SDS. The micelles formed by these surfactants appear to serve as nucleation sites for the association of hydrates. New experimental data is presented to show that some surfactants and the use of foam can significantly increase the rate of hydrate formation. Other surfactants are shown to act as inhibitors. A new experimental setup is presented that allows us to distinguish between surfactants that act as promoters and inhibitors for hydrate formation.Item Novel uses of organized media in chemical analysis(Texas Tech University, 1987-08) Spino, Larry AngeloMicelles and cyclodextrins have been utilized for years in a variety of chemical analysis techniques. This work considers some modern applications of micelles and cyclodextrins in chemical analysis. Micellar and cyclodextrin mobile phases (pseudophases) were used in liquid chromatography (LC). Cyclodextrin mobile phases were used in microcolumn LC for separating optical isomers of racemic nicotine and eight other racemic analogues of nicotine. This was the first reported facile and direct separation of these racemates. Synchronous luminescence was used as the detection method for liquid chromatography to identify polynuclear aromatic components that co-elute in the course of a LC separation. As many as five compounds could be identified from a single chromatographic peak. Several scans can be made easily for every eluting peak, however, a single scan is sufficient to produce a complete synchronous luminescence spectra of a complex mixture. The micellar matrix served as the mobile phase and produced an enhancement effect on the luminescence signals. Equations were derived which allow one to determine alphacyclodextrin: substrate complex stoichiometries as well as primary and secondary binding constants by using LC retention values. An equation was also derived which describes the binding of a monoprotic species in which either its ionized or unionized form could bind to one or two cyclodextrin molecules. Becaused multiple binding constants are difficult to evaluate graphically, a non-linear least squares computer program was utilized. The approach works equally well forthe determination of binding cqnstants in micellar media. Resonance enhancement of Raman signals requires excitation on an absorption band of a molecule. This frequently produces background fluorescence from which it is difficult or impossible to extract a vibrational spectrum. Carrying out the resonance Raman analysis in certain dilute aqueous micellar solutions allows one to circumvent the luminescence problem in many cases. Several difÃerent micellar effects can be used simultaneously to enhance Raman signals relative to the background. Both the laser excitation line and the micellar system must be properly chosen so as to produce the best signal to noise ratio. The first examples of micelle mediated resonance Raman analysis of fluorescent compounds using UV and visible laser excitation was shown. Obtaining resonance Raman spectra from thin-layerchromatography plates was also demonstrated.