Browsing by Subject "Zeta potential"
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Item Development of an inhalational formulation of Coenzyme Q₁₀ to treat lung malignancies(2011-12) Carvalho, Thiago Cardoso; McConville, Jason ThomasCancer is the second leading cause of death in the United States and its onset is highly incident in the lungs, with very low long-term survival rates. Chemotherapy plays a significant role for lung cancer treatment, and pulmonary delivery may be a potential route for anticancer drug delivery to treat lung tumors. Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. In this work, we hypothesize that formulations of CoQ10 may be developed for pulmonary delivery with a satisfactory pharmacokinetic profile that will have the potential to improve a pharmacodynamic response when treating lung malignancies. The formulation design was to use a vibrating-mesh nebulizer to aerosolize aqueous dispersions of CoQ₁₀ stabilized by phospholipids physiologically found in the lungs. In the first study, a method was developed to measure the surface tension of liquids, a physicochemical property that has been shown to influence the aerosol output characteristics from vibrating-mesh nebulizers. Subsequently, this method was used, together with analysis of particle size distribution, zeta potential, and rheology, to further evaluate the factors influencing the capability of this nebulizer system to continuously and steadily aerosolize formulations of CoQ₁₀ prepared with high pressure homogenization. The aerosolization profile (nebulization performance and in vitro drug deposition of nebulized droplets) of formulations prepared with soybean lecithin, dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) were evaluated. The rheological behavior of these dispersions was found to be the factor that may be indicative of the aerosolization output profile. Finally, the pulmonary deposition and systemic distribution of CoQ₁₀ prepared as DMPC, DPPC, and DSPC dispersions were investigated in vivo in mice. It was found that high drug amounts were deposited and retained in the mouse lungs for at least 48 hours post nebulization. Systemic distribution was not observed and deposition in the nasal cavity occurred at a lower scale than in the lungs. This body of work provides evidence that CoQ₁₀ may be successfully formulated as dispersions to be aerosolized using vibrating-mesh nebulizers and achieve high drug deposition in the lungs during inhalation.Item Waterflood and Enhanced Oil Recovery Studies using Saline Water and Dilute Surfactants in Carbonate Reservoirs(2012-02-14) Alotaibi, MohammedWater injection has been practiced to displace the hydrocarbons towards adjacent wells and to support the reservoir pressure at or above the bubble point. Recently, waterflooding in sandstone reservoirs, as secondary and tertiary modes, proved to decrease the residual oil saturation. In calcareous rocks, water from various resources (deep formation, seawater, shallow beds, lakes and rivers) is generally injected in different oil fields. The ions interactions between water molecules, salts ions, oil components, and carbonate minerals are still ambiguous. Various substances are usually added before or during water injection to enhance oil recovery such as dilute surfactant. Various methods were used including surface charge (zeta potential), static and dynamic contact angle, core flooding, inductively coupled plasma spectrometry, CAT scan, and geochemical simulation. Limestone and dolomite particles were prepared at different wettability conditions to mimic the actual carbonate reservoirs. In addition to seawater and dilute seawater (50, 20, 10, and 1 vol%), formation brine, shallow aquifer water, deionized water and different crude oil samples were used throughout this study. The crude oil/water/carbonates interactions were also investigated using short and long (50 cm) limestone and dolomite rocks at different wettability and temperature conditions. The aqueous ion interactions were extensively monitored via measuring their concentrations using advanced analytical techniques. The activity of the free ions, complexes, and ion pairs in aqueous solutions were simulated at high temperatures and pressures using OLI electrolyte simulation software. Dilute seawater decreased the residual oil saturation in some of the coreflood tests. Hydration and dehydration processes through decreasing and increasing salinity showed no impact on calcite wettability. Effect of individual ions (Ca, Mg, and Na) and dilute seawater injection on oil recovery was insignificant in compare to the dilute surfactant solutions (0.1 wt%). The reaction mechanisms were confirmed to be adsorption of hydroxide ions, complexes and ion pairs at the interface which subsequently altered the surface potential from positive to negative. Results in this study indicate multistage waterflooding can enhance oil recovery in the field under certain conditions. Mixed streams simulation results suggest unexpected ions interactions (NaCO3-1, HSO4-1, NaSO4-1 and SO4-2) with various activities trends especially at high temperatures.