The interaction of liposomes with zinc citrate particles for drug delivery on oral bacteria Streptococcus oralis
Başlık:
The interaction of liposomes with zinc citrate particles for drug delivery on oral bacteria Streptococcus oralis
Yazar:
Catuogno, Christelle Jacquie Jeannine, author.
ISBN:
9780438043398
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (286 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
The interaction of liposomes with zinc citrate particles was investigated. Liposomes were prepared using the extrusion technique. Anionic and cationic liposomes were composed of a mixture of dipalmitoylphosphatidylcholine (DPPC) and phosphatidyl inositol (PI) (30 mg in 3 ml PBS) and a mixture of DPPC, cholesterol and dimethyldioctadecylammonium bromide (DDAB) (38 mg in 3 ml PBS). Liposome adsorption was undertaken using a solution depletion method and data were fitted with a Langmuir isotherm. Adsorption was found to be dependent on the amount of charged lipid used and on the pH of experimentation. The cationic liposomes bind optimally when the composition contains 9 mol% DDAB and when the pH is alkaline. Anionic liposomes adsorption increases with the PI concentration and with increasing solution acidity. Ionic and hydrophobic forces lead the adsorption process. Thermodynamics data have indicated that the Gibbs energy for adsorption varied from -44.3 kJ.mol-1 (9 mol% DDAB, pH 2.8) to -56.2 kJ.mol-1 (9 mol% DDAB, pH 8.5). An approach to understanding the mechanism of adsorption was carried out by encapsulating radiolabelled glucose in the liposomes and by measuring the glucose released. Most liposomes adsorb intact on zinc citrate particles as only about 10% of the liposomes disrupted. Approximately one monolayer of intact liposomes was found to cover the solid surface. Stability of solid supported vesicles and free liposomes were compared in the presence of ionic and non ionic surfactants. The stability was analysed by measuring the release of liposome contents (14C-glucose). In all cases, the solid supported vesicles released less glucose than the free liposomes. Free liposomes and solid supported vesicles were targeted to S. oralis biofilm. The compositions for optimum targeting of the free liposomes were found to be 19 mol% PI/DPPC and 19 mol% DDAB/chol/DPPC. In the case of solid supported vesicles, targeting increased with the amount of lipid bound on the solid surface. The encapsulation of benzyl penicillin in the aqueous compartment of the liposomes and Triclosan in the bilayer was investigated. The optimum entrapment efficiency (about 20 %) was obtained when 15 % w/w of drug was added to the initial lipid mixture. The antibacterial properties of liposomes, drugs and particles were then checked on S. oralis biofilm. The biofilms were prepared by incubating cells in the exponential phase in immunological plates. The different antibacterial systems were left in contact with the biofilm for one hour and the cells were allowed to regrowth in nutrient broth at 37°C. Both drugs were found effective against S. oralis when used at a concentration above 125 mu/ml. Empty liposomes did not show antibacterial properties. Zinc citrate particles (5% w/v) were found to be very efficient against S. oralis regrowth principally because of the effect of the zinc ion present in the aqueous part of the dispersions. A more diluted particles dispersion did not show comparable effects. Combinations of drugs and liposomes, drugs and particles or liposomes and particles were also added to the biofilm. It was found than none of the combinations were as effective as the systems used alone. This is indicating that the systems were competing to reach the active sites on the bacteria and the competition resulted in lowering the bactericide effect of the particles. In other work this property could be used as a protective tool against possible particle or drug toxicity.
Notlar:
School code: 1543
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684276.1) | 684276-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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