The Phase Diagram Studies On The Surfactant Aggregates Formation And The Application As Drug Delivery

The self-assembled structures of amphiphile molecules in solvents, such as vesicle, micelle,micoremulsion, and lyotropic liquid crystalline phase (LLC) etc. Microemulsions have attractedmore and more attention, As the abundant of structures, microemulsions which have is studiedwidely and applied in several fields, such as foods, pharmaceutics, synthesis, preparation ofnano-materials, cosmetics, enhanced oil recovery and so on. In order to expand the application ofmicoremulsions as the drug delivery system, The phase transformation of the polyoxyethylene (10)n-oleyl ether Brij97 microemulsion systems were investigated by electric conductivity method and cyclicvoltammetry. In these investigations, varied special solvents have been focused, includingpharmaceutically accepted excipients like acetic acid esters, alcohols. Interesting and noticeableconclusions were obtained. Furthermore, application in drug carrier study of these systems havebeen investigation. In details, the thesis includes four chapters as following:Chapter I. IntroductionThe structure and characteristic of microemulsions and lyotropic liquid crystals were alsooverviewed. And the formation mechanism of microemulsion was introduced in detail:Instantaneous negative interfacial tension theory, Double film theory, Geometry theory, R ratiotheory. The research method of microemulsions were introduced in detail: Phase diagram,cyclic voltammetric and conductivity measurements. Summary of the research progress ofmicroemulsion-based the drug delivery systems. Study on microemulsions of oxyethylenatedsurfactants for drug delivery system purpose is rather limited. Therefore, as the main propertiesof microemulsions in POE surfactant Brij97 ternary systems have been studied in the second,third parts of the thesis. The release behavior of curcumin in the Brij97 microemulsion systemswere measured by uv-vis spectrophotometer in the four parts of the thesis. It is expected that the results of present study will be useful in pharmaceutical and related applications.Chapter II. Studies on the phase behavior of the microemulsion formed bynonionic surfactant Brij97 systems.The phase diagrams of the pseudo-ternary-component of Birj97/ isopropyl alcohol/ isoamylacetate/water systems were studied by dilution method at 25oC. It is found that there is asignificant effect of cosurfactant-to-surfactant mass ratio , Km = Walcohol/ WBirj97, on the area ofthe microemulsion region. Microemulsification is also dependent on chain length ofcosurfactants and oils.1. The maximum area of microemulsion region occurs at Km = 1 for investigatedcosurfactants over investigated Km value range.2. Effect of oils on the phase behavior of Brij97/ isopropyl alcohol / acetic ester /H2Osystems at Km = 1. The longer the carbon chain length of ester is, the more the alcohol andsurfactant needed to form phase microemulsion is. The solubilization power order is ethyl acetate>butyl acetate> n-amyl acetate≈isoamyl acetate> n-octyl acetate.3. Effect of cosurfactants on the phase behavior of Brij97/ alcohol/ isoamylacetate /H2Osystems at Km = 1. The solubilization power order is ethanol >isopropyl alcohol> 1, 2-propyleneglycol > polyethylene glycol。4. The solubilization of Birj97 microemulsion systems at different oil/water ratios.Thesolubility of the alcohol in the microemulsion system increases as theαvalues increase. Thevolatilization ability of the microemulsion system on water and oil decrease as theαvaluesbecomes larger.Chapter III. The phase transformation of the Brij97 microemulsion systemswere investigated by electric conductivity method and cyclic voltammetry.The structure of microemulsion the Brij97/isopropyl alcohol/ butyl acetate/watermicroemulsion system was investigated by electric conductivity method and cyclic voltammetry.The structure of microemulsion the Brij97/alcohol/acetate/water microemulsion systems alsowere investigated by electric conductivity method. The experimental results obtained indicate that the system of low toxicity can form a larger single-phase microemulsion region. Withincreasing water content, the phase transformation from water droplets in oil (W/O) to abicontinuous structure (B.C.) and a structure of oil droplets in water (O/W) happens completelycontinuously in the single-phase microemulsion region. The cyclic voltammetry results are foundto be inagreement with that of conductivity measurements.Chapte IV. The curcumin release behavior of different Brij97 microemulsionsystems.Microemulsion as drug carriers can give these active molecules good cell membranepermeability, solubility, and stability as well as physical properties such as encapsulation, slowrelease drug and protect the encapsulation of advantages,so it has attracted increasing interests asdrug carrier. In this chapter, The studies on four Brij97 / isopropyl alcohol / acetic ester / watermicroemulsion systems as drug delivery are involved. The results show that Brij97microemulsion systems as carriers produced sustained release to curcumin.