Investigation Of The Properties Of Surfactant Aggregates And The Application As Drug Delivery

Surfactant molecules can form a variety of associative structure, lyotropic liquid crystalline phase (LLC) and microemulsions are widely used in recent years. As the abundant of structures, LLC is studied widely and applied in several fields, such as synthesis, houseproduction, foods, pharmaceutics, and so on. Microemulsions are clear, thermodynamically stable, isotropic mixtures of oil, water and surfactant, frequently in combination with a cosurfactant. Microemulsions which have small particle size, penetration ability, good solubilization and targeting, are widely used in pharmaceutical engineering, nano-materials preparation, pesticide spraying, fuel, cosmetics and enhanced oil recovery and other fields. In order to expand the application of LLC and microemulsions as the drug delivery system, we select several non-ionic surfactants and block copolymer molecules which have low toxicity, and then studied the hemolytic of these types of surfactants and their compounded system. On this basis, the pseudo-ternary phase diagram of the three lyotropic liquid crystalline systerms and the three microemulsions systerms was drawn based on experimental data. In order to study the steady and dynamic rheological properties of lyotropic crystalline phases, the three lyotropic liquid crystalline phase systerms of C12APG/oleic acid/physiological saline, C12APG/oleic acid/water and C12APG/physiological saline/gernaniol have been observed, with the aid of polarizing optical microscopy and rheological techniques. The structural transformation of the Tween80/isopropanol/ethyl butyrate/physiological saline system, Tween80/EPE/isopropanol/ethyl butyrate/physiological saline system and the Tween80/C12APG/isopropanol/ethyl butyrate/physiological saline system were studied by cyclic voltammetric and conductivity measurements. Furthermore, application in drug carrier study of these systerms has been investigation. All these results will enrich the surfactant researches both theoretically and practically. In details, the thesis includes five chapters as following:1. Properties of lyotropic liquid crystalline and microemulsions.The properties and applications of lyotropic liquid crystals, lamellar, hexagonal and cubic phases are summarized. The structure and applications of microemulsion were also overviewed. Significance and various types of mixed surfactants systems were introduced Study on lyotropic liquid crystals and microemulsions of alkypolyglucosides and polyoxyethylene surfactants for drug delivery system purpose is rather limited. Therefore, the main properties of lyotropic liquid crystals and microemulsions systems have been studied in the third, fourth parts of the thesis.2. Hemolytic Action of Surfactants and the exploration of low-hemolytic systerms.In this chapter we first introduce the hemolytic action of various surfactants and the hemolysis test, the mechanism of hemolysis, the resistance to hemolysis and the descending to hemolysis. We studied the hemolytic action of alkypolyglucosides and polyoxyethylene surfactants using fresh rabbit blood. The results show: First, at the same concentration, both Tween80 and EPE can reduce the hemolytic action of APG, but from the general trend, Tween80 makes the hemolytic action to be calm, and EPE makes the hemolytic action to be clear. Second, when Tween80 and EPE were coexist, Tween80 plays a leading role. Tween80, EPE and APG are all nonionic surfactant, at low concentration, they all play low hemolysis activity, so we can consider to use them in pharmaceutical industry.3. Phase behavior and rheological properties of liquid crystalline phases formed in nonionic surfactant APG systems.In this chapter the Phase behavior and rheological properties of the three lyotropic liquid crystalline phase systerms of C12APG/oleic acid/physiological saline, C12APG/oleic acid/water and C12APG/physiological saline/gernaniol have been observed using oleic acid and gernaniol as accessories. The pseudo-ternary phase diagrams of C12APG/oleic acid/physiological saline, C12APG/oleic acid/water and C12APG/physiological saline/gernaniol systerms were drawn at 37oC, and then they were studied by the aid of polarizing optical microscopy and rheological techniques. The results show that the three lyotropic liquid crystallines were all lamellar.4. Phase behavior and the structural transformation of microemulsions in nonionic surfactant Tween80 systems.In this chapter the Phase behavior and the structural transformation of the three microemulsions of Tween80/isopropanol/ethyl butyrate/physiological saline system, Tween80/EPE/isopropanol/ethyl butyrate/physiological saline system and the Tween80/C12APG/isopropanol/ethyl butyrate/physiological saline system have been observed. The pseudo-ternary phase diagrams of Tween80/isopropanol/ethyl butyrate/physiological saline system, Tween80/EPE/isopropanol/ethyl butyrate/physiological saline system and the Tween80/C12APG/isopropanol/ethyl butyrate/physiological saline system were drawn at 37oC, then the structural transformation of them were studied by cyclic voltammetric and conductivity measurements. The results show that the structural transition from a water-in-oil microemulsion at low brine content to a bicontinuous structure at intermediate brine content and a structure of oil-in-water at high brine content happened completely continuously.5. The release kinetics of curcumin in APG lyotropic liquid crystals and Tween80 microemulsions.Both lyotropic liquid crystals and microemulsions have many characteristics: thermodynamic stability, similarity to bio-membrane, embedding and long-time releasing drugs, protecting the drugs in it and so on. so they have attracted increasing interests as drug carrier. The studies on lyotropic liquid crystals and microemulsions as drug delivery systems are involved in this chapter. The results show that both the lyotropic liquid crystals and microemulsions as carriers produced sustained release to curcumin.