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theses

At the era of high civilization, people are facing elevating amount of negative environmental impacts like polluted air or water, increased UV irradiation, carcinogens and many more. These impacts may lead to accumulation of oxidative stresses in our body which further trigger inflammations and even cancers. Fortunately, researchers found many bioactive phytochemicals could act against these oxidative stresses thus achieve multiple health benefits. However, many of them are not stable, prone to oxidation and heat during storage or productions. Besides, a large number of them have problems in water solubility and absorption. In order to overcome these barriers, various types of delivery systems are developed to encapsulate and protect the phytochemicals, to increase their solubility, bioaccessibility and bioavailability. Nano emulsions may be the most popular delivery systems and are able to significantly increase the solubility of beneficial phytochemicals. Nevertheless, they also came with some disadvantages like emulsion breakage, low encapsulation efficiency, etc. Besides, production of nano emulsion also require large amount of mechanical energy input like high pressure homogenization. Addition of preservatives to the nano emulsions also caused some health concerns. In this research, a novel lipid delivery system called electrosprayed lipid-polymer complex (ELPC) was established. ELPC was fabricated by electrospinning technique for atomizing phytochemicals and other formulation components without high energy consumption or generating noticeable heat. Unlike most of the routine electrospinning process, ELPC was prepared without toxic organic solvents or components that was highly applicable in the real world. More importantly, ELPCs are able to generate self- assembled emulsions when they are in contact with water. Since the ELPCs could be stored in dry condition and able to generate emulsions at the moment of application, they are immune to environmental impacts like ambient temperature fluctuation, physical shocks or bacterial contamination that are fatal to routine emulsions. ELPC was substantiated to achieve effective topical skin delivery of water-insoluble phytochemicals with the ability of anti-oxidation and tyrosinase inhibition, which was quantified by Franz-cell diffusion and visualized by confocal laser microscopy. The self-assembled nano emulsions generated from ELPCs have mean diameters around 300-400 nm by measured by dynamic light scattering. Cellular uptake of phytochemical loaded ELPC emulsion was proven effective against B16F10 melanoma cells. In addition, ELPC could also be adopted as an effective oral delivery system for phytochemicals. Digestion profile and characteristics of the edible ELPC was examined by USP-4 dissolution tester and an in vitro lipolysis assay, which had indicated successful digestion of the ELPC system and improved release of phytochemical comparing to the control. Afterwards, a Caco-2 monolayer membrane transport assay was carried out and proved effective transport of phytochemicals from the digested ELPC through the artificial intestinal monolayer to be able to enter the blood stream.

ETD_8719

Ph.D.

Includes bibliographical references

by Zhenyu Lin

doi:10.7282/T3KW5KGJ

ETD doctoral

The author owns the copyright to this work.