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Date of Award

2007

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)

Department

Pharmaceutical and Chemical Sciences

First Advisor

Xin Guo

First Committee Member

Bhaskara R. Jasti

Second Committee Member

Vyacheslav V. Samoshin

Abstract

Acid-sensitive liposome has drawn much interest as drug and gene carriers that release payloads specifically at the low-pH target sites, such as in solid tumors, tissues with inflammation, and ischemia sites. Also, it helps drug/gene to escape endosome trapping and followed lysosome degradation.

The goal of this thesis research is to develop novel trans-2-aminocyclohexanols based lipids and their liposome that can be switched by mildly acidic pH. NMR study · show that in certain acidic medium, the amine group on cyclohexane will attract proton and form hydrogen bond with the neighboring -OH. This change will force the bonds switch to from equatorial conformation to axial conformation. This conformational change is transmitted by the structure of the molecular, and induces consequently dramatic conformational change of the two long lipid tails. Fluorescence leakage assay was conducted on liposomes that encapsulated with ANTs/DPX fluorescence dyes. For certain special designed cyclohexane compounds, the pH triggered lipid conformation change will rupture liposome membrane, release the encapsulated content, and thus help them escape lysosome degradation. This would in tum improve the efficiency of liposome drug delivery and gene transfection.

Luciferase gene transfection was conducted on B16F10 cultured cells. The lipoplex comprising trans-2-aminocyclohexanollipid 1 significantly enhanced the Luciferase gene expression. The gene transfection efficiency correlated well with the pH-triggered membrane-rupture in the trans-aminocyclohexanol-based lipoplexes.

Pages

107

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