From the green chlorophyll in plants and algae that we depend upon to transform sunlight into useful energy, to the red heme that carries oxygen to the cells in our bodies, porphyrins are the colors of life. It is not surprising then, that porphyrins have been actively interrogated as tools for diverse applications to improve biotechnology and medicine. With the goal of improving cancer therapy and diagnosis in mind, this thesis examines new modular porphyrin architectures. These constructs have interesting properties that extend beyond their originally intended use as phototherapeutic agents. In Chapter 1, a comprehensive background on porphyrin-based activatable photosensitizers is presented. In Chapter 2, porphyrin singlet oxygen and fluorescence quenching is examined in a model system with respect to Förster theory. Chapter 3 examines a new DNA responsive molecular beacon that was quenched using multiple quenching moieties and its application for nanoparticle aggregation. Chapter 4 describes extremely self-quenched nanovesicles formed from porphyrin-lipid conjugates that displayed a number of desirable properties for nanomedicine applications. Chapter 5 presents a brief discussion and some potential future directions of the research. It is my hope that the data presented in this thesis set the stage for new porphyrin-based approaches to make a translational impact in the battle against cancer and other diseases.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 197-212).

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references.

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