| Self-assembly has become a powerful tool for fabricating abundant functional materials with novel structures and attracted increasing attention in the fields of nanoreactors, sensors and delivery of biomolecules. Porphyrins are important fluorescent agents and photosensitizers(PSs) not only in life science research but also technology field. Block copolymers are widely used in materials science and life medical field due to their advantages of designable in structure and composition, controllable in molecular weight. Thus, it is possible to unite the advantages of porphyrins and block copolymers based on their self-assembly aggregates, and contribute for development advanced functional materials and exploration the possibility of self-assembled structure. Charged porphyrins play an important role in self-assembly between prophyrins and block copolymers through the electrostatic interaction. In this dissertation, the ability of producing singlet oxygen(1O2) has be controlled successfully in complexes system based on the electrostatic interaction between 5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrin(TPPS) and two kinds of block copolymers. Meanwhile, the following results are successfully realized: the new insight for preparation well-defined morphology; the useful pathway for monitoring of the PDT process in real-time or visualization.(1) As one of the most important photosensitizers, pophyrins, play the key role in the process of photosynthetic energy conversion and possess unique advantages due to their ability to be retained in tumors and to produce cytotoxic singlet oxygen upon exposure to an appropriate wavelength of light. When overproduced or the levels of antioxidants become seriously depleted, the high quantity of singlet oxygen may cause oxidative stress through the oxidation of biomolecules, which may result in diseases and aging. Suppressing the overproduction of harmful active oxygen species is very important. We report that the production of singlet oxygen from TPPS can be reduced upon the formation of polyion micelles with PMVP41-b-PEO205 at a lower concentration. The amount of singlet oxygen can be controlled successfully, even at the same ionic strength in biological environment, which affords a new thinking of disease treatment and oxidation resistance of cells. In addition, helix structures with well-defined morphology have been prepared at a higher concentration, this result brings more insight for self-assembly of prophyrins and more possibility for advanced chiral functional materials.(2) Recently, porphyrins have been widely used in photodynamic therapy(PDT) due to high-efficiency photosensitization ability and special targeted to tumors. Porphyrins also possess excellent fluorescence properties. However, it is difficult to achieve both functions within one porphyrin nanostructure due to the limited overall quantum yield resulting from the same group of excited porphyrin molecules. In these chapters, we report a novel design of a perturbed porphyrin self-assembly self-assembled by TPPS and block polyelectrolyte PG13-b-PEO230-b-PG13, which exhibits high fluorescence intensity and demonstrates impressive PDT efficacy toward cancer cells. The aggregates have well-defined morphology of square nanorods/nanoplates but no ordered molecularly packing of TPPS. The former allows the satisfactory cellular affinity and accurate intracellular localization while the latter in the nanostructures leads to the appreciable fluorescence emission for bio-imaging and highly efficient singlet oxygen generation which is critical for the photodynamic therapy. As a result, self-light-up PDT can be achieved with a single light exposure to the perturbed porphyrin nanostructures, which makes them an attractive self-light-up PDT agent to eliminate cancer cells. The perturbed porphyrin self-assembly thus represents a facile but potent path toward a new class of PDT agents that hold great promise in real-time monitoring of the PDT process through the self-light-up fluorescence imaging. |
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