Asymmetric Michael addition of aldehydes to nitroolefins with l-proline and bifunctional organocatalyst combination

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2013
İşibol, Duygu
Since their serendipitously discovery in 1993, hydrogel of self-assembling peptides are becoming an emerging field especially in last 10 years. For their application in selective drug delivery, tissue engineering and biomedical applications, divergent peptide libraries can be constructed through chemical peptide synthesis, utilizing synthetic amino acids addition to 21 naturally occurring ones. One of the methods which were applied to obtain self-assembling peptides is incorporating strongly beta-sheet forming amino acids in the sequence of peptides. These peptides having strong beta-sheet structures can undergo self-assembly and form nano fibers resulting a hydrogel character as a macroscopic property under certain conditions. For the application of hydrogel forming peptides, self-assembly should be stimulus responsive and preferably reversible process. The target of this project is to obtain a light controlled self-assembly and hydrogelation of peptides in order to use in biomedical and biotechnological applications. For this purpose, initially, an azobenzene amino acid derivative that can respond to stimuli synthesized using coupling reaction. After the synthesis, including artificial azobenzene amino acid in the middle of peptide sequence; mainly Lysine (K), Alanine (A) / Phenylalanine (F) and Glutamic acid (E) are preferred among the natural amino acids. It is shown that the peptide composed of those mentioned amino acids can respond light. Utilizing the change in geometry and polarity of azobenzene upon irradiating with light, a control in the self-assembly and hydrogelation of the peptide is the target of this project. With the unique design of this system and its photochemical isomerization, hydrogel structure is disrupted and this feature can be used as a selective drug delivery system.

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Citation Formats
D. İşibol, “Asymmetric Michael addition of aldehydes to nitroolefins with l-proline and bifunctional organocatalyst combination,” M.S. - Master of Science, Middle East Technical University, 2013.