| Summary: | 博士 === 國立交通大學 === 材料科學與工程學系所 === 103 === In this dissertation, we have attempted to develop new types of hydrogelators based on aromatic peptide amphiphiles, which are potential materials used for numerous biomedical applications. It is divided into five parts; in the first part, we create a new system for the incorporation of a phenyl/perfluorophenyl pair in the structure of a peptide hydrogelator. The strategy is based on the idea that the integration of an end-capped perfluorophenyl group and a phenylalanine with a phenyl moiety in the side chain forms an intramolecular phenyl/perfluorophenyl pair, which can be used to promote the formation of the supramolecular nanofibers and hydrogels. In this work, we illustrates the importance of structure-hydrogelation relationship and provides new insights into the design of self-assembly nanobiomaterials.
In the second part, we intend to screen the possibility of forming self-assembled hydrogels under physiological pH. Therefore, various molar ratios of the hydrogelators based on pentafluorobenzyl-phenylalanine (PFB-F) and pentafluorobenzyl-diphenylalanine (PFB-FF) were studied. The equimolar ratio of PFB-F and PFB-FF formed coassembled nanofibers and the self-supporting hydrogel at the physiological pH of 7.4. The spectroscopic characterization of the blend gel indicates the ππ interactions and hydrogen-bonding interactions are the major driving forces behind the coassembly. In addition, we also prove that the blend hydrogel is biocompatible, thus making it a scaffolding material for biomedical applications. In this work, the utility of two distinct hydrogelators to promote the coassembly under physiological condition expands the repertoire of noncovalent interactions that can be used in the development of sophisticated noncovalent biomaterials.
In the third part, we study a new aromatic-capped peptide amphiphile which is able to form a supramolecular hydrogel under neutral pH. This hydrogel can also be obtained by enzymatic transformation from the hydrogelator precursor. The newly discovered hydrogel has excellent biocompatibility for four different cell lines, thus making it a potentially useful scaffolding material for biomedical applications.
In the fourth part, we focus on the visualizing interactions between cells and scaffolds. There are many self-assembled nanofibers with smaller diameter than 30nm, which cause the consequence of unclear images in cell and material interactions. Therefore, we have synthesized naphthaleneimide-phenylalanine (NI-Phe) with capable of fluorescence fibers and demonstrated that NI-Phe hydrogel is able to provide a means of visualizing live cell-scaffolding through a confocal microscopy. In this work, we display a new bottom-up design of hydrogel and assist the development of live cell imaging in three-dimensional enviroments without post-doping approach.
In the last part, we studied a series of different aromatic dipeptide hydrogels. The characteristics of hydrogels and biocompatibility were studied. In addition, we were interested in hydrogels as drug carriers. The drug release from hydrogel was performed and the release mechanism of hydrogel was also investigated. Based on a classic exponential equation which have been established by Ritger and Peppas, these results indicated that the drug release behavior was anomalous transportation in 1 h-8 h and changed into Case II transportation after 24 h. Without blended method, we have discovered a potential delivery carrier for slowly drug release.
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