The synthesis, characterization and amphiphilic self-assembly of polymer brush functionalized nanoparticles (PBNPs) using a block copolymer template is described herein. To study the effect of polymer brush composition on self-assembly, four samples were created using a mixture of PS-b-PAA (polystyrene-block-polyacrylic acid) and PMMA-b-PAA (poly(methyl methacrylate)-block-polyacrylic acid) diblock copolymers to create PBNPs with a CdS quantum dot (QD) core and different ratios of PS and PMMA in the coronal brush. Static light scattering showed that despite differences in brush composition, the PBNPs formed nanoparticles of similar aggregation number and chain density but showed evidence of asymmetric structure in a common solvent for both blocks at higher PS contents. After subsequent hydrolysis of the hydrophobic PMMA to hydrophilic poly(methacrylic acid) (PMAA), these amphiphilic particles were then self-assembled in THF/H2O solution in which it was determined that increasing the hydrophobic content of the brush composition, the initial nanoparticle concentration (c0) or the added salt content (RNaCl), would cause the assembly of low curvature assemblies. Compilation of this data allowed for the construction of phase diagrams for PBNP systems based on brush composition and c0 at different salt contents. Lastly, PS-b-PAA-b-PMMA triblock copolymers with variable PMMA chain length were assembled into PBNPs around a CdS QD core using a block copolymer template approach. Light scattering showed these particles also had similar aggregation number and chain density despite the difference in PMMA chain length. After hydrolysis of PMMA to PMAA these particles were then self-assembled in THF/H2O mixtures to determine the role of PMAA block length on the produced morphological structures. The resulting assemblies suggest that chain length played a minimal role in their self-assembly / Graduate / 2018-09-15

The self-assembly peptide hydrogels used as tissue culture scaffolds have drawn great attention in recent years. They have the advantages of natural polymer hydrogels including biocompatibility, biodegradability and the advantages of synthetic materials such as controlled structural properties and mechanical properties. Furthermore, the bioactive ligands which can promote bioactivities and control cell behaviours can be easily introduced to the peptide backbone through peptide synthesis. One particular self-assembly FEFEFKFK peptide was chosen in this project.FEFEFKFK peptide used in this project has been reported to self-assemble in solution, forming hydrogels with a 3D fibrous network structure above a critical gelation concentration. In this project, the self-assembly and gelation properties of FEFEFKFK peptide were further investigated, assessing the effect of pH and ionic strength on the self-assembly and gelation behaviour. The biomimetic nanofibrous hydrogels of FEFEFKFK were also assessed for their ability to support human dermal fibroblast cells. The protocols of gel preparation were developed for both 2 dimensional (2D) and 3 dimensional (3D) cell culture. A short peptide sequence homoarginine-glycine-aspartate (hRGD) has been introduced onto the amide end of the self-assembly peptide instead of bioactive ligand arginine-glycine-aspartate (RGD), creating hydrogels with a fibrous network with functionalised groups at the fibre surface. The functionalised peptide hydrogels enhanced cell adhesion on gel surface, with cell interaction assessed using various imaging and spectroscopic techniques. A preliminary 3D cell culture study also showed potential of these peptide gels to be used for encapsulated human dermal fibroblast cell studies.

This research work examines the process of block copolymer membrane fabrication by self-assembly combined by non-solvent induced phase separation. Self-assembly takes place from the preparation of the primordial solution until the moment of immersion in a non-solvent bath. These mechanisms are driven thermodynamically but are limited by kinetic factors. It is shown in this work how the ordering of the assembly of micelles is improved by the solution parameters such as solvent quality and concentration of block copolymer. Order transitions are detected, yielding changes in the morphology. The evaporation of the solvents after casting is demonstrated to be essential to reach optimum membrane structure. The non-solvent bath stops the phase separation at an optimum evaporation time.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17891号 / 工博第3800号 / 新制||工||1581(附属図書館) / 30711 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 秋吉 一成, 教授 金谷 利治, 准教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Self-assembly is an autonomous process where components organize themselves into structures via noncovalent interactions without human intervention. Ultrashort amphiphilic peptides are typical self-assembly molecules with specific sequence motifs which consist of three to seven amino acids. Due to their amphiphilic structure which carries a dominant hydrophobic tail and a polar head group, these peptides can self-assemble to construct nanofibrous scaffolds system to form hydrogels, organogels or aerogels. The nanofibrous scaffolds formed by amphiphilic peptides are very similar to the fiber structure found in collagen which plays an essential role in extracellular matrix showing the potential of applying these peptide scaffolds together in culturing native human cells. Thus the derivate of amphiphilic peptides depsipeptide in which we replaced one amide bond with an ester bond is also worthwhile to explore a novel penitential material for Tissue Engineering. At the same time, because of the perfect biocompatibility of amphiphilic peptides made up of natural l-amino acids and also the excellent gelation properties providing a solution for zinc dendrite growth in Zn batteries, it will be also meaningful to combine the rationally designed peptide gelation system to Zn batteries. This dissertation describes how to characterize and use ultrashort amphiphilic depsipeptide for tissue engineering and use ultrashort amphiphilic peptide for the electrolyte of Zn batteries. The first chapter provides us with an introduction to self-assembly material, 3D bioprinting, and Zn batteries. The second chapter introduces a novel method to synthesize the depsipeptide fully based on solid phase peptide synthesis (SPPS) and also shows the different properties, especially the gelation behavior by clarifying its mechanism via doing the characterization of depsipeptide. At the end of the second chapter, depsipeptide is proved to be a potential material in 3D bioprinting. The third chapter reveals how we synthesized and characterized the amphiphilic peptide and applied it to the Zn batteries. The cycling stability got promoted compared with bard Zn batteries in symmetrical Zn-Zn cells while the formation of Zn dendrite was also suppressed. The promising results suggest peptide gelation systems are promising electrolytes for use in Zn batteries.

No description available.

No / Peptides that self-assemble into nanostructures are of tremendous interest for biological, medical, photonic and nanotechnological applications. The enormous sequence space that is available from 20 amino acids probably harbours many interesting candidates, but it is currently not possible to predict supramolecular behaviour from sequence alone. Here, we demonstrate computational tools to screen for the aqueous self-assembly propensity in all of the 8,000 possible tripeptides and evaluate these by comparison with known examples. We applied filters to select for candidates that simultaneously optimize the apparently contradicting requirements of aggregation propensity and hydrophilicity, which resulted in a set of design rules for self-assembling sequences. A number of peptides were subsequently synthesized and characterized, including the first reported tripeptides that are able to form a hydrogel at neutral pH. These tools, which enable the peptide sequence space to be searched for supramolecular properties, enable minimalistic peptide nanotechnology to deliver on its promise.

No / Discovery of new catalysts for demanding aqueous reactions is challenging. Here, we describe methodology for selection of catalytic phages by taking advantage of localized assembly of the product of the catalytic reaction that is screened for. A phage display library covering 109 unique dodecapeptide sequences is incubated with nonassembling precursors. Phages which are able to catalyze formation of the self-assembling reaction product (via amide condensation) acquire an aggregate of reaction product, enabling separation by centrifugation. The thus selected phages can be amplified by infection of Escherichia coli. These phages are shown to catalyze amide condensation and hydrolysis. Kinetic analysis shows a minor role for substrate binding. The approach enables discovery and mass-production of biocatalytic phages.

No / We demonstrate the self-assembly of bola-amphiphile-type conjugates of dipeptides and perylene bisimide (PBI) in water and other polar solvents. Depending on the nature of the peptide used (glycine-tyrosine, GY, or glycine-aspartic acid, GD), the balance between H-bonding and aromatic stacking can be tailored. In aqueous buffer, PBI-[GY]2 forms chiral nanofibers, resulting in the formation of a hydrogel, while for PBI-[GD]2 achiral spherical aggregates are formed, demonstrating that the peptide sequence has a profound effect on the structure formed. In water and a range of other polar solvents, self-assembly of these two PBI-peptides conjugates results in different nanostructures with highly tunable fluorescence performance depending on the peptide sequence employed, e.g., fluorescent emission and quantum yield. Organogels are formed for the PBI-[GD]2 derivative in DMF and DMSO while PBI-[GY]2 gels in DMF. To the best of our knowledge, this is the first successful strategy for using short peptides, specifically, their sequence/structure relationships, to manipulate the PBI nanostructure and consequent optical properties. The combination of controlled self-assembly, varied optical properties, and formation of aqueous and organic gel-phase materials may facilitate the design of devices for various applications related to light harvesting and sensing.