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Evolution of Mechanical Properties f...

O'Neill, Sean C.

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Evolution of Mechanical Properties for Stimuli-Responsive Peptide-PEG Bioconjugates.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Evolution of Mechanical Properties for Stimuli-Responsive Peptide-PEG Bioconjugates./
作者:	O'Neill, Sean C.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
面頁冊數:	152 p.
附註:	Source: Dissertations Abstracts International, Volume: 80-08, Section: B.
Contained By:	Dissertations Abstracts International80-08B.
標題:	Bioengineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10930899
ISBN:	9780438826205

Evolution of Mechanical Properties for Stimuli-Responsive Peptide-PEG Bioconjugates.
O'Neill, Sean C.

Evolution of Mechanical Properties for Stimuli-Responsive Peptide-PEG Bioconjugates. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 152 p.

Source: Dissertations Abstracts International, Volume: 80-08, Section: B.

Thesis (Ph.D.)--The City College of New York, 2018.

This item must not be sold to any third party vendors.

The limitations to many biomedical procedures include the need for biocompatible donor materials, and surgical processes required for implantation. Stimuli-responsive molecules that self-assemble in vivo present just one of several potential solutions through the development of injectable biomaterials that form compatible tissue engineered hydrogels. This requires an understanding of hydrogel mechanical properties that govern the dynamics of cellular differentiation and proliferation. In this work, we designed a peptide conjugated poly-ethylene glycol (PEG) bioconjugate system that allow us to examine the intra- and inter-molecular dynamics of gelation. We measured the kinetics of gelation for end-functionalized linear- and star-architectures and correlate the gelation behavior with the molecular structure and self-association. The 23-amino acid peptide sequence is known to form a coiled-coil structure as a function of the solution's electrolyte concentration, and the two topologies of the PEG are peptide end-functionalized to examine formation of supramolecular assemblies. Subsequently, microrheology was used to evaluate the dynamics of self-assembly and the gelation timescales. These gelation timescales for our ion-responsive peptide bioconjugates were further evaluated for the dynamics of the sol-gel transition in increasingly chaotropic (Cl- < Br- < I-) environments. Our key findings were non-intuitive, we observe the evolution of the gel transitions faster in systems with more chaotropic anions. For our peptides in aqueous solution, we observed a reverse Hofmeister series effect where "water-breaking" ions yield faster intermolecular interactions along with a viscoelastic exponent, n, closer to unity representing self-assemblies that were Rouse-like. In contrast, ions that were "water-structuring" resulted in smaller viscoelastic exponents, where self-assembly dynamics resulted in more pronounced polymer entanglements. Furthermore, we were able to show that the dynamics of peptide folding and assembly for linear-PEG conjugated systems yield a percolated network, but the star-PEG conjugated systems yield discrete assemblies and remain viscous. Our results suggest that the degree of intra- and inter-molecular folding defines the critical gel behavior of the supramolecular system, while gelation rates can be influenced by ion-peptide interactions with the surrounding environment. Lastly, we aimed to characterize the self-assembly of peptide amphiphiles consisting of peptide chains connected to hydrophobic lipid tails, that are widely used in synthetic biocompatible hydrogel formation. Here, we wish to draw parallels between peptide secondary structure and hydrophobicity. Like the peptide-PEG conjugates, these amphiphilic structures also fold and self-assemble in response to changes in the surrounding environment. However, we have concluded that the peptide amphiphile self-assembly that occurs as a network of cross-linked fibers follows a different mechanism than the percolataion self-assembly yielded by out peptide-PEG conjugates.

ISBN: 9780438826205Subjects--Topical Terms:

657580
Bioengineering.
Subjects--Index Terms:

Biomolecules

Evolution of Mechanical Properties for Stimuli-Responsive Peptide-PEG Bioconjugates.
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500 $a Publisher info.: Dissertation/Thesis.
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502 $a Thesis (Ph.D.)--The City College of New York, 2018.
506 $a This item must not be sold to any third party vendors.
520 $a The limitations to many biomedical procedures include the need for biocompatible donor materials, and surgical processes required for implantation. Stimuli-responsive molecules that self-assemble in vivo present just one of several potential solutions through the development of injectable biomaterials that form compatible tissue engineered hydrogels. This requires an understanding of hydrogel mechanical properties that govern the dynamics of cellular differentiation and proliferation. In this work, we designed a peptide conjugated poly-ethylene glycol (PEG) bioconjugate system that allow us to examine the intra- and inter-molecular dynamics of gelation. We measured the kinetics of gelation for end-functionalized linear- and star-architectures and correlate the gelation behavior with the molecular structure and self-association. The 23-amino acid peptide sequence is known to form a coiled-coil structure as a function of the solution's electrolyte concentration, and the two topologies of the PEG are peptide end-functionalized to examine formation of supramolecular assemblies. Subsequently, microrheology was used to evaluate the dynamics of self-assembly and the gelation timescales. These gelation timescales for our ion-responsive peptide bioconjugates were further evaluated for the dynamics of the sol-gel transition in increasingly chaotropic (Cl- < Br- < I-) environments. Our key findings were non-intuitive, we observe the evolution of the gel transitions faster in systems with more chaotropic anions. For our peptides in aqueous solution, we observed a reverse Hofmeister series effect where "water-breaking" ions yield faster intermolecular interactions along with a viscoelastic exponent, n, closer to unity representing self-assemblies that were Rouse-like. In contrast, ions that were "water-structuring" resulted in smaller viscoelastic exponents, where self-assembly dynamics resulted in more pronounced polymer entanglements. Furthermore, we were able to show that the dynamics of peptide folding and assembly for linear-PEG conjugated systems yield a percolated network, but the star-PEG conjugated systems yield discrete assemblies and remain viscous. Our results suggest that the degree of intra- and inter-molecular folding defines the critical gel behavior of the supramolecular system, while gelation rates can be influenced by ion-peptide interactions with the surrounding environment. Lastly, we aimed to characterize the self-assembly of peptide amphiphiles consisting of peptide chains connected to hydrophobic lipid tails, that are widely used in synthetic biocompatible hydrogel formation. Here, we wish to draw parallels between peptide secondary structure and hydrophobicity. Like the peptide-PEG conjugates, these amphiphilic structures also fold and self-assemble in response to changes in the surrounding environment. However, we have concluded that the peptide amphiphile self-assembly that occurs as a network of cross-linked fibers follows a different mechanism than the percolataion self-assembly yielded by out peptide-PEG conjugates.
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650 4 $a Polymer chemistry. $3 3173488
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653 $a Conjugates
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653 $a Microrheology
653 $a Peptides
653 $a Polymers
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