Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

Amphiphilic supramolecular assemblies and their applications in materials and biology

Feng Wang, University of Massachusetts Amherst

Abstract

Amphiphilic assemblies have been extensively used in the past decades. This thesis discusses the design and synthesis of the amphiphilic molecules for the application in stimuli sensitive materials, selective labeling of biomolecules and biomarkers detection. A series of oligomers, containing ethylene glycol moieties, with the same composition of amphiphilic functionalities has been designed, synthesized, and characterized for their temperature sensitive behavior. The non-covalent, amphiphilic aggregates, formed from these molecules influence the temperature sensitivity of these molecules. Moreover, the covalent tethering of the amphiphilic units also has significant influence on their temperature sensitivity. The thermal sensitivity of these oligomers show increasingly sharp transitions with increasing numbers of OEG functional groups, indicating enhanced cooperativity in dehydration of the OEG moieties when covalently tethered. These molecules were also engineered to be concurrently sensitive to enzymatic reaction and pH. ^ Supramolecular assemblies formed by amphiphilic homopolymers with negatively-charged groups in the hydrophilic segment have been designed to enable high labeling selectivity towards reactive side chain functional groups in peptides. The negatively-charged interiors of the supramolecular assemblies are found to block the reactivity of protonated amines that would otherwise be reactive in aqueous solution, while maintaining the reactivity of non-protonated amines. Simple changes to the pH of the assemblies' interiors allow control over the reactivity of different functional groups in a manner that is dependent on the pKa of a given peptide functional group. The labeling studies carried out in positively charged supramolecular assemblies and free buffer solution show that, even when the amine is protonated, labeling selectivity exists only when complementary electrostatic interactions are present, thereby demonstrating the electrostatically controlled nature of these reactions. ^ The charged reverse micelle for peptide selective labeling is expanded to protein engineering. Through the labeling study of myoglobin inside both negatively and positively charged reverse micelles, as well as in free solution, we found that the macromolecules (myoglobin) behave very differently with small peptide. Not only the electrostatic interactions, but also steric effects can control the selective engineering of protein. ^ Our carboxylate-based amphiphilic homopolymer has been used for peptide enrichment and detection, however, there is a shortcoming with this polymer. At acidic condition, the carboxylate polymer is not desirable system. The analysis of the problem and the solution for it is demonstrated in this thesis. ^

Subject Area

Organic chemistry

Recommended Citation

Wang, Feng, "Amphiphilic supramolecular assemblies and their applications in materials and biology" (2014). Doctoral Dissertations Available from Proquest. AAI3615459.
http://scholarworks.umass.edu/dissertations/AAI3615459

Share

COinS