2026-09-19T20:27:08Zhttps://dspace.mit.edu/server/oai/request

oai:dspace.mit.edu:1721.1/958622026-06-17T14:44:24Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022

Joanna Aizenberg. Friedlander, Ronn S. (Ronn Samuel) Harvard--MIT Program in Health Sciences and Technology. Harvard University--MIT Division of Health Sciences and Technology 2015-03-05T15:57:20Z 2015-03-05T15:57:20Z 2014 2014 http://hdl.handle.net/1721.1/95862 904049681 Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2014. Cataloged from PDF version of thesis. Includes bibliographical references. Biofilms-surface-bound communities of microbes-are a major medical concern, as they can be sources of infection that are difficult to eradicate. Their formation starts with the attachment of bacteria to available surfaces-often implantable biomaterials. The development of materials that prevent bacterial adhesion is therefore of paramount importance, and it requires a thorough understanding of the materials and bacterial surface properties that enable adhesive interactions. We herein design model surfaces and examine the interplay between micro-scale geometry, surface energy and bacterial surface properties with respect to adhesion, with the ultimate goal of understanding bacterial adhesion in structured environments, and establishing principles for design of novel surfaces that effectively repel bacteria. We first study adhesion of Escherichia coli to engineered surfaces possessing superficially unfavorable geometries. We show that cells can overcome geometric constraints with the aid of flagella, which are able to reach between narrow crevices, thus improving adhesion and expanding the range of surfaces to which cells can adhere. We examine binding of purified flagella to abiotic surfaces by means of quartz crystal microbalance (QCM) and show that flagella bind preferentially to hydrophobic surfaces, yet they do not appreciably bind to hydrophilic surfaces. Using mutant strains, we investigate the role of flagella in surface attachment of live cells and demonstrate that flagellated cells adhere best to hydrophobic substrates; however flagella may impede cell adhesion to hydrophilic surfaces. To further explore hydrophilic, structured environments with physiological relevance, we examine mucin-a natural hydrogel that typically harbors microbes in animals, while protecting the host. We purify mucins and use them in their native, three-dimensional configuration to probe bacterial swimming behavior and surface attachment in their presence. We demonstrate that mucins maintain-and possibly enhance-swimming ability for E. coli and Pseudomonas aeruginosa, and show that they greatly reduce adhesion to underlying substrates. Finally, we build on our established design principles and construct anti-adhesive surfaces by combining hydrophilic chemistries with topographic features smaller than cellular dimensions. This work suggests a path toward anti-adhesive materials that may be optimized for mechanical robustness, longevity and specific environments of application. by Ronn S. Friedlander. Ph.D. 160 pages eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Harvard--MIT Program in Health Sciences and Technology. Bacterial adhesion in structured environments Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="8e1597b7-fb36-43ef-8581-c2bc1d756e38"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Bacterial adhesion in structured environments</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2014</PublicationDate> <Authors> <Author> <DisplayName>Friedlander, Ronn S. (Ronn Samuel)</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Harvard--MIT Program in Health Sciences and Technology.</Keyword> <Abstract>Biofilms-surface-bound communities of microbes-are a major medical concern, as they can be sources of infection that are difficult to eradicate. Their formation starts with the attachment of bacteria to available surfaces-often implantable biomaterials. The development of materials that prevent bacterial adhesion is therefore of paramount importance, and it requires a thorough understanding of the materials and bacterial surface properties that enable adhesive interactions. We herein design model surfaces and examine the interplay between micro-scale geometry, surface energy and bacterial surface properties with respect to adhesion, with the ultimate goal of understanding bacterial adhesion in structured environments, and establishing principles for design of novel surfaces that effectively repel bacteria. We first study adhesion of Escherichia coli to engineered surfaces possessing superficially unfavorable geometries. We show that cells can overcome geometric constraints with the aid of flagella, which are able to reach between narrow crevices, thus improving adhesion and expanding the range of surfaces to which cells can adhere. We examine binding of purified flagella to abiotic surfaces by means of quartz crystal microbalance (QCM) and show that flagella bind preferentially to hydrophobic surfaces, yet they do not appreciably bind to hydrophilic surfaces. Using mutant strains, we investigate the role of flagella in surface attachment of live cells and demonstrate that flagellated cells adhere best to hydrophobic substrates; however flagella may impede cell adhesion to hydrophilic surfaces. To further explore hydrophilic, structured environments with physiological relevance, we examine mucin-a natural hydrogel that typically harbors microbes in animals, while protecting the host. We purify mucins and use them in their native, three-dimensional configuration to probe bacterial swimming behavior and surface attachment in their presence. We demonstrate that mucins maintain-and possibly enhance-swimming ability for E. coli and Pseudomonas aeruginosa, and show that they greatly reduce adhesion to underlying substrates. Finally, we build on our established design principles and construct anti-adhesive surfaces by combining hydrophilic chemistries with topographic features smaller than cellular dimensions. This work suggests a path toward anti-adhesive materials that may be optimized for mechanical robustness, longevity and specific environments of application.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>