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Title:Self-organized nanostructures for the design of bioinspired anti-biofouling interfaces
Author(s):Arias Suarez, Sandra Liliana
Director of Research:Allain, Jean Paul
Doctoral Committee Chair(s):Allain, Jean Paul
Doctoral Committee Member(s):Pan, Dipanjan; Underhill, Gregory H.; Sirk, Shannon J.
Department / Program:Bioengineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):bacteria cell mechanics, nanocones, bactericidal, self-assembly, bacterial cellulose, hydrogel, low-energy ion beam irradiation
Abstract:Device-associated infections are one of the deadliest complications accompanying the use of biomaterials, and despite recent advances in the development of anti-biofouling strategies, biomaterials that exhibit both functional tissue restoration and antimicrobial activity have been challenging to achieve. Oral antibiotics are the gold standard to treat patients suffering from device-associated infections; unfortunately, intense antimicrobial exposure is one of the leading causes of multidrug-resistant microorganisms. Similarly, and even though nanoparticles have gained attention due to their broad-spectrum activity, the potentially toxic accumulation of nanoparticles in tissues like kidney and spleen have limited their extended use in humans, while their long-term effects in the environment remain to be seen. Recent advances in the field have proven that topographical cues at the micro and nanoscale affect the settlement preferences, adhesion strength, and integrity of microorganisms in a variety of biological interfaces in nature. For example, the skin of marine animals that resist high levels of biofouling in seawaters, including the starfish and shark skin, possess microscale features with sizes comparable to those of the fouling microorganisms that limit microbial settlement, swarming motility, and biofilm development. Similarly, nanoscale protrusions like those contained in the cuticles of insects like the dragonfly and cicada wings constitute a recently discovered antimicrobial system that mechanically disrupts the bacterial cell wall via a contact killing mechanism. So far, naturally occurring bactericidal nanotopographies have been mimicked mostly on metals and semiconductors, but much less work has been conducted on providing these properties to clinically relevant polymers. This limitation is probably due to the complexity of obtaining nanopatterns mechanically stable in aqueous environments with precise control of the size in very compliant polymers and hydrogels. In this dissertation, I address the needs for unique nanotopography in hydrogels and clinically relevant polymers by using low-energy singly-charged argon ions. I was able to fabricate high aspect ratio nanocones in a bacterial cellulose hydrogel and developed a semi-empirical model to explain the self-assembly mechanisms involved in nanostructure growth. This model predicts that reactive species in the material at the onset of plasma treatment accelerate the bond-breaking of weak bonds, contributing to the formation of a cross-linked amorphous carbon layer. Inspired by the wings of the dragonfly, I demonstrated that these nanocones imparted bactericidal properties to the hydrogel. By correlating the physical properties of the surface with those of the bacterial envelope, I discovered that a tension-induced mechanism caused the mechanical disruption of the bacterial envelope at the nanocone apexes, which accounted for the bactericidal activity of the hydrogel. Overall, I believe my findings are of importance not only for understanding the interaction of bacteria with material surfaces at the nanoscale but also for the design of anti-biofouling interfaces that are easy to manufacture, do not contribute to bacterial resistance, and do not pollute the environment.
Issue Date:2019-12-06
Rights Information:Copyright 2019 by Sandra L. Arias. All rights reserved.
Date Available in IDEALS:2020-03-02
Date Deposited:2019-12

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