Date of Graduation

5-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Chemical Engineering

Advisor/Mentor

Nayani, Karthik

Committee Member

Beitle, Robert R. Jr.

Second Committee Member

Almodovar, Jorge

Third Committee Member

Szilvasi, Tibor

Fourth Committee Member

Harris, Leonard A.

Fifth Committee Member

Richardson, William

Sixth Committee Member

Wickramasinghe, S. Ranil

Keywords

Liquid crystals; SARS-CoV-2; Liquid Crystalline Assembly of Collagen

Abstract

Liquid crystals (LCs) constitute a subset of soft matter possessing hybrid characteristics from both liquid and crystalline phases. In this state, the center of masses remains uncorrelated similar to an isotropic phase, while the long axis of molecules aligns in parallel, resulting in molecules exhibiting orientational and positional order, either individually or concurrently. The directional alignment inherent in LCs arises from the asymmetrical shape and structure of the constituent molecules, causing a spontaneous self-assembly into ordered phases. This cooperative molecular behavior manifests distinctive optical features when subjected to cross polarizers. The remarkable sensitivity of LCs to external stimuli, including temperature, electric and magnetic fields, and the presence of foreign entities, induces orientational shifts in the constituent molecules, consequently triggering a phase transition. This inherent sensitivity has introduced LCs into a diverse array of biomedical applications, including biosensors, ultra-filtration, and tissue engineering, apart from their extensive in other fields such as electronic displays, soft actuators, and smart windows; to name a few. This dissertation explores three specific applications of LCs, categorized into three aims. Aim 1 includes the development of a Liquid Crystal-Based Sensing Platform designed for the detection of SARS-CoV-2. The result of this aim highlights the efficacy of the sensing cell in detecting the SARS-CoV-2 spike protein. Aim 2 focuses on Liquid Crystal-Templated Membranes featuring nano-porous structures with slit-like pores. These membranes exhibit pores with high aspect ratio, making them conducive to ultrafiltration and nanofiltration applications. The unique benefit lies in achieving a high cut-off rate without compromising flux, owing to the slit-like pores that facilitate the rejection of smaller particles through their short axis while allowing solution passage along their long axis—a departure from conventional cylindrical-shaped pores sacrificing flux for high rejection rates. Aim 3 explores the Liquid Crystalline Assembly of Collagen and its subsequent impact on the Orientational Distribution of Human Schwann Cells (HSCs). The outcomes reveal the formation of 3-D liquid crystalline collagen hydrogels that can be applied as nerve conduits in peripheral nerve regeneration. These hydrogels induced favorable alignment of HSCs along the direction of collagen stripes. In summary, this dissertation underscores the important potential of LCs in crafting functional materials tailored for diverse biomedical applications.

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