Date of Award

Summer 1-1-2020

Degree Type

Thesis

Degree Name

Master of Science In Biomedical Engineering_degree

Department

Chemical And Biomedical Engineering

First Advisor

Sun, Xue-long Sun

Second Advisor

Nolan B. Holland

Third Advisor

Christopher Wirth

Abstract

Smart materials are a class of material whose physical characteristics change significantly in a controllable fashion once exposed to an external stimulus such as stress, pH, light, temperature, etc. If the temperature is the external stimuli (control variable) the material is termed thermo-responsive. Out of numerous thermo-responsive materials, elastin-like polypeptide (ELP) is a well-known protein-based biopolymer. Protein cages are well-defined biological nanostructures which are highly symmetrical and monodisperse. This class of proteins are both chemically and genetically tunable, making them a suitable recipient of new properties. Protein re-engineering is the basis of developing a hybrid platform (e.g. polymer-protein) to deliver some new functionalities and tasks. Prolonged delivery, sustained drug loading/ release, and targeting delivery are the challenges that led to introducing novel biohybrid materials to tackle shortcomings of existing drug delivery systems. Among all possible structures, a thermo-responsive VLP (viral like particle) was designed for a potential ultimate application in drug delivery. In the designed structure the outermost shell ofthe bacteriophage P22 (in its empty shell form) is homogenously decorated with ELP as each coat-protein subunit (CP) is genetically fused with a fusion tag polymer (ELP). Those recombinant subunits (CP-ELP) are self-assembled through intermolecular interactions (non-covalent bonds including hydrogen bonds, electrostatic bonds, etc.) in a highly repetitive array to end in a hairy-ball structure. v The art of gene design was incorporated with synthetic biology techniques to accomplish the idea behind this research. Utilizing these tools, a versatile genetic code with appropriate cut-sites to be edible at the C-terminus of coat protein (CP) for adding pentapeptides with different lengths (or any other peptide sequences with appropriate overlaps) was designed. After synthesizing the ELP-fused particle with different lengths, characterization assays such as dynamic light scattering (DLS) and UV-VIS spectroscopy were conducted to investigate the thermal-behavior of synthesized particles. These data along with scanning electron microscopy (SEM) confirm the formation of hybrid particles with predicted morphology. This work clearly has demonstrated the feasibility of a recombinant self-assembled nanocage structure modified with thermally responsive peptides. Such structure could comprise some potential applications in the biopharmaceutical industry and more specifically drug delivery systems.

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