Date of Graduation

5-2021

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor/Mentor

Servoss, Shannon

Abstract

Detection and identification of viral pathogens is essential in providing effective and rapid medical treatment. Well-established detection methods can be expensive, slow, and sometimes unable to provide the needed sensitivity and specificity. The Zika virus is one clinically relevant pathogen that cannot be easily identified due to cross-reactivity with other viruses from the same family. Electrochemical sensors enhanced with peptoid-functionalized gold nanoparticles (AuNPs) are an alternative to traditional techniques that offers rapid, accurate, label-free pathogen detection for point-of-care diagnostics. To this end, a peptoid capable of binding to the Zika virus envelope protein was developed and its binding affinity for flat gold surfaces assessed. Preparation of modified colloidal AuNPs with proof-of-concept peptoids was also studied. This surface modification was complicated by the tendency of AuNPs to aggregate upon addition of peptoid. Peptoid structure, concentration, diluent, solution pH, temperature, and AuNP size were all found to alter aggregation rates. A successful modification procedure using Tween 20 as an intermediate steric stabilizer was developed to prevent irreversible aggregation upon dislocation of the citrate stabilizing ions and interaction of the aromatic peptoid groups. Green fluorescent protein was then used alongside a proof-of-concept peptoid to demonstrate efficacy of the method and functionality of the bound peptoid. Fluorescence measurements indicated potential binding of green fluorescent protein to the AuNPs, although conformational changes due to the AuNP surface curvature may have limited fluorescence properties. Binding capabilities of peptoid-modified AuNPs must therefore be considered in electrochemical settings to ensure clinical applicability.

Keywords

nanotechnology, peptoid, biosensor

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