Date of Graduation

12-2019

Document Type

Thesis

Degree Name

Master of Science in Microelectronics-Photonics (MS)

Degree Level

Graduate

Department

Microelectronics-Photonics

Advisor/Mentor

Kim, Jin-Woo

Committee Member

Chen, Jingyi

Second Committee Member

Sakon, Joshua

Third Committee Member

Wise, Rick L.

Keywords

cellulose nanocrystals; gold nanoparticles; hybrid; surface plasmon resonance

Abstract

Gold nanoparticles (AuNPs) have been brought to the forefront of various applications, ranging from theranostics, to organic photovoltaics, to biosensing owing to their localized surface plasmon resonance (LSPR) property. However, this property needs to be improved in order to allow for high sensitivity and quantitative detection of biomolecules. Hybrids of AuNPs with low-dielectric cellulose nanocrystal (CNCs) would yield enhancement of the LSPR property, which is driven by the confinement of electron oscillation at their interfaces. This study proposed a seed-mediated growth method to synthesize hybrids of CNCs-AuNPs. Sulfate groups on the surface of CNCs served as the sites for the growth of AuNPs. Optimization through the number, size, and distances of AuNPs on the surface of CNCs was achieved by modulating different variables such as concentrations of reducing agent and CNCs, time, temperature, and surface charge of CNCs. The results via absorbance spectrophotometry, dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) demonstrated that AuNPs grew on the surface of sulfonated CNCs, leading to enhancing their LSPR. Optimization and tuning the optical response of AuNPs on the surface of CNCs was accomplished in this study, which could significantly advance the technology of biosensors in the future. This study could be expanded by the utilization of CNC as a template for the growth of other nanoparticles for a variety of applications, ranging from biomedicine to optoelectronics.

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