Polymer- and Bioadditives-Assisted Synthesis and Surface Modification of Anisotropic Gold Nanocrystals

This thesis presents novel approaches towards the reproducible and scalable syntheses of small anisotropic nanocrystals in high yield utilizing a polymer and small thiolated compounds as shape-directing agents during growth, which enhance the long-term shape stability and colloidal stability after functionalization. Chapter 1 is a literature review of the various methods for producing anisotropic nanoparticles followed by a description of the current growth mechanisms, applications and surface modification strategies to reduce cytotoxicity and improve biocompatibility. Chapter 2 discusses new hydroquinone-assisted seedless and seed-mediated protocols of gold nanorods (AuNRs) by incorporation of nanomolar concentration of distinct molecular weights of poly(vinylpyrrolidone) PVP after growth initiation. Surface chemistry characterization was conducted by attenuated total reflectance (ATR) and X-ray photoelectron spectroscopy (XPS) while nanorods morphological analysis was carried out by high resolution TEM. Chapter 3 describes novel seedless and seeded methods to prepare AuNRs and tune their optical properties to shorter or longer wavelengths by introducing bioadditives or small thiolated molecules such as reduced and oxidized glutathione, L-cysteine, and L-methionine once the growth has been initiated. Chapter 4 presents an improved seed-mediated synthesis of gold nanoprisms (AuNPRs) which enables smaller sizes (edge lengths from 35 to 75 nm) compared to the original protocol, whereas addition of small amounts of PVP during the growth enhances the nanoprisms quality as well as their long-term shape stability. Characterization of AuNPRs thickness ranging from 20 to 35 nm was performed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The extinction coefficient for different aspect ratio AuNPRs was determined based on inductively coupled plasma-optical emission spectrometry (ICP-OES), TEM and UV-Vis analysis. Finally, Chapter 5 discusses a new hydroquinone-assisted seeded synthesis to achieve small dimensions of monodisperse gold nanoplates (AuNPLs) with edge lengths between 50 and 81 nm by adjusting reagent concentrations and evaluating the use of PVP during the growth stage of the synthesis which increases nanoplate monodispersity and provides their long-term shape stability. The enhanced colloidal stability after functionalization with 11-mercaptoundecyltrimethylammonium bromide (MUTAB) of small anisotropic nanoparticles synthesized with the polymer or bioadditives suggests potential biomedical applications such as radiosensitization and photothermal therapy of cancer.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Natural Sciences

Grantor

Rice University

Year dc:date.issued

2019

Author dc:creator

• Requejo Roque, Katherinne I

Advisor dc:contributor.advisor

• Zubarev, Eugene R

• Polymer
• Bioadditives
• Gold Nanocrystals
• small sizes
• high shape yield
• long-term stability

Statement dc:rights

• Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1911/105438

OAI identifier oai:identifier

oai:repository.rice.edu:1911/105438