Investigations of the interaction of gold nanoparticles with proteins, cells, and tissues

Boulos, Stefano

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Description

Title

Investigations of the interaction of gold nanoparticles with proteins, cells, and tissues

Author(s)

Boulos, Stefano

Issue Date

2014-01-16T18:16:23Z

Director of Research (if dissertation) or Advisor (if thesis)

Murphy, Catherine J.

Doctoral Committee Chair(s)

Murphy, Catherine J.

Committee Member(s)

• Kraft, Mary L.
• Bailey, Ryan C.
• Sweedler, Jonathan V.

Department of Study

Chemistry

Discipline

Chemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Gold nanoparticles
• Biological applications
• Peptide
• Cancer cells
• Capillary electrophoresis
• Fluorescence correlation spectroscopy
• Protein adsorption

Abstract

The unique properties of gold nanoparticles make them ideal candidates for applications in biology and medicine. Gold nanoparticles have enhanced optical properties and their surface chemistry can be controlled, creating opportunities for their use in a variety of roles including genomics, clinical chemistry, photothermolysis of cancer cells and tumors, targeted drug delivery, and optical bioimaging of cells and tissues. Recently, there has been tremendous effort by scientists around the world to investigate these applications. However, before gold nanoparticles make it to the point of care, there is a need to better understand and control their impact on biological systems. Herein, the interaction of gold nanoparticles with proteins and cells were investigated. Their nonlinear optical signals for improve imaging in tissue was studied. Synthetic approaches to improve biocompatibility of the gold nanorods were achieved. Protein-gold nanoparticle interactions, in particularly gold nanorods, are investigated using different analytical techniques. When nanoparticles are injected in a biological environment, proteins will adsorb instantaneously to their surfaces, creating a protein corona around the nanomaterial. Different proteins will have different affinities for the nanoparticle’s surface based on their surface chemistry, and protein conformation might change upon adsorption, which can lead to changes in cellular functions. Herein, the interaction of different gold nanorods based on their size and surface charge with bovine serum albumin was investigated using different analytical techniques to obtain thermodynamic and kinetic information. Techniques which do not require harsh separation methods such has high velocity centrifugation are preferable in order to prevent protein desorption. Steady-state fluorescence based on the gold nanorod quenching effect on protein fluorescence was investigated; however, gold nanorod optical interference, led to overestimation of binding affinities. As an independent and comparative method, affinity capillary electrophoresis was used as a technique to calculate binding affinities was studied. This technique does not suffer from GNR optical interference establishing capillary electrophoresis as a robust method to probe these interactions. In addition, fluorescence correlation spectroscopy was also studied, as a robust technique to probe the kinetic of nanoparticle-protein interactions if the optical interference of the gold nanorod can be efficiently subtracted. Enhanced nanoparticle targeting of the malignant prostate cancer cells (PC-3), overexpressing EphA2 receptors was investigated. Gold nanorods were functionalized with the YSA homing peptide via a robust layer-by-layer coating approach. A measured increase in uptake of the YSA-GNRs, compared to a scrambled control (ScrYSA-GNRs), was observed. The effect of the YSA-GNRs on PC-3 cell proliferation after interaction with the EphA2 receptors was also studied; however, it remains questionable whether or not the YSA-GNRs alone can be used as a therapeutic agent. To enhance the use of gold nanorods as contrast agents in tissue imaging, the two-photon luminescence of gold nanorods was probed under varying laser pulse shape and polarizations. The intensity of the two-photon signal from the nanorods was found to vary with these parameters, suggesting the possibility of improved control in tissue imaging by limiting photodamage/deformation and excess gold nanorod signal. However, there is a need to develop a better approach to align the nanorods at different angles to better study their response under different incoming light. Lastly, the biocompatibility of the gold nanorods was enhanced. The concentration of cetyltrimethylammonium bromide surfactant used in the synthesis step was reduced to 20% of its original concentration by compensating the reaction with bromide salt. This study also highlights the importance of the bromide ions in the growth of the gold nanorods.

Graduation Semester

2013-12

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Copyright 2013 Stefano Boulos

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