Solubility Experiments with Ligated Gold Nanoparticles

By Mo Niazi
Supervisor:  Dr. Sorensen

Kansas State University Physics Department REU Program Southern Nazarene University

This program is funded by the National Science Foundation through grant number PHY-1157044.  Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Welcome to my webpage. This page summarizes my experience doing research for the Summer of 2013 in Dr. Sorensen’s laboratory. My project this summer was to experimentally determine the effects of temperature on Gold Nanoparticle solubility.

Project Overview

Gold Nanoparticles have many novel physical properties and applications that are being utilized as:

-Nanoelectronic conductors for computer chips

-Photodynamic cancer therapy

-Drug delivery methods

-Chemical catalysts

-Diagnostics

To name a few…

Because of their useful and unique properties, we have chosen to study the physics behind why these intermediate forms of matter behave the way that they do.

Project Goals

The ultimate goal of this project is to experimentally determine how the solubility of Gold Nanoparticles is affected by temperature.

Research Description

This study utilized ligated Gold Nanoparticles dissolved in a non-polar solution. This solution was then placed in a glass slip and was put through our experimental procedure for data collection and interpretation.

Experimental Procedure

Step One: Sonication

We sonicate the Gold Nanoparticles into solution.

Step Two: Equilibration

We allow the Gold Nanoparticles to come to equilibrium with our desired temperature for 15 minutes.

Step Three: Centrifugation

We then centrifuge the sample to bring down any solid state Gold Nanoparticles to form a sediment at the bottom.

Step Four: Flipping and Data Collection

The sample is then filliped before data collection. This is done to prevent an equilibrium from forming between the solid state Gold
Nanoparticles and the Nanoparticles already within solution.

Data Collection Via UV-Vis Spectrophotometry

The data is then collected via UV-Vis Spectrophotometry. The data is then analyzed and interpreted by Dr. Sorensen, Jeff Powell, And I.

Data

Absorbance vs. Wavelength Graph of seven trials overlapped.

Absorbance vs. Temperature.

This enigmatic data exhibits “Hysteresis like behavior” due to the fact that the initial temperature values influence the absorbance values of the sample. We hypothesize that this is due to the fact that the 15 minutes that we allowed the sample to come into equilibrium was not long enough.

This plot allows us to calculate the change in enthalpy of dissolution experimentally using the ideal solution equation, the slope of this graph, and the value for the universal gas constant.

Conclusions

Upon obtaining more data, these studies may result in a saturation curve for our Gold Nanoparticles

The analysis of the Arrhenius plot allowed us to experimentally determine the enthalpy of dissolution of the gold nanoparticles in solution.

We can then approximate the Δ H_dissolution ≈ Δ H _fusion

We have yet to make sense of the lack of equilibration found in the iterative temperature experiments.

Final Presentation: Click here to download my presentation in PowerPoint format. This is a much more in-depth explanation of what I did this summer.

Lectures: by Dr. Weaver. I learned many new physics topics and concepts during Dr. Weaver’s talks. The subjects varied from quantum mechanics, electricity and magnetism, special and general relativity and much more. I was always excited to learn more about physics from someone of Dr. Weaver’s stature.

Ethics Class: This class brought to my attention just how cautious scientists must be with their career choices. This is due to the fact that scientists have an obligation to society to conduct research in a way that will not be harmful to society.

About Me: I grew up in Oklahoma City, Oklahoma. I am fluent in Farsi, Turkish, English, and Spanish. I am a Biochemistry “Pre-Med” major and I am currently minoring in Mathematics, Physics, and Spanish Language. I enjoy spending time with friends and family. On my spare time I enjoy learning more about science and exercising.

Here is a picture of me, Mo Niazi.

Useful Links: 

Check out these useful sites:

American Physical Society Statements on Ethics

American Institute of Physics

My Research group's home page:

Dr. Sorensen