An In-Depth Description of My Undergraduate Research

Hi! I wanted to let you guys know a little bit more about my undergraduate research in case any of you were interested in the specifics and what the day to day operations were like for the research during the summer and throughout the semester. Check out my "Undergraduate Research" section if you want to learn about how you can get starting in research at your university. This is going to be a long post, but thanks for reading!

Funding Proposal and Acceptance
My research was generous funded by the Student-Mentor Academic Research Teams (SMART) grant. This was a grant that I applied for through my university, which had a committee on campus. I worked for about three months doing background research for my grant proposal and constantly editing. I was told that my research was going to be funded through this grant in March and then I started research in May. The way that this grant worked was that I received a $3,400 stipend in three different installments through my student bursar account in school. This stipend was for 40 hours a week for 10 weeks.

Starting My Research
I began my research the second week of my summer in 2017. During the beginning of my research, I constantly researched similar peer-reviewed published papers. This gave me a good idea of what parameters for my experiment to start with to work with my research. I would highly suggest doing this, it made my research a lot easier at the beginning. It also helps you learn the behavior of the instruments or chemicals you're working with and broadens your understanding about the subject. Always start with an obtainable goal or goals and set a timeline for your goal(s).

First Impressions
At the beginning, I was really excited to begin my research and "make a difference". However, if you're looking for research to fulfill that everyday- it's not gonna happen. It's kinda boring sometimes. Electrochemistry, at least with the instrument we were working with, sometimes requires that you sit and wait while the instrument scans. This could be as long as 20 minutes. A full 8-hour day of sitting around when your method isn't working is very frustrating. Even though I made the goal of detecting 1 part per billion of lead in a sample 8 weeks ahead of time, there are other parts of the research that were slow and frustrating. Don't get discouraged and know that your slow, uneventful days will lead to something.

How I Feel Now
My research was an awesome opportunity that I wouldn't change at all. Right now I am stuck on a plateau and haven't had any major breakthroughs in quite awhile. However, I am still working through it and starting to research more about different things I could add to my experiments to continue the research in the way I want to. The type of research that I did was perfect for me, it was a very relaxed atmosphere and I was able to discover and research in a way that I wanted to with a mentor to help me along the way. I still do research about ten hours a week in the same lab through work-study.

End-of-Research Summary
Here I am putting a summary that I turned in to the SMART committee when I was finished with my summer research that explains my research a little bit. Thank you Dr. Muna at IUSB for helping me!

Introduction 

            Lead (Pb) is a heavy metal that is harmful to humans at relatively low levels. Exposure to lead can occur through water supply through service pipes, contaminated soil through water run-off, or from homes decorated with leaded paint. In contaminated paint, lead is usually present at high enough levels that it can be tested with multiple different methods that do not require a high level of sensitive analysis. Lead in water supply, contrarily, requires a sensitive method of analysis because trace amounts of lead can be present in a water sample. Since lead is active and toxic at levels of 100 μg/L (or 0.0001 g of lead in 1 liter of water), it is crucial to have a sensitive means of testing for the presence of lead. Traditional spectroscopic means of testing for trace amounts of heavy metals, such as lead, are efficient but costly. Plasma-atomic emission spectroscopy (ICP-AES) and atomic absorption spectroscopy (AA) are sensitive but are not time efficient, cost-effective, or portable. To allow for a wide-range of individuals to have access to a test for the presence of lead in their homes, a method that is portable and relatively cheap will create a more efficient means of analysis.

            Electrochemical methods were utilized to detect lead in water samples in place of spectroscopic techniques. This could allow for an affordable, sensitive, and portable means of detection. Glassy carbon electrodes (GCEs) were used as working electrodes for a potentiostat machine due to their wide potential window as well as their durability. A potentiostat utilizes a three-electrode system. The working electrode (GCE) is the electrode where the electrochemistry takes place, the reference electrode applies the potential the system, and the auxiliary electrode completes the circuit. For this research, a Ag/AgCl reference electrode was used. The auxiliary electrode used was a platinum wire.

Electrochemistry and Cyclic Voltammetry Background

            To be able to observe a species with electrochemistry, it must be electrochemically active. This means that it can be oxidized or reduced. If a species can only be oxidized or reduced (but not both) it undergoes an irreversible reaction. If it can be oxidized and reduced (redox reaction) it is known as a reversible reaction. Cyclic voltammetry can reveal the chemistry that occurs on the surface of the working electrode. In electrochemical techniques, an electrolyte and an analyte are needed for analysis. The electrolyte, or the solvent, allows for the electrical conductivity through the solution. The analyte is sample being analyzed and is placed in the electrolyte to make a proper solution for analysis.

            In all experiments, the electrolyte is analyzed separately and alone prior to the analysis of the desired solution. This is referred to as the “background” and ensures that the data collected is due to the sample and not the background. In cyclic voltammetry, the background should be smooth and without peaks when using GCEs. When the analyte is added, peaks unique to the sample should appear. These peaks are due to the oxidation (positive portion of the y-axis) or the reduction (negative portion of the y-axis) of the sample on the electrode surface. The peak height or the peak area can be used to determine a relative amount of particles on the surface of the GCE held to the surface by utilizing chronoamperometric techniques.

            Cyclic voltammetry was used for confirmation of AuNPs and BiNPs on the GCE. Although the peak height only gives the relative amount of nanoparticles deposited on the surface of the working electrode, it can be an indicator if the conditions used in the experimentation were beneficial for the deposition of the nanoparticles as well as if the electrode will be able to detect lead at relatively low levels.

Chronoamperometry: Deposition of Nanoparticles         

            The deposition of gold and bismuth nanoparticles allowed for a more sensitive means of detection of lead in water. Nanoparticles, only 1-100 nanometers in diameter, were deposited on the GCE utilizing an electrochemical technique called chronoamperometry (CA). During CA, a negative potential (reduction potential) is applied through the potentiostat and allows for the reduction of gold/bismuth. Once gold or bismuth ions are reduced, they become nanoparticles on the surface of the electrode. The following reaction shows how the depositions of gold and bismuth nanoparticles occur on the electrode surface.

Gold:

Au³⁺ + 3e^- --------> Au_(s)

Bismuth:

Bi³⁺ + 3e^-  ---------> Bi_(s)

            During the CA, the y-axis indicated the current, or the reduction potential. The x-axis being time. The current (μA) was a reference point for the efficiency of the electrode that was modified. If the current was more negative (bigger reduction peak) than normally seen, this was an indicator that the electrode would not deposit nanoparticles correctly for the detection of lead. CA was also used to “reactivate” the electrode. For the modification of GCEs with bismuth nanoparticles, reactivation of the electrode was needed occasionally because the stabilization of the nanoparticles on the surface was not determined. As the electrode was used throughout the day with multiple experiments, the nanoparticles would fall off of the surface and go into solution. Reactivating the electrode by depositing BiNPs again for a shorter amount of time (100s) at the potential used previously for deposition (-0.6V or -1.4V). This allowed the areas affected by the destabilization of the nanoparticle layer to rebuild for further use.

Set-Up in the Lab
Here is the place where I work! In the picture is a screen-printed carbon electrode, which is what we were eventually want to use because they are cheap and disposable. However, we are not quite there yet to use them all the time.

Thank you guys for reading!

Abbie