User:Nicole Bonan/Notebook/Chem 571 Lab Notebook/2015/11/25

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Objective

Take ICP, Conductivity, and UV-Vis measurements of our samples from yesterday.

Protocol

ICP


We centrifuged all of our AuNP fiber samples from yesterday once they were done incubating. We then used 5mL from each triplicate for ICP. (Yesterday, we had created triplicates for AuNP fibers incubated in 0nM, 1nM, 10nM, 100nM, and 100nM alpha-chymotrypsin.) The ICP was set to test for the presence of gold ions in our samples.


UV-Vis


We used Ocean Optics Absorbance Spectrophotometry to measure the absorbance of each of our samples. We used 3mL of the remaining 15mL of each of our samples for this measurement.


Conductivity


We measured the conductivity of each of our samples using a conductivity probe at room temperature. We used the 15mL of each of our samples that had not been used for ICP in order to take these measurements.

Data

ICP

Figure 1: Concentration of Gold (III) Ion in AuNP Fiber Samples (mg/L) as a Function of the Concentration of alpha-Chymotrypsin Used in the 24 Hour Incubation (nM)
Icp figure.png

The above figure shows the concentration of the gold (III) ion in solution as a function of the concentration of alpha-chymotrpyisn in which each AuNP fiber sample was incubated.

UV-Vis

Figure 2: Absorbance of AuNP Fiber Fragments as a Function of the Wavelength of Incident Light (nm) for 24 Hour Incubations in Varying Concentrations of alpha-Chymotrypsin (nM)
Nbonan ocean lastday raw.png

The image above shows the absorbance of the fragments that broke off of the AuNP fibers after the samples were incubated in alpha-chymotrypsin for 24 hours. To get the absorbance data, the absorbance of each triplicate for each wavelength was first averaged to get an average absorbance at each wavelength for a given concentration of alpha-chymotrypsin. Then, the absorbance was corrected by subtracting the blank, which was the supernatant that we pipetted off of each of the AuNP fiber samples yesterday, from each of these average values for every wavelength.


Figure 3: Absorbance of AuNP of 530nm Light as a Function of the Concentration of alpha-Chymotrypsin used in the 24 Hour Incubation (nM)
Nbonan 530nm lastday.png

The image above shows the absorbance of AuNP as a function of the concentration that the AuNP fibers were incubated in. AuNP absorb 530nm light very strongly, so this wavelength was selected so that we could measure just the absorbance due to AuNP in solution. A line of best fit was applied to the graph. From the line, it is clear that the absorbance of light by AuNP increases linearly with the concentration of alpha-chymotrypsin used to degrade the fibers. This indicates that the extent to which the fibers are degraded increases linearly with alpha-chymotrypsin concentration, as AuNP are released into solution as the fibers are degraded.

Conductivity

Figure 4: Conductivity of AuNP Fiber Samples (µS/cm) as a Function of the Concentration of alpha-chymotrypsin in which they were Incubated (nM)
Nbonan conductivity.png


The above figure shows the conductivity of the AuNP fiber samples as a function of alpha-chymotrypsin concentration. The conductivity represents the gold (III) ion in solution, as this ion is the only molecule in the solution that is charged. From the graph, it is clear that the conductivity jumps up to about 1800µS/cm when alpha-chymotrypsin is added to the sample. However, the conductivity remains constant. This trend contradicts the data gathered from the ICP, which shows that the concentration of gold ion, and thus the conductivity, increases linearly with alpha-chymotrypsin concentration.