User:Michael S. Bible/Notebook/CHEM-671/690 Lab Notebook/2016/02/02

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Objective

Today's objective is to synthese AuNP+Rhodamine fibers. We will add Rhodamine at different concentrations (1, 0.1, and 0.01µM) and at different points in the synthesis (before and after fibers have been placed in the oven).

Protocol

First, Nicole, Maxi, and Matt used volumetric flasks to make the following stock solution of lysozyme in DI water:

  • 25mL of 41.43µM lysozyme stock solution
    • Molecular weight of lysozyme solid is 14307g/mol

We used the same gold stock (3316µM) and rhodamine stocks (107.9, 10.79, and 1.079µM) as last week.

Our goal was to make 18 1mL fiber samples and 3 controls. For each sample, the concentration of lysozyme was 5.556µM and the concentration of gold was 0.25µM (these concentrations were ideal for fiber formation). Each sample and control had the following ingredients:

Sample Number Time Rhodamine is Added Final Concentration of Rhodamine (µM) Volume of Rhodamine Added Volume of 41.43µM Lysozyme Stock (µL) Volume of Gold Stock (µL) Volume of DI Water (µL)
Sample 1 Before Oven 0.01 9.27µL of the 1.079µM Stock 134.1 75.39 790.5
Sample 2 Before Oven 0.01 9.27µL of the 1.079µM Stock 134.1 75.39 790.5
Sample 3 Before Oven 0.01 9.27µL of the 1.079µM Stock 134.1 75.39 790.5
Sample 4 Before Oven 0.1 9.27µL of the 10.79µM Stock 134.1 75.39 790.5
Sample 5 Before Oven 0.1 9.27µL of the 10.79µM Stock 134.1 75.39 790.5
Sample 6 Before Oven 0.1 9.27µL of the 10.79µM Stock 134.1 75.39 790.5
Sample 7 Before Oven 1 9.27µL of the 107.9µM Stock 134.1 75.39 790.5
Sample 8 Before Oven 1 9.27µL of the 107.9µM Stock 134.1 75.39 790.5
Sample 9 Before Oven 1 9.27µL of the 107.9µM Stock 134.1 75.39 790.5
Sample 10 After Oven 0.01 9.27µL of the 1.079µM Stock 134.1 75.39 790.5
Sample 11 After Oven 0.01 9.27µL of the 1.079µM Stock 134.1 75.39 790.5
Sample 12 After Oven 0.01 9.27µL of the 1.079µM Stock 134.1 75.39 790.5
Sample 13 After Oven 0.1 9.27µL of the 10.79µM Stock 134.1 75.39 790.5
Sample 14 After Oven 0.1 9.27µL of the 10.79µM Stock 134.1 75.39 790.5
Sample 15 After Oven 0.1 9.27µL of the 10.79µM Stock 134.1 75.39 790.5
Sample 16 After Oven 1 9.27µL of the 107.9µM Stock 134.1 75.39 790.5
Sample 17 After Oven 1 9.27µL of the 107.9µM Stock 134.1 75.39 790.5
Sample 18 After Oven 1 9.27µL of the 107.9µM Stock 134.1 75.39 790.5
Control 1 Control for Rhodamine Addition Before Oven 0 9.27µL of DI water added before oven (instead of Rhodamine) as a control 134.1 75.39 790.5 (plus the water that was added in place of Rhodmaine)
Control 2 Control for Rhodamine Addition After Oven 0 9.27µL of DI water added after oven (instead of Rhodamine) as a control 134.1 75.39 790.5 (plus the water that was added in place of Rhodmaine)
Control 3 Rhodamine Only 1 9.27µL of the 107.9µM Stock 0 10µL of 25µM HCL were added (instead of gold) to keep the pH constant 990

We added the Rhodamine to the samples either just before we put them in the oven (samples 1-9) or about an hour after we took the samples out of the oven (samples 10-18). For samples 10-18, we waited an hour to let the fibers cool before adding Rhodamine. We let all the samples sit overnight at room temperature.

The bolded parts indicate substitutions that were made for the controls.

Just as last week, we assumed the volume of rhodamine added (9.27µL) was negligible.

Fluorescence of Rhodamine B Calibration Curve

5 concentrations of Rhodamine B were prepared using volumetric flasks:

  • 1 μM
  • 0.5 μM
  • 0.25 μM
  • 0.1 μM
  • 0.01 μM

Samples were excited at 520 nm and the emission was scanned from 540-700 nm.

The following calibration curve was produced using the midpoint method to integrate the fluorescence curves:

Rhodamine B Calibration Curve.png Figure 1: The relationship between peak integration and concentration does not appear to be linear, so the graph has been fitted with a polynomial function. The use of this calibration curve should be limited to concentrations that fall within the range of 0.01 μM and 1.0 μM.