User:Eleni N. Kalivas/Notebook/CHEM-571/2013/10/23

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To take spectra of all 20 samples from Yesterday. Today we will create 10 new samples of the same Au:protein ratio, using myoglobin. Also, since no fibers formed 10 new samples will be prepared with a higher concentration. Lastly, we will be measuring pepsin activity of pepsin in solution, and also of pepsin-AuNPs in solution.


The following protocol was taken from Matt Hartings notebook.

Make a 37C water bath that can hold at least 3 test tubes (same size as you used yesterday) at a time --- START THIS FIRST

  1. Pepsin Digest
    1. Stock Solutions
      1. 2.5 w/v Hemoglobin in 0.06N HCl
      2. 1M perchloric acid
      3. 0.5mg/mL pepsin in 0.01N HCl
      4. pepsin-AuNP (at ratio that I need to decide on)
    2. Directions (You can decide how you want to split your effort here. I'd suggest doing one set, i.e. pepsin blank, pepsin trial, pepsin-AuNP blank, or pepsin-AuNP trial, at a time)
      1. Make 1mL pepsin dilutions for the regular pepsin AND the pepsin-AuNPs in 0.01N HCl
        1. 10μg/mL
        2. 15μg/mL
        3. 20μg/mL
      2. Blank (perform this for each pepsin or pepsin-AuNP dilution)
        1. Place 2.5mL hemoglobin solution in a test tube in the 37C water bath
        2. Add 5mL of perchloric acid
        3. Add 0.5mL pepsin dilution
        4. Remove from water bath after 5minutes
        5. Filter
        6. Measure the absorbance at 280 --- This will be your A280(Blank)
      3. Test (perform this for each pepsin or pepsin-AuNP dilution)
        1. Place 2.5mL hemoglobin solution in a test tube in the 37C water bath
        2. Add 0.5 mL pepsin dilution
        3. Wait 10 minutes
        4. Add 5mL of perchloric acid
        5. Remove from water bath after 5minutes
        6. Filter
        7. Measure the absorbance at 280 --- This will be your A280(Test)
      4. Calculate the number of units/mg of active enzyme in each sample
        1. Units/mg = [A280(Test) - A280(Blank)]*1000/[10minutes*mg enzyme in reaction mixture]</s>
  2. Protein-AuNP analysis
    1. Take a picture and note physical description of each ratio
    2. Place 1mL of each ratio in an 1.5mL eppendorf tube.
    3. Centrifuge for 30 minutes (Be considerate of other uses here. Act quickly, and get as many tubes in the centrifuge as you can at once.)
    4. Take a UV-Vis spectrum of each sample (Be considerate of other users here)
    5. After taking the spectrum, save the sample in a fresh eppy tube.
  3. Synthesis of HRP-AuNPs and Hemoglobin-AuNPs
    1. Into test tube that will contain a total of 5mL add
    2. Au solution such that the final concentration is 0.25mM
    3. For Myoglobin make the following solutions to reflect an Au:Protein ratios
      1. 30
      2. 50
      3. 70
      4. 90
      5. 110
      6. 130
      7. 150
      8. 170
      9. 190
      10. 210
    4. For HRP make the following solutions to reflect an Au:Protein ratios
      1. 230
      2. 250
      3. 270
      4. 290
      5. 310
      6. 330
      7. 350
      8. 370
      9. 390
      10. 410
    5. Water up to 5mL

Samples before placed into the oven and heated

  • all samples appeared clear before entering the oven

HRP-AuNP and Myoglobin-AuNP

  • The protein-AuNP solutions prepared on 10/22/2013 did not produce fibers. As such, new protein-AuNP solutions with increased ratios of protein-AuNP were prepared in order to determine the optimal concentration of Au to protein to synthesize fibers.
  • The general protocol for the synthesis of HRP-AuNP and Pepsin-AuNP follows the general protocol for the preparation of protein wrapped Au-NPs described on 08/28/2013.
  • 5mL of each solution was prepared.

Table 1. Stock solutions used in the preparation of Protein-AuNP solutions

Concentration HRP Day 2(M) Concentration Gold Stock (M) Myoglobin (M)

Table 2. Preparation of HRP-AuNP solutions

Ratio Amount of gold added (mL) Concentration HRP (M) Volume HRP (mL) Volume H2O added (mL)

Table 3. Preparation of Myoglobin-AuNPs

Ratio Amount of gold added (mL) Concentration Myoglobin (M) Volume of myogloblin(mL) Volume Water Myoglobin(mL)


Corrected Absorbance spectra of pepsin-AuNPs

  • Both 30:1 and 70:1 pepsin-AuNP had an absorbance peak at 518nm.

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