User:Roberta Diaz Jimenez/Notebook/CHEM 472/2016/04/12

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Objective

  1. Prepare 20mL AgNP and AuNP reactions for all five proteins: casein, soy, whey, rice, and pea.
  2. Conduct UV/Vis and Fluorescence analysis before placing samples in the oven for reaction to proceed.
  • Note: standardized silver reaction protein concentrations were used, as opposed to previous concentrations where casein had a larger concentration. This was deemed not necessary to obtain successful results.

Materials

  1. Used same nutritional proteins as used in all previous reaction sample preps.
  2. Protein and gold stocks prepared fresh every day.
  3. Main UV/Vis machine was used to record UV/VIS Spectra of Casein AgNPs, not ocean optics.
    1. A water blank in the same quartz cuvette was subtracted from the spectra before running any samples.

Procedure

  • 20mL reaction samples
    1. Preparation of 20mL reaction samples to synthesize large quantities of the reactions that have previously worked.
    2. Water blanks prepared as well for both gold and silver, as well as gold-water mix at acidic pH, silver-water mix at basic pH.
    3. For the samples that were made basic, same amounts of base were used for all reaction samples.
    4. UV/Vis spectra of reaction mixes was taken from 200nm - 800nm
    5. Fluorescence spectra was taken using 280nm as excitation wavelength for tryptophan and tyrosine fluorescence for both before and after reaction. Emission spectra was scanned from 300nm to 540nm to avoid excitation peaks at 280nm and 570nm.
    6. Reactions run on p1 cycle of oven: 4hrs at 80˚C
  • Reaction mix, measurements as well as UV-Vis and Fluorescence Spectroscopy data can be found at the link SRB Lab Notebook Data

Data

  1. Detailed notes on colour change as well as UV/Vis and Fluorescence information can be found at the link SRB Lab Notebook Data
  2. AuWhey and AuSoy were in neutral reaction, AgPea, AgCasein and AgRice protein were basic – all experienced color change (silver=yellow, red/purple = gold)
  3. AuCasein worked, though it was slightly opalescent indicating the presence of some precipitate
  • Note: silver reactions only worked with proteins in basic conditions (first noticed with casein, pea and rice which are only soluble in basic conditions, thus were the first three to make silver nanoparticles). Perhaps dissolving casein, pea and rice protein in acidic conditions (even though not fully soluble) will yield gold nanoparticles


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