User:Madeleine Y. Bee/Notebook/Single Molecule Fluorescence/2013/06/14

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June 14, 2013

Notes from Meeting

  • Look at percentages for the AuNP/thiol-DNA attachment spectra
    • Compare Sup 2 to Sup 1, etc rather than comparing each supernatant to the original sample
  • Redo bar graph image to make it less fuzzy
  • Repeat DNA/ThT fluorescence spectra: DNA/ThT mix, DNA alone, ThT alone
    • Excite at 440, not 417nm!
  • Label peaks for the DNA/ThT absorbance (and eventually fluorescence) spectra to be used for calibration curve
    • Note that ThT concentration stays the same so the peak stays the same whereas the DNA concentrations are varied, therefore so are the peaks
  • Write out conclusions for each set of data
  • Look up the information sheet for the thiol-DNA and MB sequences
  • Include explanations for each set of data
  • Look into testing pH for AuNP and AuNP@SiO2 solutions
  • Work with Eleni to see AuNP@SiO2 under microscope (?)
  • Export FCS data to include in presentation and notebook

Absorbance Data

Abs data AuNP dilutions 24hr 0614.png<br.> Absorbance spectra of various concentrations of 10nm AuNPs, taken 24 hours after samples were diluted and refrigerated. PBS used as solvent and reference solution. Samples did not show absorbance spectra as expected. <br.> Abs data AuNP dilutions immediate 0614.png<br.> Absorbance spectra of various concentrations of 10nm AuNPs, taken immediately after samples were diluted. PBS used as solvent and reference solution. Expected absorbance spectra were observed. 9.4nM sample may be run again due to inconsistent peak around 200nm. <br.>

Observations and Notes

  • Samples left overnight in the refrigerator did not show absorbance as expected and exhibited a loss of charateristic 'pink' color, independent of the solvent used for dilution
  • Samples diluted and used immediately showed absorbance as expected
  • Sonicating or vortexing samples before taking abosrbance measurements did not change outcome
  • PBS was chosen over water in this case to help prevent nanoparticles from aggregating
  • Measurements may be taken again under the following conditions for further comparison:
    • Diluted in water and used immediately
    • Diluted in water and left overnight unrefrigerated
    • Diluted in PBS and left overnight unrefrigerated
  • Redo: immediate use after dilution of the 9.4nM AuNPs in PBS

Relevance: AuNPs must be used immediately after dilution for silica-coating procedure