User:Karlena L. Brown/Notebook/PVOH Research/2013/02/15

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(PVOH 146K Prepared Samples & Dye Preparations)
Current revision (22:23, 8 April 2013) (view source)
(Notes)
 
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==Fluorescence Analysis: Diffusion Testing==
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# In a 10mL beaker containing one of the hydrogel samples with Rhodamine 6G, place ~ 4mL of H<sub>2</sub>O
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# Using a timer, every 15 minutes using a plastic pipette remove ~ 1-2mL of the sample
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# In glass cuvette marked for fluorescence, dispense the sample collected into the glass cuvette
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# Then place the sample filled cuvette within the sample holder to run fluorescence of the sample
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# Once a fluorescence reading has been run of the sample, dispose of the sample collected into a waste container
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# After each addition collected and disregarded of the sample, add ~ 1-2mL more H<sub>2</sub>O ensuring enough sample for the next reading
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# Repeat this process again for each sample over a 2 hour period
==Notes==
==Notes==

Current revision

PVOH Research Main project page
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OBJECTIVES

  • Continue to run fluorescence testing on samples containing Rhodamine 6G dye
  • Prepare new microsphere samples using new method of preparation

New Method of PVOH Clay Microsphere Preparation

  1. In 50mL beaker, dissolve ~ 1.0g total of PVOH 146K or PVOH 130K along with clay additive selected in 25mL hot deionized H2O
  2. Place a stir bar in the 50mL beaker and then heat solution at 100°C for ~ 12-15 minutes until complete dissolution of PVOH / clay sample
  3. Cool solution for ~ 5 minutes, then remove the stir bar, and add PVOH clay sample to a blender
  4. Afterwards, then add 25mL of mineral oil to the sample in the blender
  5. Blend sample solution prepared in blender for ~ 7 minutes on high to form a more homogeneous mixture / emulsion (creating a suspension of microspheres)
  6. After 7 minutes, quicklya dd some Rhodamine 6G dye to the solution based upon the ratio selection (90:10 vs. 50:50)
  7. After the addition of the dye, allow the solution to go through freeze / thaw crosslinking process for ~ 2-3 days
  8. Place microsphere solution in a freezer at -20°C for 24 hours and then remove and allow to solution to thaw for 24 hours


Reference: http://www.sciencedirect.com/science/article/pii/S0168365998000893

PVOH 146K Prepared Microsphere Samples & Dye Preparations

1μM Rhodamine 6G Dye Concentration (90:10)

  M1V1 = M2V2
  1μM (RG6)x 25mL = (92μM)V2    V2 = 271.74μL

1μM Rhodamine 6G Dye Concentration (50:50)

  M1V1 = M2V2
  1μM (RG6)x 25mL = (165μM)V2    V2 = 152.00μL
PVOH vs. Clay Ratio Clay Selection PVOH 146K Mass (g) Actual Clay Mass (g) H2O Added (mL) Dye Concentration (μM) Dye Amount Added (μL)
50:50110% CEC NaMT w/ DMHXLBR0.507600.4913025165152
90:10110% CEC NaMT w/ DMHXLBR0.909900.104502592272
90:10110% CEC Laponite w/ DMHXLBR.901000.099802592272

Fluorescence Analysis: Diffusion Testing

  1. In a 10mL beaker containing one of the hydrogel samples with Rhodamine 6G, place ~ 4mL of H2O
  2. Using a timer, every 15 minutes using a plastic pipette remove ~ 1-2mL of the sample
  3. In glass cuvette marked for fluorescence, dispense the sample collected into the glass cuvette
  4. Then place the sample filled cuvette within the sample holder to run fluorescence of the sample
  5. Once a fluorescence reading has been run of the sample, dispose of the sample collected into a waste container
  6. After each addition collected and disregarded of the sample, add ~ 1-2mL more H2O ensuring enough sample for the next reading
  7. Repeat this process again for each sample over a 2 hour period

Notes

  • Hydrogels that completed the freeze / thaw cycle which had ~ 4mL of H2O added in order for fluorescent analysis include:
  # 50:50 PVOH 130K 110% CEC NaMT w/ DMHXLBR
  # 90:10 PVOH 130K 110% CEC Laponite w/ DMHXLBR
  # 50:50 PVOH 130K 110% CEC Laponite w/ DMHXLBR
  # 90:10 PVOH 130K 110% CEC NaMT w/ DMHXLBR
  • For fluorescence analysis, samples were taken every 15 minutes for 2hrs to determine a dye leaching / diffusion rate from hydrogels
  • Fluorescent samples run and completed for 2hr diffusion rate determinations:
  # Hydrogel 50:50 PVOH 146K 50% CEC NaMT w/ Bu3HdP+
  # Hydrogel 90:10 PVOH 146K 50% CEC NaMT w/ Bu3HdP+
  # Hydrogel 50:50 PVOH 146K NaMT
  # Hydrogel 90:10 PVOH 146K NaMT
  # Hydrogel control PVOH 146K 
  # Hydrogel 90:10 PVOH 146K Laponite
  • In regards to the spectra, all samples maintained a quick diffusion rate indicating that dye crosslinking during the freeze / thaw cycle is pertinent when making hydrogels because it slows down the diffusion rate
  • For the hydrogels in which the dye was added, but not crosslinked into the material, their diffusion rate was the quickest -- a significant amount of dye leaked out of those hydrogels throughout the 2 hour period
  • Comparing the 50:50 vs. the 90:10 ratio of PVOH / clay, the hydrogels with 50:50 ratio had more dye leak out than the 90:10 ratio hydrogels indicating a more effective pressure stimuli


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