User:Moira M. Esson/Notebook/CHEM-581/2013/02/15

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# The magnetic stir bar was removed and 25mL of mineral oil was added to the beaker.
# The magnetic stir bar was removed and 25mL of mineral oil was added to the beaker.
# The contents of the beaker were poured into a blender to homogenize the solution and create an emulsion of the aqueous and organic layer in the attempt to create a suspension of microspheres.
# The contents of the beaker were poured into a blender to homogenize the solution and create an emulsion of the aqueous and organic layer in the attempt to create a suspension of microspheres.
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# The blender was turned on a low setting for 5 minutes.
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# The blender was turned on a low setting for 7 minutes.
# The contents of the blender were poured into a beaker and the appropriate amount of DMSO/Rhodamine 6G solution was added.
# The contents of the blender were poured into a beaker and the appropriate amount of DMSO/Rhodamine 6G solution was added.
# The microsphere solution was placed in a freezer at -20°C for 24 hours and then removed and allowed to thaw for 24 hours.
# The microsphere solution was placed in a freezer at -20°C for 24 hours and then removed and allowed to thaw for 24 hours.
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This procedure was adapted from [http://www.sciencedirect.com/science/article/pii/S0168365998000893]
This procedure was adapted from [http://www.sciencedirect.com/science/article/pii/S0168365998000893]
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<br>
Preparation of Microspheres:
Preparation of Microspheres:
*New calculations for the amount of DMSO/Rhodamine 6G to be added:
*New calculations for the amount of DMSO/Rhodamine 6G to be added:
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Spectra:
Spectra:
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Figure 1. Diffusion test fluorescence spectra for 50:50 PVA MW 146,000-186,00: 50% NaMT hydrogel
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[[Image:2 hr diffusion test 50 MW 146 50% NaMT correct.png]]
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<br>
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'''Correction''': The x-axis should be labeled Wavelength(nm). The image will be corrected.
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Figure 2. Diffusion test fluorescence spectra for 50:50 PVA MW 146,000-186,000: NaMT hydrogel
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<br>
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[[Image:2 hr diffusion test 50 MW 146 NaMT.png]]
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Figure 3. Diffusion test fluorescence spectra for 90:10 ratio of PVA MW 146,000-186,000:Lamponite
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[[Image:2 hr diffusion test 90 MW 146 LP.png]]
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<br>
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Figure 4. Diffusion test fluorescence spectra for a 90:10 ratio of PVA MW 146,000-186,000:NaMT
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<br>
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[[Image:2hr diffusion test 90 MW 146 NaMT.png]]
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<br>
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Figure 5. Diffusion test fluorescence spectra for a 90:10 ratio of PVA MW 146,000-186,000:50% NaMT
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<br>
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[[Image:2hr rhodamine diffusion test 90 MW 146 50% NaMT.png]]
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*'''Correction: The x-axis should be labeled Wavelength(nm). The image will be corrected'''
Observations:
Observations:
*Each of the samples had a very fast diffusion rate. If the spectra are viewed additively for each hydrogel sample, a significant amount of dye leaked out of the hydrogel sample in only 2 hours, in comparison to the hydrogels which remained in distilled H<sub>2</sub>O for one week and had minimal dye diffusion. This indicates that the dye must be added prior to the freeze-thaw crosslinking method.  
*Each of the samples had a very fast diffusion rate. If the spectra are viewed additively for each hydrogel sample, a significant amount of dye leaked out of the hydrogel sample in only 2 hours, in comparison to the hydrogels which remained in distilled H<sub>2</sub>O for one week and had minimal dye diffusion. This indicates that the dye must be added prior to the freeze-thaw crosslinking method.  
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*Comparing the 50:50 ratio of PVA:clay and the 90:10 ratio, the hydrogels with 50:50 ratio had more dye leak out of the hydrogel than the 90:10 ratio. Perhaps indicates a more effective pressure stimuli.
*Comparing the 50:50 ratio of PVA:clay and the 90:10 ratio, the hydrogels with 50:50 ratio had more dye leak out of the hydrogel than the 90:10 ratio. Perhaps indicates a more effective pressure stimuli.
*In the future, when performing the diffusion tests, after taking a sample every fifteen minutes, the sample will be readded to the test beaker rather than discarded.  
*In the future, when performing the diffusion tests, after taking a sample every fifteen minutes, the sample will be readded to the test beaker rather than discarded.  
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Revision as of 19:14, 7 March 2013

Project name Main project page
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Objectives

  1. Prepare PVA-clay microspheres.
  2. Run diffusion tests on hydrogels prepared on 2013/01/30 with Rhodamine 6G dye added on 2013/02/08.


Microsphere Preparation

  • Due to the relatively unsuccessful preparation of PVA/clay microspheres(the prepared spheres were either larger than a micrometer or did not appear at all), a new method was used for the preparation of PVA/clay microspheres.

General Protocol:

  1. The desired ratio of PVA and clay was measured out. The total mass was ~1g.
  2. The PVA/clay was placed in a 50mL beaker with a magnetic stir bar. 25mL distilled H2O were added to the beaker and the solution was heated to ~100°C and allowed to stir until complete dissolution of PVA/clay.
  3. The magnetic stir bar was removed and 25mL of mineral oil was added to the beaker.
  4. The contents of the beaker were poured into a blender to homogenize the solution and create an emulsion of the aqueous and organic layer in the attempt to create a suspension of microspheres.
  5. The blender was turned on a low setting for 7 minutes.
  6. The contents of the blender were poured into a beaker and the appropriate amount of DMSO/Rhodamine 6G solution was added.
  7. The microsphere solution was placed in a freezer at -20°C for 24 hours and then removed and allowed to thaw for 24 hours.
  8. Repeat this freeze-thaw cycle three times.


This procedure was adapted from [1]
Preparation of Microspheres:

  • New calculations for the amount of DMSO/Rhodamine 6G to be added:

For a 90:10 ratio:

 (25mL)(1μM)/(92μM)=0.272mL

For a 50:50 ratio:

 (25mL)(1μM)/(165μM)=0.152mL
  • Information about prepared microspheres:
Prepared Clay-PVA(MW 146,000-186,000) microspheres ' ' ' '
Composition of hydrogel(ratio of PVA to clay)Amount of PVA added(g)Amount of clay added(g)Concencentration of DMSO/dye stock solution added(μM)Amount of DMSO/dye added(mL)
90:10 PVA:110% NaMT0.90990.1045920.272
50:50 PVA:110% NaMT0.50760.49131650.152
90:10 PVA:110% Lamponite0.90100.0998920.272


Observations:

  • After the addition of dye/DMSO to the 110% Lamponite, the dye appeared to stick to very small spheres at the bottom of the beaker. Bright pink spheres immediately formed. This did not occur for the samples containing 110% NaMT.


Fluorescence

  • The six hydrogel samples that were allowed to soak in Rhodamine 6G were tested for the rate of diffusion of Rhodamine 6G from the samples.

General Protocol:

  1. Excess Rhodamine 6G sample still present in the beaker was removed.
  2. Hydrogel samples were removed from the beakers, pat dry with a paper towel, and placed in a new, clean beaker.
  3. 25mL distilled H2O were added to each beaker sample.
  4. A timer was started, and every 15 minutes, a sample of distilled H2O was removed from the beaker and placed in an unfrosted cuvette.
  5. The sample was discarded into a waste beaker.
  6. This process was repeated for 2 hours.


Spectra:
Figure 1. Diffusion test fluorescence spectra for 50:50 PVA MW 146,000-186,00: 50% NaMT hydrogel Image:2 hr diffusion test 50 MW 146 50% NaMT correct.png
Correction: The x-axis should be labeled Wavelength(nm). The image will be corrected. Figure 2. Diffusion test fluorescence spectra for 50:50 PVA MW 146,000-186,000: NaMT hydrogel
Image:2 hr diffusion test 50 MW 146 NaMT.png
Figure 3. Diffusion test fluorescence spectra for 90:10 ratio of PVA MW 146,000-186,000:Lamponite
Image:2 hr diffusion test 90 MW 146 LP.png
Figure 4. Diffusion test fluorescence spectra for a 90:10 ratio of PVA MW 146,000-186,000:NaMT
Image:2hr diffusion test 90 MW 146 NaMT.png
Figure 5. Diffusion test fluorescence spectra for a 90:10 ratio of PVA MW 146,000-186,000:50% NaMT
Image:2hr rhodamine diffusion test 90 MW 146 50% NaMT.png

  • Correction: The x-axis should be labeled Wavelength(nm). The image will be corrected

Observations:

  • Each of the samples had a very fast diffusion rate. If the spectra are viewed additively for each hydrogel sample, a significant amount of dye leaked out of the hydrogel sample in only 2 hours, in comparison to the hydrogels which remained in distilled H2O for one week and had minimal dye diffusion. This indicates that the dye must be added prior to the freeze-thaw crosslinking method.
  • Due to the fact that the dye did not immediately, completely diffuse out, the crosslinking of PVA/clay hydrogels slowed the diffusion rate of the dye.
  • Comparing the 50:50 ratio of PVA:clay and the 90:10 ratio, the hydrogels with 50:50 ratio had more dye leak out of the hydrogel than the 90:10 ratio. Perhaps indicates a more effective pressure stimuli.
  • In the future, when performing the diffusion tests, after taking a sample every fifteen minutes, the sample will be readded to the test beaker rather than discarded.




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