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
- In 50mL beaker, dissolve ~ 1.0g total of PVOH 146K or PVOH 130K along with clay additive selected in 25mL hot deionized H2O
- 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
- Cool solution for ~ 5 minutes, then remove the stir bar, and add PVOH clay sample to a blender
- Afterwards, then add 25mL of mineral oil to the sample in the blender
- Blend sample solution prepared in blender for ~ 7 minutes on high to form a more homogeneous mixture / emulsion (creating a suspension of microspheres)
- After 7 minutes, quicklya dd some Rhodamine 6G dye to the solution based upon the ratio selection (90:10 vs. 50:50)
- After the addition of the dye, allow the solution to go through freeze / thaw crosslinking process for ~ 2-3 days
- 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)
|
| 50:50 |
110% CEC NaMT w/ DMHXLBR |
0.50760 |
0.49130 |
25 |
165 |
152
|
| 90:10 |
110% CEC NaMT w/ DMHXLBR |
0.90990 |
0.10450 |
25 |
92 |
272
|
| 90:10 |
110% CEC Laponite w/ DMHXLBR |
.90100 |
0.09980 |
25 |
92 |
272
|
Fluorescence Analysis: Diffusion Testing
- In a 10mL beaker containing one of the hydrogel samples with Rhodamine 6G, place ~ 4mL of H2O
- Using a timer, every 15 minutes using a plastic pipette remove ~ 1-2mL of the sample
- In glass cuvette marked for fluorescence, dispense the sample collected into the glass cuvette
- Then place the sample filled cuvette within the sample holder to run fluorescence of the sample
- Once a fluorescence reading has been run of the sample, dispose of the sample collected into a waste container
- After each addition collected and disregarded of the sample, add ~ 1-2mL more H2O ensuring enough sample for the next reading
- 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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PVOH Research
