User:Moira M. Esson/Notebook/CHEM-581/2013/02/15: Difference between revisions
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== | ==Objectives== | ||
* | # Prepare PVA-clay microspheres. | ||
# Run diffusion tests on hydrogels prepared on [[User:Moira_M._Esson/Notebook/CHEM-581/2013/01/30|2013/01/30]] with Rhodamine 6G dye added on [[User:Moira_M._Esson/Notebook/CHEM-581/2013/02/08|2013/02/08]]. | |||
<br> | |||
==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: | |||
# The desired ratio of PVA and clay was measured out. The total mass was ~1g. | |||
# The PVA/clay was placed in a 50mL beaker with a magnetic stir bar. 25mL distilled H<sub>2</sub>O were added to the beaker and the solution was heated to ~100°C and allowed to stir until complete dissolution of PVA/clay. | |||
# 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 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 microsphere solution was placed in a freezer at -20°C for 24 hours and then removed and allowed to thaw for 24 hours. | |||
# Repeat this freeze-thaw cycle three times. | |||
<br> | |||
This procedure was adapted from [http://www.sciencedirect.com/science/article/pii/S0168365998000893] | |||
<br> | |||
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: | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Prepared Clay-PVA(MW 146,000-186,000) microspheres''' | |||
| align="center" style="background:#f0f0f0;"|'''''' | |||
| align="center" style="background:#f0f0f0;"|'''''' | |||
| align="center" style="background:#f0f0f0;"|'''''' | |||
| align="center" style="background:#f0f0f0;"|'''''' | |||
|- | |||
| 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% NaMT||0.9099||0.1045||92||0.272 | |||
|- | |||
| 50:50 PVA:110% NaMT||0.5076||0.4913||165||0.152 | |||
|- | |||
| 90:10 PVA:110% Lamponite||0.9010||0.0998||92||0.272 | |||
|} | |||
<br> | |||
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. | |||
<br> | |||
==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: | |||
# Excess Rhodamine 6G sample still present in the beaker was removed. | |||
# Hydrogel samples were removed from the beakers, pat dry with a paper towel, and placed in a new, clean beaker. | |||
# 25mL distilled H<sub>2</sub>O were added to each beaker sample. | |||
# A timer was started, and every 15 minutes, a sample of distilled H<sub>2</sub>O was removed from the beaker and placed in an unfrosted cuvette. | |||
# The sample was discarded into a waste beaker. | |||
# This process was repeated for 2 hours. | |||
<br> | |||
Spectra: | |||
<br> | |||
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]] | |||
<br> | |||
'''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 | |||
<br> | |||
[[Image:2 hr diffusion test 50 MW 146 NaMT.png]] | |||
<br> | |||
Figure 3. Diffusion test fluorescence spectra for 90:10 ratio of PVA MW 146,000-186,000:Lamponite | |||
<br> | |||
[[Image:2 hr diffusion test 90 MW 146 LP.png]] | |||
<br> | |||
Figure 4. Diffusion test fluorescence spectra for a 90:10 ratio of PVA MW 146,000-186,000:NaMT | |||
<br> | |||
[[Image:2hr diffusion test 90 MW 146 NaMT.png]] | |||
<br> | |||
Figure 5. Diffusion test fluorescence spectra for a 90:10 ratio of PVA MW 146,000-186,000:50% NaMT | |||
<br> | |||
[[Image:2hr rhodamine diffusion test 90 MW 146 50% NaMT.png]] | |||
<br> | |||
*'''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 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. | |||
*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. | |||
<br> | |||
Revision as of 17:14, 7 March 2013
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Objectives
Microsphere Preparation
General Protocol:
For a 90:10 ratio: (25mL)(1μM)/(92μM)=0.272mL For a 50:50 ratio: (25mL)(1μM)/(165μM)=0.152mL
Fluorescence
General Protocol:
Observations:
|