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| ==Objective== | | ==Objective== |
| To continue to find a usable PVA-NaMT bead synthesis method.
| | The AU Biomaterial Design Lab was closed for Fall Break. |
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| Notes below were recorded in [[User:Mary_Mendoza/Notebook/CHEM_581:_Experimental_Chemistry_I/2014/10/31| Mary's Notebook]]
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| ==Continuation of Bead Synthesis Trials==
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| * The burette set-up utilized by Eleni, Melvin, and Becca's group will be used; details of their assembly can be found on Kalivas' entry for [[User:Eleni N. Kalivas/Notebook/CHEM-571/2014/10/29|10/29/2014]].
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| * The assembly was prepared as shown in the picture.
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| [[Image:IMG 3226.JPG|thumb|center|600x600px]]
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| ==Description==
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| # A column was set up with glutaraldehyde and hexane. Air is being bubbled through the column to mix the two liquids.
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| # PVA-Clay will be dropped down the column
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| <u>Hexane Trial</u>
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| * The PVA-Clay formed beads within the hexane and floated down the column. They did not cross-link fast enough if at all and they dissolved into the glutaraldehyde.
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| <u>Organic-Glutaraldehyde Solution</u>
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| * We attempted to add acetone to glutaraldehyde and then add hexane to get rid of the solvent layers. The solution was not hydrophobic enough to form beads however. When only a slight layer of hexane and stirring were applied, it yielded no good results.
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| # We have decided to abandon the beads and begin synthesis of ribbons
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| ## We filled a column with acetone and 1.5mL of Glutaraldehyde
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| ## we then dropped in the PVA-Clay
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| ==Trial of Several Organic Solvents==
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| * ''I observed that as soon as the organic phase, formed bead comes into contact with the aqueous phase of the glutaraldehyde, the bead disperses into the aqueous solution. I decided to conduct my own trials and have my group members continue the burette-ribbon experiments.''
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| * ''I concluded that the dilemma in the formation of beads is the immiscibility of the organic phase which forms the beads and the aqueous phase that cross-links the beads.''
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| * ''Therefore, I thought, I can resolve this issue by choosing several organic solvents slightly miscible with water but hydrophobic enough to form the beads.''
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| * ''In an attempt to keep the reaction mixture homogenized, motion is required. Thus, the reaction should be kept stirring on a stir plate. Also, stirring prevents the formed beads from clumping together."
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| * I used the solvent miscibility table provided by Dr. Hartings taken from chemical company, phenomenex, as shown in the picture.
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| [[Image:Solvent miscibility chart.jpg|thumb|center|494x599px]]
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| <u>Acetonitrile Trial</u>
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| * A drop of the PVA-clay was added into 3 mL of acetonitrile contained in a 12x100 mm, 8 mL disposable test tube.
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| * The PVA-clay did not form beads.
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| * Acetonitrile was tested without the use of the solvent miscibility chart. Upon checking the chart, the solubility in water of acetonitrile (%w/w) is 100.
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| <u>DMSO and Ethyl Acetate</u>
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| * Hence, I selected the top 5 least immiscible organic solvent according to their solubility in water (%w/w) as shown in the picture.
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| * I first tested dimethyl sulfoxide (DMSO) and ethyl acetate. For DMSO, a quick formation of bead was observed but readily dispersed as it settled on the bottom of the tube. On the other hand, as the drop of PVA-clay-HCl passed through the ethyl acetate, the bead retained its shape for at least 5 to 7 seconds and gradually dispersed.
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| * Without testing the remaining organic solvents, I chose ethyl acetate as my organic solvent. It had the suitable features such that it enables the bead formation and its slight immiscibility with water.
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| * Next, it was time to test ethyl acetate with glutaraldehyde. The following amounts for the ethyl acetate trial were not exactly measured but made by approximation. I took a 50 mL beaker with a magnetic stir bar. I approximately added 15-20 mL of ethyl acetate. In a drop wise manner, I added my PVA-clay-HCl solution using a pasteur pipette. I added at least 500 uL of glutaraldehyde.
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| * With this experimental set-up, I was able to form beads but had to resolve the ratio of materials I used since everything was performed by approximation.
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| [[Image:Solvents.png|center]]
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| |} | | |} |
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| __NOTOC__ | | __NOTOC__ |
Biomaterials Design Lab
