- Prepare PVA(MW 130,000) microspheres through suspension cross-linking of a polymeric solution with glutaraldehyde.
- Remove prepared MW 130,000 PVA hydrogels from freezer and begin soaking in water.
- Finish preparing PVA(MW 130,000) hydrogels for freeze-thaw method.
- Filter prepared clay exchanges.
- Prepared DSC samples of all used clays.
- Reaction should be carried out using a reflux condenser and a thermostatic water bath of 55°C.
- Dissolve 1g total of PVA and clay additive in 5mL hot,deionized water.
- Acidify the solution using 0.25mL 0.5M H2SO4.
- Dissolve 0.6g Cellulose acetate butyrate(CAB) in 25mL 1,2-dichloroethane.
- Pour the acidified PVA solution into the 25mL 1,2-dichloroethane solution. Place all in a clean round bottom(RB) flask.
- Stir the water/1,2-dichlorethane solution for 30 minutes.
- After 30 minutes stirring, add 0.75mL glutaraldehyde(GA) to the solution.
- After the addition of glutaraldehyde, allow the reaction to carry out for 3 additional hours at 55°C.
- Filter the produced microspheres from the solution using a a sintered glass filter and a vacuum.
- Wash the collected microspheres using the following solvents in the following order:
- hot water
- cold water
- Scrap all collected microspheres into a small vial.
- Freeze microspheres in liquid nitrogen for ~2 minutes.
- Place on [ask Dr. Hartings name of machine again] overnight to completely dry.
- The following procedure was adapted from the article Poly(vinyl alcohol) microspheres with pH- and thermosensitive properties as temperature-controlled drug delivery 
- 1,2-dichloroethane is highly flammable. Care must be used at all times when dealing with 1,2-dichloroethane
- Avoid all 1,2-dichloroethane skin contact by wearing gloves and googles.
- Avoid any 1,2-dichlorethane contact with extreme heat, open flame, or electrical sparks.
- 1,2-dichloroethane should be kept in the flammable storage safety cabinet when not in use.
- When in use, 1,2-dichloroethane should be kept in the fume hood.
PVA Microsphere information:
|Preparation of Microspheres using PVA MW 146,000-186,000
| Amount of PVA added(g)||0.9001
| Amount of Lamponite clay added(g)||0.1004
| Amount of cellulose acetate butyrate added(g)||0.6066
| Amount of GA added(mL)||0.75
| Amount of H2SO4 added(mL)||0.25
- The dispersion agent(hereout referred to as CAB), lamponite clay and PVA formed a sort of suspension in the water/organic solvent solution. It did not appear to fully dissolve. Used a spatula to scrape the side of the RB flask in order to try and break up the large chunks.
- After addition to heat, the large chunks generally broke apart. Small spheres seemed to be forming after approximately an hour spinning.
- After 3 hour spinning and heat, large clumps of spheres formed. Upon scraping with a spatula these clumps broke apart into what appeared to be smaller spheres.
- Large clumps indicates that we may want to change portion of our method to produce smaller microspheres.
- The spheres were a cloudy, white color throughout.
- The general protocol described on January 30th was followed.