Week 6

Ideas for Hydrogel Mold

• Two glass plates held together with teflon spacers and binder clips
• Gel drying frame
• Glass plates for gel electrophoresis 
• Petri dish with cover
• Customized/ Standardized mold

Hydrogel and UV/Vis Spectroscopy Notes

Change in Hydrogel Design

Per recommendation by project adviser, Dr. Margaret Wheatley, the hydrogel will now be created with the addition of D-(+)-gluconic acid delta-lactone (GDL) so that it will no longer be necessary to dunk the mold enclosing an alginate solution in a calcium carbonate solution. By adding GDL, which partially hydrolyzes to gluconic acid upon addition to water, the cross-linking of aliginate is slowed down enough that it does not immediately form a gel when in contact with calcium ions. This way, the GDL, alginate, ibuprofen, and calcium carbonate can be stirred into one solution and poured into the desired mold.


Preliminary Hydrogel Sample

Image of the 1% Alginate and Calcium Carbonate Solutions

A sample hydrogel was created during lab to obtain a preliminary idea of the amount of reagents necessary and the liquidity of a hydrogel produced with a specified ratio of sodium alginate to calcium carbonate. The following recommended parameters were used:

• 5.5 g/L calcium carbonate aqueous solution
• Final GDL concentration of 80 mM
• 1% alginate in water solution
• Ratio of 0.5 mL calcium carbonate per mL alginate solution

To obtain these parameters, the following calculations were necessary:

• Amount of GDL (in grams) to add to the hydrogel solution
• 80 mM = 0.08 M
• Total volume of sample (decided based on size of petri dish) = 0.018 L
• 0.08 M = (#moles)/(0.018 L)
• 0.00144 mol GDL
• Molecular weight of GDL = 178.14 g/mol



Image of the sample hydrogel settled in petri dish mold.

• 0.00144 mol x 178.14 g/mol = 0.2565 g GDL
• Amount of calcium carbonate to add to water to create 6 mL of 5.5 g/L solution
• 6 mL = 0.006 L
• 5.5 g/L x 0.006 L = 0.033 g calcium carbonate

Thus the final hydrogel solution contained the following:

• 6 mL 5.5 g/L calcium carbonate aqueous solution
• 12 mL 1% alginate aqueous solution
• 0.2565 g GDL