- What is a hydrogel?
- See background!
- Also check out this link that we used while researching.
- What materials are being/were used for this project?
- Sodium alginate and calcium chloride for forming the physical hydrogels
- Methylene blue dye used to measure the concentration as the hydrogels released the dye
- Pipettes (disposable) and glassware - volumetric flasks, beakers, etc. - for measuring and distributing the liquids
- UV/vis spectrometer
- Other lab equipment including: parafilm, stirring rod, automatic pipette, hot plate, stir bar
The following is a table displaying the budget that we set aside for this project:
Items that were purchased online at Amazon.com included the disposable pipettes and sodium alginate. All other materials and equipment were provided in a chemistry lab on campus.
- What procedures are involved in producing hydrogels?
- How does one measure the release rate? What method did our group decide on?
- How are hydrogels used?
- Why are these hydrogel beads blue?
The sodium alginate is dissolved into a solution, which is then dropped into the calcium chloride solution with a pipette. This creates beads of calcium alginate (the hydrogel) which can be filtered out of the calcium chloride solution. The approximate concentrations used are 1% sodium alginate and 2% calcium chloride, although the concentration of sodium alginate was varied for this experiment.
*Supervision was required while these procedures were completed in a lab setting*
Our group used a UV/vis spectrophotometer to measure the concentration of dye in the solution as it was released from the hydrogel beads. We calculated the absorbtivity of the dye by using Beer's law and a calibration curve, and then gradually took measurements over the course of an hour for each concentration of sodium alginate we tested.
Hydrogels have a variety of therapeutic applications, from drug delivery to bandages. Their unique structure and properties make them very useful in ways that other materials can not imitate.
The dye used, methylene blue, is blue. This dye was chosen because it has high absorbance, which will make the change in concentration more obvious. The dye also had an optimal molecular weight, large enough that it wouldn't slip through the hydrogel and release early.
- What affect does the concentration of sodium alginate have on the hydrogel?
The concentration of sodium alginate controls the relative abundance of alginate chains in solution. Upon addition of calcium chloride, the concentration of alginate chains controls how many crosslinked hydrogel fibers there are. The higher the abundance of alginate chains, the smaller the pores through which a dye( or medication) can diffuse. Hydrogel made with a lower concentration of sodium alginate has bigger holes for the dye to slip through. These differences are supported by the experiments this group has run. 98.66% of the variance in release rate(which, all other things equal, is controlled by pore size) is explained by alginate concentration.