Tutorial

If you'd like to know exactly how to recreate our project, you've come to the right page. The following tutorial and video will show you exactly how to make each layer of our hydrogel wound dressing.

Materials:

1. Food-grade sodium alginate, 9.0 g

2. Pure water, 200 mL

3. 150-mL glass beakers, 3

4. Soap mold with at least 2 8 x 7.1 x 1 inch compartments, 1

5. 30% calcium chloride solution, at least 15 mL

6. Self-adherent medical wrap, 2 x 12 inches

Procedure:

Mixing the alginate solution:

1. Add 2.0 g of food-grade sodium alginate to 100 mL of pure water. Mix thoroughly. There may be chunks of alginate that are difficult to dissolve, but after mixing for several minutes the solution should have a uniform consistency with no chunks.
2. In a separate beaker, mix 7.0 g of sodium alginate with 100 mL of pure water. This solution will be even harder to mix properly, so it is best to add the sodium alginate in small amounts.
3. Add food dye to these solutions if desired.

Preparing the calcium chloride:

4. Add 5 mL of 30% calcium chloride solution to 25 mL of water. This will make 30 mL of 5% calcium chloride solution. This will likely not be enough to create the entire wound dressing, so make more of this solution as needed.

Making the gel:

5. Pour the alginate solutions prepared in steps 1 & 2 into separate compartments of a soap mold. The gel prepared in step 2 will be especially viscous, so it will need to be smashed down with an instrument such as a spoon. Pour enough so that it covers the bottom of the compartment. The solution prepared in step 1 should be about half the thickness of the solution prepared in step 2.

6. Pour enough calcium chloride over each solution so that there is a thin layer covering each solution. The solution should form a gel upon contact with the calcium chloride, but allow it to sit for a few minutes to make certain that the solution has completely gelled.

Putting together the prototype:

7. Remove the gels from the soap mold, and combine. The 7% alginate hydrogel (from the solution in step 2) should be in placed in contact with a long strip of the medical wrap (about 10 inches), with the 2% alginate hydrogel (from the solution prepared in step 1) should be placed on top of the 7% layer.

8. Thin strips of the self-adherent wrap should be cut and placed across the double-layered hydrogel on opposite sides, securing it to the bandage.

See the video below for a demonstration of steps 5 and 6. This demonstration shows the formation of the thick, high-density layer of hydrogel made from 7% sodium alginate solution (prepared in step 2).

Comments

Week Four Progress

Our focus this week was finding the correct placebo for our design. Prior to this week, we had expected to use zinc oxide in our module but we realized it did not have a high enough molecular weight. Therefore, the zinc oxide would disperse from the hydrogel beads too rapidly. After some research and guidance from our professor, we decided to use Fluorescein Isothiocyanate-Bovine Serum Album (FITC-BSA), which is a hydrophilic protein with a molecular weight of 66 kg/mol [1]. FITC-BSA will also be our signal source for measuring the rate of dispersion from the beads. As seen in Figure 1, FITC-BSA is vivid in color and allows the protein's diffusion throughout the hydrogel to be observed easily. We've decided to initially use 0.25 mg/ml as the concentration of FITC-BSA within our design. Figure 1: FITC-BSA (green) seen in samples of HeLa cells [2] References: [1] Bovine Serum Albumin Conjugates Product Information , 1st ed. Molecular Probes, 2005. [2] S. Sarker, R....

Week One Progress

Figure 1: Diagram of preliminary design The culmination of the hydrogel modulation design will yield a hydrogel wound dressing utilized for the therapeutic treatment of first-degree and second-degree exterior burns. A physical prototype of the hydrogel wound dressing will be produced by precipitating food-grade sodium alginate in a calcium chloride solution. The reaction yields spheres of low-density gel surrounded by a thin gelatinous membrane. The construction of an alginate dressing necessitates ionic cross-linking of the alginate solution with calcium ions, as to form the gel component. Both the high-density and low- density hydrogel layers will be generated in unison, before undergoing the freeze-drying process as to produce porous sheets. The physical prototype will be accompanied by a computer generated model of the hydrogel wound dressing, as evidenced in figure 1. The required components to construct the hydrogel adhesive were determined and subsequently purchased. The r...

Week Three Progress

During Week Three, we discussed and determined our therapeutic agent for the hydrogel module. After extensive research and comparison of our options, we decided the best-suited therapeutic would be zinc oxide. This substance fits our design so well because it is hydrophobic and will slowly disperse through the pores in the bottom hydrogel layer. Zinc oxide has been used in past hydrogel models and has been proven to be effective. It is an agent that has been used in ointments and supplements to treat burns and prevent infections. Likewise, the possibility of overdosing on zinc-oxide necessitates a solution for controlled therapeutic release. The predominant delivery system for zinc oxide is through medicinal cream, the delivery through which enables the therapeutic threshold of zinc oxide to be increased to levels of high toxicity. Symptoms of zinc-oxide overdose include: fever, chills, vomiting, mouth irritation, stomach pain, and yellowing of the eyes and skin. Consequently, the phar...

Group 076-11: Modulating Hydrogel Structure for Therapeutic Release

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