Group 076-11: Modulating Hydrogel Structure for Therapeutic Release

During the eighth week of the hydrogel restructuring module, testing trials were conducted to determine the therapeutic release rates of variant hydrogel densities, including sample of: high-density, low-density, intermediate-density, and a layered sample of both high and low densities. The testing of the hydrogel layers was conducted by the injection of the fluorescent signal protein, FITC-BSA, within each sample. The hydrogel samples containing FITC-BSA were constructed at three-six hour intervals, then tested concurrently through the spectrophotometer. The testing phase was completed twice during week eight. During the first testing phase, the employment of tap water in the construction of the samples had produced hydrogel samples that were not uniform in consistency. As such, a second trial was conducted in which pure water was utilized to account for the mistakes of the first testing phase. The second trial proceeded to the spectrophotometer phase of testing. The results of the s...

This week, the group's main focus was to create samples of hydrogel for testing. As we set out to test absorbance values, we developed a procedure that would allow us to create several samples of gel over a long period of time. Table 1, below, was used to organize and label the samples during their preparation. Table 1: Labeling Method Used for Preparing Samples Table 2: Volumes Required for Mixture in Step 1 Procedure 1: Mixing the Alginate Solution 1. In a 150-mL beaker, mix the volumes of water and sodium alginate required for the solution you are making, found in Table 2. (This step must be done for each of the 3 sodium alginate solutions. Then, the volumes for the 7% and the 2% solutions must be halved and mixed separately, only to be combined into a test tube at the end of this procedure). 2. Add .01 mL of FITC-BSA to the sodium alginate solution created in step 1. Mixing the Calcium Chloride 3. Mix 25 mL of water and 5 mL of 30% calcium chloride i...

Progress on the hydrogel adhesive prototype has entailed the finalization of the proposed design. As such, it was determined that differentiation of hydrogel density must be attained by varying the concentration of sodium alginate utilized within the individual hydrogel layers. The initial design had called for the variation of calcium chloride concentration, though it was concluded that the variation in calcium chloride density will not contribute appreciably to the densities of the layers. Moreover, the finalized design will exclude hydrogel bead suspensions, as the beads will not contribute to the release of FITC-BSA. Thus, FITC-BSA will become encapsulated within the high-density hydrogel layer, as shown below in Figure 1. To encapsulate the prototype drug, FITC-BSA will be mixed with sodium alginate before calcium chloride solution is added. To quantify the therapeutic release three hydrogel mixtures will be created, including: a high density layer, a low d...

During week five, more research was done and the group was able to decide on the exact concentrations of calcium chloride to use in making each hydrogel layer as well as in the beads. The higher the concentration of calcium chloride, the more dense the hydrogel layer will be. Thus, for the thin, low-density layer, as well as for the low-density beads, a 5% calcium chloride solution will be used. For the thick, high-density layer, a 7% calcium chloride solution will be used. Refer to Figure 1, below, for a visual of the design. Figure 1: Preliminary Diagram of the Hydrogel Wound Dressing   Another task that was completed this week was additional planning for the testing phase. Once the hydrogel has been constructed, samples of it will be placed into cuvettes, and fluorescently-labeled bovine serum albumin (FITC-BSA) will be injected into the cuvettes, one at a time, in intervals of four hours. This will occur over a period of two days, and at the end of the two day...

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....

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...