Week 9

During Week Nine, the group worked to improve and repeat experimental trials to create the final deliverable of the alginate sheet. Daniel Nguyen and Talaial Alina conducted these experiments in Dr. Hao Cheng's Nanobiomaterials and Cell Engineering Laboratory as seen below.

In a second experimental trial, portrayed in Figures 1 and 2, Nguyen changed the experimental procedure to allow for the immediate preparation of all the materials that would later be mixed into a test tube. The contents of this test tube would be poured later into a petri dish. Unfortunately, the resulting material, seen in Figure 3, was of a similar and clumpy composition to the alginate sheet formed during the first experiment in Week Eight.

Figure 1: Daniel Nguyen removing deionized water from a cylinder and placing it into a test tube (second experimental trial)

Figure 2: Daniel Nguyen releasing the mixed composition of alginate and acrylamide into the petri dish (second experimental trial).

Figure 3: Side view of the results of the second experimental trial

Figure 4: Top down view of the results of the second experimental trial

As a result, Nguyen explored potential solutions with Sean, a PhD student in the lab, to create a uniform alginate sheet. Nguyen finally arrived at the idea of reviewing the "Supporting Information" subsection of the article "Strengthening Alginate/Polyacrylamide Hydrogels Using Various Multivalent Cations". This article was published in Applied Materials and Interfaces, and was used to create the project procedure.

Through a thorough examination for two hours, Nguyen began to understand that the group experimental procedure for the hydrogel sheet was incorrectly written. It used the amounts of materials listed in a University of South Carolina alginate experiment through the procedure listed in the document of the Harvard alginate experiment referenced earlier.The group also wrote inaccurate amounts for calcium sulfate in which 0.04 grams was thought to be needed when actually 0.40 grams was required. In addition, the group used a significant amount of deionized water, 10 mL, to dissolve both alginate and acrylamide when only 5 mL was necessary. Furthermore, the combined materials, except the crosslinker calcium sulfate which would be added afterwards, needed to be heated for three hours under a temperature of fifty degrees Celsius.

After correcting these errors, Nguyen worked for three hours in a third experimental trial. This trial created a uniform and circular hydrogel sheet with several bumps near the edge of the sheet; a massive improvement from the two hydrogel sheets created prior. Sean noted that the bumps may have been the result of not pressing out the alginate material before placing it in the oven.

Figure 5: Side view of the results of the third experimental trial

Figure 6: Top down view of the results of the third experimental trial

The next phase of the project could involve some minor testing to evaluate the sheet's feasibility as a material for an actual hydrogels condom. Furthermore, the group would create the final report and presentation during Week Ten to analyze and communicate project results to a public audience.