Previous Scholars Labs
Here are some of the labs we have done with Scholars students in the past:
Nanocrystalline Solar Cell Lab
In this lab, students were given a challenge: How can we engineer a device that operates like the process of photosynthesis? To answer this question, students assembled and built their own nanocrystalline solar cells. To assemble the nanocrystalline cell, students obtained two glass slides and added a thin layer of titanium dioxide (TiO2) to each slide. Anthocyanin dye from raspberry juice was the chemical used to trap solar energy between the slides, which then enabled charges to be passed to the TiO2. Students then filled the space between the slides with a liquid electrolyte solution of potassium iodide which serves to transport charge (by way of a redox reaction) from the bottom electrode to the Anthocyanin dye to complete the circuit. Finally, students were able to measure changes in the electrical output of their solar cells after exposing them to both UV light and sunlight.
Salivary Cortisol Lab
For this lab, students learned about stress responses and the role that cortisol plays in helping our body’s respond to stress. In our body, about 90% of cortisol is bound to blood proteins while the remaining 10% enters the saliva. By obtaining samples of their saliva, students examined the cortisol levels in their system before and after exercise. The objective of the experiment was to determine if the students’ cortisol levels changed significantly after exercise, indicating that their body was under physical stress. Students worked in pairs and one group member obtained an initial, baseline saliva sample. The same group member performed a quick burst of intense exercise, then obtained a second saliva sample 30 minutes after exercising (based on previous research, it has been determined that on average it takes about 30 minutes for cortisol levels to rise after the stress response has been initiated). Students performed a competitive ELISA (enzyme-linked immunosorbent assay) to determine their salivary cortisol levels.
Creating and Using Gold Nanoparticles as Sensors
Gold nanoparticles have been used to ‘label’ cancer cells and microscopy is used to detect these labels. Using these principles, students created their own gold nanoparticles and used these nanoparticles to sense the electrolyte levels in common sports drinks. To begin, students added distilled water to gold ions, then placed the solution on a hot plate. When the gold ion solution began boiling, trisodium citrate was added causing the solution to change from a yellow to a deep red color. This color change indicated the formation of individual gold nanoparticles within the solution. Students then added a few drops of NaCl (salt) to a sample of their nanoparticle solution which led to the sample changing from a deep red to a purple color. Using a spectrophotometer, students measured the absorbance value of their nanoparticle only solution and compared it to the absorbance of their solution that contained both nanoparticles and NaCl. At this point, students learned that adding salt to gold nanoparticle solutions leads to the aggregation of nanoparticles.
For the second half of the lab, students used their gold nanoparticles to measure the salt levels in common electrolyte-rich sports drinks. Students had the option to test the electrolyte levels in Zero Sugar Powerade, Lower Sugar Gatorade, organic lemonade, Signature Care Electrolyte Solution, Gatorade Frost, Gatorade Lemonade Thirst Quencher, Zero Sugar Gatorade, and Pedialyte Electrolyte Solution. For qualitative analysis, students examined the change in color of each nanoparticle solution as they added electrolytes to them. To quantitatively determine which drinks contained higher amounts of electrolytes, students measured the absorbance of their solutions using a spectrophotometer.
The principles of nanotechnology: Self-assembly and Nanoencapsulation Lab
Nanocapsules are small particles (1 billionth of a meter; about 1/80,000 of the diameter of a human hair). Nanomedicine uses nanocapsules to deliver agents to treat disease, most notably cancer. A challenge for scientists is to create nanocapsules that contain the agents, such as medicines, that can be delivered specifically to diseased cells. In the first half of this lab, students mixed a solution of sodium alginate and calcium chloride to create macrocapsules using the same principles of self-assembly that are used to produce nanocapsules. Next, to examine how chemicals can be released from nanocapsules, students created food dye-encapsulated nanoparticle-assembled capsules (NACs). By adding the NACs to either water or vinegar, students were able to examine how changes in the pH of a solution can affect the release of chemicals from nanocapsule
Column Chromatography is a technique that uses a long, transparent tube or column to separate the different chemicals in a mixture or solution. For this lab, we used this chromatography technique to separate the two food dyes found in grape soda. In this experiment, students used nonpolar (hydrophobic) Space Sand, which interacted with and grabbed onto other nonpolar chemicals from the grape soda in their chromatography columns. Based on the differences in chemical properties, the interaction between the sand and grape soda caused the colors to separate.
Examining the Roles of Pyruvate and Lactate Dehydrogenase (LDH) During Exercise
The goal of this activity was to examine the roles that pyruvate and lactate dehydrogenase (LDH) play during exercise. The objective was to have students test athlete samples, gather data, then graph and interpret their results. Students were asked if analyzing these samples could give an indication of how athletic a person is and if this analysis could help them determine an athlete’s anaerobic respiration capacity. In addition, students discussed the mechanisms involved in the production of energy in our bodies. Lastly, students examined glycolysis and the differences between aerobic and anaerobic respiration.