Testing Dye Binding

Yesterday (February 7th), I continued work on my new project. I ran a preliminary test to confirm the way in which dye binds to slides with PBS and Casein. From this experiment, we expected that the slide incubated with casein would be stained, while the slide incubated with PBS would not. To test this, I incubated one slide with 3 mL of 10X Casein and one slide with 3 mL of PBS for an hour on the shaker. Once the incubation was complete, I drained the solutions into the biologic waste container and washed both of the slides with PBS three times for 10 minutes each time. I then added 3 mL of LabSafe GEL Blue stain onto each slide for 20 minutes.

Once this process was complete, we found a surprising result. The PBS slide, as expected, had not bound the dye. However, the Casein slide did not bind the dye either. Instead, the protein had bound the dye, and the protein was no longer bound to the slide. In the image below, the Casein slide (left) and PBS slide (right) are both pictured with the dye solution still on the slides.

After seeing this result, we decided that either a small amount of Casein was stuck under the slide and came up to bind the dye, preventing us from seeing the protein on the surface of the slide, or the dye eluted the Casein from the slide. In an attempt to see if there was still protein bound to the surface of the slide, I poured the dye off of the slide, washed it with PBS, sprayed it with water, and added 3 mL of dye back onto the slide in a different container. After 10 minutes, the slide showed no change in color, leading us to believe that there was no protein bound to the slide. We will test another Casein slide to see if we get the same result. If the dye is found to elute the Casein from the slide, we will need to reconsider the procedure for my project.

While waiting for the slides in this experiment to incubate, I labeled the trays for my project and prepared my slides by washing them in ethanol.

I look forward to finding out if the dye does indeed elute the Casein from the slides.