Week 3: Testing Different Ions (Sodium vs. Calcium)

Week 3: Testing Different Ions (Sodium vs. Calcium)

This week, I started Phase 2 of my methodology. I tested the first set of experimental variables (0.1M Sodium Chloride and 0.1M Calcium Chloride) to create MLVs.

The main reason for selecting these specific salts is to see how different ionic charges affect the DOPC lipid headgroups and in turn the formation of MLVs. Calcium is a divalent cation (2+ charge), which means it binds strongly to the negatively charged lipids and can potentially cause the membrane to become too rigid. Sodium is a monovalent cation (1+ charge), so it interacts weakly in comparison, which should theoretically allow the lipids to have greater flexibility needed to form proper MLVs, without forming clumps, tubes, or other residues.

Over the past few days, I completed the entire thin film hydration protocol six times for these two buffers. I dried the lipid films, hydrated them with their solvents, and vortexed them for exactly five minutes to ensure consistency across all my samples.

When I took the completed samples to the darkroom for fluorescence microscopy, the difference between the two groups was immediately obvious. Even without running the images through the ImageJ counting software, I could clearly see that the NaCl samples were much more uniform. The overall yield of multilamellar vesicles in the Sodium buffer was also visibly higher, whereas the Calcium Chloride samples looked noticeably sparser and often clumped together. I was elated to see my results align perfectly with the biophysical theory right away.

For tomorrow, I plan to finish the imaging process for the final calcium chloride replicates. Once everything is captured, I will organize the tile scans so that they are fully prepped for the quantitative data analysis phase. Seeing such a noticeable difference, even before data analysis, already gives me a lot of confidence moving forward. I am eagerly looking forward to getting the actual numbers to confirm this later in my project.

-Samahith