User talk:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/10/19/Lipids discussion

Brian P. Josey 22:14, 19 October 2009 (EDT) So I don't have too many questions about the actual subject matter of what you had to say, it is fairly self contained and easy to understand. There is only one thing that I would want point out. You said that phospholipids were used in cellular wall structures, they are actually used in membranes. Cell walls are made from carbohydrates, like cellulose in plants. The distinction between the two is that cell membranes are fluid and can move with respect to the environment, while cell walls are rigid. Beyond that I have a couple of comments and questions.

• • Andy Maloney 22:38, 19 October 2009 (EDT): I didn't know that about cell walls. Of course it makes sense since animals have cell membranes and not cell walls.

• I like the idea of using amphilic lipids, especially the phospholipids. When you use them, you are in essence recreating the environment that the kinesin moves in. It is like having an extended vacuole across the whole surface of the slide that the kinesin is attached too.
  • Andy Maloney 22:38, 19 October 2009 (EDT): That was one of my original ideas. We shall see if it works though. I hope so.
• I was wondering how will we ensure that the lipids will be upright? I imagine that you would have the polar heads upward, and that the tails would attracted to the hydrophobic slide, while the heads are attracted to the aqueous solution. This will naturally draw them together, creating a blanket with the heads facing away from the slide.
  • Andy Maloney 22:38, 19 October 2009 (EDT): Lipids will self agregate into a lowest energy configuration. This means that if we use the hydrophobic slides, the lipids will align themselves such that the tails will be pointing to the hydrophobic surface. If we add too many lipids then we will get an inverted bilayer. If we add way too many lipids and add water, we will get three layers of lipids with the surface of the lipid trilayer in water and on the hydrophobic slides.
• I also like the explanation for what is wrong with using casein, and what we use it for in the real world. I didn't know that and it is good to have it written out.
• How can we tell the difference between an assay that isn't working because kinesin doesn't interact with the lipids from one that isn't working because of a change in osmotic pressure? Here I assume that there is a difference between the osmotic pressure in each of the assays, and I bet this is mostly from ignorance on my part.
  • Andy Maloney 22:38, 19 October 2009 (EDT): Well, you are describing two different experiments. One where we look at different surface passivations and one where we change the osmotic pressure. It would be nice to find a lipid that does work as a surface passivator. That way we can compare the new passivation with different osmolytes and a casein passivation experiment using the same osmolytes added.
• What happened to using silicon nanoparticles? Are we still doing that, or did we already answer the questions we have about the structure verses chemical nature of the surface?
  • Andy Maloney 22:38, 19 October 2009 (EDT): I still haven't abandoned the nanoparticles. I'm just more concerned about finding some lipids that work since I have to find something quickly for the conference.
• I love the idea of using the lipids with the different charges, it is simple and easy to understand.

I am sure that I will have more questions in the morning, but this is what I have for tonight. If I think of anything else I will add it to the list, or talk to you about it tomorrow.