User:Brian P. Josey/Notebook/2010/06/09

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Ferritin on Microscope

After a couple of technical issues with iMovie, I was able to put ferritin onto the microscope and film some kind of movement. I am not sure yet if this is from the magnet, or if it is just the result of Brownian motion.

Through the microscope, the ferritin droplets suspended in the oil come out very well. The quantum dots today however, did not come out as well, and I was unable to find any droplets. This is what the ferritin looks like:

Microscope ferritin before mag.png

This photo was taken before I applied a magnetic field to the flow cell. When I applied the magnetic field I did it twice. The first time, I placed one of the small cylindrical magnets on top of the slide so that it was as close as possible to the field of view without obstructing it. I was unable to see any motion with my naked eye.

The second time, I held one of the 2 in long cylinder magnets with a cone attached against the slide. Because of the awkward geometry of the magnet and the microscope, I had to hold it by hand. Due to my hands shaking, I was unable to keep it at a constant distance, but examining the film there may be some motion:

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This is a time lapse of two minutes under the magnet. It appears to me that the droplets are drifting to the upper left corner. The problem with this however, is that I cannot guarantee that this is caused by the magnet. From how the microscope is set up, a movement to the left in the camera would indicate a movement to the left looking down on the slide. I believed that I held the magnet to the right side of the slide, meaning the droplets were moving away from the magnet, but with the computer being on the left side of the microscope it would make sense if I was standing on the left side. Because of the slip-up, I will have to repeat the experiment on Tuesday.

Here is an after picture of the same field of view as above:

Microscope ferritin after mag.png

Because it is difficult to distinguish individual droplets, it might be impossible to demonstrate that there is a net motion using only before and after pictures.

If I can definitively show that there is a net motion towards a magnet when I hold it against the slide, this will be a major breakthrough for my project. To do this I need to try several things:

  • Film ferritin sitting in the slide without a magnetic field and with a field to compare them. This will show the difference between the random Brownian motion and any other drifts compared to any drifts that occur when I apply the field.
  • Be able to distinguish individual droplets and measure both their velocity and diameter. From this I can prove whether or not my theoretical calculations match the real effect. Maybe I could alter Larry's tracking software in some way to do this, which also has the added benefit of teaching me some LabVIEW, something I would like to do.
  • Successfully mount some kind of magnet on the microscope stage to eliminate the induced error from holding it in my hand.
  • Create a flow cell out of just cover slips so that I remove as much glass as possible between the magnet and ferritin. Either Andy or Ant have already done this, and they can show me how to do this.
  • Just place a magnet on a flow cell containing the emulsion and compare the droplets before and after in the microscope. This will be similar to my initial experiments where I aggregated it in the yoke. Note to self: use the magnetic yoke and not one of the smaller magnets because you already know it supplies the greatest field and force.

I am planning on attacking all of these different ideas next week, and hopefully I will be able to measure the force experimentally soon, and move on to more elaborate ideas too.