User:Anthony Salvagno/Notebook/Research/2009/12/16/Tethering and Unzipping with Igor

Tethering

{{#widget:Google Spreadsheet |key=tAC8wkbiNjA8wMB7CjrIcZQ |width=500 |height=300 }} I made 2 samples. The first I labeled small and contained the same beads I normally use. The second I labeled big and was beads that Igor made me. These are uncoated Silica beads that range in size from 1-3um. Igor wanted to see if we would get tethers by chance. It turned out that these beads are too large to tell if they do tether as their motion is slow and there isn't as much brownian noise as there is with the 0.5um beads. Also identifying tethers is easier in Evans's lab because they have a 100x magnification objective.

Unzipping

I will be working with Igor and I will post any results here if I achieve anything. I will post some comments afterward as well. I need an iPhone, or even better this.

Notes

There were some good tethers in the sample with my beads. So good that I found two tethers immediately (as in once I found the bottom surface there were 2 tethers). In all I tried unzipping 3 tethers and only one separated. This means that I either unzipped that tether or the bead came off. Not sure. The data for this is seen below (see Figures). There is deflection in both directions because we unzipped off center (meaning we didn't center x and y). In the x graph there is a jump at around 8 seconds and I don't know how to explain this.

Tomorrow Koch will be more involved and hopefully can help with the data analysis.

Experimental Parameters:

• 0.5um beads
• 500mW power of laser (I think)
• 0.1um/s piezo speed
• pBR322 tethers

Figures