Team:UCLA/Notebook/Materials/14 July 2015

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Spinning more Tamura

• Fasih prepared a pooled Tamura fraction
  • concentration is 1.6 mg/mL

• want to spin total volume of 300 uL
• Let's prepare a dope such that the Tamura:silk mass ratio is 1:500, and 15% w/v.

• recipe
  • 225 uL of 20% w/v silk dope
  • 56.1 uL of the pooled Tamura fraction
  • 19.4 uL of ddH2O

• procedure
  • spun at 6uL/min into 70% v/v ethanol
  • spun silk was wound around tweezers

• results
  • the spin appears to be successful

the majority of the spin ended up in a single contiguous fiber. The fiber looks and feels much more like regular silk.

• • the resulting thread was much more resilient than the previous spin.
  • visual inspection under the UV box shows that it fluoresces

the same silk sample under the UV box. Its glow is very apparent. Sample on the right is Tamura co-spin. Sample on the left is native b.mori silk. Note that this picture was taken on July 20, while the sample was co-spun on July 14. Even after a week, it' still fluorescent!

• • UV microscopy verified its fluorescence.

20x magnification. 100% excitation light intensity.

• thoughts
  • The fact that the fiber was stronger and thinner during this spin could be due to a number of factors:
    • this spin was 15% w/v. Last time's spin was 12% w/v.
    • As we wound the thread around tweezers, we were stretching the thread.
  • This spin's fluorescence is much less than last time's spin, which was much thicker. This is despite the fact that last time's spin had a silk:tamura ratio of 4000:1, while this time's spin has a ratio of 500:1. This indicates that the thickness of fiber under the microscope does matter -- thicker threads fluoresce more due to having a greater amount of GFP per length of thread.