Team:UCLA/Notebook/Materials/18 August 2015

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• Started new dialysis on 2 silk samples (10 mL of LiBr silk, each)
  • START: 10:10 AM
  • Change 1: 11:10 AM
  • Change 2: 3:07 PM

• Removed the silk from the concentration dialysis that was started yesterday at 900 AM
  • that is around 19 hrs, 20 minutes on the concentration
  • managed to only get around ~300 uL back from the cassette
    • 4 mg in 20 uL = 200 mg/mL = 20g/100mL = 20% w/v.
    • I don't know how this managed to get so concentrated in less than 20 hrs.
  • I think concentration dialysis is to difficult and wasteful (20 hr dialysis to obtain less than 1 mL of silk)
    • going forward, HFIP is probably easier to work with
    • If we do do concentration, it will have to be for less than 19 hrs.

• Prepared some Tamura dope (15% w/v, 500:1 silk:Tamura)

liquid	volume	total mass
silk (200 mg/mL)	250 uL	50 mg
Tamura (2.97 mg/mL)	33.67 uL	0.1 mg
water	50.33 uL	N/A

• • Spun at the rate recommended in the Lewis paper (1 mm/min plunger rate = 0.0167 mL/min for a plunger with diameter 4.78 mm)
  • 70% v/v EtOH and water for coagulation bath
  • godet at rate of 187 steps/second
    • is not fast enough to keep the fiber taut from the PEEK tubing tip
    • the silk starts to droop
  • however, 2*187 is too fast, and breaks the fiber
  • at the end, we settled for godet rate of 187

• • at the end of the spin, the silk was allowed to soak in the bath for 1 hour, then taken out to dry in the fume hood
  • Resulting fiber was incredibly brittle

Dried fiber collected on the godet

• • We were unable to take it off the godet without breaking it

• • However, it glowed.

Fragments of the Tamura fiber are in the dish on the right. On the left is a tangle of natural silk, barely visible. Image was taken in a blue light box with a UV filter

• Some observations about the spinning process:
  • It was extremely difficult for several reasons
  1. the silk emerges from the PEEK tubing tip too quickly
  2. emerging silk fiber is too difficult to see in the bath
  3. very hard to grab and guide the silk to the godet
  4. Silk breaks frequently from the godet. This is probably because we don't know exactly what godet speed to use
  5. Silk slips off the bottom of the godet often
  6. Current setup requires us to hover over the solvent bath as we guide the fiber