User:Daniel Catt/Notebook/Protein Biofilms Exploration/2011/06/06

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06.06.2011

Method: Temperature Dependence of Baking Procedure Exploration

  • Three samples, all heated at 80°C for 1 hour, 2 hours and overnight (~19hours).
  • Zein preparation: 2g zein and 18mL ethanol combined, mixed for about 30 minutes. Added 800μL of glycerol and let mix an additional 3 hours. Combined with 0.015 mM BSA that had been heated in a 60°C water bath for 1 hour -- done drop by drop to prevent precipitation of the zein. 0.6 mL of the BSA soln was added to each sample that contained 6mL of zein. The three samples were poured into three glass 9 cm petri dishes and placed into the oven at 80°C.

Observations

  • Allowing the samples to cool 30 minutes after removal makes the process of removing one cohesive film much easier -- simply a matter of running a thin spatula along the edge of the dish and then prying up on the flat of the film while moving slowly and circularly around the plate.
  • The 1 hour sample did not initially appear different from the 2 hour sample, though the 1 hour sample was pried up and inspected almost immediately (after 30 minutes) while the 2 hour sample was left unmoved (upside down for the fun of it) at room temperature overnight. It was peeled up the next morning and compared to the 1 hour sample, which had become more brittle and greasy after having been left out overnight. By comparison it was more pliant, which is either attributable to the duration of baking or the storage technique. It might be that removal of the film from the dish accelerates the transition to a more brittle form.