Silk Tubes (step 24, options A and B)
There are two methods for preparing silk tubes. If sterilized tubes are required, incubate the tubes in a solution of 70 v/v% ethanol overnight and then rinse in sterile water prior to use.
Dip Method The first protocol focuses on a simple dip method to create thin-walled tubes (Fig 3)(Option A). With this method, silk tubes with various inner diameters can be obtained. The thickness of the tube walls can also be varied by increasing or decreasing the number of layers deposited on the mandrel. With this method, we have formed tubes with an approximate wall thickness of 200 μm35. In addition, if porous tubes are required, various amounts of polyethylene oxide (PEO, 900 kDa) can be added to the silk solution and then leached out in water after the tubes have been formed. These tubes have been previously characterized by the use of scanning electron microscopy (SEM) for overall morphology and the diffusion characteristics have been studied with the use of a fluorescent label and a confocal microscope35.
The purified silk can then be used for a variety of applications summarized in Figures 3--1111.