3D Bioprinting
Fiorenzo Omenetto (Tufts)
In the biofabrication and additive manufacturing module, we discussed how we can use naturally derived materials for making and building.
The guiding principle is to reinvent structural biopolymers into high-technological materials through basic principles of materials science, advanced fabrication and ingenuity. The class was focused on silk and keratin, materials with thousands of years of history and that now can be engineered to serve at the interface between the biotic and abiotic world.
Lab homework assignments
1.Regeneration of silk fibroin into an aqueous suspension (refer to Step 1-23 in Rockwood et al. Nature Protocols, 6, 1612–1631 (2011) in background reading)
2. Fabrication of an implantable, biodegradable diffraction grating through soft lithography
The silk fibroin can now be used to prepare a number of different materials. Using the concentrated solution you can prepare silk tubes by either a simple dip method to create thin-walled tubes or by gel spinning, wherein the fibroin is extruded onto a rotating mandrel Alternatively, silk solution may be used to prepare hydrogels via vortexing, sonication, electrical current or pH change; nonpatterned or patterned silk films silk microspheres using the DOPC or PVA method; electrospun silk fibers; or silk sponges that are either aqueous-based or HFIP-based.
We followed Step 25H in Rockwood et al. Nature Protocols, 6, 1612-1631 (2011) in background reading and how results we obtained this:
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The following protocols can help with the design and implementation of a variety of silk-based biomaterials for a range of potential applications.
Schematic of the silk fibroin extraction procedure. Going from the raw material (cocoons) to the final aqueous-based solution takes 4 d.
 Bombyx mori silk cocoons |  Day 1: 500mL of ultrapure water + 2,5g cocoons + 2,12g sodium carbonate (boiled for 30min) Removed the silk fibroin and cooled it by rinsing in ultrapure water for a total a three rinses. Leave the silk fibroin to dry overnight a room temperature |
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 Day 2: Dissolve silk fibroin in LiBr and leave fibroin dissolve in an incubator at 60°C overnight. It appeared amber in color and transparent. |  Day 3: Inserted 10mL of the Silk-LiBr solution intro a dyalisis cassette. Hydrated dialysis cassettes in ultrapure water |
 Day 5: once the tubes of the centrifuge are removed, we determine the concentration of the silk. The result was 0,158 g/ml |  Day 5: Removed silk from the cassettes and Centrifuged to remove impurities. (9000 rpm, 4°C, 20 min) |
Describe tu imagen
Slowly pour the PDMS over the diffraction grating
Try not to introduce bubbes
Remove any bubbles with a needle.
Leave at room temperature for over 24 h
Remove the PDMS and be careful not to rip