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Team:StanfordBrownSpelman/Cellulose Acetate
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| - | <h6>One alteration we intend to make in order to produce a functional UAV is to draw circuits on the biomaterial to conduct electricity. In order to produce a biodegradable circuit, we worked with a company called AgiC, which prints circuits out of silver nano particles (see our Building a UAV page for a full circuit). By taking silver ink and painting it on to our bacterial cellulose, we were able to test the conductive capabilities of our building material.</h6> | + | <h6>One alteration we intend to make in order to produce a functional UAV is to draw circuits on the biomaterial to conduct electricity. In order to produce a biodegradable circuit, we worked with a company called <a href="http://agic.cc" target="_blank">AgiC</a>, which prints circuits out of silver nano particles (see our <a href="https://2014.igem.org/Team:StanfordBrownSpelman/Building_The_Drone">Building a UAV</a> page for a full circuit). By taking silver ink and painting it on to our bacterial cellulose, we were able to test the conductive capabilities of our building material.</h6> |
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Revision as of 08:55, 16 October 2014
Biomaterials
The body of the UAV is designed to consist a styrofoam-like filler consisting of fungal mycelia, coated with a cellulose acetate covering. The skin will be biologically waterproofed.
Material Waterproofing,
Biosensors can be linked to the cellulose acetate skin (see
Amberless Hell Cell),
through a biological cross-linker
(see
Cellulose Cross Linker.)
Cellulose acetate is a biodegradable thermoplastic polymer used for a variety of industrial applications.[1] The monomer of cellulose acetate is glucose with one or more of its available hydroxyl groups replaced with acetyl groups. Cellulose acetate is industrially produced by treating cellulose, typically from wood or cotton, with acetic anhydride and sulfuric acid at high temperatures.[1] Our aim is to engineer bacterial cells to produce industrial-grade cellulose acetate biologically, allowing this plastic to be produced anywhere that bacterial colonies can be grown (i. e. in space). This material could then be used as a basis or coating for a biodegradable UAV. Many species of bacteria produce cellulose fibers; however, Gluconacetobacter hansenii has been identified as species producing the highest yield of cellulose. [2] Another strain of bacteria, the SBW25 isolate of the species Pseudomonas fluorescens, produces a biofilm containing cellulose fibers with a small degree of acetylation (.14 acetyl groups per glucose monomer).[3] Industrial-grade cellulose acetate must have at least 1.71 acetyl groups per glucose monomer. [4] In order to engineer a bacterium to efficiently produce cellulose acetate, our strategy is to transform G. hansenii with the four genes, wssF, wssG, wssH, and wssI, that have been identified [3] as being involved in cellulose acetylation in P. fluorescens, and to use directed evolution to further increase percent acetylation of the polymer.
In addition, we seek to create a streptavidin/cellulose-binding-domain fusion protein which will have the capacity to both cross-link bacterial cellulose acetate polymers (improving material properties) and allow the modular addition of cells (e.g. biosensors). This will be accomplished through the expression on the cells of a biotinylated membrane protein. This will allow biological sensors to be added directly to our cellulose acetate fibers, allowing bacterial sensors to be attached directly to the body of our UAV.
Approach & Methods
The first step in working towards producing our building material was to grow cultures of cellulose producing bacteria. After these cultures grew for 1-2 weeks, we removed the produced cellulose sheet from the culture to test various methods of drying. We experimented with drying the sheet in an oven, to produce an extreme thin layer of cellulose. We also wrapped fungal mycelium, which we intend to be the body of our UAV, with wet cellulose, and allowed the cellulose to dry on its own. This will provide the platform for us to alter the biomaterial for flight, by making it waterproof, for example.
Figure 1: Production of dried cellulose. a) A wet cellulose sheet, soaking in 50% alcohol solution. b) The cellulose was placed between two acrylic gel casters and left in a 75ºC oven for 2 days. c) A thin, dry cellulose sheet. d) Fungal mycelium wrapped in dry cellulose.
One alteration we intend to make in order to produce a functional UAV is to draw circuits on the biomaterial to conduct electricity. In order to produce a biodegradable circuit, we worked with a company called AgiC, which prints circuits out of silver nano particles (see our Building a UAV page for a full circuit). By taking silver ink and painting it on to our bacterial cellulose, we were able to test the conductive capabilities of our building material.
