2016 Project Description

The Stanford-Brown 2016 iGem team is building a biologically produced balloon for space exploration. Biological materials have a variety of advantages over traditional balloon materials; most importantly, they are light and self-replicating. These characteristics make functional biological components ideally suited for space exploration applications. To make a functional balloon, we need at least two elements. The balloon has to be made of something, and the balloon has to do something. To that end our team is working on both producing (relatively) gas impermeable biological membranes and creating biological sensors that can either attach directly to those membranes, or be embedded in a balloon payload.

Specifically, our membrane team is researching ways to biologically produce a variety of materials that could be assembled into a membrane. At the moment, many materials are actively on the table, including but not limited to: elastin, collagen, kevlar, nylon, spider-silk, and more. We hope to stimulate the production of at least one of these monomers in E. coli and demonstrate that, with the right cross-linking reagents, these biologically isolated monomers can be assembled into functional membranes. Finally, we are working on creating robust models of our balloon’s load-bearing capabilities based on the atmospheric pressure of different possible balloon destinations (Earth, Mars, Titan etc.) which will incorporate experimental data we collect about the actual gas permeability of the test membranes.

Meanwhile, our sensors team is working on a variety of approaches to biologically sense both temperature and specific small molecule ligands. With regards to temperature, while there are a large variety of well documented BioBricked chromoproteins, no one to our knowledge has ever examined the thermodynamic stability of these proteins, nor the extent to which they can be denatured and renatured while still maintaining their color. We are in the process of collecting that data, in the hopes that we can discover a wide dynamic temperature range represented by the denaturing of different colors and assemble the collection into a functional biological thermometer for our balloon.

Finally, we are working on several cell-free approaches that incorporate RNA or DNA aptamers, extremely specific nucleic acid sequences that bind to specific small molecules, as molecular sensors to go on or in our balloon. We are particularly interested in two specific mechanisms -- IRES (internal ribosome entry site) and FQ (fluorophore-quencher). In both cases, when the aptamer specific for the target molecule is un-bound, the sensor is “off”, and when the specific aptamer is bound, the sensor is “on”. The difference is in how we detect the “on” phase. In the IRES system, the aptamer binding the target ligand frees the previously inaccessible ribosome binding site, allowing translation of GFP to begin. This system is useful because it is self contained to a single mRNA transcript, allowing for in vivo self replication. In the FQ system, the aptamer binding the target ligand pulls the quencher away from the fluorophore, producing detectable fluorescence. This system is useful because we aim to be able to attach the sensor molecules directly to our protein membrane. We hope to use this part of our project not only to create novel sensors for molecules that are of interest to NASA, but also to carefully standardize and document both platforms so that other teams in the future can build on this work to create robust aptamer sensors for targets of their choice.

Wiki template information

We have created these wiki template pages to help you get started and to help you think about how your team will be evaluated. You can find a list of all the pages tied to awards here at the Pages for awards link. You must edit these pages to be evaluated for medals and awards, but ultimately the design, layout, style and all other elements of your team wiki is up to you!