​The use of cell-free extracts is important to the progress and future development of the arsenic circuit, and other similarly styled circuits.

The first advantage is that the use of cell-free extracts increases the shelf-life of the assay. We expect to be able to lyophilize the enzymes and proteins used in the arsenic circuit, so we do not have to be concerned with keeping bacteria cells alive and healthy.

The second advantage is that there will be no chance of accidentally releasing a modified bacteria to the environment. Although there is a low risk that the bacteria we use would adversely affect the environment, due to the required selective pressure needed to maintain the plasmid and the relative safety of the produced proteins, we will maintain laboratory safety standards and laws that prohibit the release of genetically modified organisms.

The third advantage is that we expect to be able to detect a broader range of arsenic using a cell-free system. Using live cells requires arsenic to be able to transport into the cell and interact with the necessary proteins. Having the proteins readily available in solution should reduce the barrier of arsenic accessing ArsR.