<p>When we were creating our heavy metal biosensors, the goal we had in mind was a simple test that anyone could use, even if they had no knowledge of or experience in synthetic biology. To do this, we would need to have a test which gave an easy to interpret output, such as colour or fluorescence. We propose that our biosensor could be freeze dried on cellulose discs, so that when the discs are rehydrated in heavy metal contaminated water, they fluoresce under blue light. Our proposed implementation of these is to use a cassette where the discs can be swapped out and reused for multiple simple tests of various heavy metals (see figure 1).</p>
<pstyle="text-align:center;">Figure 1. Proposed designs for our biosensor. Biosensor constructs are immobilised on cellulose discs, and when in contact with heavy metals they will fluoresce green. The casette is reusable, and the immobilised biosensors can easily be swapped out.</p>
<h3id="1.2"class="anchor">End users</h3>
<p>From our human practices research, we found that people living in rural areas would benefit from a simple diagnostic test for heavy metal contamination. However, these are not the only possible end users. Environmental agencies around the world could also use an accurate field test for heavy metal contamination; our interactions with the Scottish Environmental Protection Agency confirmed their interest in this. Other end users include industry and people in laboratory settings, if they need to test easily whether a sample heavy metal contamination. However, since they would not be in the field, it would be possible for them to use our biosensor as a chemical test instead. </p>
<h3id="1.3"class="anchor">Safety considerations and dual use</h3>
