Biosensors are ubiquitous tools in modern life sciences. They offer a robust, rapid and cost-effective method of monitoring the presence of a target ligand through implementation of a selective recognition element and a biotransducer component that recognizes the ligand-bioreceptor interaction and subsequently generates a measurable signal. Due to the variability of both components, a huge range of biosensors with varying functionality is offered today as diagnostics tools . Biosensors can roughly be divided into two categories – single-shot analysis tools, such as pregnancy tests, or long-term monitoring analysis tools, as used in pollution monitoring . One type of long-term monitoring biosensors that is commonly employed in environmental and biomedical screening processes is whole-cell biosensors, as they allow exploiting the natural machinery of the cell . With the emergence of advanced recombinant DNA technology and rapid high-throughput sequencing and synthesis of DNA in recent years, expression of heterologous and novel pathways in well-characterized chassis has been made possible   . Thus, biological receptor elements can be employed with minimal variance in situ.
As evaluated in the project description, a prevalent obstacle in the engagement against microplastic pollution lies in the cumbersomeness of detecting the plastic particles. With the discussed benefits of whole-cell biosensors in mind, we set out to realize such a biosensor for efficient detection of microplastics. Expanding on the groundwork laid out by the 2012 UCL iGEM team that recognized the viability of approaching the detection of microplastics through indirect means, a logic AND-gate will be constructed and implemented in Escherichia coli, responding to the input of two molecules associated with plastic particles found in water – plasticizers and organic pollutants   .