Overview
Our team made huge contributions by adding new parts to the iGEM Parts Registry, enhancing the BioBrick collections for future iGEM teams and providing valuable evidence to support their use.We developed two constructs: WIST_SENSE_MedArsR_StrArsC_001_A, a sensor construct responsive to arsenic, and WIST_REPORT_OC2, a reporter construct generating a green fluorescent signal. Our system demonstrated reliable activation at 50 ppb arsenic, with a modest yet stable signal despite some leakiness, establishing proof of concept. We also engineered a novel promoter, ParsOC2, to expand the toolkit for arsenic-responsive systems. All plasmids, including maps and sequences, will be uploaded to the iGEM Registry, enabling other teams to build upon our work. By sharing both functional and leaky circuits, we provide a foundation for future teams to refine or enhance our designs without starting from scratch.
Hardware
We designed a proof-of-concept cell-free, paper-based biosensor, including a prototype end-user kit, to detect arsenic in rice or rice products. While lyophilization was not achieved, the current prototype demonstrates the feasibility of a portable detection system, featuring components such as a UV flashlight, long-pass filter, grinding device, and lyophilized biosensor strips for future optimization. Future iGEM teams can adapt our design and protocols for monitoring contaminants in water, soil, or additional food products, and utilize our workflow as a model for developing community-friendly diagnostic tools. This hardware contribution illustrates the potential for biosensors to become portable and accessible, facilitating the transition of synthetic biology solutions beyond laboratory settings.
Software
To complement the biosensor hardware, we developed a proof-of-concept smartphone application that allows users to photograph a biosensor strip, estimate arsenic concentration, and receive guidance if levels exceed the FDA safety threshold. The software framework is designed to be flexible, enabling future iGEM teams to modify it for use with other colorimetric biosensors. We collected experimental data across a concentration range of 0 to 800 ppb arsenic and conducted interferent testing with metals (Cu, Pb, Fe) to assess specificity, completing up to stage 7 of development, which included testing on real rice samples. This dataset includes a reference response curve, raw values for analysis with tools such as ImageJ, and a foundation for computational modeling or benchmarking other biosensors. By making these results openly available, we support future teams in understanding circuit performance, troubleshooting leakiness, and enhancing sensitivity, bridging wet-lab efforts with digital tools.
Education
Our project incorporates education to raise arsenic awareness, targeting students from elementary to high school. We designed lessons to educate the public on the importance of rice in human nutrition, the health risks of excessive arsenic consumption, and preventive measures such as proper rice washing. By sharing these resources, we provide future iGEM teams with adaptable, age-appropriate teaching tools for local contexts, applicable to food safety, water quality, or synthetic biology literacy.
