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From 2011.igem.org

The project

The development of sensitive and selective biosensors is an important research field in synthetic biology. Biosensors can be applied in a wide range of uses - from the detection of environmental toxics up to clinical diagnostics. Because cells have to sense their surroundings, there are a lot of natural systems that are similar to a biosensor. Prejudicial cellular biosensors often show negative side effects that complicate any practical application. Common problems are the limited use outside of a gene laboratory due to the use of genetically engineered cells, the low durability because of the usage of living cells and the appearance of undesired signals induced by endogenous metabolic pathways.

To solve these problems, the iGEM-Team Bielefeld 2011 aims to develope a cell-free bisphenol A (BPA) biosensor based on a coupled enzyme reaction fused to S-layer proteins for everyday use. Bisphenol A is a supposedly harmful substance which is used in the production of polycarbonate. To detect BPA it is degraded by a fusion protein under formation of NAD⁺ which is detected by an NAD⁺-dependent enzymatic reaction with a molecular beacon. Both enzymes are fused to S-layer proteins which build up well-defined nanosurfaces and are attached to the surface of beads. By providing these nanobiotechnological building blocks the system is expandable to other applications.