Figure 3.

Approaches for universal cell‐based biosensor platforms: Universal biosensors aim to link specific recognition elements to a generic platform to expand the range of target molecules capable of being sensed through cell‐based biosensors, whilst generating a system that allows quick construction and optimisation of new cell‐based biosensors. a) Split protein biosensor systems work by adding the ligand binding domain (LBD) to each separate half of a protein which when brought back together generates a response. i) Split T7 polymerase (Split T7) is used to activate expression of a reporter protein from the T7 promoter (P_T7).48 ii) Split glucose dehydrogenase is used to control the degradation of glucose releasing electrons which can be detected through a range of methods.49 b) The target molecule is broken down using a natural metabolic pathway (metabolic transducer) into a metabolic product which can be detected by a transcription factor to activate expression of a reporter from a responsive promoter (P_R).51