Development of a whole-cell biosensor for the determination of tyrosine in urine for point-of-care diagnostics

Most disorders associated with tyrosine metabolism lead to elevated tyrosine levels in biological fluids. In this work, we used genetic engineering techniques to develop a simple and low-cost biosensor for tyrosine quantification. Here, two tyrosine-responsive promoters are used to differentially control the production of red and green fluorescent proteins signals in response to tyrosine levels in a culture. We also conducted a systematic examination of various modular components (promoters and ribosome binding sites) in order to ensure that our biosensor was capable of rapidly producing a pronounced fluorescence signal. To make the device more user-friendly, we developed a reagentless platform in which biocompatible agarose is used as an entrapment agent with cell sensors and growth media mounted within the gel matrix.