Continuous Production of a Shelf‐Stable Living Material as a Biosensor Platform

Abstract The advancements made in biological engineering have led to the development of whole‐cell biosensors and their successful application in diagnostics. However, due to the sensitivity of the systems, as well as the need for advanced readout devices, the use of such sensors is limited to a laboratory environment. Here, a biosensor platform for the diffusion‐based quantification of a small molecule analyte is presented. The platform consists of Bacillus subtilis endospores carrying a genetic reporter construct. The spores are embedded in a poly(vinyl alcohol) matrix casted to a poly(ethylene terephthalate) support material. It is shown that the biosensor platform can be produced continuously on a large scale. The scalable process results in a price per sensor, which is three orders of magnitude lower than the price of a comparable biological lateral flow assay. The performance of the biosensor platform for the quantification of isopropyl‐β‐d‐thiogalactopyranoside is demonstrated and it is shown that the readout can be performed with a 3D‐printed smartphone‐based device. Finally, it is demonstrated that the material is stable under various environmental conditions and that it can be stored for an extended period without losing its functionality. Aforementioned progress makes the presented living material feasible for the application by an untrained user in the field.