(335c) Programmable Living Material Containing Reporter Micro-Organisms Permits Quantitative Detection of Disease-Relevant Molecules

Authors: 
Mora, C. A., ETH Zurich
Herzog, A. F., ETH Zurich
Raso, R. A., ETH-Zürich
Stark, W. J., ETH-Zürich
The increasing molecular understanding of many diseases permits the development of new diagnostic methods. However, few easy-to-handle and inexpensive tools exist for common diseases such as food disorders. Recently, bioinspired stimuli-responsive materials containing living organisms have been reported [1, 2]. By enclosing micro-organisms into a sandwich consisting of a solid bottom and a size-selective porous top polymer sheet, the organisms could not escape but were still able to interact with the outer environment. Based on this, we developed a whole-cell biosensor platform that combines the diffusion behavior of an analyte with an analyte-specific bacterial fluorescence reporter system [3]. The analysis requires only a photo camera, a blue-light source and a blue-light optical filter sheet. The well-established model bacterium Escherichia coli, genetically modified with a fluorescent reporter system, was incorporated in a matrix of different polymers to create a programmable living material-based analytical sensor (LiMBAS). This material shows an easily quantifiable and specific response when coming into contact with dissolved analyte anywhere on its surface. In a realistic application, we programmed LiMBAS to detect lactose directly from cow's milk and galactose from lactose-free milk without previous dilution. We chose milk for our proof-of-principle experiment since it is a widely used food product and a source of several common food disorders including lactose intolerance, allergies as well as galactosaemia. LiMBAS could accurately quantify lactose or galactose in undiluted food samples and was able to measure food intolerance relevant concentrations in the range of 1â??1000 mM requiring a sample volume of 1â??10 μL. It worked at ambient temperature and humidity conditions and was storable ready-to-use for more than one week. We additionally discuss how the quantification principle of combining diffusion behavior with matrix-embedded microbial whole cell reporter systems could be applied to develop a variety of biomedical diagnosis tools for the analysis of food, blood or environmental constituents that can be used in domestic or outdoor applications. A wide range of genetic tools for E. coli are readily available thus allowing the reprogramming of the material to serve as biosensor for other molecules. LiMBAS as biomaterial offers the possibility to safely use engineered micro-organisms outside of a laboratory environment without the need for culturing or complicated analysis. In combination with smartphones, an automated diagnostic analysis becomes feasible which would also allow untrained people to use LiMBAS.

[1] L.C. Gerber, F.M. Koehler, R.N. Grass, W.J. Stark, Proc. Natl. Acad. Sci. U. S. A 109 (2012), pp. 90â??94

[2] L.C. Gerber, F.M. Koehler, R.N. Grass, W.J. Stark, Angew. Chem. Int. Ed., 51 (2012), pp. 11293â??11296

[3] C.A. Mora, A.F. Herzog, R.A. Raso, W.J. Stark, Biomaterials, 61 (2015), pp. 1-9