Printed Dual Cell Arrays for Multiplexed Sensing.

We demonstrated inkjet printing of large-scale dual-type encapsulated bacterial cell arrays for prospective multiplexing sensing. The dual cell arrays were constructed on the basis of two types of bioengineered E. coli cells hosting fluorescent reporters (green-GFPa1 and red-turboRFP) capable of detecting different target chemicals. The versatility of inkjet printing allows for the fabrication of uniform multilayered confined structures composed of silk ionomers that served as nests for in-printing different cells. Furthermore, sequential encapsulation of "red" and "green" cells in microscopic silk nest arrays with the preservation of their function allowed for facile confinement of cells into microscopic silk nests, where cells retained dual red-green response to mixed analyte environment. Whole-cell dual arrays immobilized in microscopic biocompatible silk matrices were readily activated after prolonged storage (up to 3 months, ambient conditions), showing red-green pattern and demonstrating an effective prototype of robust and long-living multiplexed biosensors for field applications.