Randomly distributed arrays of optically coded functional microbeads for toxicity screening and monitoring.

We have successfully developed optically coded functional microbeads by co-encapsulating both bioluminescent reporter bacterial cells and fluorescent microspheres within a common alginate microbead. These microbeads harboring an individual self-identification code using fluorescent microspheres could be randomly scattered on any multi-well chip plate as long as the size of the microbeads are made to fit on it with the result that, since cell types are identified on the basis of fluorescent color, microbead arrays were fabricated without pre-designation of an individual well. As an example of this method, five different stress specific bioluminescent bacterial strains, each with a different optical code, were successfully implemented to make five different types of optically coded functional microbeads, with a speed of about 30 microbeads/min. Each functional microbead has a specific stress-specific bacterial strain and, as an identification optical code, one of five optical codes generated from fluorescence microspheres such as yellow, green, red, yellow + green, or no fluorescence. This final randomly scattered functional microbeads array biochip, with a fast fabrication of each chip at every 2 min, successfully demonstrated its ability in toxicity screening and monitoring for samples with a few examples for five different stress chemicals. This simple and fast, but not tedious and complicated procedure should be widely and practically used in making cell array chips for the monitoring of environmental toxicity, new-borne chemicals, pharmaceutical drugs and cosmic rays in the space station or spaceships in future.