STAR is a new technology that can be used for implementing RNA logic in bacterial cells. STAR system consists of two short RNA segments, namely Target and Antisense respectively. The hairpin structure in Target acts like terminator or attenuator in the gene circuit, which is often inserted in the upstream of the open reading frame to block the expression. Antisense is a short RNA which is strictly complementary strand of part of Target. As soon as the strong combination between Target and Antisense occurs, the hairpin structure in Target will be altered, which further activates the expression of downstream proteins.


STAR is an effective RNA logic technology. It acts like a bridge to connect sensors such environment-sensitive promoters, with reporters such as fluorescent proteins. Considering its strong logical feature, we determine to use STAR to construct a multi-factor bio-detector. There is a series of STARs which have been rationally designed and well characterized. Based on previous work, we choose one existing STAR (denoted as STAR1) which possesses the highest activation efficiency as one of our regulators, and design a new one (denoted as STAR3) by modifying an old one (denoted as STAR2). Finally, we integrate STAR1, STAR3, sensors and reporters to create the multi-factor bio-detector.


In order to construct a visible detection system, we determine to use chromoprotein as our reporter. Chromoprotein is a kind of protein which contains the structure of pigment so it can display relevant color under light. We choose it as the reporter for two main reasons: easy-to-detect and variability. The property of easy identification by naked eyes makes it a more convenient tool comparing to fluorescent proteins which require specific excitation light. Also, with the same feature as pigment, mixing two different chromoproteins can form a third color under the color mixing theory.

Small CAT

Chromoproteins have been wildly used these years, but we haven't found any effective and convenient way to measure their concentration. So, we develop a new method to achieve the concentration measurement by taking pictures and analyzing the colorimetric values in mobile device. This detection system is called small Chromoprotein Analyze Toolbox, short for smallCAT, which can also identify any mixed color by generating a color chart or colorimetric card. A customized plastic box is used for controlling environmental impacts and the analyze program can be installed as an APP in mobile device or run in MATLAB in desktops.