Detection of bile acids using optical biosensors based on cholesteric liquid crystal droplets

We report a novel highly sensitive bile acids (cholic acid and deoxycholic acid) biosensor based on PVA/SC12S-stabilized cholesteric liquid crystal droplets. These CLC droplets are monodisperse in nature and are generated by fabricating a capillary microfluidic flow focusing device. The homeotropic-to-planar transition of the CLC droplets will be triggered during the competitive adsorption of bile acids at the surface of the CLC droplets. This sensor detects bile acids at a minimal cost and in a simple and quick manner. The detection limit of our method for CA is (1 μM) 80% lower and for DCA is 50% lower than that of the previously reported method using nematic droplets for detection. Furthermore, the response times and detection limits of these bile acids can be adjusted as a function of the pH, bile acid volume, and droplet size. Bile acids can be identified without the use of crossed polarizers using this novel method.