Optical biosensor based on liquid crystal droplets for detection of cholic acid

• A low-cost, simple and fast strategy for sensing of CA has been developed.
• The LC droplets size, and the pH value of SDS solution have been studied.
• A radial-to-bipolar transition has been triggered.
• The detection limit is 5 μM, which is reduced by 58.3% compare to LC film.

A highly sensitive cholic acid biosensor based on 4-cyano-4′-penthlbiphenyl (5CB) Liquid crystal droplets in phosphate buffer saline solution was reported. A radial-to-bipolar transition of 5CB droplet would be triggered during competitive reaction of CA at the sodium dodecyl sulfate surfactant-laden 5CB droplet surface. Our liquid crystal droplet sensor is a low-cost, simple and fast method for CA detection. The detection limit (5 μM) of our method is 2.4 times lower than previously report by using liquid crystal film to detection of CA.