Abstract: A novel liquid crystal immunosensor based on the indirect competitive assay format was developed for the detection of ochratoxin A (OTA). In this method, the OTA was tethered onto the self-assembled film surface on a glass slide via a cross-linker glutaradehyde. The specific binding event of anti-OTA antibody and ochratoxin A induced the homeotropic-to-tilted transition of LCs, resulting in the corresponding changes of opitical images under the crossed polarized light. The LC-based imaging method has a good signal-to-noise ratio and a clear distinction between positive and negative results. When the concentration of analyte OTA exceeds a critical value (0.01 ng/mL) , the opitical images gives a very sharp response. The opitical images changes with the concentration of OTA in a dynamic range of 0.01–10 ng/mL .The fabricated sensor is show to exhibit high sensitivity, desirable selectivity, label free and ease in operation。

Key words: liquid crystal, self-assembled film, immunosensor, ochratoxin A