A novel liquid crystal immunosensor based on the indirect competitive assay format was developed for the detection of ochratoxin A (OTA). OTA was tethered onto the self-assembled film surface on a glass slide via a cross-linker glutaradehyde. The specific binding 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 had a good signal-to-noise ratio and a clear distinction between positive and negative results. When the concentration of an...