Label-free liquid crystal biosensor for cecropin B detection.

A label-free liquid crystal (LC) biosensor based on orientation changes of LC molecules was reported for the detection of cecropin B. The homeotropic-to-tilted alignment transition of LC molecules, induced by the specific binding event between cecropin B and anti-cecropin B antibody immobilized via glutaraldehyde, could result in obvious change of the optical appearance from a dark to a bright response and as a result, the detection limit of cecropin B was as low as 50 ng/mL. The average gray-scale intensities (GIs) of optical appearances were calculated to quantitatively analyse cecropin B concentrations. This study offers a simple, highly sensitive and specific, lable-free method for cecropin B detection.