A liquid-crystal-based immunosensor for the detection of cardiac troponin I.

Cardiac troponin I (cTnI) is one of the most sensitive and specific markers of myocardial cell injury, which can detect even minor myocardia damage. It is recognized as the main biochemical marker of rapid diagnosis of acute myocardial infarction (AMI) and acute coronary syndromes (ACS). In this study, a label-free biosensor that utilizes the birefringence property of nematic liquid crystal (LC) for detection of cTnI is demonstrated. A chemically sensitive film with specific molecular recognition ability is decorated on the surface of the substrate, the LC molecules are arranged in a vertically oriented order under the influence of the sensitive film and a dark background signal is obtained under polarizing optical microscope. When the antigen-antibody specifically binds to form a stronger acting force, the orientation of LC molecules changes, resulting in a bright optical appearance. This LC-based immunosensor has not only the advantages of facile structure, low cost and excellent specificity, but also high sensitivity (low detection limit of 1 pg/ml), which has a promising future in biomedical related fields.