Liquid-Crystal-Based Immunosensor for Diagnosis of Tuberculosis in Clinical Specimens

Tuberculosis (TB) is a serious global health problem, although it is easily preventable and curable. The prevalence of TB is caused by a lack of simple, rapid, cheap, and effective TB diagnostic tests. In this study, we have established a novel liquid crystal (LC)-based immunosensor to diagnose TB in clinical specimens. The clinical serum samples were incubated on a TB antigen-immobilized substrate, and their optical LC responses were observed using a polarized light microscope. Specific binding of anti-TB antibodies to the TB antigen-immobilized surface only occurred in clinical specimens from TB patients, inducing the disruption of the orientation of LCs. This was followed by the distinctive change in the optical appearance of LCs from uniform to random. However, when clinical serum samples from healthy people or latent TB patients were incubated, the orientation of LCs remained uniform. Through the change of optical LC images, in 76% of TB patients, this essay correctly identified the patients as having antibodies to TB in their serums. 91% of healthy people free of TB were correctly identified as not having antibodies to TB. Thus, this LC-based immunosensor is a promising platform, particularly in clinical TB diagnostics, which does not require complicated preparation of clinical specimens or complex instrumentation.