LAUSR

Abstract Tuberculosis (TB) is a serious threat to human health. Although it is simple to prevent and treat TB, its prevalence is high due to the lack of facile, rapid, and low-cost diagnostic methods. In this paper, we present a liquid crystal (LC)-based on/off immunosensor (composed of two glass pieces) for the experimental as well as clinical diagnosis of TB. A variety of antigens are mixed and immobilized on the functionalized glass substrate (the bottom surface), and nanoparticle-doped LCs are arranged in an order that is determined by an electron transfer effect between nanoparticles and ITO glass (the top surface). After incubation of the substrate with TB antibody, substrate surface morphology significantly changes due to specific binding, disrupting the ordered arrangement of the LCs. The intensity of the optical signals, as seen under a polarized optical microscope, varies according the changes in the arrangements of LCs resulting from the presence or absence of binding with TB antibody. Based on these optical signals, we observed that 94% patients showed positive results, confirming the presence of the corresponding TB antibodies in the patients' serum. When samples from healthy people were used, 98% showed negative results, confirming the absence of TB antibodies. Hence, using this method, efficiently identifying the presence of TB antibodies in a sample is possible. This is especially beneficial in the diagnosis of clinical samples as this method does not require any special instrumentation or processes and will contribute to the development of novel, simple, and rapid methods for the diagnosis of TB.