Liquid crystals as signal transducers for sensing of analytes using aptamer as a recognition probe

The long-range orientational order of liquid crystals (LCs) makes them excellent responsive materials for amplification and transduction of various biochemical events occurring at their interfaces. LC interfaces have been vastly explored for sensing of various macromolecules such as endotoxin, proteins, and disease markers. LC-based sensors possess several advantages over conventional methods in terms of not requiring intensive labour, label-free detection, and low-cost fabrication. However, the first challenge is to ensure the specificity of LC response towards a particular analyte. The second challenge is to design sensing platforms for the detection of small molecule analytes with equal selectivity and sensitivity. In this regard, aptamers have emerged as promising recognition probes due to their high binding affinity towards small molecules, high stability over antibodies, and fast response. The integration of aptamer-based sensing with LC interfaces has enabled the detection of deoxyribonucleic acid (DNA) targets, biologically important toxins, environmental pollutants, heavy metal ions, etc., with applicability in clinical samples. In this review, we recapitulate the recent advancements in the design of aptamer-based LC biosensors for the detection of DNA targets (by DNA hybridization), various biomolecules, and metal ions.