Biosensor Assays Types and Their Roles Toward Ligand-Receptor Interactions in Drug Discovery.

Ligand-receptor interactions (LRIs) are the basis for all the biological processes taking place in living cells and have been exploited to develop and implement in medical field a number of highly sensitive biosensors for the detection of various biomarkers in complex biological fluids. Drug-target interactions, one of the LRIs, are important to understand the biological processes that further help in developing new and better therapeutic molecules. Biosensors based on these interactions give us an idea for the need of modification of existing drugs or to develop new drugs. Common approach to develop biosensors requires the labeling; however, label-free systems provide advantages in avoiding the chances of conformational changes, off-site labeling, and labeling-based hindrances, thus saving time and effort toward assay development. Preliminary drug screening assays are carried out in two-dimensional (2D) models, followed by animal models, which require huge capital investment to reach from bench-top to clinical trials, where only 21% of new compounds make way to phase-1 clinical trials. Three-dimensional culture or organoid culture or organ-on-chip technology has made way for predictive and complex in vitro approach that recapitulates human physiology and represents more similar in vivo behavior than 2D. Multiplexing and nanotechnology have remarkably enhanced the efficacy of biosensors and might lead to a generation of miniaturized biosensors and more than just point-of-care kits. This review provides in-depth analysis of different types of biosensor assays based on drug-target interactions, their advantages, and limitations based on cost, sensitivity, and selectivity and industrial applications.