Chiral-based optical and electrochemical biosensors: Synthesis , classification, mechanisms, nanostructures, and applications

Chirality is a phenomenon commonly observed in biomolecules, which supports various applications such as biosensing, bioimaging, and disease treatments. Chiral molecules and ions are building blocks of advanced materials and technologies enabling intermolecular communication between species competing in receiving, sending, or recognizing chemical scenarios. Therefore, chiral molecules nowadays are at the core of attention in developing sensing materials and devices. A sub-class of stereoisomers known as enantiomers or optical antipodes takes the privilege of chiral structures, supporting distinct optical and electrochemical responses required in sensing and identification applications. Therefore, it is critical to establish a reliable and fast method for chiral identification and separation. Big technological advances have been made in the field of bio-inspired and controlled self-assembly sensing, but there is still a great demand for improving the sensitivity and accuracy of chiral-based biosensors. This review seeks to collect, summarize, classify and discuss the latest advances in chiral-based optical biosensors. Starting from the identification of chiral molecules, photoluminescence, and electrochemical sensors, applications of chiral structures in biosensing molecules are reviewed. Then, biosensors working on the basis of chirality are classified, followed by summarizing the outcomes of research works on design, synthesis, and mechanisms of performances of chiral-based optical biosensors. Electrochemically active molecules are subsequently reviewed, emphasizing molecularly imprinted polymers (MIP), doped electrodeposited conducting polymers, enzymatic chiral sensors, and metal-organic framework (MOF) based chiral molecules applied in biosensing applications.