Nanomaterials based electrochemical nucleic acid biosensors for environmental monitoring: A review

The ecosystem delivers natural services to humans and other living beings that are crucial for health, quality of life and existence. The purpose of environmental monitoring is to realize whether the quality of the environment is getting better or worse. Different types of techniques are used for environmental monitoring. Traditional methods are mostly time-consuming, involve expensive equipment and skilled personnel. Biosensors represent an exciting and pertinent approach to overcome the limitations of existing devices used in the diverse areas of environmental monitoring. It can complement laboratory‐based techniques and can also be applied for remote testing. Electrochemical nucleic acid (NA) biosensor integrates the sensitivity of electroanalytical methods with the inherent bio-selectivity of NA. The acceptance of NA biosensors depends on specificity, sensitivity, small molecule detection as well as cost-effectiveness. Considering these factors, a huge number of nanomaterials have been employed to facilitate immobilization of NA as well as to enhance conductivity and sensitivity. The NA component in the biosensor detects the analyte(s) based on signal generation owing to binding or catalytic event, which is proportional to the concentration of the analyte(s). This review compiled the components and strategies of building electrochemical NA biosensors, methods of transducing NA, the process of enhancing conductivity with nanomaterials and recent progress and innovative tactics used in the field. Besides these, applications of electrochemical NA biosensors for qualitative and quantitative analysis of environmental pollutants, steroid compounds, mycotoxins, heavy metals, antibiotic residues and pesticides have been discussed with illustrations along with limitations, challenges, future directions for the electrochemical NA biosensor applications and development.