Electrochemical aptasensing strategies for emerging organic pollutants in environmental analysis

Emerging organic pollutants (EOPs), encompassing a vast array of substances like pharmaceuticals, pesticides, endocrine disruptors, and industrial chemicals, pose a significant threat to environmental integrity and human health. Traditional analytical methods for their detection, while accurate, are often laboratory-bound, costly, and time-consuming, hindering effective environmental monitoring. Electrochemical aptasensors (hereafter, 'aptasensors') have surfaced as a highly promising alternative, merging the high sensitivity, potential for portability, and cost-effectiveness of electrochemical transduction with the specific molecular recognition capabilities and stability of aptamers - short, synthetic nucleic acid sequences. This review comprehensively examines the fundamental principles underpinning these sensors, including aptamer selection methodologies like SELEX, particularly addressing the challenges associated with small molecule targets characteristic of many EOPs. It delves into various electrochemical transduction mechanisms such as voltammetry, impedance spectroscopy, and electrochemiluminescence, alongside critical aptamer immobilization techniques onto electrode surfaces. The significant role of diverse nanomaterials (e.g., gold nanoparticles, carbon-based materials, metal oxides, and MOFs) in enhancing sensor performance through increased surface area, improved conductivity, and signal amplification is thoroughly discussed. Furthermore, this review surveys recent advancements and applications of these aptasensors for detecting key classes of EOPs in environmental matrices like water and soil, critically evaluating reported analytical performance metrics like limits of detection and selectivity.