The role of electrochemical and optical biosensors in the detection of chemical and biological agents: a critical review.

The increasing risk associated with chemical and biological warfare agents has amplified the need for rapid, sensitive, and portable detection technologies, particularly in the context of CBRN (chemical, biological, radiological, and nuclear) threats. While conventional analytical techniques such as high-performance liquid chromatography, gas chromatography/mass spectrometry, and the polymerase chain reaction remain the gold standard for analytical accuracy, they are often hindered by high operational costs, complex instrumentation, and limited field applicability. In response, biosensor technologies have emerged as promising alternatives, offering advantages such as real-time analysis, portability, and cost-effectiveness. This critical review provides a comparative evaluation of recent advances in electrochemical and optical biosensor platforms for detecting CBRN-relevant chemical and biological agents. The performance of each platform is analyzed in terms of sensitivity, specificity, operational stability, and environmental robustness. Electrochemical biosensors demonstrate strong potential for on-site applications due to their low cost and adaptability, whereas optical biosensors exhibit exceptional sensitivity and multiplexing capabilities, though with certain limitations in terms of portability and environmental resilience. Selected case studies are discussed to highlight prevailing design strategies, material innovations, and detection principles. Moreover, current challenges are identified, including the lack of standardized validation protocols, limited multi-analyte detection capabilities, and insufficient field testing. The review concludes by outlining future perspectives, emphasizing the importance of integrating artificial intelligence, sustainable materials, and modular sensor designs to enhance real-world applicability in diverse and unpredictable CBRN scenarios.