Next-generation electrochemical sensors for opioid detection: from nanostructured interfaces towards real-time clinical monitoring.

The increasing prevalence of opioid misuse, substance abuse, and drug addiction, and the rapid emergence of highly potent synthetic analogues have intensified the demand for rapid, sensitive and decentralized analytical technologies for opioid monitoring in public healthcare. Conventional laboratory-based methods, although highly accurate, are often constrained by expensive instrumentation, complex sample preparation and limited portability, making them less suitable for real-time clinical and forensic applications. In response to these limitations, electrochemical point-of-care sensing platforms have emerged as promising alternatives due to their low cost, rapid response, portability and compatibility with miniaturized and wearable diagnostic systems. This review comprehensively discusses recent advances in electrochemical sensing technologies developed for the detection of natural opiates, semi-synthetic opioids, and synthetic opioids, with particular emphasis on point-of-care and wearable sensing devices. This review highlights the role of nanostructured materials, molecularly imprinted polymers, aptamer-based recognition systems, screen-printed electrodes, microneedle platforms, and flexible bioelectronic devices in enhancing analytical sensitivity, selectivity and real-sample applicability. Furthermore, emerging smart technologies involving smartphone-assisted sensing, artificial intelligence-driven signal processing, wireless data transmission, and Internet of Things-enabled healthcare systems are discussed as next-generation strategies for decentralized opioid surveillance and real-time monitoring. The review also critically examines current challenges associated with electrochemical opioid sensing, including electrode fouling, matrix interference, reproducibility limitations and insufficient large-scale clinical validation. Overall, this work provides a detailed overview of the recent progress, technological advancements and future directions of electrochemical point-of-care opioid sensing systems, emphasizing their growing significance in forensic toxicology, therapeutic monitoring, emergency diagnostics and personalized healthcare applications.