From Lab to Body: Advanced Electrochemical Biosensors for Illicit Drug Detection via Nanomaterials, AI, and Wearable Tech.

Illicit drug detection is entering a transformative era, driven by the convergence of electrochemical sensing, nanomaterials engineering, and artificial intelligence. Traditional analytical approaches, despite their precision, are increasingly misaligned with the demands of real-time, on-site, and personalized monitoring. In recent years, electrochemical biosensors have emerged as a disruptive class of technologies capable of bridging this gap, offering miniaturized platforms that combine molecular specificity, rapid response, and adaptability to diverse biological matrices. This review captures the current momentum in the development of advanced electrochemical systems tailored for the detection of psychoactive substances, with a particular focus on opioids, stimulants, cannabinoids, and date rape drugs. We highlight how the integration of high-surface-area nanomaterials (e.g., MXenes, carbon nanostructures, metal organic frameworks) and programmable biorecognition interfaces (e.g., aptamers, synthetic polymers) has redefined the sensitivity, selectivity, and stability of drug sensors. Beyond material innovation, we explore how modern transduction strategies are being repurposed into flexible, wearable formats and seamlessly coupled with AI-driven data analytics to enable intelligent, autonomous sensing. Key technical challenges, including signal interference, fouling, multianalyte discrimination, and regulatory translation, are critically assessed alongside emerging solutions such as antifouling coatings, multiplexed recognition chemistries, and artificial intelligence (AI)-assisted calibration. Looking ahead, we outline a paradigm shift toward decentralized, user-adaptable drug sensing platforms that could radically improve forensic readiness, clinical toxicology, and public health surveillance. The path forward lies in translating these innovations into robust, field-deployable devices capable of meeting the complex demands of modern drug monitoring ecosystems.