Wearable electrochemical biosensors for non-invasive sport doping control: sweat and saliva as dual biofluid platforms

The integrity of competitive athletics is increasingly compromised by sophisticated pharmacologies, rendering traditional sporadic testing of urine and blood insufficient for comprehensive oversight. This critical review examines the emergence of wearable electrochemical biosensors as a non-invasive alternative capable of bridging the gap between laboratory precision and real-time field monitoring. We propose a dual biofluid framework wherein sweat functions as a cumulative reservoir for lipophilic anabolic androgenic steroids due to ion trapping mechanisms, while saliva serves as a dynamic plasma ultrafiltrate suitable for tracking the pharmacokinetics of stimulants and psychotropic substances. The text provides a detailed analysis of biorecognition engineering, emphasizing the shift from labile enzymatic systems to robust synthetic receptors, including structure-switching aptamers and molecularly imprinted polymers, which offer superior stability under harsh environmental conditions. Furthermore, we evaluate the integration of functional nanomaterials such as metal-organic frameworks and MXenes that amplify signal transduction to meet the stringent Minimum Required Performance Levels established by the World Anti-Doping Agency. Technical challenges regarding biological interface fouling and sample handling are addressed through the discussion of zwitterionic antifouling coatings and active microfluidic routing. The review concludes by conceptualizing the Internet of Anti-Doping Bodies, a framework leveraging encrypted wireless data transmission and artificial intelligence pattern recognition to transform anti-doping into a continuous and preventive data-driven discipline.