Non-invasive quantification of methadone in exhaled breath condensates using PtNPs/AgNP-modified GCE: an electrochemical sensor for narcotic bioanalysis.

Methadone (MTD) is a synthetic opioid frequently used to treat opioid addiction. The therapeutic use of this drug must be prescribed carefully because, in addition to toxicity, its suboptimal use can cause addiction. Therefore, there is an urgent need to fabricate reliable methods for sensitive and specific recognition of MTD in biological fluids. In this study, a novel platinum nanoparticles (PtNPs)/cluster-like-AgNPs/glassy carbon electrode (GCE)-based electrochemical sensor was developed for quantifying MTD in human exhaled breath condensate (EBC) samples. After morphological characterization of the probe, the utilization of this platform for MTD detection was examined by cyclic voltammetry and square wave voltammetry techniques. The analyte-related electrochemical signal of the probe was linear at two linear ranges of 30 ng/mL to 0.1 µg/mL and 0.1 to 2.5 µg/mL with a limit of detection of 21 ng/mL. The validation results confirmed the high repeatability and accuracy with relative standard deviation and absolute relative error of 4.8% and 1.76%, respectively. Additionally, the specificity, stability, and reproducibility of the probe were studied under the Food and Drug Guidelines, approving the reliability of the probe for use in MTD detection in EBC samples. The engineered sensor (PtNPs/cluster-like-AgNPs/GCE) was successfully employed for the detection of MTD in human EBC samples. The results demonstrated the potential of the probe for non-invasive monitoring of MTD in patient EBC samples. The main limitation of the probe is its low reusability.