Detection of opioids and their metabolites in sweat by carbon nanotube FET sensor array

In this study, we report the development of a multiplexed carbon nanotube-based field-effect transistor (FET) sensor platform for the rapid and reliable detection of opioids and their metabolites in human sweat. Our approach utilizes gold nanoparticle-decorated, semiconductor-enriched single-walled carbon nanotubes (Au-SWCNTs) functionalized with specific antibodies to achieve sensitive and selective detection of opioid metabolites to indicate opioid exposure. First, norfentanyl antibody-functionalized FET sensors exhibited high sensitivity toward norfentanyl with a limit of detection of 34 pg/mL (146 pM). To extend the detection capabilities, we constructed a sensor array comprising FET sensors functionalized with antibodies targeting morphine, norfentanyl, and 6-monoacetylmorphine (6-MAM). Notably, the cross-reactivity of the antibodies among structurally similar compounds broadened the detection range of the sensor array, enabling simultaneous probing of both opioid metabolites and their parent drugs. The sensor array was further incorporated into an automated sensing platform, facilitating high-throughput measurements and enhanced data reliability. In addition, the sensor technology was successfully adapted into a portable configuration, underscoring its potential for rapid, reliable opioid screening in real-world settings.