A Polydopamine-Based Molecularly Imprinted Electrochemical Sensor for Fentanyl Determination

A molecularly imprinted polymer (MIP)-based electrochemical sensor for the rapid detection of fentanyl is reported. The sensor was prepared by electrochemically grafting polydopamine on a carbon nanofiber-Pt nanoparticle composite-modified screen-printed electrode. Dopamine was identified as a suitable functional monomer via in-silico modeling and was electropolymerized via cyclic voltammetry in the presence of fentanyl to form the MIP sensor. The properties and morphology of the sensing material were characterized with spectroscopy, microscopy, and electrochemical techniques. Factors influencing the sensor performance were studied and optimized. Under optimized conditions, the MIP sensor response followed the Langmuir-Freundlich binding isotherm with a dissociation constant (k _d) of 16.13 μM and a limit of detection of 0.094 μM fentanyl. The sensor displayed good run-to-run repeatability and batch-to-batch performance reproducibility with relative standard deviations of 6.7% (n = 5) and 9.1% (n = 3), respectively. Three sensors, prepared and tested in parallel, showed excellent storage stability in a fridge under a humidified environment for 4 weeks with relative standard deviations of ≤10%. The developed MIP sensor presented suitable selectivity when interrogated with solutions composed of equimolar concentrations of fentanyl and glucose, acetaminophen, theophylline, morphine, naloxone, codeine, or norfentanyl. The sensor was also successfully tested in artificial urine samples, indicating that it is a promising candidate as a rapid testing method in fentanyl investigation.