Electrochemical Strip Sensor Based on a Graphene-Au-PEDOT Nanocomposite for Detection and Continuous Monitoring of Dacarbazine

We are aiming to develop an electrochemical strip sensor for the detection and continuous monitoring of dacarbazine (DTIC), which is a chemotherapeutic drug used to treat various cancers. This new type of drug sensing meets the increasing need for personalized medicine, which aims to improve treatment outcomes while reducing side effects and controlling pollution from pharmaceutical and industrial production. The DTIC strip sensor was fabricated by modifying a screen-printed carbon electrode (SPCE) with graphene-gold nanocomposites embedded with a poly(3,4-ethylene dioxythiophene) (PEDOT) conducting polymer. The nanocomposites were characterized using advanced analytical instruments such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The modified sensor showed significant enhancement in the electrochemical oxidation signals of DTIC due to facilitated electron transfer at the interface between the analyte DTIC and SPCE/AuNPs-PEDOT/rGO with Ag/AgCl as the reference electrode and carbon as the working and counter electrode. The interfacial studies of the DTIC sensor were carried out by cyclic voltammetry and electrochemical impedance spectroscopy. Further, its electroanalytical performance was tested using square-wave voltammetry with a wide range of 2.5-1450 nM (working potential range of 1 to -1.5 V vs the Ag/AgCl reference electrode) and chronoamperometry with a wide linear range of 2.5-1675 nM (at a constant potential of 0.65 V). The sensor's practical potency was confirmed in human serum with a dynamic linear range of 2.5-1500 nM with an LOD of 0.09 nM. The sensor exhibited high sensitivity, selectivity, reproducibility, and long-term storage stability. The simple sensor design and its attractive analytical performance suggest considerable promise for its use in the onsite screening of anticancer drugs, including in human serum and industrial wastewater.