Fabrication of a new ultrasensitive AuNPs-MIC-based sensor for electrochemical determination of streptomycin

In this study, a new electrochemical sensor is prepared based on the concept of molecularly imprinted composite (MIC) through electro‒oxidation of 3-methyl-4-nitrophenol (MNP) on a glassy carbon electrode (GCE) in the presence of Au(III) and streptomycin (STR), as the template molecule. In the employed process, gold nanoparticles (AuNPs) are incorporated in the MIC layer via electrochemical entrapment to increase sensor sensitivity. In this way, a sensor is fabricated for determination of STR with high selectivity and very high sensitivity. The modified electrode is characterized using atomic force microscopy (AFM), field emission-scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The performance of the sensor is optimized by evaluating the effect of the involved parameters and its activity was investigated in the presence of some other pharmaceutical compounds. The incubation of the MIC-based sensor, with respect to STR concentration, resulted in a suppression of the K₄[Fe(CN)₆] oxidation peak current as a probe. The current variations were determined using differential pulse voltammetry (DPV). According to the findings, the electrode presents a linear response over the STR concentration ranges of 0.35–4.5 and 4.5–250 pM and provides a detection limit of 0.25 pM, under the optimized conditions. Also, the sensor is found applicable to the measurement of STR in vial, plasma and urine samples.