In place modification of graphite screen-printed electrodes with spark generated copper nanoparticles for creatinine sensing

This study describes a non-enzymatic voltammetric sensor for the determination of creatinine, a vital biomarker utilized in diagnosing kidney diseases. The surface of a graphite screen-printed electrode (SPE) was modified with copper nanoparticles via a direct electrical discharge between the SPE and a copper pin at 1.2 kV at ambient conditions, using a G-code controlled 3D positioning device bearing a sparking head, without the need for any chemicals or liquids. Characterization of the Cu-sparked surface was performed using scanning electron microscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Differential pulse voltammetry in 0.1 M acetate buffer pH 4.6 revealed a linear relationship between the peak current at ca. 0.05 V, associated with the oxidative formation of cupric ions creatinine complex, and the concentration of creatinine within the range of 5-125 mu M. The limit of detection (3 sigma/m) was found to be 2.3 mu M. Interference studies with uric acid, ascorbic acid, urea, and glucose demonstrated the high selectivity of the method towards creatinine. The sensor was effectively utilized for the determination of creatinine in artificial urine, yielding relative error values (%) ranging from 4.6 % to 6.7 %. This novel sensor offers distinct advantages over existing ones in terms of cost, fabrication simplicity, ease of surface modification, operational simplicity, and adherence to green chemistry principles in electroanalysis.