Low-Pressure Air Plasma Activation of Screen-Printed Carbon Electrodes for NiO-Based Lactose Sensing in Milk

High Resolution Image Download MS PowerPoint Slide Screen-printed carbon electrodes (SPCEs) are a promising platform for the development of inexpensive, easily functionalized electrochemical sensors; however, ink components remaining on their surface after fabrication hinder electron transfer. In this work, we demonstrate that low-pressure air plasma treatment is an effective method for SPCE activation, leading to improved electrochemical performance. Electrochemical studies of the unmodified electrode revealed that plasma treatment enhances electron transfer kinetics, decreasing peak-to-peak separation and increasing peak currents. The plasma-treated electrodes were modified with nickel oxide nanoparticles (NiO NPs) to construct a nonenzymatic sensor for lactose detection. Physicochemical characterization (XRD, SEM, AFM, and DLS) confirmed the successful synthesis of NiO NPs and their uniform distribution on the electrode surface. The NiO-modified electrodes exhibit pronounced electrocatalytic activity toward lactose oxidation in an alkaline medium. Chronoamperometric measurements revealed a linear response in the range of 0.0125–2.0000 mM with a limit of detection of 0.14 mM and a sensitivity of 37.1 μA mM –1 . The sensor was successfully applied to lactose quantification in a complex medium, such as milk, showing good agreement with the labeled values. These results demonstrate that SPCEs can be readily activated, functionalized, and effectively applied to point-of-care food quality control.