Palladium nanoparticle-modified filament for the detection of nitrite in foodstuff using additive manufactured electrodes

To create high-performance additive manufactured electrodes that can form the basis of electroanalytical platforms for real-world applications, the development of unique bespoke filament is required. To this end, this study presents the first report of a palladium nanoparticle (PdNP) embedded conductive filament for additive manufacturing electrochemistry, sustainably produced using an environmentally friendly aqueous synthesis, recycled poly(lactic acid) (PLA), bio-based plasticiser castor oil, and solvent-free thermal mixing. Once printed, the additive manufactured electrodes, with palladium nanoparticles supported on acid-activated graphite (PdNPs-AAGr), are applied towards the electrochemical detection of nitrite in food samples. The acid treatment of graphite enhanced PdNP formation, improving electrochemical properties and enabling sensitive nitrite detection via square wave voltammetry, with a linear range of 1 to 120 μM and a detection limit of 0.042 μM. The electrode exhibited excellent repeatability (RSD 4 %) and selectivity, with minimal interference from food matrix components. Real sample analysis in sausage, chicken ham, and pickled vegetables showed recoveries comparable to ion chromatography, confirming analytical accuracy. This work integrates an eco-friendly PdNPs on graphite synthesis method with recycled PLA, carbon black and bio-based castor oil plasticiser, offering a sustainable platform for food monitoring.