Graphite and silver nanoparticles-loaded polylactic acid matrix: A pioneering tailor-lab-made filament for manufacturing eco-friendly and robust electrochemical sensors towards pyridoxine detection

Tailor-made conductive filaments have been an innovative approach to additively manufacturing affordable and enhanced electrochemical sensors targeted for the proposed application. In this context, carbon-metal composite materials exhibit relevant conductive and catalytic properties, while a polylactic acid (PLA) matrix provides printable characteristics and adds a sustainable aspect to the device. Thus, a new eco-friendly composite material using graphite (G) and silver nanoparticles (AgNPs) dispersed within a PLA matrix was proposed here. Efforts were directed towards selecting the best proportion between materials, considering the compromise between printability, mechanical stability, and electrochemical response. The electrodes were printed using a 3D pen, an user-friendly and accessible tool. Pyridoxine (PYR), a B-complex vitamin, was selected as a proof-of-concept analyte. In-depth electrochemical studies demonstrated that AgNPs drastically improved the electrochemical response of the sensor, achieving a 3.6-fold increase in charge transfer, if compared to the AgNPs-free electrode. The developed 3D-printed G/AgNPs/PLA sensor was assembled onto a 3D-printed BIA cell, and rapid amperometric measurements were performed for the determination of PYR. Utilizing the AgNPs-based sensor, a wide linear range (0.1 to 400 µmol L−1), and a low detection limit (0.03 µmol L−1) with suitable precision (RSD < 5.7 %) were obtained. Furthermore, selectivity was achieved in the presence of excipient compounds and other B-complex vitamins. The method was applied to pharmaceutical samples, and the results were validated against the reference method (UV–vis spectrometry). Therefore, it can be stated that our analytical approach is accurate and reliable, showing promise for implementation in routine analyses. In addition, our conductive filament material is sustainable and accessible to laboratories with minimal infrastructure aimed at producing high-performance electrochemical sensors.