Fabrication of 3D printed electrodes with ZnO nanostructures for dopamine detection

The foundation of technological advancement lies in the integration of scientific and empirical knowledge through interdisciplinary collaboration. In this context, nanotechnology has emerged as one of the prominent fields of the 21st century, offering the potential to produce solutions not only within the scope of natural sciences but also across diverse areas such as engineering, environmental management, economics, and policy. The controlled synthesis of materials at the nanoscale, the development of application-oriented materials, and their sustainable design are essential for the advancement of the field. In recent years, the increase in computational power has facilitated the widespread adoption of technologies such as three-dimensional (3D) modeling and printing, which has simplified prototyping processes and contributed to scalable manufacturing. In the field of electrochemistry—one of the most powerful branches of chemistry—the use of 3D printing has gone beyond fabricating simple apparatuses and has, over the past decade, been applied directly to electrochemical systems. This relatively new technological research area holds considerable potential for the development and application of novel electrodes. Despite advancements in printing speed and capability, the fabrication, surface modification, and preparation of 3D-printed working electrodes for specific applications still require the use of nanomaterials. While various synthesis methods exist for nanomaterials, the increasing awareness of the harmful effects of chemical reagents necessitates the adoption of environmentally friendly chemical approaches. Just as electrochemical 3D printing technology needs further development, sustainable green chemistry practices must also be advanced to replace harsh chemicals. In this thesis, an electrochemical system was developed by prioritizing environmentally friendly chemical methods to minimize resource use and reduce waste. Zinc oxide (ZnO) nanoparticles were synthesized using dried leaves of Salvia heldreichiana, an endemic plant species, and 3D electrodes were printed using a polylactic acid (PLA) composite filament containing carbon black for electrical conductivity. These synthesized nanoparticles were then used to modify the electrode surfaces in the presence of a quaternary ammonium salt, diallyldimethylammonium chloride (DDA), both as a monomer and polymer. The synthesized ZnO nanoparticles had an average particle size of 35.98 nm and a calculated band gap of 2.97 eV. The printed electrodes were characterized using electrochemical and microscopic techniques. Furthermore, their applicability as sensors for dopamine detection was investigated. The unmodified 3D-printed electrode exhibited a linear detection range of 50–300 µM for dopamine, while the DDA-ZnO NP-modified electrode extended this range to 10–8000 µM. In addition, the synergistic effects achieved through nanoscale surface modification led to a detection limit of 8.56 µM and a sensitivity of 456.84 µA/mM·cm2. Considering the low production cost of approximately $0.03 per electrode, the study successfully achieved its intended objectives.