Engineering Cobalt-Doped Nickel Oxide/Gadolinium-Doped Cerium Dioxide Heterojunction Nanofibers for Highly Selective and Sensitive Dopamine Detection

Developing accurate and effective methods of dopamine (DA) detection is vital for the rapid diagnosis of diseases related to abnormal DA levels. Herein, we developed a high-performance, nonenzymatic dopamine electrochemical sensor for DA detection. The sensor was fabricated by synthesizing metal-oxide heterojunction porous nanofibers (PNFs), specifically cobalt-doped nickel oxide and gadolinium-doped cerium dioxide (Co-NiO/GDC), on a carbon nanofiber template using electrospinning and high-temperature annealing. The doping of Co²⁺ and Gd³⁺ was shown to induce lattice distortions in NiO and CeO₂, which in turn generated microstrains and surface defects at the phase interface. These structural enhancements played a key role in significantly boosting the material's catalytic activity for DA detection. The Co-NiO/GDC PNFs sensor demonstrated remarkable performance metrics, including a wide linear dynamic range (0.1 to 1100 μM), a high sensitivity (508.7 μA·mM^-1·cm^-2) and an exceptionally low detection limit (LOD = 0.018 μM, S/N = 3). The sensor also exhibited superior anti-interference properties, repeatability, reproducibility, and long-term stability. The sensor's practical utility was further validated by its ability to accurately detect DA levels in complex biological matrices such as animal serum and artificial urine, showcasing its potential for practical clinical applications.