Fiber Optic SPR Sensor Modified With Copper Oxide Nanoparticles for Highly Sensitive and Selective Detection of Dopamine

In modern biomedical technology, the fabrication of high-performance sensors for dopamine detection is an important issue because dopamine is a major neurotransmitter and abnormal level of its concentration in the human body is accountable for several neurological diseases. Here, we report a highly sensitive and selective surface plasmon resonance (SPR) sensor modified with small copper oxide nanoparticles (CuO NPs) for experimentally detecting dopamine. Fiber optic sensing probes were fabricated by depositing a 50-nm-thick gold film over the unclad portion of a multimode optical fiber using magnetron sputtering and then further modified with synthesized CuO NPs (~7 nm). Detection of dopamine with the designed SPR sensor was achieved for a wide range of concentrations from very low concentrations with a limit of detection at 1.11 nM and up to 50 nM. The maximum sensitivity was achieved as 0.787 nm/nM and the limit of quantification was at 1.43 nM. To evaluate the selectivity of the studied sensor, experiments were also performed with ascorbic acid and uric acid, which usually coexist with dopamine in the biological fluids. Moreover, sensing characteristics, such as repeatability, linearity, and response time, were studied in detail. Taken together, these findings show that CuO NPs are excellent candidates as SPR sensitizer effectively improving the sensing performance of dopamine.