A reliable gold nanoparticle/Cu-TCPP 2D MOF/gold/D-shaped fiber sensor based on SPR and LSPR coupling for dopamine detection

The optical fiber sensor, which exploits surface plasmon resonance (SPR), finds extensive application in biological detection owing to its miniaturized and real-time measurement capabilities. Nevertheless, SPR sensors alone exhibit limited sensitivity when detecting small biological molecules. This paper presents a novel gold nanoparticle (AuNPs)/two-dimensional metal-organic framework (2D MOF Cu-TCPP)/Au/D-shaped fiber SPR sensor for dopamine detection. The composite structure of AuNPs/2D MOF/Au was designed to facilitate the coupling of SPR and local surface plasmon resonance (LSPR), resulting in a substantial enhancement of the intensity of the surface electric field. A 104.61% increase in sensitivity and a 73.87% increase in figure of merit (FOM) were achieved by optimizing the optimal deposition concentration of AuNPs/2D MOF. The finite element method was utilized in COMSOL software to demonstrate that the coupling of SPR and LSPR can significantly enhance the sensitivity value (10,000 nm/RIU). Additionally, the sensitization mechanism of the sensor is elucidated by the energy band theory. Moreover, probe DNA was utilized as a linker to capture dopamine molecules, achieving a low limit of detection (LOD) of 1.07±0.07*10−14 M. These results demonstrated that the proposed sensor enables accurate and highly sensitive detection of dopamine molecules.