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

[Display omitted] •A cost-effective and highly sensitive dopamine molecule detection system was developed by designing an AuNPs/2D MOF/Au/D-shaped fiber SPR sensor.•The composite structure of AuNPs/2D MOF/Au achieved the secondary amplification of SPR signal, facilitated the coupling between SPR and LSPR, offered abundant active sites, and effectively ensured the detection of small biological molecules.•The optimal deposition concentration and time of AuNPs/2D MOF were optimized, resulting in a remarkable 104.61% increase in sensitivity and a significant 73.87% increase in figure of merit (FOM).•The electric field enhancement and electron transition of composite structures were verified using the finite element method and band theory, respectively.•Modified amino acid probe DNA is used as an aptamer to couple with dopamine molecules, enabling low limit detection in PBS solution and serum solution. 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.