High-performance surface plasmon resonance sensor utilizing AuNPs/Au nanocone array for ultrasensitive dopamine detection in complex biological matrices

A high-performance optical fiber surface plasmon resonance (SPR) biosensor for the determination of dopamine (DP) is reported based on gold nanocone arrays combined with gold nanoparticles (AuNPs). The sensor was fabricated via thermal nanoimprinting, gold sputtering, and single-stranded DNA-assisted AuNPs immobilization to form gap hotspots. Finite element simulation and experimental results verified strong electromagnetic field enhancement via extraordinary optical transmission and SPR-LSPR coupling. The sensor achieved a detection limit of 2.7 × 10 -14 M for DA, with sensitivity and FOM improved by 37.4% and 54.2% relative to conventional gold film structures. It showed excellent selectivity and stability in serum, cerebrospinal fluid (CSF), and whole blood. This robust, scalable design provides a promising label-free platform for ultrasensitive DA detection in clinical point-of-care applications. Graphical abstract