Researchers at Sungkyunkwan University (SKKU), Hong Kong University of Science and Technology (HKUST) and Jeonbuk University have developed a graphene oxide–wrapped hybrid electrode platform that allows real-time, label-free monitoring of dopamine activity from living neuronal cells and brain organoids. The innovation, named SIDNEY (Smart Interfacial Dopamine-sensing platform for NEurons and organoid physiologY), addresses a long-standing challenge in neuroscience: how to measure functional maturation of stem-cell-derived dopaminergic neurons without destroying the sample.
Built around a hierarchical nanostructure of vertically aligned gold nanopillars adorned with smaller gold nanoparticles and encased in a thin graphene oxide layer, SIDNEY forms a high-conductivity, high-selectivity interface that supports long-term cell culture and differentiation. The graphene oxide coating plays a crucial role - its aromatic carbon rings engage in π–π stacking while negatively charged carboxyl groups attract dopamine’s positively charged amine moiety, ensuring selective capture and efficient electron transfer.
This multiscale design yields outstanding analytical performance, reaching detection limits as low as 7.51 nM in artificial cerebrospinal fluid - well within the physiological range of dopamine found in the human brain. Importantly, it maintains minimal interference from related neurotransmitters like serotonin and norepinephrine, demonstrating superior stability and antifouling capability.
Using the SIDNEY platform, researchers cultured and differentiated SH-SY5Y cells and human iPSC-derived dopaminergic neurons directly on the electrode surface, tracking their dopaminergic output over time. Moving to human midbrain organoids, the team showed the platform’s power for non-destructive functional assessment: only mature organoids (around 95 days old) produced measurable dopamine release of approximately 9.16 nM, confirming physiological activity at the single-organoid level.
Unlike conventional approaches such as chromatography or immunoassays - which require large sample volumes and destroy cells—SIDNEY provides results within one minute from microliter-scale samples while preserving the organoid’s viability. This capability paves the way for longitudinal studies of neuronal maturation, personalized drug screening, and neurodegenerative disease modeling, bringing functional neuroscience a step closer to real-time, non-invasive measurement powered by graphene nanotechnology.
