Graphene Oxide‐Wrapped Hierarchical Gold Nanopillar Hybrids for Real‐Time, Non‐Destructive Dopamine Sensing in Neurons and Midbrain Organoids

Abstract Advances in stem‐cell‐derived neuronal models have opened new possibilities for drug discovery and disease modeling; however, functional evaluation of dopaminergic activity remains a critical bottleneck in assessing neuronal maturity. To address this challenge, SIDNEY (Smart Interfacial Dopamine‐sensing platform for NEurons and organoid physiologY) is presented as a graphene oxide‐wrapped hierarchical gold nanopillar hybrid that enables label‐free, non‐destructive electrochemical monitoring of dopamine (DA) under live‐cell conditions. The electrode features a hierarchical nanostructure consisting of vertically aligned gold nanopillars (primary structure) decorated with smaller gold nanoparticles (secondary nanostructure), all wrapped with a thin layer of graphene oxide. This multiscale architecture provides enhanced conductivity, a large electroactive surface area, and molecular selectivity, while supporting long‐term culture and differentiation of SH‐SY5Y and iPSC‐derived dopaminergic neurons directly on the electrode surface. SIDNEY achieves a limit of detection of 29.5 n m in phosphate‐buffered saline and 7.51 n m in artificial cerebrospinal fluid, exhibiting high selectivity against interferents through π – π stacking, hydrogen bonding, and electrostatic interactions. Beyond conventional neuronal models, SIDNEY also enables real‐time functional assessment of dopaminergic activity in midbrain organoids without labeling or sample destruction. This platform establishes a practical strategy for quantitative neurochemical monitoring, offering broad utility in drug screening and neurodegenerative disease research.