Stable Copper‐Noble Metal Dual‐Atom Catalysts on 3D Graphene Microneedles for Enzyme‐Mimetic Biosensing of Phenolic Biomarkers

Metalloenzymes set the benchmark for sensitivity and selectivity in biosensing, but their use is limited by denaturation and susceptibility to fouling. Here, we present an enzyme‐inspired electrochemical sensor based on dual single‐atom catalysts (SACs) composed of Cu paired with Pt or Au, anchored onto MoS ₂ ‐coated laser‐scribed graphene microneedles (LSGE MNs). Synthesized using sequential electrochemical deposition, these dual SACs replicate the cooperative binuclear active site of tyrosinase and catalyze phenol electro‐oxidation. The Cu/Pt and Cu/Au modified electrodes were applied to levodopa (L‐DOPA) detection, a frontline therapy for Parkinson's disease, achieving limits of detection of 0.32 and 0.42 µM, respectively, which is comparable to tyrosinase‐based sensors while maintaining their stability for over 100 cycles. The 3D LSGE MNs, fabricated via a two‐step graphitization of polyimide MNs, provided sufficient mechanical strength for skin penetration and were validated in ex vivo human skin. Density functional theory (DFT) simulations and electrochemical testing confirm a synergistic effect between Cu and noble metal atoms, where one facilitates electron transfer and the other stabilizes analyte adsorption. This dual SAC‐microneedle platform offers a generalizable strategy for enzyme‐inspired biosensors and a pathway toward wearable systems for continuous, closed‐loop drug monitoring in Parkinson's disease and related disorders.