Zheng, DiPisano, FilippoCollard, LiamBalena, AntonioPisanello, MarcoSpagnolo, BarbaraMach-Batlle, RosaTantussi, FrancescoCarbone, LuigiDe Angelis, FrancescoValiente, Manuelde la Prida, Liset MCiracì, CristianDe Vittorio, MassimoPisanello, Ferruccio2024-03-132024-03-132023-03Adv Mater . 2023 ;35(11):e2200902http://hdl.handle.net/20.500.12105/18931Integration of plasmonic nanostructures with fiber-optics-based neural probes enables label-free detection of molecular fingerprints via surface-enhanced Raman spectroscopy (SERS), and it represents a fascinating technological horizon to investigate brain function. However, developing neuroplasmonic probes that can interface with deep brain regions with minimal invasiveness while providing the sensitivity to detect biomolecular signatures in a physiological environment is challenging, in particular because the same waveguide must be employed for both delivering excitation light and collecting the resulting scattered photons. Here, a SERS-active neural probe based on a tapered optical fiber (TF) decorated with gold nanoislands (NIs) that can detect neurotransmitters down to the micromolar range is presented. To do this, a novel, nonplanar repeated dewetting technique to fabricate gold NIs with sub-10 nm gaps, uniformly distributed on the wide (square millimeter scale in surface area), highly curved surface of TF is developed. It is experimentally and numerically shown that the amplified broadband near-field enhancement of the high-density NIs layer allows for achieving a limit of detection in aqueous solution of 10-7  m for rhodamine 6G and 10-5  m for serotonin and dopamine through SERS at near-infrared wavelengths. The NIs-TF technology is envisioned as a first step toward the unexplored frontier of in vivo label-free plasmonic neural interfaces.engVoRhttp://creativecommons.org/licenses/by-nc-nd/4.0/NanostructuresMetal NanoparticlesOptical FibersGoldSpectrum Analysis, RamanNeurotransmitter AgentsAttribution-NonCommercial-NoDerivatives 4.0 Internacional364797413511e220090210.1002/adma.2022009021521-4095Advanced materials (Deerfield Beach, Fla.)open access