Toward Plasmonic Neural Probes: SERS Detection of Neurotransmitters through Gold-Nanoislands-Decorated Tapered Optical Fibers with Sub-10 nm Gaps

Adv Mater. 2023 Mar;35(11):e2200902. doi: 10.1002/adma.202200902. Epub 2023 Feb 2.


Integration 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.

Keywords: gold nanoislands; gold-nanoparticles-decorated tapered fibers; label-free detection; neurotransmitters; plasmonics; solid-state dewetting; tapered fibers.

MeSH terms

  • Gold / chemistry
  • Metal Nanoparticles* / chemistry
  • Nanostructures* / chemistry
  • Neurotransmitter Agents
  • Optical Fibers
  • Spectrum Analysis, Raman / methods


  • Gold
  • Neurotransmitter Agents