title: Gold-nanorod-assisted near-infrared stimulation of primary auditory neurons.
abstract: Infrared stimulation offers an alternative to electrical stimulation of neuronal tissue, with potential for direct, non-contact activation at high spatial resolution. Conventional methods of infrared neural stimulation (INS) rely on transient heating due to the absorption of relatively intense laser beams by water in the tissue. However, the water absorption also limits the depth of penetration of light in tissue. Therefore, the use of a near-infrared laser at 780 nm to stimulate cultured rat primary auditory neurons that are incubated with silica-coated gold nanorods (Au NRs) as an extrinsic absorber is investigated. The laser-induced electrical behavior of the neurons is observed using whole-cell patch clamp electrophysiology. The nanorod-treated auditory neurons (NR-ANs) show a significant increase in electrical activity compared with neurons that are incubated with non-absorbing silica-coated gold nanospheres and control neurons with no gold nanoparticles. The laser-induced heating by the nanorods is confirmed by measuring the transient temperature increase near the surface of the NR-ANs with an open pipette electrode. These findings demonstrate the potential to improve the efficiency and increase the penetration depth of INS by labeling nerves with Au NRs and then exposing them to infrared wavelengths in the water window of tissue.
authors.affiliation: Faculty of Science, Engineering and Technology, Swinburne University of Technology, P. O. Box 218, Hawthorn, Victoria, 3122, Australia.
authors.forename: Jiawey
authors.initials: J
authors.lastname: Yong
authors.forename: Karina
authors.initials: K
authors.lastname: Needham
authors.forename: William G A
authors.initials: WG
authors.lastname: Brown
authors.forename: Bryony A
authors.initials: BA
authors.lastname: Nayagam
authors.forename: Sally L
authors.initials: SL
authors.lastname: McArthur
authors.forename: Aimin
authors.initials: A
authors.lastname: Yu
authors.forename: Paul R
authors.initials: PR
authors.lastname: Stoddart
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D006046:Gold / Q000737:chemistry*; D007259:Infrared Rays; D007834:Lasers; D008027:Light; D053758:Nanoparticles / Q000008:administration & dosage; D043942:Nanotubes / Q000737:chemistry*; D009474:Neurons / Q000502:physiology*; D051381:Rats; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D006046:Gold; D012822:Silicon Dioxide
keywords: gold nanorods; infrared neural stimulation; photothermal therapy; spiral ganglion neurons