Large-area surface-enhanced Raman spectroscopy imaging of brain ischemia by gold nanoparticles grown on random nanoarrays of transparent boehmite

ACS Nano. 2014 Jun 24;8(6):5622-32. doi: 10.1021/nn4065692. Epub 2014 Jun 2.

Abstract

Although SERS spectroscopy, which is sensitive to molecular vibration states, offers label-free visualization of molecules, identification of molecules and their reliable large-area imaging remains to be developed. Limitation comes from difficulties in fabricating a SERS-active substrate with homogeneity over a large area. Here, we overcome this hurdle by utilizing a self-assembled nanostructure of boehmite that is easily achieved by a hydrothermal preparation of aluminum as a template for subsequent gold (Au) deposition. This approach brought about random arrays of Au-nanostructures with a diameter of ∼125 nm and a spacing of <10 nm, ideal for the hot-spots formation. The substrate, which we named "gold nanocoral" (GNC) after its coral reef-like shape, exhibited a small variability of signal intensities (coefficient value <11.2%) in detecting rhodamine 6G molecule when 121 spots were measured over an area of 10 × 10 mm(2), confirming high uniformity. The transparent nature of boehmite enabled us to conduct the measurement from the back-side of the substrate as efficiently as that from the front-side. We then conducted tissue imaging using the mouse ischemic brain adhered on the GNC substrate. Through nontargeted construction of two-dimensional-Raman-intensity map using differential bands from two metabolically distinct regions, that is, ischemic core and contralateral-control areas, we found that mapping using the adenine ring vibration band at 736 cm(-1) clearly demarcated ischemic core where high-energy adenine phosphonucleotides were degraded as judged by imaging mass spectrometry. Such a detection capability makes the GNC-based SERS technology especially promising for revealing acute energy derangement of tissues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Hydroxide / chemistry*
  • Aluminum Oxide / chemistry*
  • Animals
  • Brain / pathology
  • Brain Ischemia / pathology*
  • Computer Simulation
  • Gold / chemistry*
  • Imaging, Three-Dimensional
  • Male
  • Mass Spectrometry
  • Metal Nanoparticles / chemistry*
  • Mice
  • Mice, Inbred C57BL
  • Nanotechnology / methods*
  • Rhodamines / chemistry
  • Spectrum Analysis, Raman*
  • Substrate Specificity
  • Surface Properties
  • Vibration

Substances

  • Rhodamines
  • rhodamine 6G
  • Aluminum Hydroxide
  • aluminum oxide hydroxide
  • Gold
  • Aluminum Oxide