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

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.

• Authors: Shogo Yamazoe, Masayuki Naya, Megumi Shiota, Takayuki Morikawa, Akiko Kubo, Takeharu Tani, Takako Hishiki, Tadashi Horiuchi, Makoto Suematsu, Mayumi Kajimura
• Journal: ACS nano (ACS Nano) Vol. 8 Issue 6 Pg. 5622-32 (Jun 24 2014) ISSN: 1936-086X [Electronic] United States
• PMID: 24865176 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

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

Topics

• 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