New SERS Substrate Enables Large-Area Imaging

Fabricating substrates for surface-enhanced Raman spectroscopy (SERS) that are uniformly active over a large area is a challenge. Masayuki Naya of Fujifilm Corp., in Kanagawa, Japan; Mayumi Kajimura of Keio University, in Tokyo; and coworkers have met that challenge by making a SERS substrate large enough for imaging tissue slices from a mouse brain (ACS Nano 2014, DOI: 10.1021/nn4065692). To make the substrate, the researchers generated a self-assembled layer of nanostructured boehmite—aluminum oxide hydroxide, AlO(OH)—on glass as a template for the deposition of gold nanoparticles. The resulting gold nanocoral, named for its resemblance to a coral reef, consists of an array of gold nanostructures with diameters of about 125 nm and spacing less than 10 nm. SERS spectra of the dye rhodamine 6G showed that the 24- × 24-mm substrate, which can be analyzed from either side because boehmite is transparent, is uniformly SERS active. The team used the substrate for SERS imaging of mouse brain slices as large as 10 × 8 mm, in which they detected blood-deprived regions.