Porous anodized aluminum oxide (AAO) was widely used in the SERS substrate

fabrication for the existence of large-area BX-795 high-ordered array of nanopores and the simple EX 527 manufacturer production process. Porous AAO can be used directly as SERS substrate after depositing Au or Ag on the surface [30] and can also be used as template to fabricate ordered array nanostructure SERS substrate [31–36]. Previous studies have shown that nanorod array and nanowire network, with dense nanojunctions and nanogaps, can support stronger SERS than porous structures [37–41]. The question, whether the nanorod array and nanowire network structure can be fabricated just by making a simple change to the production process of porous AAO, has not attracted the researcher’s attention. In this work, a simple film-eroding process was added after the production process of porous AAO to fabricate large-area low-cost nanowire network AAO which can be used as high-performance SERS substrate after depositing 50 nm of Au onto its surface. The Raman spectra of benzene thiol on the nanowire network AAO SERS substrates are measured and the average

Raman NVP-BGJ398 enhancement factors (EFs) are calculated. Comparing with the porous AAO SERS substrates, the Raman peak intensities and the average EFs of nanowire network AAO SERS substrates have a significant enhancement. The average EF of our sensitive SERS substrate can reach 5.93 × 106, about 35 times larger than that of porous AAO SERS substrate and about 14% larger than that of Klarite® substrates (Renishaw Diagnostics, Glasgow, UK), which indicates an Phosphatidylinositol diacylglycerol-lyase enormous electromagnetic enhancement that exists in the nanowire network AAO SERS substrate. Repeated measurements and spatial mapping show an excellent reproducibility of the nanowire network AAO SERS substrate. The relative standard deviations in the SERS intensities are limited to only approximately 7%. Comparing with other fabrication methods of the high-performance SERS substrates, our method based on the mature production process of porous AAO is simpler, has lower cost, and is easier for commercial production. Therefore, we believe that our nanowire network AAO SERS substrates have great potential

for applications. Methods Sample fabrication We commissioned Hefei Pu-Yuan Nano Technology Ltd to fabricate the porous AAOs and nanowire network AAOs. Production process [36] of porous AAO is already quite mature. The aluminum foil was first degreased with acetone under an ultrasonic bath for 10 min and then annealed at 350°C for 2 h. It was electropolished in a mixed solution (20% H2SO4 + 80% H3PO3 + 2% K2CrO4) under a constant voltage of 9 V and a temperature of 90°C to 100°C for 10 min. During this process, the aluminum was used as the anode and a platinum plate as the cathode. To obtain ordered nanopore arrays, we used a two-step anodizing process. The foil was anodized first in 0.3 M oxalic acid at 33 V at 0°C to 5°C for 14 h. It was then immersed in a mixed solution of 5.0 wt.