Porous alumina aerogel with tunable pore structure for facile, ultrasensitive, and reproducible SERS platform.

Porous alumina aerogel synthesized by sol–gel method was used as facile and sensitive surface‐enhanced Raman scattering (SERS) platform. In a simple "drop‐test" SERS detection, low concentration dye solution mixed with silver nanoparticles was directly dropped on the surface of aerogel platform for SERS detection immediately. The pore structure of alumina aerogel was tuned by adding PEG‐400 and varying the gelation temperature. The effects of surface morphology and pore size of alumina aerogel platform on SERS performance of crystal violet (CV) were investigated. The result shows that large specific surface area and interconnected pore network of aerogel are helpful for fast permeation of solution, generation of "hot spots," and adsorption of probe molecules. The Raman signal of CV was largely enhanced, enabling a detection concentration to 5 × 10−10 M with a SERS enhancement factor of 3.4 × 107. The SERS enhancement of alumina aerogel platform is remarkably improved with the increase of specific surface area and pore size, which is also confirmed by the finite‐difference time‐domain simulation. Moreover, the relative standard deviation of SERS intensity at 1619 cm-1 band for 5 × 10−8 M CV on aerogel platform is about 12%, indicating a good reproducibility. [ABSTRACT FROM AUTHOR]