AuNPs@mesoSiO2 composites for SERS detection of DTNB molecule.

A surface enhanced Raman spectroscopy (SERS) substrate made of gold nanoparticles-embedded mesoporous silica (AuNPs@mesoSiO2) varying with size and gold concentrations was applied for SERS applications. In this study, the AuNPs@mesoSiO2 substrate produced notable intensity and more distinguishable peaks when compared with the spectra collected directly from an Au/Cr-coated substrate with regard to the detection of a lower concentration of chemicals or environmental contamination. Both aqueous and dried coffee rings of 5-5'-Dithio-bis (2-nitrobenzoic acid) (DTNB) solutions were examined. SERS spectra obtained from the substrate showed more fingerprint peaks with significant enhancement on the spectra signals. The correlation between the SERS signal and the DTNB concentration was found to be linear within a range of 10(-2) to 10(-12) M. SERS enhancement between 25 and 8 times greater can be achieved for DTNB detection using AuNPs@mesoSiO2 compared with the normal Raman spectra obtained from the aqueous solution and the contact line of the dried coffee ring, respectively.