Quantitative SERS-based detection using Ag-Fe3O4 nanocomposites with an internal reference

Surface Enhanced Raman Spectroscopy (SERS) is an excellent tool that provides information about the vibrational modes of molecules. However, quantitative analysis using SERS has remained a challenge largely because of the difficulty in reproducing the SERS substrates. We report a facile synthesis method of Ag-Fe3O4 nanocomposites that can be used as SERS substrates in solutions. Quantitative SERS measurements using the Ag-Fe3O4 nanocomposites are successfully demonstrated with 4-aminothiophenol and dopamine as analytes. The inclusion of an internal reference significantly improves the reliability and quality of quantification of the analytes. The scheme is versatile and has the potential for the detection of a wide range of analytes.