Construction of functionalized SERS substrates based on Schiff base reaction for detection of γ-aminobutyric acid in human serum

Due to the small molecular weight and low Raman activity of γ-Aminobutyric acid (GABA), a Schiff base reaction was introduced. 4-mercaptobenzaldehyde (4-MBA) was assembled onto AuNPs via Au-S bond to form functional nanoparticles (AuNPs@4-MBA). Then, under certain conditions, it reacts with GABA to form a Schiff base, which increases the Raman scattering cross section area and enhances the Raman signal of GABA. In addition, because 4-MBA was assembled on AuNPs in advance through Au-S bond, the characteristic peak at 1080 cm −1 was selected as the internal standard, and compared with the characteristic peak at 1560 cm −1 of the newly generated C=N double bond. A linear standard curve was drawn between the peak intensity ratio of I 1560 /I 1080 and the concentration of GABA. The proposed material has a good linear relationship between 1 × 10 −5 and 1 × 10 −9  mol/L, R 2 was 0.9942, and the detection limit was 3.2 × 10 −11  mol/L. SERS detection of GABA was realized, and it was successfully applied to the detection of GABA in human serum that has important application value for future practical.