Three-dimensional NTF-Ag composites for ultrasensitive SERS-based detection of malachite green on crucian carp skin

Three-dimensional (3D) Na₂Ti₃O₇ flower (NTF) systems were synthesized, followed by sputter coating with silver (Ag) nanoparticles to increase surface-enhanced Raman scattering (SERS) activity. By varying the sputtering time, SERS activity of the Ag-decorated NTF (NTF-Ag) structures was optimized. Furthermore, the theoretical evidence from finite difference time domain (FDTD) simulations confirmed that an appropriate density of Ag particles increased the electromagnetic field contribution. The electromagnetic field contribution is high because the special petal-shaped structure can promote multiple reflections and scattering, thus providing efficient resonance absorption for charge-transfer (CT) and exciton enhancements. Highly SERS-active NTF-Ag composites were developed and exploited for the detection of malachite green (MG), a model contaminant in the food industry. The detection limit of this method for MG reached 3.78 × 10^-10 M, with a standard deviation of homogeneity of 6.83 %. This method was successfully applied to detect MG on crucian carp skin, and it showed high recovery, indicating that it can serve as a practical method for MG evaluation. All results demonstrated that the prepared NTF-Ag composite has great potential in the application of SERS-based contamination assessment in the food industry.