Synergistic Signal Amplification in a 3D MXene-Hydrogel Framework With Ethanol-Induced Contraction for Sensitive SERS Detection

Conventional two-dimensional SERS substrates are often limited by low hot-spot density and poor reproducibility. In this work, a novel three-dimensional (3D) SERS substrate was developed by in situ growing fractal gold nanostructures on a Ti 3 C 2 T x MXene network incorporated into a hydrogel. The coexistence of Au and MXene, confirmed by EDS analysis, provides a composite platform that combines the electromagnetic enhancement of Au nanostructures with the potential chemical-enhancement contribution of MXene. An ethanol-induced hydrogel shrinkage strategy was further introduced to simultaneously concentrate analytes and compress the 3D framework, thereby increasing the local density of active sites and enhancing the SERS response. The substrate exhibited a linear detection range of 10 −8 -10 −4 M for crystal violet (CV) and was successfully applied to the quantitative analysis of ginsenoside Rg3 in ginseng. A detection limit of approximately 0.23 µg mL −1 and an estimated sample content of approximately 1.31 µg g −1 were obtained. This work demonstrates a contraction-assisted Au/MXene 3D SERS platform for sensitive molecular detection. Graphical Synergistic enhancement of SERS signals from Raman reporter molecules (ginsenoside Rg3 in ginseng) arises from the electromagnetic enhancement of gold nanoflowers and the synergistic contribution of MXene.