School of Optical and Electronic Information and Wuhan National Laboratory of Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
Nanoscale. 2019 Nov 28;11(46):22230-22236. doi: 10.1039/c9nr08340e.
Surface-enhanced Raman scattering (SERS) spectroscopy aims to augment the relatively weak molecular vibrations based on electromagnetic enhancement (EE) and chemical enhancement (CE) mechanisms, and offers a potential way for material identification, even up to the single-molecule level, under atmospheric conditions. We have subtly combined the advantages of EE and CE, and propose new MXene (Ti3C2TX) nano-sheet/Au nanostructure architectures to break through the limitations of the Raman detection with long-time stability. The MXene nanosheets with excellent biocompatibility can effectively prevent structural distortion from the interaction with the Au NSs, and can also guarantee a high enhancement effect owing to the spatially extended electromagnetic field distribution and electron injection into the molecules. The self-assembled Au nanostructures are aggregated based on the Volmer-Weber growth model, and the electromagnetic field distribution radically evolves depending on the morphologies of the resultant Au nanostructures, leading to a drastic compensation for the limited EE of the MXene nano-sheets. Consequently, the intensified Raman vibrational signals of R6G molecules lead to a high enhancement factor of 2.9 × 107, even at an ultra-low concentration of 10-10 M. Similarly, the Raman signals of the methylene blue (MB) and crystal violet (CV) molecules can also be detected at low concentrations below 10-8 M, manifesting universal applications of the MXene/Au architectures for ultra-sensitive molecular detection under atmospheric conditions.
表面增强拉曼散射（SERS）光谱旨在基于电磁增强（EE）和化学增强（CE）机制增强相对较弱的分子振动，并提供一种潜在的方法来进行材料识别，甚至在大气条件下达到单分子水平。我们巧妙地结合了 EE 和 CE 的优点，并提出了新的 MXene（Ti3C2TX）纳米片/Au 纳米结构架构，以突破具有长期稳定性的拉曼检测的限制。具有优异生物相容性的 MXene 纳米片可以有效地防止与 Au NSs 相互作用引起的结构变形，并且由于空间扩展的电磁场分布和电子注入到分子中，也可以保证高增强效果。自组装的 Au 纳米结构基于 Volmer-Weber 生长模型聚集，并且电磁场分布根据所得 Au 纳米结构的形态发生剧烈演变，从而对 MXene 纳米片的有限 EE 进行了剧烈补偿。因此，R6G 分子的增强拉曼振动信号导致高增强因子为 2.9×107，即使在 10-10 M 的超低浓度下也是如此。同样，亚甲基蓝（MB）和结晶紫（CV）分子的拉曼信号也可以在 10-8 M 以下的低浓度下检测到，表明 MXene/Au 架构在大气条件下对超灵敏分子检测具有普遍适用性。
