High sensitivity, good signal repeatability, and facile fabrication of flexible surface enhanced Raman scattering (SERS) substrates are common pursuits of researchers for the detection of probe molecules in a complex environment. However, fragile adhesion between the noble-metal nanoparticles and substrate material, low selectivity, and complex fabrication process on a large scale limit SERS technology for wide-ranging applications. Herein, we propose a scalable and cost-effective strategy to a fabricate sensitive and mechanically stable flexible Ti₃C₂T_x MXene@graphene oxide/Au nanoclusters (MG/AuNCs) fiber SERS substrate from wet spinning and subsequent in situ reduction processes. The use of MG fiber provides good flexibility (114 MPa) and charge transfer enhancement (chemical mechanism, CM) for a SERS sensor and allows further in situ growth of AuNCs on its surface to build highly sensitive hot spots (electromagnetic mechanism, EM), promoting the durability and SERS performance of the substrate in complex environments. Therefore, the formed flexible MG/AuNCs-1 fiber exhibits a low detection limit of 1 × 10^–11 M with a 2.01 × 10⁹ enhancement factor (EF_exp), signal repeatability (RSD = 9.80%), and time retention (remains 75% after 90 days of storage) for R6G molecules. Furthermore, the l-cysteine-modified MG/AuNCs-1 fiber realized the trace and selective detection of trinitrotoluene (TNT) molecules (0.1 μM) via Meisenheimer complex formation, even by sampling the TNT molecules at a fingerprint or sample bag. These findings fill the gap in the large-scale fabrication of high-performance 2D materials/precious-metal particle composite SERS substrates, with the expectation of pushing flexible SERS sensors toward wider applications.

中文翻译：

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用于超灵敏 SERS 传感的柔性 MXene/氧化石墨烯纤维上 Au 纳米团簇的等离子体耦合

高灵敏度、良好的信号重复性和柔性表面增强拉曼散射（SERS）基板的易制备是研究人员在复杂环境中检测探针分子的共同追求。然而，贵金属纳米粒子与基底材料之间的脆弱附着力、低选择性以及大规模制造过程的复杂性限制了 SERS 技术的广泛应用。在此，我们提出了一种可扩展且具有成本效益的策略来制造敏感且机械稳定的柔性 Ti ₃ C ₂ T _xMXene@graphene oxide/Au 纳米团簇 (MG/AuNCs) 纤维 SERS 基底来自湿法纺丝和随后的原位还原过程。MG 纤维的使用为 SERS 传感器提供了良好的柔韧性（114 MPa）和电荷转移增强（化学机制，CM），并允许 AuNCs 在其表面进一步原位生长以构建高灵敏度热点（电磁机制，EM），提高衬底在复杂环境中的耐久性和 SERS 性能。^{因此，形成的柔性 MG/AuNCs-1 纤维具有 1 × 10 –11} M的低检测限和2.01 × 10 ⁹的增强因子 (EF _exp )、信号重复性 (RSD = 9.80%) 和时间保留（剩余R6G 分子储存 90 天后为 75%）。此外，升-半胱氨酸修饰的 MG/AuNCs-1 纤维通过 Meisenheimer 复合物的形成实现了三硝基甲苯 (TNT) 分子 (0.1 μM) 的痕量和选择性检测，甚至通过在指纹或样品袋中对 TNT 分子进行采样。这些发现填补了大规模制造高性能二维材料/贵金属粒子复合SERS衬底的空白，有望将柔性SERS传感器推向更广泛的应用领域。