微腔型银修饰光纤SERS探针的制备及性能研究

提出了一种基于银修饰的微腔型光纤表面增强拉曼散射（SERS）探针，采用湿法检测，将光纤SERS探针直接放入待测溶液中，以罗丹明6G（R6G）溶液为探针分子，对所制备的光纤SERS探针进行远端实验性能研究。利用氢氟酸化学腐蚀的方法制备了一种微腔型光纤结构，通过控制氢氟酸的腐蚀时间得到了一系列不同腐蚀时间、不同微腔长度的光纤结构。实验研究了光纤结构的微腔长度对光纤SERS探针性能的影响，以浓度为10-3 mol·L-1的R6G溶液为探针分子，通过不断地优化纳米银溶胶与R6G溶液的混合顺序及比例，采用裸光纤微腔结构对混合溶液进行拉曼检测，发现当混合溶液的混合顺序及比例为先后混合等体积的纳米银溶胶和R6G溶液时，此时得到的混合溶液的拉曼信号增强性能最佳。利用得到的混合溶液去寻找拉曼信号增强效果最高时光纤微腔结构的结构参数，实验结果表明，在相同的实验条件下，当光纤放入氢氟酸中腐蚀时间为5 min时，此时光纤微腔结构的拉曼信号增强效果最佳。在显微镜下测量的多组腐蚀时间为5 min的光纤，其微腔长度平均约为81 μm。对得到的光纤微腔结构，采用制备过程可控的磁控溅射技术制备了一系列银纳米薄膜/多模光纤（Ag/MMF）的复合材料。当磁控溅射时间为10 min时，获得了光纤SERS探针（Ag/MMF-10）。实验以去离子水配制了不同浓度的R6G溶液，以不同浓度的R6G溶液为探针分子，Ag/MMF-10探针的远端检测限（LOD）低至10-7 mol·L-1。该光纤SERS探针拉曼信号的再现性光谱检测中显示各个特征峰的相对标准偏差（RSD）均小于10%。同时，该光纤SERS探针对浓度为10-6 mol·L-1的R6G溶液的增强因子（AEF）可高达2.64×106。实验结果表明所制备的银修饰的光纤SERS基底具有较高的灵敏度和良好的再现性。因此，该光纤SERS探针在生物医学检测、农残化学分析等痕量检测方面有潜在的应用价值。

Preparation and Properties of Micro-Cavity Silver Modified Fiber SERS Probe

In this paper, a silver modified micro-cavity fiber surface-enhanced Raman scattering (SERS) probe was proposed. Using Rhodamine 6G (R6G) solution as the probe molecule, the wet detection method was used to place the fiber SERS probe directly into R6G, and the far-end experimental performance of the prepared fiber SERS probe was studied. A micro-cavity fiber structure was fabricated by etching of hydrofluoric acid (HF). By controlling HF’s etching time, a series of fiber structures with different etching times and different micro-cavity lengths were obtained. The effect of the length of the micro-cavity on the fiber SERS probe’s performance was studied experimentally. The R6G with a 10-3 mol·L-1 concentration was used as the probe molecule. The mixing of the nano silver sol and the R6G was continuously optimized, and the structure of bare fiber micro-cavity was used for Raman detection of the mixed solution. It was found that the Raman signal was highest when the mixed order and the ratio of the mixed solution were the equal volumes of nano silver sol and R6G solution. The obtained mixed solution was used to find the -fiber micro-cavity structure parameters when the Raman signal enhancement effect was the highest. The experimental results showed that under the same experimental conditions, when the fiber’s etching time was 5 minutes, the fiber micro-cavity structure had the best Raman signal enhancement effect. The average length of micro-cavities observed under the microscope for multiple sets of fiber was about 81 μm. For the obtained fiber micro-cavity structure, a series of silver nanofilm/multi-mode fiber (Ag/MMF) composite materials were fabricated by the magnetron sputtering technology with a controllable preparation process. When the magnetron sputtering time was 10 minutes, the fiber SERS probe (Ag/MMF-10) was obtained. In the experiment, deionized water was used to prepare different concentrations of R6G solutions. Using different concentrations of R6G as probe molecules, the remote detection limit (LOD) of the Ag/MMF-10 was as low as 10-7 mol·L-1. The detection of Raman signal reproducibility of Ag/MMF-10 showed that the relative standard deviation (RSD) of each characteristic peak was less than 10%. Simultaneously, the analytical enhancement factor (AEF) of Ag/MMF-10 to R6G with 10-6 mol·L-1 concentration can be as high as 2.64×106. The experimental results showed that the Ag/MMF-10 had high sensitivity and good reproducibility. Therefore, the fiber SERS probe may have potential application value in trace detection, such as biomedical detection, chemical analysis of pesticide residues.