基于超疏水界面光极定向蒸发预浓缩的表面增强拉曼分析器件的研制及其应用研究

Surface enhanced Raman Scattering (SERS) is a highly sensitive spectroscopic analytical technique, which is based on nanomaterials of coinage metals (SERS substrate). SERS optrode is a recently developed remote fiber optic SERS sensor. On the optrode, SERS substrate was built on the distal end while the proximal end of the fiber was used to couple laser in. Both the laser and SERS signal travel through the same fiber. Such kind of sensor is well suited for field and remote analysis..On the surface of certain type of superhydrophobic materials, the solutes will recede along with the contact line of a droplet and the superhydrophobic surface upon evaporation, and finally precipitate on a very small area when dry. This could be used for preconcentration of trace analytes. Near single molecule sensitivity SERS analysis of model anlyte R6G has been established based on superhydrophobic-SERS dual functional substrate. .In this proposal, however, SERS optrode will be used in combination of superhydrophobic materials to develop a new type of SERS device for trace analysis. Instead of random precipitation on the dual functional substrates reported by others, in this configuration solutes in the sample droplet will be directed to the optrode during evaporation. The SERS optrode acts as sensing as well as preconcentration platform. Factors that affect the superhydrophobicity and the receding of contact line, as well as the surface modification and geometry of the SERS optrode, will be explored for best preconcentration results. Field analytical methods of trace chemicals, such as TNT/DNT, paraquat, and tetracycline will be developed based on the SERS optrode-superhydrophobic substrate analytical device.Preliminary results showed that a ppt level sensitivity can be easily obtained using this device, which is 3 oders of magnitude lower than optrode only analysis.

表面增强拉曼散射(SERS)光极是指在光纤一端构建有SERS 基底，激发激光和产生的SERS 信号沿同一光纤传输的传感器，适合遥感和现场分析。在某些超疏水材料表面，由于特有的自清洁效应，溶液液滴随蒸发而收缩变小，并将溶质浓缩到一点上，这一现象已用于样品预浓缩。本课题拟将本实验室开发高灵敏度SERS光极与超疏水材料集成，构建新型SERS分析器件。即利用亲水性SERS光极操纵超疏水界面的样品液滴，让SERS光极对样品分子进行主动"捕获"，从而兼有自清洁效应带来的高效富集和光极的优点，适用于现场超痕量样品定性定量分析。课题拟考察和阐明影响器件分析灵敏度的因素，如材料超疏水特性、样品浓度，光极表面修饰和几何尺寸等。在此基础上，建立对环境中微量化合物如爆炸物TNT，农药百草枯，以及四环素类抗生素的现场分析方法。初步实验结果发现本SERS器件分析灵敏度可达ppt，比单独使用光极时提高至少3个数量级。

表面增强拉曼散射（SERS）是在20世纪70年代发展起来的一种高灵敏度的定性定量方法，具有对痕量和超痕量物质进行定性和定量分析的能力。不过，传统的SERS技术对样品量、SERS基底有一定要求，当样品量过少或者样品浓度过低的时候，传统的SERS技术就很难满足分析要求。为解决这一难题，文献中广泛采用了构建超疏水-拉曼增强双功能SERS基底的方法。但超疏水-拉曼增强双功能基底也存在一定问题。溶液液滴在超疏水表面挥发后，其溶质沉积的点直径只有20-50微米，很难被找到，会带来很大的操作问题。.基于此，我们提出了利用超疏水材料和SERS光极共同构成分析器件，即让样品溶液在超疏水材料表面挥发，让SERS光极充当“钓鱼”鱼钩，即利用亲水性SERS 光极操纵超疏水界面的样品液滴，让SERS 光极对样品分子进行主动“捕获”，从而兼有自清洁效应带来的高效富集和光极的优点，实测（绝对量）灵敏度提高倍数可达5个数量级，浓度灵敏度也可提升约3个数量级。相对于文献报道的理论预测，我们实测值提高了约1个数量级，适用于现场超痕量样品定性定量分析。发现了提升SERS基底，特别是基于银纳米材料的非液相SERS基底在空气中保存寿命的方法。这一发现对今后SERS技术走向实用化具有极大的意义。提出了研制柔性SERS基底，集采样和拉曼增强于一身，可以更便捷的应用于现场表面污染物分析，如公共安全领域行李表面残留爆炸物、食品安全领域残留农药和非法添加剂等的分析。建立了针对有机磷农药、爆炸物、非法添加剂等的分析方法，申请了超疏水-SERS光极分析器件的中国发明专利。一些方法的灵敏度已经达到或者超过了文献中报道的大型设备的灵敏度。.迄今，我们已经基本完成本课题，在国际期刊上发表署名本课题资助的SCI期刊论文10篇，课题相关英文专著一章，授权中国发明专利一项，参加国际学术会议2次（其中一次属于分会场组织人），培养硕士研究生3人。