纳米多孔金薄膜的表面等离子体共振传感特性

对淀积在玻璃衬底上厚度约60 nm的金银合金溅射薄膜进行硝酸腐蚀脱银处理, 得到纳米多孔金薄膜. 利用自建的波长检测型表面等离子体共振(SPR)传感装置研究了腐蚀时间对纳米多孔金薄膜SPR特性的影响, 结果发现纳米多孔金薄膜与水溶液接触后在400-900 nm光谱范围内不具有SPR效应, 而当薄膜置于空气中时会产生明显的传播等离子体共振吸收峰, 其共振波长随腐蚀时间增加逐渐红移. 纳米多孔金薄膜在空气气氛中的SPR效应使其能够用于原位监测气相分子在孔内的吸附, 还可对在液相中吸附的生化分子进行离位测试. 本文对L-谷胱甘肽、L-半胱氨酸、2-氨基乙硫醇三种含巯基的生化小分子在纳米多孔金薄膜内的吸附进行了离位分析, 结果表明与传统的致密金薄膜SPR芯片比较, 纳米多孔金薄膜对这些分子显示出更高的灵敏度和更低的检测下限, 这归功于多孔金的大比表面积使其能够吸附大量的生化小分子. 实验还对乙醇蒸气在纳米多孔金薄膜内的吸附进行了原位监测, 发现吸附平衡所用时间较长, 约为160 min.

Surface Plasmon Resonance Sensing Properties of Nanoporous Gold Thin Films

Nanoporous gold films were prepared by immersing Au-Ag alloy films with a thickness of ca 60 nm sputtered on glass substrates in nitrate acid to remove the Ag component. Using a home-made wavelength-interrogated surface plasmon resonance (SPR) sensor platform, the influence of the immersion time on the SPR properties of the nanoporous gold film was investigated. If the nanoporous gold film was immersed in aqueous solution, SPR was not detected in the wavelength range from 400 to 900 nm. However, when the nanoporous gold films were exposed to air, a strong SPR absorption peak was detected in the same spectral range. The peak position gradually moved to longer wavelength as the immersion time extended. The SPR of the nanoporous gold film in air enables the film to be used for in situ monitoring of gas-phase molecular adsorption and ex situ detection of biochemical molecules adsorbed in the liquid phase. Ex situ detection of three kinds of small molecules (L-glutathione, L-cysteine, and cysteamine) adsorbed to the nanoporous gold film was fulfilled. The results were compared with those obtained using a conventional SPR chip with a dense gold film, revealing that the nanoporous gold films have a higher sensitivity and lower detection limit than the dense gold layer because of their larger surface area. Adsorption of ethanol molecules in the gas phase was monitored in situ, and the time required to reach adsorption equilibrium was about 160 min.