纳米多孔金膜(NPGF)化学和热力学稳定性好,比表面积大,具有显著的表面等离子体共振(SPR)效应,适宜于用作SPR生化传感芯片。本文对NPGF的SPR效应进行了理论分析,得到了在NPGF/空气界面传播的表面等离子体色散曲线,获得了优化NPGF-SPR传感性能所需的最佳薄膜厚度约为60 nm;在此基础上利用溅射沉积-化学脱合金两步法在玻璃基板上制备出大面积均匀的超薄NPGF,采用Krestchmann棱镜耦合结构测试了NPGF在可见-近红外波段的SPR共振光谱及其传感特性,通过利用菲涅耳公式并结合Bruggeman介电常数近似理论对测得的共振波长进行拟合,得出NPGF的孔隙率约为0.38。未经修饰的NPGF是亲水薄膜,能够有效富集水中的双酚A,使得NPGF-SPR传感器对双酚A的探测下限达到5 nmol·L-1;经过疏水化处理后,NPGF对非极性苯并芘分子的富集能力获得显著增强,使得传感器对苯并芘的探测下限达到1 nmol·L-1。
Nanoporous gold films (NPGFs) are chemically robust and thermally stable, have large specific area and salient surface plasmon resonance (SPR) effect. Due to these features, NPGFs are quite applicable for high-sensitivity SPR sensors. In this study, the SPR effect of NPGFs was theoretically analyzed and the dispersion relation was obtained for propagating surface plasmons at the NPGF/air interface. The optimal thickness of NPGF required for optimizing its SPR sensing performance was determined to be -60 nm. Large-area, uniform and ultrathin NPGFs were prepared by a two-step approach involving sputtering deposition and chemical dealloying. The SPR resonance band in the visible-near-infrared region and the sensing properties of NPGFs were measured with the Kretschmann prism-coupling configuration. Porosity of the NPGF was determined to be -0.38 by fitting the measured resonance wavelengths based on a combination of the Fresnel formula and the Bruggeman dielectric constant approximation theory. Since the non-modified NPGFs are hydrophilic and enable effective enrichment of bisphenol A (BPA) in water, the NPGF-SPR sensor can easily detect BPA at concentrations as low as 5 nmol·L-1. After hydrophobilization of NPGFs, the sensor enables detection of trace amounts of benzo[a]pyrene (BaP) in water, with the detection limit being 1 nmol·L-1.