Metal-Enhanced Fluorescence Platforms Based on Plasmonic Ordered Copper Arrays: Wavelength Dependence of Quenching and Enhancement Effects
Metal-Enhanced Fluorescence Platforms Based on Plasmonic Ordered Copper Arrays: Wavelength Dependence of Quenching and Enhancement Effects
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DOI：
10.1021/nn403925d
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发表时间：
2013-11-01
期刊：
影响因子：
17.1
通讯作者：
Ushijima, Hirobumi
中科院分区：
文献类型：
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作者：
Sugawa, Kosuke;Tamura, Takahiro;Ushijima, Hirobumi
有序阵列的铜纳米结构被制造并用卟啉分子修饰，以评估由于局域表面等离子体共振引起的荧光增强。通过在二维二氧化硅胶体晶体的上半球上热沉积铜来制备纳米结构。通过控制下面的二氧化硅颗粒的直径，将纳米结构的表面等离子体共振产生的波长调谐到比铜的带间过渡区域（> 590 nm）更长的波长。通过 16-巯基十六烷酸的自组装实现了卟啉单层在纳米结构上的固定，这也抑制了铜表面的氧化。由于表面等离子体共振的产生，与平面铜板（CuP）上相比，卟啉的最大荧光增强达到了89.2倍。此外，还发现，虽然卟啉的荧光在带间过渡区域内被猝灭，但在较长波长下却被有效增强。事实证明，荧光团接近纳米结构所引起的增强足以克服金属的高效猝灭效应。从这些结果推测，铜的表面等离子体共振作为高功能等离子体传感器和器件具有巨大的实际应用潜力。
Ordered arrays of copper nanostructures were fabricated and modified with porphyrin molecules in order to evaluate fluorescence enhancement due to the localized surface plasmon resonance. The nanostructures were prepared by thermally depositing copper on the upper hemispheres of two-dimensional silica colloidal crystals. The wavelength at which the surface plasmon resonance of the nanostructures was generated was tuned to a longer wavelength than the interband transition region of copper (>590 nm) by controlling the diameter of the underlying silica particles. Immobilization of porphyrin monolayers onto the nanostructures was achieved via self-assembly of 16-mercaptohexadecanoic acid, which also suppressed the oxidation of the copper surface. The maximum fluorescence enhancement of porphyrin by a factor of 89.2 was achieved as compared with that on a planar Cu plate (CuP) due to the generation of the surface plasmon resonance. Furthermore, it was found that while the fluorescence from the porphyrin was quenched within the interband transition region, it was efficiently enhanced at longer wavelengths. It was demonstrated that the enhancement induced by the proximity of the fluorophore to the nanostructures was enough to overcome the highly efficient quenching effects of the metal. From these results, it is speculated that the surface plasmon resonance of copper has tremendous potential for practical use as high functional plasmonic sensor and devices.