Flexible ultrathin free-standing fluorescent films of CdSexS1−x/ZnS nanocrystalline and protein
Flexible ultrathin free-standing fluorescent films of CdSexS1−x/ZnS nanocrystalline and protein
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DOI：
10.1039/c0jm03400b
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发表时间：
2011-03
影响因子：
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通讯作者：
Xinsheng Peng;Qing Yu;Z. Ye;Izumi Ichinose
中科院分区：
文献类型：
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作者：
Xinsheng Peng;Qing Yu;Z. Ye;Izumi Ichinose
将荧光无机纳米晶体集成到具有理想光电性能的杂化薄膜中是其应用的强烈需求。我们准备了灵活的独立的蛋白质薄膜含有荧光纳米晶体的过滤技术的辅助下，由金属氢氧化物纳米链具有高的纵横比和极高的正电荷的表面。首先，带负电荷的蛋白质（脱铁铁蛋白），CdSxSe 1 −x/ZnS纳米晶体（和/或荧光染料）通过静电相互作用组装在水中的氢氧化镉纳米链表面。在多孔膜上过滤所得的纳米复合纤维分散体，得到薄滤饼。在交联脱铁铁蛋白后，除去纳米链，并将剩余的蛋白质/脱铁蛋白复合物层从乙醇中的基底上剥离，作为独立的荧光膜。薄膜厚度可薄至40 nm，直径不受限制。独立的荧光膜足够坚固，可以转移到任何固体基底上而不会破裂。通过选择荧光纳米晶体（和/或荧光染料）固定到蛋白质基质中，可获得具有不同颜色的荧光膜。纳米晶与荧光染料的结合改变了薄膜的光学性质，并在一定条件下观察到荧光共振能量转移的猝灭（或增强）。薄膜中CdSxSe 1 −x/ZnS纳米晶体的含量高达41%（重量）和13%（体积）。高分辨透射电子显微镜（HR-TEM）证实，荧光膜是透明的，没有明显的纳米晶偏析。荧光发射是明亮的，均匀的，和在纳米晶体的原始溶液中一样窄。这对于荧光无机纳米晶体在柔性固体光学器件中的应用是显著的。
The integration of fluorescent inorganic nanocrystals into hybrid thin films with desirable optoelectronic properties is strongly demanded for their applications. We prepared flexible free-standing ultrathin protein films containing fluorescent nanocrystals by means of a filtration technique assisted by metal hydroxide nanostrands with high aspect ratio and extremely high positive charges on the surfaces. First, negatively charged proteins (apoferritin), CdSxSe1−x/ZnS nanocrystals (and/or fluorescent dye) were assembled on the surfaces of cadmium hydroxide nanostrands in water through electrostatic interaction. The resultant dispersion of nanocomposite fibers was filtered on a porous membrane to give a thin filter cake. After cross-linking apoferritin, the nanostrands were removed, and the remaining protein/nanocrystal composite layer was peeled off from the substrate in ethanol as a free-standing fluorescent film. The film thickness could be as thin as 40 nm, without limitation in the diameter. The free-standing fluorescent films are robust enough to be transferred onto any solid substrate without rupturing. The fluorescent films with different colors were obtainable by choosing fluorescent nanocrystals (and/or fluorescent dye) to be immobilized into the protein matrix. The optical properties of these films were changed with the combination of the nanocrystals and fluorescent dye, and the fluorescent resonance energy transfer quenching (or enhancement) was clearly observed in certain conditions. The amount of CdSxSe1−x/ZnS nanocrystals in the film was as high as 41% in weight, and 13% in volume. The fluorescent film was transparent and without obvious segregation of the nanocrystals, as confirmed by high-resolution transmission electron microscope (HR-TEM). The fluorescent emission was bright, uniform, and as narrow as that in the original solution of the nanocrystals. This is remarkable for the application of fluorescent inorganic nanocrystals to flexible solid optical devices.