Gold Nanorod Size-Dependent Fluorescence Enhancement for Ultrasensitive Fluoroimmunoassays
Gold Nanorod Size-Dependent Fluorescence Enhancement for Ultrasensitive Fluoroimmunoassays
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DOI：
10.1021/acsami.0c20303
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发表时间：
2021-02-23
影响因子：
9.5
通讯作者：
Singamaneni, Srikanth
中科院分区：
文献类型：
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作者：
Liang, Chao;Luan, Jingyi;Singamaneni, Srikanth
等离子体增强荧光 (PEF) 是一种简单而高效的方法，可提高各种基于荧光的生物分析技术的信噪比和灵敏度。在这里，我们表明，广泛用于 PEF 的金纳米棒 (AuNR) 的荧光增强功效高度依赖于它们的绝对尺寸（即长度和直径）。值得注意的是，在保持纵横比恒定的情况下，AuNR 的尺寸（长度 x 直径）从 46 x 14 增加到 120 x 38 nm(2)，导致荧光增强效率提高近 300%。 AuNR尺寸的进一步增加导致荧光增强效率的降低。通过时域有限差分（FDTD）模拟，我们揭示了 AuNR 的尺寸依赖性荧光增强效率源于等离子体纳米结构周围尺寸依赖性的电磁场。具有最佳尺寸的 AuNR 使结合到表面的分子荧光团的整体荧光发射增强了近 120 倍。与 PEF 中常规使用的较小尺寸的 AuNR 相比，这些具有最佳尺寸的等离子体纳米结构还使人白细胞介素 6 (IL-6) 的检测限提高了近 30 倍。
Plasmon-enhanced fluorescence (PEF) is a simple and highly effective approach for improving the signal-to-noise ratio and sensitivity of various fluorescence-based bioanalytical techniques. Here, we show that the fluorescence enhancement efficacy of gold nanorods (AuNRs), which are widely employed for PEF, is highly dependent on their absolute dimensions (i.e., length and diameter). Notably, an increase in the dimensions (length x diameter) of the AuNRs from 46 x 14 to 120 x 38 nm(2) while holding the aspect ratio constant leads to nearly 300% improvement in fluorescence enhancement efficiency. Further increase in the AuNR size leads to a decrease of the fluorescence enhancement efficiency. Through finite-difference time-domain (FDTD) simulation, we reveal that the size-dependent fluorescence enhancement efficiency of AuNR stems from the size-dependent electromagnetic field around the plasmonic nanostructures. AuNRs with optimal dimensions resulted in a nearly 120-fold enhancement in the ensemble fluorescence emission from molecular fluorophores bound to the surface. These plasmonic nanostructures with optimal dimensions also resulted in a nearly 30-fold improvement in the limit of detection of human interleukin-6 (IL-6) compared to AuNRs with smaller size, which are routinely employed in PEF.