Unksov Ivan N, Anttu Nicklas, Verardo Damiano, Höök Fredrik, Prinz Christelle N, Linke Heiner
NanoLund and Solid State Physics, Lund University Box 118 22100 Lund Sweden
Physics, Faculty of Science and Engineering, Åbo Akademi University FI-20500 Turku Finland.
Nanoscale Adv. 2023 Feb 20;5(6):1760-1766. doi: 10.1039/d2na00749e. eCollection 2023 Mar 14.
The optical properties of vertical semiconductor nanowires can allow an enhancement of fluorescence from surface-bound fluorophores, a feature proven useful in biosensing. One of the contributing factors to the fluorescence enhancement is thought to be the local increase of the incident excitation light intensity in the vicinity of the nanowire surface, where fluorophores are located. However, this effect has not been experimentally studied in detail to date. Here, we quantify the excitation enhancement of fluorophores bound to a semiconductor nanowire surface by combining modelling with measurements of fluorescence photobleaching rate, indicative of the excitation light intensity, using epitaxially grown GaP nanowires. We study the excitation enhancement for nanowires with a diameter of 50-250 nm and show that excitation enhancement reaches a maximum for certain diameters, depending on the excitation wavelength. Furthermore, we find that the excitation enhancement decreases rapidly within tens of nanometers from the nanowire sidewall. The results can be used to design nanowire-based optical systems with exceptional sensitivities for bioanalytical applications.
垂直半导体纳米线的光学特性能够增强表面结合荧光团的荧光，这一特性在生物传感中已被证明是有用的。荧光增强的一个促成因素被认为是纳米线表面附近（荧光团所在位置）入射激发光强度的局部增加。然而，迄今为止，这种效应尚未得到详细的实验研究。在此，我们通过结合建模与荧光光漂白速率（指示激发光强度）的测量，利用外延生长的GaP纳米线，量化了与半导体纳米线表面结合的荧光团的激发增强。我们研究了直径为50 - 250 nm的纳米线的激发增强情况，并表明激发增强在特定直径处达到最大值，这取决于激发波长。此外，我们发现激发增强在距纳米线侧壁几十纳米内迅速下降。这些结果可用于设计对生物分析应用具有卓越灵敏度的基于纳米线的光学系统。
