Tatar Andra-Sorina, Boca Sanda, Falamas Alexandra, Cuibus Denisa, Farcău Cosmin
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca, Romania.
Interdisciplinary Research Institute in Bio-Nano-Sciences, Babes-Bolyai University, 42 Treboniu Laurian, 400271 Cluj-Napoca, Romania.
Analyst. 2023 Aug 21;148(17):3992-4001. doi: 10.1039/d3an00682d.
Colloidal nanoparticles exhibiting anisotropic morphologies are preferred in the structural design of spectroscopically active substrates due to the remarkable optical properties of this type of nano-object. In the particular case of star-like nanoparticles, their sharp tips can act as antennae for capturing and amplifying the incident light, as well as for enhancing the light emitted by nearby fluorophores or the scattering efficiency of Raman active molecules. In the current work, we aimed to implement such star-shaped nanoparticles in the fabrication of nanoparticle films and explore their use as solid plasmonic substrates for surface-enhanced optical spectroscopies. High-density, compact and robust self-assembled gold nanostar films were prepared by directly depositing them from aqueous colloidal suspension on polystyrene plates through convective self-assembly. We investigated the role of the polymeric coating, herein polyvinylpyrrolidone (PVP), in the particle assembly process, the resulting morphology and consequently, the plasmonic response of the obtained films. The efficacy of the plasmonic films as dual-mode surface-enhanced fluorescence (SEF) and surface-enhanced Raman scattering (SERS) substrates was evidenced by testing Nile Blue A (NB) and Rhodamine 800 (Rh800) molecular chromophores under visible (633 nm) NIR (785 nm) laser excitation. Steady-state and time-resolved fluorescence investigations highlight the fluorescence intensity and fluorescence lifetime modification effects. The experimental results were corroborated with theoretical modelling by finite-difference time-domain (FDTD) simulations. Furthermore, to prove the extended applicability of the proposed substrates in the detection of biologically relevant molecules, we tested their SERS efficiency for sensing metanephrine, a metabolite currently used for the biochemical diagnosis of neuroendocrine tumors, at concentration levels similar to other catecholamine metabolites.
由于这类纳米物体具有卓越的光学性质，在光谱活性基底的结构设计中，具有各向异性形态的胶体纳米颗粒更受青睐。在星形纳米颗粒的特殊情况下，其尖锐的尖端可充当天线，用于捕获和放大入射光，以及增强附近荧光团发出的光或拉曼活性分子的散射效率。在当前工作中，我们旨在将此类星形纳米颗粒应用于纳米颗粒薄膜的制备，并探索其作为用于表面增强光谱学的固体等离子体基底的用途。通过对流自组装将其从水性胶体悬浮液直接沉积在聚苯乙烯板上，制备了高密度、致密且坚固的自组装金纳米星薄膜。我们研究了聚合物涂层（本文中为聚乙烯吡咯烷酮（PVP））在颗粒组装过程中的作用、由此产生的形态以及所得薄膜的等离子体响应。通过在可见光（633 nm）和近红外（785 nm）激光激发下测试尼罗蓝A（NB）和罗丹明800（Rh800）分子发色团，证明了等离子体薄膜作为双模表面增强荧光（SEF）和表面增强拉曼散射（SERS）基底的功效。稳态和时间分辨荧光研究突出了荧光强度和荧光寿命的修饰效应。实验结果通过有限时域差分（FDTD）模拟的理论建模得到了证实。此外，为了证明所提出的基底在检测生物相关分子方面的广泛适用性，我们测试了它们在与其他儿茶酚胺代谢物相似的浓度水平下检测间甲肾上腺素（一种目前用于神经内分泌肿瘤生化诊断的代谢物）的SERS效率。
