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Controlled assembly of metal colloids on dye-doped silica particles to tune the photophysical properties of organic molecules†
Photochemical & Photobiological Sciences ( IF 3.1 ) Pub Date : 2018-06-04 00:00:00 , DOI: 10.1039/c8pp00022k
Giulia Zampini 1, 2, 3, 4, 5 , Luigi Tarpani 1, 2, 3, 4, 5 , Giuseppina Massaro 1, 2, 3, 4, 5 , Marta Gambucci 1, 2, 3, 4, 5 , Eugenio Peli 1, 2, 3, 4, 5 , Loredana Latterini 1, 2, 3, 4, 5
Affiliation  

The use of plasmonic nanomaterials is a challenging strategy to control radiation and radiation-induced processes at a nanometric scale. The localized surface plasmons of metal nanoparticles have been shown to affect the efficiency of a variety of radiative and non-radiative processes occurring in organic molecules. In this contribution, we present an overview of the results obtained through an original approach based on the hierarchical assembly of plasmonic gold colloids on silica templates, covalently doped with organic dyes. The detailed morphological characterization demonstrates the disposition of gold colloids on silica achieved through the tight control of the synthetic conditions. The studies carried out while gradually increasing the concentration of gold nanoparticles allow the detailed investigation of the effects of the progressive addition of plasmonic particles on the photophysical behaviour of organic molecules. In particular, the fluorescence behaviour of three dyes with different spectral properties, namely fluorescein, rhodamine B and 9-aminoacridine, are investigated in the presence of increasing concentrations of gold nanoparticles. In order to fix the distance between the dye and the gold nanoparticles, the dyes are anchored to silica nanoparticles, and the metal colloids are chemically adsorbed on the silica surface. The steady state and time-resolved data are analysed to evaluate the impact of plasmonic nanoparticles on the radiative and non-radiative processes of the dyes; the data provide evidence that the modulation of the fluorescence intensity (enhancement or quenching) can be achieved by changing the concentration of gold colloids. The plasmonic nanostructures can be employed to favour one deactivation process over the others. For example, we demonstrate that the photoinduced formation of reactive oxygen species (ROS) can be enhanced upon the plasmonic engineering of a photosensitizing agent (Protoporphyrin IX, PpIX). The Vis-excitation of silica-PpIX samples in the presence of gold nanoparticles results in a faster and more efficient photoinduced formation of ROS species either in solution or in a hydrogel. The ROS efficiency data and the fluorescence behaviour of PpIX in the presence of gold colloids suggest that the enhancement of the excitation field occurs through a plasmonic effect. For the application of the assembled hybrid materials, further advantages come from the development of photosensitizer-containing hydrogel films that are able to efficiently produce ROS upon visible excitation. Our preliminary results are herein reported and discussed.

中文翻译:

染料掺杂的二氧化硅颗粒上金属胶体的受控组装,以调节有机分子的光物理性质

等离子体纳米材料的使用是在纳米级控制辐射和辐射诱导过程的挑战性策略。已经证明金属纳米粒子的局部表面等离子体激元会影响有机分子中发生的各种辐射和非辐射过程的效率。在这项贡献中,我们介绍了通过等离子共生掺杂有机染料的二氧化硅模板上等离激元金胶体的分层组装,通过原始方法获得的结果的概述。详细的形态学表征表明,通过严格控制合成条件,可实现金胶体在二氧化硅上的沉积。在逐渐增加金纳米颗粒的浓度的同时进行的研究,可以详细研究逐步添加等离激元颗粒对有机分子的光物理行为的影响。特别是,在金纳米颗粒浓度增加的情况下,研究了三种具有不同光谱特性的染料的荧光行为,即荧光素,若丹明B和9-氨基ac啶。为了固定染料和金纳米颗粒之间的距离,将染料锚固在二氧化硅纳米颗粒上,并将金属胶体化学吸附在二氧化硅表面上。分析稳态和时间分辨数据,以评估等离激元纳米粒子对染料的辐射和非辐射过程的影响;数据提供了证明,通过改变金胶体的浓度可以实现荧光强度的调节(增强或猝灭)。等离子体纳米结构可用于促进一种失活过程而不是其他失活过程。例如,我们证明了在光敏剂(原卟啉IX,PpIX)的等离子体工程化后,可以增强活性氧(ROS)的光诱导形成。在金纳米颗粒的存在下对二氧化硅-PpIX样品的可见光激发可以在溶液中或在水凝胶中更快,更有效地光诱导形成ROS物种。在金胶体存在下,ROS效率数据和PpIX的荧光行为表明,激发场的增强是通过等离子体效应产生的。对于组装的杂化材料的应用,进一步的优势来自于含光敏剂的水凝胶薄膜的开发,该薄膜能够在可见光激发下有效产生ROS。我们的初步结果在此进行了报道和讨论。
更新日期:2018-06-04
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