Self-assembled synthesis of SEF-active silver dendrites by galvanic displacement on copper substrate
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Self-assembled synthesis of SEF-active silver dendrites by galvanic displacement on copper substrate Jun Dong • Hairong Zheng
Received: 21 August 2012 / Accepted: 1 February 2013 / Published online: 4 March 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract In this paper, an effective substrate for surfaceenhanced fluorescence, which consists of dendritic silver nanostructure on copper surface, was fabricated by modified galvanic displacement reaction at room temperature. It was found that the fluorescence efficiency of Rh6G probe molecules on the substrate depended on the period of the nanostructure growth. And it increased with the enrichment of fine-branches of the dendritic silver nanostructure. The experimental results indicated that the fine nanostructure with dendritic distribution can produce better fluorescence enhancement with the help of proper control over the reaction condition. It is important for studying the mechanism and the potential applications of enhanced fluorescence effect.
1 Introduction Surface-enhanced fluorescence (SEF), a phenomenon where the quantum yield and photostability of weakly fluorescing species are dramatically increased, is becoming a powerful technique for the fluorescence-based applications, such as in optical devices, biological and chemical sensing and diagnosis, protein–protein detection and so on [1–3]. It is widely accepted that the locally enhanced electromagnetic (EM) field formed at a nanostructure
J. Dong (&) School of Electronic Engineering, Xi’an University of Posts and Telecommunications, 710121 Xi’an, China e-mail: [email protected] J. Dong H. Zheng School of Physics and Information Technology, Shaanxi Normal University, 710062 Xi’an, China e-mail: [email protected]
surface is mostly responsible for SEF effect [4, 5]. So many efforts in the fabrication of effective SEF substrate with high local EM field or ‘‘hot spots’’ have been made for producing strong fluorescence signals with higher contrast level. In the past few years, various shapes of metallic nanostructures have been developed and investigated as SFE-active substrates, including metallic island films, metallic nanograting, metallic nanohole arrays, metal nanorods, nanoparticles arrays and fractal-like nanostructure [6–12]. However, to the best of our knowledge, few studies on the metal dendrites with random atom distribution as SEF-active substrate were reported [13, 14]. Here, we present SEF results from dendritic silver nanostructure and highlight the applicability of such nanodendritic substrate for fluorescence-based biological sensing. In this paper, a simple method for the synthesis of unique heterogeneous dendritic silver nanostructure, acted as SEF substrate, is developed in a reliable way. The synthesis is based on a galvanic displacement reaction between AgNO3 aqueous solution and copper substrate. Comparing with the physically polished copper surface and clean glass slide, we found that the heterogeneous dendritic silver nanostructures, fabricated with proper control over
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