Analytical Sciences

Preparation of Nafion-Ru(bpy)₃²⁺-Chitosan/Gold Nanoparticles Composite Film and Its Electrochemiluminescence Application

Yingjuan QU, Xiaoli LIU, Xingwang ZHENG, and Zhihui GUO

School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710062, P. R. China

In this research, it was found that a composite film could be formed by mixing Nafion with chitosan on the graphite electrode surface. Then, based on the strong absorption of both chitosan for AuCl₄⁻ and Nafion for Ru(bpy)₃²⁺, respectively, the gold nanoparticles and electrochemiluminescence (ECL) active molecules, Ru(bpy)₃²⁺, were effectively incorporated into the composite film of chitosan with Nafion. Lastly, based on the interaction of Ru(bpy)₃²⁺ with Nafion inside the Nafion-chitosan/gold nanoparticles film, Ru(bpy)₃²⁺ was successfully immobilized within this composite film. In this case, a new composite film for fabricating Ru(bpy)₃²⁺-based ECL sensors was developed. The performances of this composite film were characterized by transmission electron microscopy (TEM), electrochemistry and electrochemiluminescence methods. Our results showed that: firstly, the gold nanoparticles in the resulting composite film could act as conducting pathways to connect Ru(bpy)₃²⁺ sites; the electrode surface accelerated the charge transport through the composite film, and the diffusion coefficient of Ru(bpy)₃²⁺ within this composite film modified electrode was 65 times higher than that of the pure Nafion film modified electrode. Secondly, due to its unique polymeric cationic character and better film-forming properties, chitosan could improve the compact structure of pure Nafion and greatly enhance the mass-transfer speed of Ru(bpy)₃²⁺. Then, the co-reactant tripropylamine (TPA) inside the composite film could offer better ECL performances such as more rapid ECL response speed, longer-term stability and higher sensitivity compared with the performances of pure Nafion film.

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