Au@SiO2@RuDS nanocomposite based plasmon-enhanced electrochemiluminescence sensor for the highly sensitive detection of glutathione

Abstract

A novel plasmon enhanced electrochemiluminescence (ECL) sensor was fabricated for the highly sensitive detection of glutathione (GSH). First, Au nanoparticles (AuNPs) were coated with silica dioxide to prevent the direct contact of AuNPs and luminophore Ru(bpy)32+; then Ru(bpy)32+-containing silica layer (RuDS) was allowed to grow onto the obtained Au@SiO2. Owing to the high luminescence efficiency of RuDS and the surface plasmon resonance of AuNPs, the nanocomposite Au@SiO2@RuDS exhibited large ECL signal. As free radical scavenger, GSH could react with tri-n-propylamine radical (i.e. TPA+•) and effectively suppress the excitation of Ru(bpy)32+, thus made the ECL signal significantly decrease. By using Nafion as immobilization reagent, the resulting Au@SiO2@RuDS/GCE sensor showed wide linear response ranges (1.0 fM–1.0 nM and 1.0 nM–1.0 μM) and low detection limit (0.5 fM, S/N=3) for GSH. In addition, it had excellent stability, repeatability and reproducibility. The sensor was applied to the detection of GSH in human serum samples and satisfactory results were achieved.