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Abstract: A novel electrochemiluminescence (ECL) strategy based on the sandwich-type immunosensor for sensitive detection of retinol-binding protein (RBP) was developed. The primary antibody anti-RBP was immobilized onto multiwalled carbon nanotubes (MWCNTs), which have large surface area and high electrical conductivity. The RBP antigen and Ru–Nafion@SiO2-labeled secondary antibody were then successively conjugated to form sandwich-type immunocomplexes through the specific interaction between antigen and antibody. The ECL signal amplification was significantly improved due to the synergistic effect of MWCNTs and mesoporous silica nanospheres (mSiO2). The developed ECL immunosensor exhibited high sensitivity and specificity for the detection of RBP and responded linearly to the clinically-relevant concentration of RBP from 78 to 5000ngmL−1. Moreover, the MWCNT-based ECL immunosensor displayed excellent stability and reproducibility, as well as successfully achieved the detection of RBP in patient urine samples with desirable results. The present work provided a promising technique for the clinical screening of RBP and point-of-care diagnostics. [Copyright &y& Elsevier]

Abstract: A novel melamine electrochemiluminescence (ECL) sensor was developed based on mesoporous SiO2 nanospheres/Ru(bpy)3 2+/Nafion modified electrodes. The homogeneous mesoporous silica nanospheres, synthesized using modified Stöber sol–gel process, were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) and Brunauer–Emmett–Teller (BET). The ECL and electrochemistry of the modified electrodes were investigated with tri-n-propylamine (TPA) as the coreactant. Furthermore, the mesporous SiO2 nanospheres/Ru(bpy)3 2+-based modified electrodes were used for ECL determination of melamine. The analytical performances of this ECL sensor for melamine based on its enhancement ECL emission of Ru(bpy)3 2+ were investigated. The results indicated that the sensor exhibited excellent performance during melamine determination with a wide linear range (7.81×10−9–5×10−6 M), low detection limit (2.6×10−9 M). The high sensitivity and stability mainly resulted from the high surface area and special structure of the mesoporous silica nanospheres. The proposed ECL approach was used to analyze the melamine content in powdered milk with satisfactory results. [Copyright &y& Elsevier]