Synthesis of multiwall carbon nanotubes-graphene oxide-thionine-Au nanocomposites for electrochemiluminescence detection of cholesterol

In this work, we developed a facile approach to synthesize multiwall carbon nanotubes-graphene oxide-thionine-Au (MWCNTs-GO-Thi-Au) nanocomposites with the synergistic effect of GO and Thi, resulting in reducing AuCl4− to Au nanoparticles (AuNPs). Meanwhile, the AuNPs reduced by GO and Thi promoted the electrochemiluminescence (ECL) of luminol-H2O2 system and offered active sites for immobilization of numerous enzymes. Additionally, it was also found that the synergetic interactions of Thi with MWCNTs and GO was employed for enhancing ECL of luminol-H2O2, which was applied to develop an ECL biosensor for the first time. Using cholesterol oxidase as model enzyme, the proposed biosensor employed by MWCNTs-GO-Thi-Au nanocomposites showed a high sensitivity for cholesterol in a concentration range of 0.15-828 μM with a detection limit of 50 nM (signal-to-noise ratio of 3). In addition, the proposed cholesterol biosensor exhibited high sensitivity, good selectivity and excellent stability. Taking into account the integrated advantages of MWCNTs-GO-Thi-Au nanocomposites and ECL detection, we confidently expect that this biosensing approach would have potential applications in clinical diagnosis.