Gold Nanoparticles Doped Three‐Dimensional Sol‐gel Matrix for Amperometric Human Chorionic Gonadotrophin Immunosensor

A novel electrochemical immunosensor for human chorionic gonadotrophin (hCG) was proposed by immobilization of hCG in gold nanoparticles doped three‐dimensional (3D) sol‐gel matrix and an interfacial competitive immunoreaction. The 3D organized composite structure was prepared by assemble of gold nanoparticles into a hydrolyzed (3‐mercaptopropyl)‐trimethoxysilane sol‐gel matrix, which showed good biocompatibility. After the interfacial competitive immunoreaction the formed HRP‐labeled immunoconjugate showed good enzymatic activity for the oxidation of o‐phenylenediamine by H₂O₂. With a competitive format, a method comprising of o‐phenylenediamine‐H₂O₂‐immobilized HRP labeled hCG immunoconjugate system for immunoassay of hCG from 5.0 to 30.0 mIU mL^?1 was developed. The immunosensor showed good precision, high sensitivity, acceptable stability and reproducibility and could be used for detection of hCG in human serum with the consistent results in comparison with those obtained by a commercial analyzer.