Dual-amplification of antigen-antibody interactions via backfilling gold nanoparticles on (3-mercaptopropyl) trimethoxysilane sol-gel functionalized interface

A new dual-amplification strategy of electrochemical signaling from antigen-antibody interactions was proposed via backfilling gold nanoparticles on (3-mercaptopropyl) trimethoxysilane sol-gel (MPTS) functionalized interface. The MPTS was employed not only as a building block for the electrode surface modification but also as a matrix for ligand functionalization with first amplification. The second signal amplification strategy introduced in this study was based on the backfilling immobilization of nanogold particles to the immunosensor surface. Several coupling techniques, such as with nanogold but not MPTS or with MPTS but not nanogold, were investigated for the determination of carcinoembryonic antigen (CEA) as a model, and a very good result was obtained with nanogold and MPTS coupling immunosensor. With the noncompetitive format, the formation of the antigen-antibody complex by a simple one-step immunoreaction between the immobilized anti-CEA and CEA in sample solution introduced membrane potential change before and after the antigen -antibody interaction. Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to CEA in a dynamic concentration range of 4.4 to 85.7 ng/mL with a detection limit of 1.2 ng/mL (at 3 8). Moreover, the precision, reproducibility and stability of the as-prepared immunosensor were acceptable. Importantly, the proposed methodology would be valuable for diagnosis and monitoring of carcinoma and its metastasis.