Electrochemiluminescence PSA assay using an ITO electrode modified with gold and palladium, and flower-like titanium dioxide microparticles as ECL labels

We report on the synthesis of flower-like 3D titanium dioxide (fl-TiO2) using a hydrothermal method. This material possesses a large specific surface and displays an electrochemiluminescence (ECL) intensity that is much stronger than the one of TiO2 nanoparticles having smooth surfaces. It was used to label the secondary antibody in a sandwich immunoassay. A thin layer of metallic gold (Au) and palladium (Pd) was deposited on an indium tin oxide (ITO) electrode by code-position at a potential of 0.2 V in the respective chloride solutions. The Au/Pd-modified ITO electrode showed good conductivity. An ECL based immunoassay for the prostate specific antigen (PSA) was then worked out by immobilizing the first antibody on the Au/Pd layer on the ITO electrode, then exposing the electrode to a sample containing PSA, then forming the sandwich with the fl-TiO2 labeled secondary antibody, and finally measuring the intensity of ECL at a potential of -1.5 V. This ECL sensor has a response range that extends from 0.001 to 600 nga (TM) mL(-1), a lower detection limit of 0.32 pga (TM) mL(-1), good specificity, acceptable stability and good reproducibility. It gave satisfactory results when used for the determination of PSA in (spiked) diluted solutions of human serum.