Immunoassays represent an important quantitative technique and are applied in many fields such as environmental monitoring, food safety, and clinical diagnosis. In general, whereas highly specific antigen/antibody recognition usually ensures the specificity of the assay, the sensitivity is ultimately enhanced by increasing the amount of captured label per binding event.

Patrik Schmuki, University of Erlangen-Nuremberg, Germany, Yan-Yan Song, Northeastern University, Shenyang, China, and co-workers apply an electrochemiluminescent (ECL) technique and show that TiO₂ nanotube (TiNT) layers have advantageous properties over conventional 3D nanostructured electrodes. Further, they use TiO₂ nanoparticles to achieve multiple quantum dot (QD) responses from a single recognition event. The antibody-modified TiNT layers bind the antigens, which then are bound by an immunosensing probe in a sandwich-type immunoassay. The sensing probe consists of an antibody-modified QDs/TiNP hybrid, which in the event of binding leads to a measurable ECL signal at low-level antigen concentrations.

Signal Amplification Strategy Based on TiO₂-Nanotube Layers and Nanobeads Carrying Quantum Dots for Electrochemiluminescent Immunosensors,
Zhi-Da Gao, Qian-Lan Zhuang, Yan-Yan Song, Kiyoung Lee, Patrik Schmuki,
ChemistryOpen 2013.
DOI: 10.1002/open.201300003