A signal-on electrochemiluminescence immunosensor for A2780 cell detection based on the excellent catalytic performance of Co2+ doped TiO2 nanodisks

Abstract

This study aimed at fabricating a new analysis platform for ovarian cancer cells based on metal organic frameworks derived Co²⁺ doped TiO₂ nanodisk (Co-TiO₂ ND) mediated cathodic electrochemiluminescence (ECL) of Ru(bpy)₃²⁺. Concretely, Co-TiO₂ NDs were synthesized by applying a facile strategy and were revealed to possess a mesoporous structure, high surface area, good stability and conductivity, particularly excellent catalytic performance for the oxygen reduction reaction (ORR). Therefore, Co-TiO₂ NDs did not only serve as a promising scaffold to carry amounts of folic acid (FA) for the subsequent immuno-identification reaction but were also utilized to catalyze the ORR reaction and produce substantial ˙OH to improve the ECL signals of Ru(bpy)₃²⁺. Moreover, helical carbon nanotubes (HCNTs) with strong mechanical strength, excellent electronic transport properties and abundant active sites have emerged as a fascinating sensing matrix for fixing a high quantity of biomolecules (Ab_CA125). Then, the target cells A2780 were captured by the specific recognition between Ab_CA125 and CA125 on A2780 cells, and the FA functionalized probe was attached through the recognition of the FA acceptor on the surface of the cells, which established a “signal on” ECL cytosensor for A2780 detection with a linear range from 2.6 × 10² to 2.6 × 10⁶ cells per mL. Promisingly, the successful application of Co-TiO₂ NDs opens up a new avenue for developing excellent ECL sensors and broadens the application of metal organic frameworks.