In Situ Formation of Gold Nanoparticles Decorated Ti₃C₂ MXenes Nanoprobe for Highly Sensitive Electrogenerated Chemiluminescence Detection of Exosomes and Their Surface Proteins

Abstract

In this work, an ultrasensitive electrogenerated chemiluminescence (ECL) biosensor for exosomes and their surface proteins was developed by the in situ formation of gold nanoparticles (AuNPs) decorated Ti₃C₂ MXenes hybrid with aptamer modification (AuNPs-MXenes-Apt). In this strategy, the exosomes were efficiently captured on an exosome recognized CD63 aptamer modified electrode interface. Meanwhile, in situ formation of gold nanoparticles on single layer Ti₃C₂MXenes with aptamer (MXenes-Apt) modification was obtained, in which MXenes acted as both reductants and stabilizer, and no additional reductant and stabilizer involved. The in situ formed AuNPs-MXenes-Apt hybrid not only presented highly efficient recognition of exosomes specifically, but also provide naked catalytic surface with high electrocatalytic activity of gold nanoparticles with predominated (111) facets that significantly improved the ECL signal of luminol. In this way, a highly sensitive ECL biosensor for exosomes detection was constructed ascribing to the synergistic effects of large surface area, excellent conductivity, and catalytic effects of the AuNPs-MXenes-Apt. The detection limit is 30 particles μL^-1 for exosomes derived from HeLa cell line, which was over 1000 times lower than that of conventional ELISA method and the linear range was from 10² particles μL^-1 to 10⁵ particles μL^-1. This ECL sensing platform possessed high selectivity toward exosomes and their surface proteins derived different kinds of tumor cell lines (HeLa cells, OVCAR cells and HepG2 cells), and enabled sensitive and accurate detection of exosomes from human serum, which implied that the ECL biosensor provided a feasible, sensitive, and reliable tool for exosomes detection in exosomes-related clinical diagnostic.